patch, 22 partsSome updates since v3

parse-options.c, parse-options.h

diff --git a/parse-options.c b/parse-options.c
index 0fa79bc..cbb49d3 100644
--- a/parse-options.c
+++ b/parse-options.c
@@ -374,7 +374,7 @@ int parse_options_step(struct parse_opt_ctx_t *ctx,
 			if (parse_nodash_opt(ctx, arg, options) == 0)
 				continue;
 			if (ctx->flags & PARSE_OPT_STOP_AT_NON_OPTION)
-				break;
+				return PARSE_OPT_NON_OPTION;
 			ctx->out[ctx->cpidx++] = ctx->argv[0];
 			continue;
 		}
@@ -456,6 +456,7 @@ int parse_options(int argc, const char **argv, const char *prefix,
 	switch (parse_options_step(&ctx, options, usagestr)) {
 	case PARSE_OPT_HELP:
 		exit(129);
+	case PARSE_OPT_NON_OPTION:
 	case PARSE_OPT_DONE:
 		break;
 	default: /* PARSE_OPT_UNKNOWN */
diff --git a/parse-options.h b/parse-options.h
index 7435cdb..407697a 100644
--- a/parse-options.h
+++ b/parse-options.h
@@ -161,7 +161,8 @@ extern NORETURN void usage_msg_opt(const char *msg,
 enum {
 	PARSE_OPT_HELP = -1,
 	PARSE_OPT_DONE,
-	PARSE_OPT_UNKNOWN
+	PARSE_OPT_NON_OPTION,
+	PARSE_OPT_UNKNOWN,
 };
 
 /*

parse-options.c, parse-options.h

diff --git a/parse-options.c b/parse-options.c
index cbb49d3..e0c3641 100644
--- a/parse-options.c
+++ b/parse-options.c
@@ -439,6 +439,25 @@ unknown:
 	return PARSE_OPT_DONE;
 }
 
+const char *parse_options_current(struct parse_opt_ctx_t *ctx)
+{
+	return ctx->argv[0];
+}
+
+int parse_options_next(struct parse_opt_ctx_t *ctx, int keep)
+{
+	if (ctx->argc <= 0)
+		return -1;
+
+	if (keep)
+		ctx->out[ctx->cpidx++] = ctx->argv[0];
+
+	ctx->argc--;
+	ctx->argv++;
+
+	return 0;
+}
+
 int parse_options_end(struct parse_opt_ctx_t *ctx)
 {
 	memmove(ctx->out + ctx->cpidx, ctx->argv, ctx->argc * sizeof(*ctx->out));
diff --git a/parse-options.h b/parse-options.h
index 407697a..d3b1932 100644
--- a/parse-options.h
+++ b/parse-options.h
@@ -187,6 +187,10 @@ extern int parse_options_step(struct parse_opt_ctx_t *ctx,
 			      const struct option *options,
 			      const char * const usagestr[]);
 
+extern const char *parse_options_current(struct parse_opt_ctx_t *ctx);
+
+extern int parse_options_next(struct parse_opt_ctx_t *ctx, int keep);
+
 extern int parse_options_end(struct parse_opt_ctx_t *ctx);
 
 extern int parse_options_concat(struct option *dst, size_t, struct option *src);

Makefile, diffcore.h, line.c, line.h, revision.h

diff --git a/Makefile b/Makefile
index 4179186..c194e79 100644
--- a/Makefile
+++ b/Makefile
@@ -496,6 +496,7 @@ LIB_H += grep.h
 LIB_H += hash.h
 LIB_H += help.h
 LIB_H += levenshtein.h
+LIB_H += line.h
 LIB_H += list-objects.h
 LIB_H += ll-merge.h
 LIB_H += log-tree.h
@@ -582,6 +583,7 @@ LIB_OBJS += help.o
 LIB_OBJS += hex.o
 LIB_OBJS += ident.o
 LIB_OBJS += levenshtein.o
+LIB_OBJS += line.o
 LIB_OBJS += list-objects.o
 LIB_OBJS += ll-merge.o
 LIB_OBJS += lockfile.o
diff --git a/diffcore.h b/diffcore.h
index 491bea0..13d8e93 100644
--- a/diffcore.h
+++ b/diffcore.h
@@ -23,6 +23,7 @@
 #define MINIMUM_BREAK_SIZE     400 /* do not break a file smaller than this */
 
 struct userdiff_driver;
+struct diff_options;
 
 struct diff_filespec {
 	unsigned char sha1[20];
diff --git a/line.c b/line.c
new file mode 100644
index 0000000..fdec93a
--- /dev/null
+++ b/line.c
@@ -0,0 +1,460 @@
+#include "line.h"
+#include "cache.h"
+#include "tag.h"
+#include "blob.h"
+#include "tree.h"
+#include "commit.h"
+#include "diff.h"
+#include "decorate.h"
+#include "revision.h"
+#include "xdiff-interface.h"
+#include "strbuf.h"
+#include "log-tree.h"
+
+static void cleanup(struct diff_line_range *r)
+{
+	while (r) {
+		struct diff_line_range *next = r->next;
+		DIFF_LINE_RANGE_CLEAR(r);
+		free(r);
+		r = next;
+	}
+}
+
+static struct object *verify_commit(struct rev_info *revs)
+{
+	struct object *commit = NULL;
+	int found = -1;
+	int i;
+
+	for (i = 0; i < revs->pending.nr; i++) {
+		struct object *obj = revs->pending.objects[i].item;
+		if (obj->flags & UNINTERESTING)
+			continue;
+		while (obj->type == OBJ_TAG)
+			obj = deref_tag(obj, NULL, 0);
+		if (obj->type != OBJ_COMMIT)
+			die("Non commit %s?", revs->pending.objects[i].name);
+		if (commit)
+			die("More than one commit to dig from: %s and %s?",
+			    revs->pending.objects[i].name,
+				revs->pending.objects[found].name);
+		commit = obj;
+		found = i;
+	}
+
+	if (commit == NULL)
+		die("No commit specified?");
+
+	return commit;
+}
+
+static void fill_blob_sha1(struct commit *commit, struct diff_line_range *r)
+{
+	unsigned mode;
+	unsigned char sha1[20];
+
+	while (r) {
+		if (get_tree_entry(commit->object.sha1, r->spec->path,
+			sha1, &mode))
+			goto error;
+		fill_filespec(r->spec, sha1, mode);
+		r = r->next;
+	}
+
+	return;
+error:
+	die("There is no path %s in the commit", r->spec->path);
+}
+
+static void fill_line_ends(struct diff_filespec *spec, long *lines,
+	unsigned long **line_ends)
+{
+	int num = 0, size = 50;
+	long cur = 0;
+	unsigned long *ends = NULL;
+	char *data = NULL;
+
+	if (diff_populate_filespec(spec, 0))
+		die("Cannot read blob %s", sha1_to_hex(spec->sha1));
+
+	ends = xmalloc(size * sizeof(*ends));
+	ends[cur++] = 0;
+	data = spec->data;
+	while (num < spec->size) {
+		if (data[num] == '\n' || num == spec->size - 1) {
+			ALLOC_GROW(ends, (cur + 1), size);
+			ends[cur++] = num;
+		}
+		num++;
+	}
+
+	/* shrink the array to fit the elements */
+	ends = xrealloc(ends, cur * sizeof(*ends));
+	*lines = cur;
+	*line_ends = ends;
+}
+
+static const char *nth_line(struct diff_filespec *spec, long line,
+		long lines, unsigned long *line_ends)
+{
+	assert(line < lines);
+	assert(spec && spec->data);
+
+	if (line == 0)
+		return (char *)spec->data;
+	else
+		return (char *)spec->data + line_ends[line] + 1;
+}
+
+/*
+ * copied from blame.c, indeed, we can even to use this to test
+ * whether line log works. :)
+ */
+static const char *parse_loc(const char *spec, struct diff_filespec *file,
+			     long lines, unsigned long *line_ends,
+			     long begin, long *ret)
+{
+	char *term;
+	const char *line;
+	long num;
+	int reg_error;
+	regex_t regexp;
+	regmatch_t match[1];
+
+	/* Allow "-L <something>,+20" to mean starting at <something>
+	 * for 20 lines, or "-L <something>,-5" for 5 lines ending at
+	 * <something>.
+	 */
+	if (1 < begin && (spec[0] == '+' || spec[0] == '-')) {
+		num = strtol(spec + 1, &term, 10);
+		if (term != spec + 1) {
+			if (spec[0] == '-')
+				num = 0 - num;
+			if (0 < num)
+				*ret = begin + num - 2;
+			else if (!num)
+				*ret = begin;
+			else
+				*ret = begin + num;
+			return term;
+		}
+		return spec;
+	}
+	num = strtol(spec, &term, 10);
+	if (term != spec) {
+		*ret = num;
+		return term;
+	}
+	if (spec[0] != '/')
+		return spec;
+
+	/* it could be a regexp of form /.../ */
+	for (term = (char *) spec + 1; *term && *term != '/'; term++) {
+		if (*term == '\\')
+			term++;
+	}
+	if (*term != '/')
+		return spec;
+
+	/* try [spec+1 .. term-1] as regexp */
+	*term = 0;
+	begin--; /* input is in human terms */
+	line = nth_line(file, begin, lines, line_ends);
+
+	if (!(reg_error = regcomp(&regexp, spec + 1, REG_NEWLINE)) &&
+	    !(reg_error = regexec(&regexp, line, 1, match, 0))) {
+		const char *cp = line + match[0].rm_so;
+		const char *nline;
+
+		while (begin++ < lines) {
+			nline = nth_line(file, begin, lines, line_ends);
+			if (line <= cp && cp < nline)
+				break;
+			line = nline;
+		}
+		*ret = begin;
+		regfree(&regexp);
+		*term++ = '/';
+		return term;
+	}
+	else {
+		char errbuf[1024];
+		regerror(reg_error, &regexp, errbuf, 1024);
+		die("-L parameter '%s': %s", spec + 1, errbuf);
+	}
+}
+
+static void parse_range(long lines, unsigned long *line_ends,
+		struct range *r, struct diff_filespec *spec)
+{
+	const char *term;
+
+	term = parse_loc(r->arg, spec, lines, line_ends, 1, &r->start);
+	if (*term == ',') {
+		term = parse_loc(term + 1, spec, lines, line_ends,
+			r->start + 1, &r->end);
+		if (*term) {
+			die("-L parameter's argument should be <start>,<end>");
+		}
+	}
+
+	if (*term)
+		die("-L parameter's argument should be <start>,<end>");
+
+	if (r->start > r->end) {
+		long tmp = r->start;
+		r->start = r->end;
+		r->end = tmp;
+	}
+
+	if (r->start < 1)
+		r->start = 1;
+	if (r->end >= lines)
+		r->end = lines - 1;
+}
+
+static void parse_lines(struct commit *commit, struct diff_line_range *r)
+{
+	int i;
+	struct range *old_range = NULL;
+	long lines = 0;
+	unsigned long *ends = NULL;
+
+	while (r) {
+		struct diff_filespec *spec = r->spec;
+		int num = r->nr;
+		assert(spec);
+		fill_blob_sha1(commit, r);
+		old_range = r->ranges;
+		r->ranges = NULL;
+		r->nr = r->alloc = 0;
+		fill_line_ends(spec, &lines, &ends);
+		for (i = 0; i < num; i++) {
+			parse_range(lines, ends, old_range + i, spec);
+			diff_line_range_insert(r, old_range[i].arg,
+				old_range[i].start, old_range[i].end);
+		}
+
+		free(ends);
+		ends = NULL;
+
+		r = r->next;
+		free(old_range);
+	}
+}
+
+/*
+ * Insert a new line range into a diff_line_range struct, and keep the
+ * r->ranges sorted by their starting line number.
+ */
+struct range *diff_line_range_insert(struct diff_line_range *r, const char *arg,
+		int start, int end)
+{
+	int i = 0;
+	struct range *rs = r->ranges;
+	int left_merge = 0, right_merge = 0;
+
+	assert(r != NULL);
+	assert(start <= end);
+
+	if (r->nr == 0 || rs[r->nr - 1].end < start - 1) {
+		int num = 0;
+		DIFF_LINE_RANGE_GROW(r);
+		rs = r->ranges;
+		num = r->nr - 1;
+		rs[num].arg = arg;
+		rs[num].start = start;
+		rs[num].end = end;
+		return rs + num;
+	}
+
+	for (; i < r->nr; i++) {
+		if (rs[i].end < start - 1)
+			continue;
+		if (rs[i].end == start - 1) {
+			rs[i].end = end;
+			right_merge = 1;
+			goto out;
+		}
+
+		assert(rs[i].end > start - 1);
+		if (rs[i].start <= start) {
+			if (rs[i].end < end) {
+				rs[i].end = end;
+				right_merge = 1;
+			}
+			goto out;
+		} else if (rs[i].start <= end + 1) {
+			rs[i].start = start;
+			left_merge = 1;
+			if (rs[i].end < end) {
+				rs[i].end = end;
+				right_merge = 1;
+			}
+			goto out;
+		} else {
+			int num = r->nr - i;
+			DIFF_LINE_RANGE_GROW(r);
+			rs = r->ranges;
+			memmove(rs + i + 1, rs + i, num * sizeof(struct range));
+			rs[i].arg = arg;
+			rs[i].start = start;
+			rs[i].end = end;
+			goto out;
+		}
+	}
+
+out:
+	assert(r->nr != i);
+	if (left_merge) {
+		int j = i;
+		for (; j > -1; j--) {
+			if (rs[j].end >= rs[i].start - 1)
+				if (rs[j].start < rs[i].start)
+					rs[i].start = rs[j].start;
+		}
+		memmove(rs + j + 1, rs + i, (r->nr - i) * sizeof(struct range));
+		r->nr -= i - j - 1;
+	}
+	if (right_merge) {
+		int j = i;
+		for (; j < r->nr; j++) {
+			if (rs[j].start <= rs[i].end + 1)
+				if (rs[j].end > rs[i].end)
+					rs[i].end = rs[j].end;
+		}
+		if (j < r->nr) {
+			memmove(rs + i + 1, rs + j, (r->nr - j) * sizeof(struct range));
+		}
+		r->nr -= j - i - 1;
+	}
+	assert(r->nr);
+
+	return rs + i;
+}
+
+void diff_line_range_clear(struct diff_line_range *r)
+{
+	int i = 0, zero = 0;
+
+	for (; i < r->nr; i++) {
+		struct range *rg = r->ranges + i;
+		RANGE_CLEAR(rg);
+	}
+
+	if (r->prev) {
+		zero = 0;
+		if (r->prev->count == 1) {
+			zero = 1;
+		}
+		free_filespec(r->prev);
+		if (zero)
+			r->prev = NULL;
+	}
+	if (r->spec) {
+		zero = 0;
+		if (r->spec->count == 1) {
+			zero = 1;
+		}
+		free_filespec(r->spec);
+		if (zero)
+			r->spec = NULL;
+	}
+
+	r->status = '\0';
+	r->alloc = r->nr = 0;
+
+	if (r->ranges)
+		free(r->ranges);
+	r->ranges = NULL;
+	r->next = NULL;
+}
+
+void diff_line_range_append(struct diff_line_range *r, const char *arg)
+{
+	DIFF_LINE_RANGE_GROW(r);
+	r->ranges[r->nr - 1].arg = arg;
+}
+
+struct diff_line_range *diff_line_range_merge(struct diff_line_range *out,
+		struct diff_line_range *other)
+{
+	struct diff_line_range *one = out, *two = other;
+	struct diff_line_range *pone;
+
+	while (one) {
+		struct diff_line_range *ptwo;
+		two = other;
+		ptwo = other;
+		while (two) {
+			if (!strcmp(one->spec->path, two->spec->path)) {
+				int i = 0;
+				for (; i < two->nr; i++) {
+					diff_line_range_insert(one, NULL,
+						two->ranges[i].start,
+						two->ranges[i].end);
+				}
+				if (two == other) {
+					other = other->next;
+				} else {
+					ptwo->next = two->next;
+				}
+				DIFF_LINE_RANGE_CLEAR(two);
+				free(two);
+				two = NULL;
+
+				break;
+			}
+
+			ptwo = two;
+			two = two->next;
+		}
+
+		pone = one;
+		one = one->next;
+	}
+	pone->next = other;
+
+	return out;
+}
+
+void add_line_range(struct rev_info *revs, struct commit *commit, struct diff_line_range *r)
+{
+	struct diff_line_range *ret = NULL;
+
+	if (r != NULL) {
+		ret = lookup_decoration(&revs->line_range, &commit->object);
+		if (ret != NULL) {
+			diff_line_range_merge(ret, r);
+		} else {
+			add_decoration(&revs->line_range, &commit->object, r);
+		}
+		commit->object.flags |= RANGE_UPDATE;
+	}
+}
+
+struct diff_line_range *lookup_line_range(struct rev_info *revs, struct commit *commit)
+{
+	struct diff_line_range *ret = NULL;
+
+	ret = lookup_decoration(&revs->line_range, &commit->object);
+	return ret;
+}
+
+void setup_line(struct rev_info *rev, struct diff_line_range *r)
+{
+	struct commit *commit = NULL;
+	struct diff_options *opt = &rev->diffopt;
+
+	commit = (struct commit *)verify_commit(rev);
+	parse_lines(commit, r);
+
+	add_line_range(rev, commit, r);
+	/*
+	 * Note we support -M/-C to detect file rename
+	 */
+	opt->nr_paths = 0;
+	diff_tree_release_paths(opt);
+}
+
diff --git a/line.h b/line.h
new file mode 100644
index 0000000..caf84c7
--- /dev/null
+++ b/line.h
@@ -0,0 +1,128 @@
+#ifndef LINE_H
+#define LINE_H
+
+#include "diffcore.h"
+
+struct rev_info;
+struct commit;
+struct diff_line_range;
+struct diff_options;
+
+struct print_range {
+	int start, end;
+	int pstart, pend;
+	int line_added : 1;
+};
+
+struct print_pair {
+	int alloc, nr;
+	struct print_range *ranges;
+};
+
+#define PRINT_RANGE_INIT(r) \
+	do { \
+		(r)->start = (r)->end = 0; \
+		(r)->pstart = (r)->pend = 0; \
+		(r)->line_added = 0; \
+	} while (0)
+
+#define PRINT_PAIR_INIT(p) \
+	do { \
+		(p)->alloc = (p)->nr = 0; \
+		(p)->ranges = NULL; \
+	} while (0)
+
+#define PRINT_PAIR_GROW(p) \
+	do { \
+		(p)->nr++; \
+		ALLOC_GROW((p)->ranges, (p)->nr, (p)->alloc); \
+	} while (0)
+
+#define PRINT_PAIR_CLEAR(p) \
+	do { \
+		(p)->alloc = (p)->nr = 0; \
+		if ((p)->ranges) \
+			free((p)->ranges); \
+		(p)->ranges = NULL; \
+	} while (0)
+
+struct range {
+	const char *arg;	/* The argument to specify this line range */
+	long start, end;	/* The start line number, inclusive */
+	long pstart, pend;	/* The end line number, inclusive */
+	struct print_pair pair;
+			/* The changed lines inside this range */
+	unsigned int diff:1;
+};
+
+struct diff_line_range {
+	struct diff_filespec *prev;
+	struct diff_filespec *spec;
+	char status;
+	int alloc;
+	int nr;
+	struct range *ranges;
+	unsigned int	touch:1,
+			diff:1;
+	struct diff_line_range *next;
+};
+
+#define RANGE_INIT(r) \
+	do { \
+		(r)->arg = NULL; \
+		(r)->start = (r)->end = 0; \
+		(r)->pstart = (r)->pend = 0; \
+		PRINT_PAIR_INIT(&((r)->pair)); \
+		(r)->diff = 0; \
+	} while (0)
+
+#define RANGE_CLEAR(r) \
+	do { \
+		(r)->arg = NULL; \
+		(r)->start = (r)->end = 0; \
+		(r)->pstart = (r)->pend = 0; \
+		PRINT_PAIR_CLEAR(&r->pair); \
+		(r)->diff = 0; \
+	} while (0)
+
+#define DIFF_LINE_RANGE_INIT(r) \
+	do { \
+		(r)->prev = (r)->spec = NULL; \
+		(r)->status = '\0'; \
+		(r)->alloc = (r)->nr = 0; \
+		(r)->ranges = NULL; \
+		(r)->next = NULL; \
+		(r)->touch = 0; \
+		(r)->diff = 0; \
+	} while (0)
+
+#define DIFF_LINE_RANGE_GROW(r) \
+	do { \
+		(r)->nr ++; \
+		ALLOC_GROW((r)->ranges, (r)->nr, (r)->alloc); \
+		RANGE_INIT(((r)->ranges + (r)->nr - 1)); \
+	} while (0)
+
+#define DIFF_LINE_RANGE_CLEAR(r) \
+	diff_line_range_clear((r));
+
+extern struct range *diff_line_range_insert(struct diff_line_range *r,
+		const char *arg, int start, int end);
+
+extern void diff_line_range_append(struct diff_line_range *r, const char *arg);
+
+extern void diff_line_range_clear(struct diff_line_range *r);
+
+extern struct diff_line_range *diff_line_range_merge(
+		struct diff_line_range *out,
+		struct diff_line_range *other);
+
+extern void setup_line(struct rev_info *rev, struct diff_line_range *r);
+
+extern void add_line_range(struct rev_info *revs, struct commit *commit,
+		struct diff_line_range *r);
+
+extern struct diff_line_range *lookup_line_range(struct rev_info *revs,
+		struct commit *commit);
+
+#endif
diff --git a/revision.h b/revision.h
index 36fdf22..c0d5065 100644
--- a/revision.h
+++ b/revision.h
@@ -14,7 +14,8 @@
 #define CHILD_SHOWN	(1u<<6)
 #define ADDED		(1u<<7)	/* Parents already parsed and added? */
 #define SYMMETRIC_LEFT	(1u<<8)
-#define ALL_REV_FLAGS	((1u<<9)-1)
+#define RANGE_UPDATE	(1u<<9) /* for line level traverse */
+#define ALL_REV_FLAGS	((1u<<10)-1)
 
 #define DECORATE_SHORT_REFS	1
 #define DECORATE_FULL_REFS	2
@@ -68,7 +69,8 @@ struct rev_info {
 			cherry_pick:1,
 			bisect:1,
 			ancestry_path:1,
-			first_parent_only:1;
+			first_parent_only:1,
+			line_level_traverse:1;
 
 	/* Diff flags */
 	unsigned int	diff:1,
@@ -137,6 +139,8 @@ struct rev_info {
 	/* commit counts */
 	int count_left;
 	int count_right;
+	/* line level range that we are chasing */
+	struct decoration line_range;
 };
 
 #define REV_TREE_SAME		0

builtin/blame.c, line.c, line.h

diff --git a/builtin/blame.c b/builtin/blame.c
index 01e62fd..17b71cd 100644
--- a/builtin/blame.c
+++ b/builtin/blame.c
@@ -21,6 +21,7 @@
 #include "parse-options.h"
 #include "utf8.h"
 #include "userdiff.h"
+#include "line.h"
 
 static char blame_usage[] = "git blame [options] [rev-opts] [rev] [--] file";
 
@@ -541,11 +542,16 @@ static void dup_entry(struct blame_entry *dst, struct blame_entry *src)
 	dst->score = 0;
 }
 
-static const char *nth_line(struct scoreboard *sb, int lno)
+static const char *nth_line(struct scoreboard *sb, long lno)
 {
 	return sb->final_buf + sb->lineno[lno];
 }
 
+static const char *nth_line_cb(void *data, long lno)
+{
+	return nth_line((struct scoreboard *)data, lno);
+}
+
 /*
  * It is known that lines between tlno to same came from parent, and e
  * has an overlap with that range.  it also is known that parent's
@@ -1907,83 +1913,6 @@ static const char *add_prefix(const char *prefix, const char *path)
 }
 
 /*
- * Parsing of (comma separated) one item in the -L option
- */
-static const char *parse_loc(const char *spec,
-			     struct scoreboard *sb, long lno,
-			     long begin, long *ret)
-{
-	char *term;
-	const char *line;
-	long num;
-	int reg_error;
-	regex_t regexp;
-	regmatch_t match[1];
-
-	/* Allow "-L <something>,+20" to mean starting at <something>
-	 * for 20 lines, or "-L <something>,-5" for 5 lines ending at
-	 * <something>.
-	 */
-	if (1 < begin && (spec[0] == '+' || spec[0] == '-')) {
-		num = strtol(spec + 1, &term, 10);
-		if (term != spec + 1) {
-			if (spec[0] == '-')
-				num = 0 - num;
-			if (0 < num)
-				*ret = begin + num - 2;
-			else if (!num)
-				*ret = begin;
-			else
-				*ret = begin + num;
-			return term;
-		}
-		return spec;
-	}
-	num = strtol(spec, &term, 10);
-	if (term != spec) {
-		*ret = num;
-		return term;
-	}
-	if (spec[0] != '/')
-		return spec;
-
-	/* it could be a regexp of form /.../ */
-	for (term = (char *) spec + 1; *term && *term != '/'; term++) {
-		if (*term == '\\')
-			term++;
-	}
-	if (*term != '/')
-		return spec;
-
-	/* try [spec+1 .. term-1] as regexp */
-	*term = 0;
-	begin--; /* input is in human terms */
-	line = nth_line(sb, begin);
-
-	if (!(reg_error = regcomp(&regexp, spec + 1, REG_NEWLINE)) &&
-	    !(reg_error = regexec(&regexp, line, 1, match, 0))) {
-		const char *cp = line + match[0].rm_so;
-		const char *nline;
-
-		while (begin++ < lno) {
-			nline = nth_line(sb, begin);
-			if (line <= cp && cp < nline)
-				break;
-			line = nline;
-		}
-		*ret = begin;
-		regfree(&regexp);
-		*term++ = '/';
-		return term;
-	}
-	else {
-		char errbuf[1024];
-		regerror(reg_error, &regexp, errbuf, 1024);
-		die("-L parameter '%s': %s", spec + 1, errbuf);
-	}
-}
-
-/*
  * Parsing of -L option
  */
 static void prepare_blame_range(struct scoreboard *sb,
@@ -1993,9 +1922,9 @@ static void prepare_blame_range(struct scoreboard *sb,
 {
 	const char *term;
 
-	term = parse_loc(bottomtop, sb, lno, 1, bottom);
+	term = parse_loc(bottomtop, nth_line_cb, sb, lno, 1, bottom);
 	if (*term == ',') {
-		term = parse_loc(term + 1, sb, lno, *bottom + 1, top);
+		term = parse_loc(term + 1, nth_line_cb, sb, lno, *bottom + 1, top);
 		if (*term)
 			usage(blame_usage);
 	}
diff --git a/line.c b/line.c
index fdec93a..4314cee 100644
--- a/line.c
+++ b/line.c
@@ -95,25 +95,29 @@ static void fill_line_ends(struct diff_filespec *spec, long *lines,
 	*line_ends = ends;
 }
 
-static const char *nth_line(struct diff_filespec *spec, long line,
-		long lines, unsigned long *line_ends)
+struct nth_line_cb {
+	struct diff_filespec *spec;
+	long lines;
+	unsigned long *line_ends;
+};
+
+static const char *nth_line(void *data, long line)
 {
-	assert(line < lines);
-	assert(spec && spec->data);
+	struct nth_line_cb *d = data;
+	assert(d && line < d->lines);
+	assert(d->spec && d->spec->data);
 
 	if (line == 0)
-		return (char *)spec->data;
+		return (char *)d->spec->data;
 	else
-		return (char *)spec->data + line_ends[line] + 1;
+		return (char *)d->spec->data + d->line_ends[line] + 1;
 }
 
 /*
- * copied from blame.c, indeed, we can even to use this to test
- * whether line log works. :)
+ * Parsing of (comma separated) one item in the -L option
  */
-static const char *parse_loc(const char *spec, struct diff_filespec *file,
-			     long lines, unsigned long *line_ends,
-			     long begin, long *ret)
+const char *parse_loc(const char *spec, nth_line_fn_t nth_line,
+		void *data, long lines, long begin, long *ret)
 {
 	char *term;
 	const char *line;
@@ -160,7 +164,7 @@ static const char *parse_loc(const char *spec, struct diff_filespec *file,
 	/* try [spec+1 .. term-1] as regexp */
 	*term = 0;
 	begin--; /* input is in human terms */
-	line = nth_line(file, begin, lines, line_ends);
+	line = nth_line(data, begin);
 
 	if (!(reg_error = regcomp(&regexp, spec + 1, REG_NEWLINE)) &&
 	    !(reg_error = regexec(&regexp, line, 1, match, 0))) {
@@ -168,7 +172,7 @@ static const char *parse_loc(const char *spec, struct diff_filespec *file,
 		const char *nline;
 
 		while (begin++ < lines) {
-			nline = nth_line(file, begin, lines, line_ends);
+			nline = nth_line(data, begin);
 			if (line <= cp && cp < nline)
 				break;
 			line = nline;
@@ -189,11 +193,12 @@ static void parse_range(long lines, unsigned long *line_ends,
 		struct range *r, struct diff_filespec *spec)
 {
 	const char *term;
+	struct nth_line_cb data = {spec, lines, line_ends};
 
-	term = parse_loc(r->arg, spec, lines, line_ends, 1, &r->start);
+	term = parse_loc(r->arg, nth_line, &data, lines, 1, &r->start);
 	if (*term == ',') {
-		term = parse_loc(term + 1, spec, lines, line_ends,
-			r->start + 1, &r->end);
+		term = parse_loc(term + 1, nth_line, &data, lines,
+				r->start + 1, &r->end);
 		if (*term) {
 			die("-L parameter's argument should be <start>,<end>");
 		}
diff --git a/line.h b/line.h
index caf84c7..8b30ada 100644
--- a/line.h
+++ b/line.h
@@ -8,6 +8,8 @@ struct commit;
 struct diff_line_range;
 struct diff_options;
 
+typedef const char *(*nth_line_fn_t)(void *data, long lno);
+
 struct print_range {
 	int start, end;
 	int pstart, pend;
@@ -125,4 +127,7 @@ extern void add_line_range(struct rev_info *revs, struct commit *commit,
 extern struct diff_line_range *lookup_line_range(struct rev_info *revs,
 		struct commit *commit);
 
+const char *parse_loc(const char *spec, nth_line_fn_t nth_line,
+		void *data, long lines, long begin, long *ret);
+
 #endif

diff --git a/builtin/log.c b/builtin/log.c
index 08b8722..84d781e 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -19,6 +19,7 @@
 #include "remote.h"
 #include "string-list.h"
 #include "parse-options.h"
+#include "line.h"
 
 /* Set a default date-time format for git log ("log.date" config variable) */
 static const char *default_date_mode = NULL;
@@ -27,11 +28,24 @@ static int default_show_root = 1;
 static int decoration_style;
 static const char *fmt_patch_subject_prefix = "PATCH";
 static const char *fmt_pretty;
+static const char *dashdash = "--";
 
-static const char * const builtin_log_usage =
+static char builtin_log_usage[] =
 	"git log [<options>] [<since>..<until>] [[--] <path>...]\n"
+	"git log [<options>] -L n,m <path>\n"
 	"   or: git show [options] <object>...";
 
+static const char *log_opt_usage[] = {
+	builtin_log_usage,
+	NULL
+};
+
+struct line_opt_callback_data {
+	struct diff_line_range **range;
+	struct parse_opt_ctx_t *ctx;
+	struct rev_info *rev;
+};
+
 static int parse_decoration_style(const char *var, const char *value)
 {
 	switch (git_config_maybe_bool(var, value)) {
@@ -49,12 +63,42 @@ static int parse_decoration_style(const char *var, const char *value)
 	return -1;
 }
 
+static int log_line_range_callback(const struct option *option, const char *arg, int unset)
+{
+	struct line_opt_callback_data *data = option->value;
+	struct diff_line_range *r = *data->range;
+	struct parse_opt_ctx_t *ctx = data->ctx;
+
+	if (!arg)
+		return -1;
+
+	if (r->nr == 0 && r->next == NULL) {
+		ctx->out[ctx->cpidx++] = dashdash;
+	}
+
+	diff_line_range_append(r, arg);
+	data->rev->line_level_traverse = 1;
+	return 0;
+}
+
 static void cmd_log_init(int argc, const char **argv, const char *prefix,
 			 struct rev_info *rev, struct setup_revision_opt *opt)
 {
 	int i;
 	int decoration_given = 0;
 	struct userformat_want w;
+	const char *path = NULL, *pathspec = NULL;
+	static struct diff_line_range *range = NULL, *r = NULL;
+	static struct parse_opt_ctx_t ctx;
+	static struct line_opt_callback_data line_cb = {&range, &ctx, NULL};
+	static const struct option options[] = {
+		OPT_CALLBACK('L', NULL, &line_cb, "n,m", "Process only line range n,m, counting from 1", log_line_range_callback),
+		OPT_END()
+	};
+
+	line_cb.rev = rev;
+	range = xmalloc(sizeof(*range));
+	DIFF_LINE_RANGE_INIT(range);
 
 	rev->abbrev = DEFAULT_ABBREV;
 	rev->commit_format = CMIT_FMT_DEFAULT;
@@ -75,6 +119,58 @@ static void cmd_log_init(int argc, const char **argv, const char *prefix,
 	 */
 	if (argc == 2 && !strcmp(argv[1], "-h"))
 		usage(builtin_log_usage);
+
+	parse_options_start(&ctx, argc, argv, prefix, PARSE_OPT_KEEP_DASHDASH |
+			PARSE_OPT_KEEP_ARGV0 | PARSE_OPT_STOP_AT_NON_OPTION);
+	for (;;) {
+		switch (parse_options_step(&ctx, options, log_opt_usage)) {
+		case PARSE_OPT_HELP:
+			exit(129);
+		case PARSE_OPT_DONE:
+			goto parse_done;
+		case PARSE_OPT_NON_OPTION:
+			path = parse_options_current(&ctx);
+			pathspec = prefix_path(prefix, prefix ? strlen(prefix) : 0, path);
+			range->spec = alloc_filespec(pathspec);
+			free((void *)pathspec);
+			if (range->nr == 0) {
+				if(range->next) {
+					die("Path %s need a -L <range> option\n"
+					"If you want follow the history of the whole file "
+					"whether to using 'git log' without -L or using "
+					"'git log -L 1,$ <path>'", range->spec->path);
+				} else {
+					parse_options_next(&ctx, 1);
+					continue;
+				}
+			}
+			r = xmalloc(sizeof(*r));
+			DIFF_LINE_RANGE_INIT(r);
+			r->next = range;
+			range = r;
+			parse_options_next(&ctx, 1);
+			continue;
+		case PARSE_OPT_UNKNOWN:
+			parse_options_next(&ctx, 1);
+			continue;
+		}
+
+		parse_revision_opt(rev, &ctx, options, log_opt_usage);
+	}
+parse_done:
+	argc = parse_options_end(&ctx);
+
+	/* die if '-L <range>' with no pathspec follow */
+	if (range->nr > 0 && range->spec == NULL) {
+		die("Each -L should follow a pathspec");
+	}
+	/* clear up the last range */
+	if (range->nr == 0) {
+		struct diff_line_range *r = range->next;
+		DIFF_LINE_RANGE_CLEAR(range);
+		range = r;
+	}
+
 	argc = setup_revisions(argc, argv, rev, opt);
 
 	memset(&w, 0, sizeof(w));
@@ -125,6 +221,11 @@ static void cmd_log_init(int argc, const char **argv, const char *prefix,
 		rev->show_decorations = 1;
 		load_ref_decorations(decoration_style);
 	}
+
+	/* Test whether line level history is asked for */
+	if (range && range->nr > 0) {
+		setup_line(rev, range);
+	}
 }
 
 /*

diff.c, diff.h

diff --git a/diff.c b/diff.c
index 17873f3..9efca95 100644
--- a/diff.c
+++ b/diff.c
@@ -144,7 +144,7 @@ int git_diff_basic_config(const char *var, const char *value, void *cb)
 	return git_color_default_config(var, value, cb);
 }
 
-static char *quote_two(const char *one, const char *two)
+char *quote_two(const char *one, const char *two)
 {
 	int need_one = quote_c_style(one, NULL, NULL, 1);
 	int need_two = quote_c_style(two, NULL, NULL, 1);
@@ -325,7 +325,7 @@ static void emit_line_0(struct diff_options *o, const char *set, const char *res
 		fputc('\n', file);
 }
 
-static void emit_line(struct diff_options *o, const char *set, const char *reset,
+void emit_line(struct diff_options *o, const char *set, const char *reset,
 		      const char *line, int len)
 {
 	emit_line_0(o, set, reset, line[0], line+1, len-1);
@@ -2564,7 +2564,7 @@ static int similarity_index(struct diff_filepair *p)
 	return p->score * 100 / MAX_SCORE;
 }
 
-static void fill_metainfo(struct strbuf *msg,
+void fill_metainfo(struct strbuf *msg,
 			  const char *name,
 			  const char *other,
 			  struct diff_filespec *one,
diff --git a/diff.h b/diff.h
index 063d10a..9676ab9 100644
--- a/diff.h
+++ b/diff.h
@@ -12,6 +12,7 @@ struct diff_queue_struct;
 struct strbuf;
 struct diff_filespec;
 struct userdiff_driver;
+struct diff_filepair;
 
 typedef void (*change_fn_t)(struct diff_options *options,
 		 unsigned old_mode, unsigned new_mode,
@@ -301,4 +302,20 @@ extern size_t fill_textconv(struct userdiff_driver *driver,
 
 extern struct userdiff_driver *get_textconv(struct diff_filespec *one);
 
+/* some output functions line.c need */
+extern void fill_metainfo(struct strbuf *msg,
+			  const char *name,
+			  const char *other,
+			  struct diff_filespec *one,
+			  struct diff_filespec *two,
+			  struct diff_options *o,
+			  struct diff_filepair *p,
+			  int *must_show_header,
+			  int use_color);
+
+extern void emit_line(struct diff_options *o, const char *set, const char *reset,
+		      const char *line, int len);
+
+extern char *quote_two(const char *one, const char *two);
+
 #endif /* DIFF_H */

line.c, line.h

diff --git a/line.c b/line.c
index 4314cee..c9ff934 100644
--- a/line.c
+++ b/line.c
@@ -382,6 +382,45 @@ void diff_line_range_append(struct diff_line_range *r, const char *arg)
 	r->ranges[r->nr - 1].arg = arg;
 }
 
+struct diff_line_range *diff_line_range_clone(struct diff_line_range *r)
+{
+	struct diff_line_range *ret = xmalloc(sizeof(*ret));
+	int i = 0;
+
+	DIFF_LINE_RANGE_INIT(ret);
+	ret->ranges = xcalloc(r->nr, sizeof(struct range));
+	memcpy(ret->ranges, r->ranges, sizeof(struct range) * r->nr);
+
+	ret->alloc = ret->nr = r->nr;
+
+	for (; i < ret->nr; i++)
+		PRINT_PAIR_INIT(&ret->ranges[i].pair);
+
+	ret->spec = r->spec;
+	assert(ret->spec);
+	ret->spec->count++;
+
+	return ret;
+}
+
+struct diff_line_range *diff_line_range_clone_deeply(struct diff_line_range *r)
+{
+	struct diff_line_range *ret = NULL;
+	struct diff_line_range *tmp = NULL, *prev = NULL;
+
+	assert(r);
+	ret = tmp = prev = diff_line_range_clone(r);
+	r = r->next;
+	while (r) {
+		tmp = diff_line_range_clone(r);
+		prev->next = tmp;
+		prev = tmp;
+		r = r->next;
+	}
+
+	return ret;
+}
+
 struct diff_line_range *diff_line_range_merge(struct diff_line_range *out,
 		struct diff_line_range *other)
 {
diff --git a/line.h b/line.h
index 8b30ada..7563536 100644
--- a/line.h
+++ b/line.h
@@ -119,6 +119,10 @@ extern struct diff_line_range *diff_line_range_merge(
 		struct diff_line_range *out,
 		struct diff_line_range *other);
 
+extern struct diff_line_range *diff_line_range_clone(struct diff_line_range *r);
+
+extern struct diff_line_range *diff_line_range_clone_deeply(struct diff_line_range *r);
+
 extern void setup_line(struct rev_info *rev, struct diff_line_range *r);
 
 extern void add_line_range(struct rev_info *revs, struct commit *commit,

line.c, revision.h

diff --git a/line.c b/line.c
index c9ff934..3593b33 100644
--- a/line.c
+++ b/line.c
@@ -502,3 +502,492 @@ void setup_line(struct rev_info *rev, struct diff_line_range *r)
 	diff_tree_release_paths(opt);
 }
 
+struct take_range_cb_data {
+	struct diff_line_range *interesting;	/* currently interesting ranges */
+	struct diff_line_range *range;
+		/* the ranges corresponds to the interesting ranges of parent commit */
+	long plno, tlno;
+		/* the last line number of diff hunk */
+	int diff;
+		/* whether there is some line changes between the current commit and its parent */
+};
+
+#define SCALE_FACTOR 4
+/*
+ * [p_start, p_end] represents the pre-image of current diff hunk,
+ * [t_start, t_end] represnets the post-image of the current diff hunk,
+ * [start, end] represents the currently interesting line range in
+ * post-image,
+ * [o_start, o_end] represents the original line range that coresponds
+ * to current line range.
+ */
+void map_lines(long p_start, long p_end, long t_start, long t_end,
+		long start, long end, long *o_start, long *o_end)
+{
+	/*
+	 * Normally, p_start should be less than p_end, so does the
+	 * t_start and t_end. But when the line range is added from
+	 * scratch, p_start will be greater than p_end. When the line
+	 * range is deleted, t_start will be greater than t_end.
+	 */
+	if (p_start > p_end) {
+		*o_start = *o_end = 0;
+		return;
+	}
+	/* A deletion */
+	if (t_start > t_end) {
+		*o_start = p_start;
+		*o_end = p_end;
+		return;
+	}
+
+	if (start == t_start && end == t_end) {
+		*o_start = p_start;
+		*o_end = p_end;
+		return;
+	}
+
+	/*
+	 * A heuristic for lines mapping:
+	 *
+	 * When the pre-image is no more than 1/4 of the post-image,
+	 * there is no effective way to find out which part of pre-image
+	 * corresponds to the currently interesting range of post-image.
+	 * And we are in the danger of tracking totally useless lines.
+	 * So, we just treat all the post-image lines as added from scratch.
+	 */
+	if (SCALE_FACTOR * (p_end - p_start + 1) < (t_end - t_start + 1)) {
+		*o_start = *o_end = 0;
+		return;
+	}
+
+	*o_start = p_start + start - t_start;
+	*o_end = p_end - (t_end - end);
+
+	if (*o_start > *o_end) {
+		int temp = *o_start;
+		*o_start = *o_end;
+		*o_end = temp;
+	}
+
+	if (*o_start < p_start)
+		*o_start = p_start;
+	if (*o_end > p_end)
+		*o_end = p_end;
+}
+
+/*
+ * When same == 1:
+ * [p_start, p_end] represents the diff hunk line range of pre-image,
+ * [t_start, t_end] represents the diff hunk line range of post-image.
+ * When same == 0, they represents a range of idnetical lines between
+ * two images.
+ *
+ * This function find out the corresponding line ranges of currently
+ * interesting ranges which this diff hunk touches.
+ */
+static void map_range(struct take_range_cb_data *data, int same,
+		long p_start, long p_end, long t_start, long t_end)
+{
+	struct range *ranges = data->interesting->ranges;
+	long takens, takene, start, end;
+	int i = 0, out = 0, added = 0;
+	long op_start = p_start, op_end = p_end, ot_start = t_start, ot_end = t_end;
+
+	for (; i < data->interesting->nr; i++) {
+		added = 0;
+		if (t_start > ranges[i].end)
+			continue;
+		if (t_end < ranges[i].start)
+			break;
+
+		if (t_start > ranges[i].start) {
+			start = t_start;
+			takens = p_start;
+			if (t_end >= ranges[i].end) {
+				end = ranges[i].end;
+				takene = p_start + end - t_start;
+			} else {
+				end = t_end;
+				takene = p_end;
+				out = 1;
+			}
+		} else {
+			start = ranges[i].start;
+			takens = p_start + start - t_start;
+			if (t_end >= ranges[i].end) {
+				end = ranges[i].end;
+				takene = p_start + end - t_start;
+			} else {
+				end = t_end;
+				takene = p_end;
+				out = 1;
+			}
+		}
+
+		if (!same) {
+			struct print_pair *pair = &ranges[i].pair;
+			struct print_range *rr = NULL;
+			PRINT_PAIR_GROW(pair);
+			rr = pair->ranges + pair->nr - 1;
+			PRINT_RANGE_INIT(rr);
+			rr->start = start;
+			rr->end = end;
+			map_lines(op_start, op_end, ot_start, ot_end, start, end,
+					&takens, &takene);
+			if (takens == 0 && takene == 0) {
+				added = 1;
+				rr->line_added = 1;
+			}
+			rr->pstart = takens;
+			rr->pend = takene;
+			data->diff = 1;
+			data->interesting->diff = 1;
+			ranges[i].diff = 1;
+		}
+		if (added) {
+			/* Code movement/copy detect here, now place two dummy statements here */
+			int dummy = 0;
+			dummy = 1;
+		} else {
+			struct range *added_range = diff_line_range_insert(data->range,
+					NULL, takens, takene);
+			assert(added_range);
+			ranges[i].pstart = added_range->start;
+			ranges[i].pend = added_range->end;
+		}
+
+		t_start = end + 1;
+		p_start = takene + 1;
+
+		if (out)
+			break;
+	}
+}
+
+/*
+ * [p_start, p_end] represents the line range of pre-image,
+ * [t_start, t_end] represents the line range of post-image,
+ * and they are identical lines.
+ *
+ * This function substracts out the identical lines between current
+ * commit and its parent, from currently interesting ranges.
+ */
+static void take_range(struct take_range_cb_data *data,
+		long p_start, long p_end, long t_start, long t_end)
+{
+	struct range *ranges = data->interesting->ranges;
+	long takens, takene, start, end;
+	int i = 0, out = 0, added = 0;
+
+	for (; i < data->interesting->nr; i++) {
+		added = 0;
+		if (t_start > ranges[i].end)
+			continue;
+		if (t_end < ranges[i].start)
+			break;
+
+		if (t_start > ranges[i].start) {
+			long tmp = ranges[i].end;
+			ranges[i].end = t_start - 1;
+			start = t_start;
+			takens = p_start;
+			if (t_end >= tmp) {
+				end = tmp;
+				takene = p_start + end - t_start;
+				p_start = takene + 1;
+				t_start = end + 1;
+			} else {
+				end = t_end;
+				takene = p_end;
+				diff_line_range_insert(data->interesting, NULL,
+					t_end + 1, tmp);
+				out = 1;
+			}
+		} else {
+			start = ranges[i].start;
+			takens = p_start + start - t_start;
+			if (t_end >= ranges[i].end) {
+				int num = data->interesting->nr - 1;
+				end = ranges[i].end;
+				takene = p_start + end - t_start;
+				t_start = end + 1;
+				p_start = takene + 1;
+				memmove(ranges + i, ranges + i + 1, (num - i) * sizeof(*ranges));
+				data->interesting->nr = num;
+				i--;
+			} else {
+				end = t_end;
+				takene = p_end;
+				ranges[i].start = t_end + 1;
+				out = 1;
+			}
+		}
+
+		diff_line_range_insert(data->range, NULL, takens, takene);
+
+		if (out)
+			break;
+	}
+}
+
+static void take_range_cb(void *data, long same, long p_next, long t_next)
+{
+	struct take_range_cb_data *d = data;
+	long p_start = d->plno + 1, t_start = d->tlno + 1;
+	long p_end = p_start + same - t_start, t_end = same;
+
+	/* If one file is added from scratch, we should not bother to call
+	 * take_range, since there is nothing to take
+	 */
+	if (t_end >= t_start)
+		take_range(d, p_start, p_end, t_start, t_end);
+	d->plno = p_next;
+	d->tlno = t_next;
+}
+
+static void map_range_cb(void *data, long same, long p_next, long t_next)
+{
+	struct take_range_cb_data *d = data;
+
+	long p_start = d->plno + 1;
+	long t_start = d->tlno + 1;
+	long p_end = same - t_start + p_start;
+	long t_end = same;
+
+	/* Firstly, take the unchanged lines from child */
+	if (t_end >= t_start)
+		map_range(d, 1, p_start, p_end, t_start, t_end);
+
+	/* find out which lines to print */
+	t_start = same + 1;
+	p_start = d->plno + t_start - d->tlno;
+	map_range(d, 0, p_start, p_next, t_start, t_next);
+
+	d->plno = p_next;
+	d->tlno = t_next;
+}
+
+static void assign_range_to_parent(struct rev_info *rev, struct commit *c,
+		struct commit *p, struct diff_line_range *r,
+		struct diff_options *opt, int map)
+{
+	struct diff_line_range *rr = xmalloc(sizeof(*rr));
+	struct diff_line_range *cr = rr, *prev_r = rr;
+	struct diff_line_range *rg = NULL;
+	struct tree_desc desc1, desc2;
+	void *tree1 = NULL, *tree2 = NULL;
+	unsigned long size1, size2;
+	struct diff_queue_struct *queue;
+	struct take_range_cb_data cb = {NULL, cr, 0, 0};
+	xpparam_t xpp;
+	xdemitconf_t xecfg;
+	int i, diff = 0;
+	xdiff_emit_hunk_consume_fn fn = map ? map_range_cb : take_range_cb;
+
+	DIFF_LINE_RANGE_INIT(cr);
+	memset(&xpp, 0, sizeof(xpp));
+	memset(&xecfg, 0, sizeof(xecfg));
+	xecfg.ctxlen = xecfg.interhunkctxlen = 0;
+
+	/*
+	 * Compose up two trees, for root commit, we make up a empty tree.
+	 */
+	assert(c);
+	tree2 = read_object_with_reference(c->tree->object.sha1, "tree", &size2, NULL);
+	if (tree2 == NULL)
+		die("Unable to read tree (%s)", sha1_to_hex(c->tree->object.sha1));
+	init_tree_desc(&desc2, tree2, size2);
+	if (p) {
+		tree1 = read_object_with_reference(p->tree->object.sha1, "tree", &size1, NULL);
+		if (tree1 == NULL)
+			die("Unable to read tree (%s)", sha1_to_hex(p->tree->object.sha1));
+		init_tree_desc(&desc1, tree1, size1);
+	} else {
+		init_tree_desc(&desc1, "", 0);
+	}
+
+	DIFF_QUEUE_CLEAR(&diff_queued_diff);
+	diff_tree(&desc1, &desc2, "", opt);
+	diffcore_std(opt);
+
+	queue = &diff_queued_diff;
+	for (i = 0; i < queue->nr; i++) {
+		struct diff_filepair *pair = queue->queue[i];
+		struct diff_line_range *rg = r;
+		mmfile_t file_p, file_t;
+		assert(pair->two->path);
+		while (rg) {
+			assert(rg->spec->path);
+			if (!strcmp(rg->spec->path, pair->two->path))
+				break;
+			rg = rg->next;
+		}
+
+		if (rg == NULL)
+			continue;
+		rg->touch = 1;
+		if (rg->nr == 0)
+			continue;
+
+		rg->status = pair->status;
+		assert(pair->two->sha1_valid);
+		diff_populate_filespec(pair->two, 0);
+		file_t.ptr = pair->two->data;
+		file_t.size = pair->two->size;
+
+		if (rg->prev)
+			free_filespec(rg->prev);
+		rg->prev = pair->one;
+		rg->prev->count++;
+		if (pair->one->sha1_valid) {
+			diff_populate_filespec(pair->one, 0);
+			file_p.ptr = pair->one->data;
+			file_p.size = pair->one->size;
+		} else {
+			file_p.ptr = "";
+			file_p.size = 0;
+		}
+
+		if (cr->nr != 0) {
+			struct diff_line_range *tmp = xmalloc(sizeof(*tmp));
+			cr->next = tmp;
+			prev_r = cr;
+			cr = tmp;
+		} else if (cr->spec)
+			DIFF_LINE_RANGE_CLEAR(cr);
+
+		DIFF_LINE_RANGE_INIT(cr);
+		if (pair->one->sha1_valid) {
+			cr->spec = pair->one;
+			cr->spec->count++;
+		}
+
+		cb.interesting = rg;
+		cb.range = cr;
+		cb.diff = 0;
+		cb.plno = cb.tlno = 0;
+		xdi_diff_hunks(&file_p, &file_t, fn, &cb, &xpp, &xecfg);
+		if (cb.diff)
+			diff = 1;
+		/*
+		 * The remain part is the same part.
+		 * Instead of calculating the true line number of the two files,
+		 * use the biggest integer.
+		 */
+		if (map)
+			map_range(&cb, 1, cb.plno + 1, 0x7FFFFFFF, cb.tlno + 1, 0x7FFFFFFF);
+		else
+			take_range(&cb, cb.plno + 1, 0x7FFFFFFF, cb.tlno + 1, 0x7FFFFFFF);
+	}
+	opt->output_format = DIFF_FORMAT_NO_OUTPUT;
+	diff_flush(opt);
+
+	/*
+	 * Collect the untouch ranges, this comes from the files not changed
+	 * between two commit.
+	 */
+	rg = r;
+	while (rg) {
+		/* clear the touch one to make it usable in next round */
+		if (rg->touch) {
+			rg->touch = 0;
+		} else {
+			struct diff_line_range *untouch = diff_line_range_clone(rg);
+			if (prev_r == rr && rr->nr == 0) {
+				rr = prev_r = untouch;
+			} else {
+				prev_r->next = untouch;
+				prev_r = untouch;
+			}
+		}
+		rg = rg->next;
+	}
+
+	if (cr->nr == 0) {
+		DIFF_LINE_RANGE_CLEAR(cr);
+		free(cr);
+		if (prev_r == cr) {
+			rr = NULL;
+		} else {
+			prev_r->next = NULL;
+		}
+	}
+
+	if (rr) {
+		assert(p);
+		add_line_range(rev, p, rr);
+	}
+
+	/* and the ranges of current commit c is updated */
+	c->object.flags &= ~RANGE_UPDATE;
+	if (diff)
+		c->object.flags |= NEED_PRINT;
+
+	if (tree1)
+		free(tree1);
+	if (tree2)
+		free(tree2);
+}
+
+static void diff_update_parent_range(struct rev_info *rev, struct commit *commit)
+{
+	struct diff_line_range *r = lookup_line_range(rev, commit);
+	struct commit_list *parents = commit->parents;
+	struct commit *c = NULL;
+	if (parents) {
+		assert(parents->next == NULL);
+		c = parents->item;
+	}
+
+	assign_range_to_parent(rev, commit, c, r, &rev->diffopt, 1);
+}
+
+static void assign_parents_range(struct rev_info *rev, struct commit *commit)
+{
+	struct commit_list *parents = commit->parents;
+	struct diff_line_range *r = lookup_line_range(rev, commit);
+	struct diff_line_range *copy = NULL, *range = NULL;
+	int nontrivial = 0;
+
+	/*
+	 * If we are in linear history, update range and flush the patch if
+	 * necessary
+	 */
+	if (parents == NULL || parents->next == NULL) {
+		return diff_update_parent_range(rev, commit);
+	}
+
+	/*
+	 * Loop on the parents and assign the ranges to different
+	 * parents, if there is any range left, this commit must
+	 * be an evil merge.
+	 */
+	copy = diff_line_range_clone_deeply(r);
+	parents = commit->parents;
+	while (parents) {
+		struct commit *p = parents->item;
+		assign_range_to_parent(rev, commit, p, r, &rev->diffopt, 1);
+		assign_range_to_parent(rev, commit, p, copy, &rev->diffopt, 0);
+		parents = parents->next;
+	}
+
+	/*
+	 * yes, this must be an evil merge.
+	 */
+	range = copy;
+	while (range) {
+		if (range->nr) {
+			commit->object.flags |= NEED_PRINT | EVIL_MERGE;
+			nontrivial = 1;
+		}
+		range = range->next;
+	}
+
+	if (nontrivial) {
+		add_decoration(&rev->nontrivial_merge, &commit->object, copy);
+	} else {
+		cleanup(copy);
+	}
+}
+
diff --git a/revision.h b/revision.h
index c0d5065..2627ec4 100644
--- a/revision.h
+++ b/revision.h
@@ -15,7 +15,9 @@
 #define ADDED		(1u<<7)	/* Parents already parsed and added? */
 #define SYMMETRIC_LEFT	(1u<<8)
 #define RANGE_UPDATE	(1u<<9) /* for line level traverse */
-#define ALL_REV_FLAGS	((1u<<10)-1)
+#define NEED_PRINT	(1u<<10)
+#define EVIL_MERGE	(1u<<11)
+#define ALL_REV_FLAGS	((1u<<12)-1)
 
 #define DECORATE_SHORT_REFS	1
 #define DECORATE_FULL_REFS	2
@@ -141,6 +143,7 @@ struct rev_info {
 	int count_right;
 	/* line level range that we are chasing */
 	struct decoration line_range;
+	struct decoration nontrivial_merge;
 };
 
 #define REV_TREE_SAME		0

diff --git a/line.c b/line.c
index 3593b33..bd63d99 100644
--- a/line.c
+++ b/line.c
@@ -991,3 +991,244 @@ static void assign_parents_range(struct rev_info *rev, struct commit *commit)
 	}
 }
 
+struct line_chunk {
+	int lone, ltwo;
+	const char *one, *two;
+	const char *one_end, *two_end;
+	struct diff_line_range *range;
+};
+
+static void flush_lines(struct diff_options *opt, const char **ptr, const char *end,
+		int slno, int elno, int *lno, const char *color, const char heading)
+{
+	const char *p = *ptr;
+	struct strbuf buf = STRBUF_INIT;
+	const char *reset;
+
+	if (*color)
+		reset = diff_get_color_opt(opt, DIFF_RESET);
+	else
+		reset = "";
+
+	strbuf_addf(&buf, "%s%c", color, heading);
+	while (*ptr < end && *lno < slno) {
+		if (**ptr == '\n') {
+			(*lno)++;
+			if (*lno == slno) {
+				(*ptr)++;
+				break;
+			}
+		}
+		(*ptr)++;
+	}
+	assert(*ptr <= end);
+	p = *ptr;
+
+	while (*ptr < end && *lno <= elno) {
+		if (**ptr == '\n') {
+			fprintf(opt->file, "%s", buf.buf);
+			if (*ptr - p) {
+				fwrite(p, *ptr - p, 1, opt->file);
+			}
+			fprintf(opt->file, "%s\n", reset);
+			p = *ptr + 1;
+			(*lno)++;
+		}
+		(*ptr)++;
+	}
+	if (*lno <= elno) {
+		fprintf(opt->file, "%s", buf.buf);
+		if (*ptr - p) {
+			fwrite(p, *ptr - p, 1, opt->file);
+		}
+		fprintf(opt->file, "%s\n", reset);
+	}
+	strbuf_release(&buf);
+}
+
+static void diff_flush_range(struct diff_options *opt, struct line_chunk *chunk,
+		struct range *range)
+{
+	struct print_pair *pair = &range->pair;
+	const char *old = diff_get_color_opt(opt, DIFF_FILE_OLD);
+	const char *new = diff_get_color_opt(opt, DIFF_FILE_NEW);
+	int i, cur = range->start;
+
+	for (i = 0; i < pair->nr; i++) {
+		struct print_range *pr = pair->ranges + i;
+		if (cur < pr->start)
+			flush_lines(opt, &chunk->two, chunk->two_end,
+				cur, pr->start - 1, &chunk->ltwo, "", ' ');
+
+		if (!pr->line_added)
+			flush_lines(opt, &chunk->one, chunk->one_end,
+				pr->pstart, pr->pend, &chunk->lone, old, '-');
+		flush_lines(opt, &chunk->two, chunk->two_end,
+			pr->start, pr->end, &chunk->ltwo, new, '+');
+
+		cur = pr->end + 1;
+	}
+
+	if (cur <= range->end) {
+		flush_lines(opt, &chunk->two, chunk->two_end,
+			cur, range->end, &chunk->ltwo, "", ' ');
+	}
+}
+
+static void diff_flush_chunks(struct diff_options *opt, struct line_chunk *chunk)
+{
+	struct diff_line_range *range = chunk->range;
+	const char *set = diff_get_color_opt(opt, DIFF_FRAGINFO);
+	const char *reset = diff_get_color_opt(opt, DIFF_RESET);
+	int i;
+
+	for (i = 0; i < range->nr; i++) {
+		struct range *r = range->ranges + i;
+		long lenp = r->pend - r->pstart + 1, pstart = r->pstart;
+		long len = r->end - r->start + 1;
+		if (pstart == 0)
+			lenp = 0;
+
+		fprintf(opt->file, "%s@@ -%ld,%ld +%ld,%ld @@%s\n",
+			set, pstart, lenp, r->start, len, reset);
+
+		diff_flush_range(opt, chunk, r);
+	}
+}
+
+static void diff_flush_filepair(struct rev_info *rev, struct diff_line_range *range)
+{
+	struct diff_options *opt = &rev->diffopt;
+	struct diff_filespec *one = range->prev, *two = range->spec;
+	struct diff_filepair p = {one, two, range->status, 0};
+	struct strbuf header = STRBUF_INIT, meta = STRBUF_INIT;
+	const char *a_prefix, *b_prefix;
+	const char *name_a, *name_b, *a_one, *b_two;
+	const char *lbl[2];
+	const char *set = diff_get_color_opt(opt, DIFF_METAINFO);
+	const char *reset = diff_get_color_opt(opt, DIFF_RESET);
+	struct line_chunk chunk;
+	int must_show_header;
+
+	/*
+	 * the ranges that touch no different file, in this case
+	 * the line number will not change, and of course we have
+	 * no sensible rang->pair since there is no diff run.
+	 */
+	if (one == NULL) {
+		return;
+	}
+
+	if (range->status == DIFF_STATUS_DELETED)
+		die("We are following an nonexistent file, interesting!");
+
+	name_a  = one->path;
+	name_b = two->path;
+	fill_metainfo(&meta, name_a, name_b, one, two, opt, &p, &must_show_header,
+			DIFF_OPT_TST(opt, COLOR_DIFF));
+
+	diff_set_mnemonic_prefix(opt, "a/", "b/");
+	if (DIFF_OPT_TST(opt, REVERSE_DIFF)) {
+		a_prefix = opt->b_prefix;
+		b_prefix = opt->a_prefix;
+	} else {
+		a_prefix = opt->a_prefix;
+		b_prefix = opt->b_prefix;
+	}
+
+	name_a = DIFF_FILE_VALID(one) ? name_a : name_b;
+	name_b = DIFF_FILE_VALID(two) ? name_b : name_a;
+
+	a_one = quote_two(a_prefix, name_a + (*name_a == '/'));
+	b_two = quote_two(b_prefix, name_b + (*name_b == '/'));
+	lbl[0] = DIFF_FILE_VALID(one) ? a_one : "/dev/null";
+	lbl[1] = DIFF_FILE_VALID(two) ? b_two : "/dev/null";
+	strbuf_addf(&header, "%sdiff --git %s %s%s\n", set, a_one, b_two, reset);
+	if (lbl[0][0] == '/') {
+		strbuf_addf(&header, "%snew file mode %06o%s\n", set, two->mode, reset);
+	} else if (lbl[1][0] == '/') {
+		strbuf_addf(&header, "%sdeleted file mode %06o%s\n", set, one->mode, reset);
+	} else if (one->mode != two->mode) {
+			strbuf_addf(&header, "%sold mode %06o%s\n", set, one->mode, reset);
+			strbuf_addf(&header, "%snew mode %06o%s\n", set, two->mode, reset);
+	}
+
+	fprintf(opt->file, "%s%s", header.buf, meta.buf);
+	strbuf_release(&meta);
+	strbuf_release(&header);
+	fprintf(opt->file, "%s--- %s%s\n", set, lbl[0], reset);
+	fprintf(opt->file, "%s+++ %s%s\n", set, lbl[1], reset);
+	free((void *)a_one);
+	free((void *)b_two);
+
+	chunk.one = one->data;
+	chunk.one_end = one->data + one->size;
+	chunk.lone = 1;
+	chunk.two = two->data;
+	chunk.two_end = two->data + two->size;
+	chunk.ltwo = 1;
+	chunk.range = range;
+	diff_flush_chunks(&rev->diffopt, &chunk);
+}
+
+#define EVIL_MERGE_STR "nontrivial merge found"
+static void flush_nontrivial_merge(struct rev_info *rev, struct diff_line_range *range)
+{
+	struct diff_options *opt = &rev->diffopt;
+	const char *reset = diff_get_color_opt(opt, DIFF_RESET);
+	const char *frag = diff_get_color_opt(opt, DIFF_FRAGINFO);
+	const char *meta = diff_get_color_opt(opt, DIFF_METAINFO);
+	const char *new = diff_get_color_opt(opt, DIFF_FILE_NEW);
+
+	fprintf(opt->file, "%s%s%s\n", meta, EVIL_MERGE_STR, reset);
+
+	while (range) {
+		if (range->nr) {
+			int lno = 1;
+			const char *ptr = range->spec->data;
+			const char *end = range->spec->data + range->spec->size;
+			int i = 0;
+			fprintf(opt->file, "%s%s%s\n\n", meta, range->spec->path, reset);
+			for (; i < range->nr; i++) {
+				struct range *r = range->ranges + i;
+				fprintf(opt->file, "%s@@ %ld,%ld @@%s\n", frag, r->start,
+					r->end - r->start + 1, reset);
+				flush_lines(opt, &ptr, end, r->start, r->end,
+					&lno, new, ' ');
+			}
+			fprintf(opt->file, "\n");
+		}
+		range = range->next;
+	}
+}
+
+static void line_log_flush(struct rev_info *rev, struct commit *c)
+{
+	struct diff_line_range *range = lookup_line_range(rev, c);
+	struct diff_line_range *nontrivial = lookup_decoration(&rev->nontrivial_merge, &c->object);
+	struct log_info log;
+
+	if (range == NULL)
+		return;
+
+	log.commit = c;
+	log.parent = NULL;
+	rev->loginfo = &log;
+	show_log(rev);
+	rev->loginfo = NULL;
+	/*
+	 * Add a new line after each commit message, of course we should
+	 * add --graph alignment later when the patches comes to master.
+	 */
+	fprintf(rev->diffopt.file, "\n");
+
+	if (c->object.flags & EVIL_MERGE)
+		return flush_nontrivial_merge(rev, nontrivial);
+
+	while (range) {
+		if (range->diff)
+			diff_flush_filepair(rev, range);
+		range = range->next;
+	}
+}
+

builtin/log.c, line.c, line.h, revision.c

diff --git a/builtin/log.c b/builtin/log.c
index 84d781e..0aa982b 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -616,7 +616,10 @@ int cmd_log(int argc, const char **argv, const char *prefix)
 	memset(&opt, 0, sizeof(opt));
 	opt.def = "HEAD";
 	cmd_log_init(argc, argv, prefix, &rev, &opt);
-	return cmd_log_walk(&rev);
+	if (rev.line_level_traverse)
+		return cmd_line_log_walk(&rev);
+	else
+		return cmd_log_walk(&rev);
 }
 
 /* format-patch */
diff --git a/line.c b/line.c
index bd63d99..c17659a 100644
--- a/line.c
+++ b/line.c
@@ -1232,3 +1232,57 @@ static void line_log_flush(struct rev_info *rev, struct commit *c)
 	}
 }
 
+int cmd_line_log_walk(struct rev_info *rev)
+{
+	struct commit *commit;
+	struct commit_list *list = NULL;
+	struct diff_line_range *r = NULL;
+
+	if (prepare_revision_walk(rev))
+		die("revision walk prepare failed");
+
+	list = rev->commits;
+	if (list) {
+		list->item->object.flags |= RANGE_UPDATE;
+		list = list->next;
+	}
+	/* Clear the flags */
+	while (list) {
+		list->item->object.flags &= ~(RANGE_UPDATE | EVIL_MERGE | NEED_PRINT);
+		list = list->next;
+	}
+
+	list = rev->commits;
+	while (list) {
+		struct commit_list *need_free = list;
+		commit = list->item;
+
+		if (commit->object.flags & RANGE_UPDATE) {
+			assign_parents_range(rev, commit);
+		}
+
+		if (commit->object.flags & NEED_PRINT) {
+			line_log_flush(rev, commit);
+		}
+
+		r = lookup_line_range(rev, commit);
+		if (r) {
+			cleanup(r);
+			r = NULL;
+			add_line_range(rev, commit, r);
+		}
+
+		r = lookup_decoration(&rev->nontrivial_merge, &commit->object);
+		if (r) {
+			cleanup(r);
+			r = NULL;
+			add_decoration(&rev->nontrivial_merge, &commit->object, r);
+		}
+
+		list = list->next;
+		free(need_free);
+	}
+
+	return 0;
+}
+
diff --git a/line.h b/line.h
index 7563536..3f5c827 100644
--- a/line.h
+++ b/line.h
@@ -134,4 +134,6 @@ extern struct diff_line_range *lookup_line_range(struct rev_info *revs,
 const char *parse_loc(const char *spec, nth_line_fn_t nth_line,
 		void *data, long lines, long begin, long *ret);
 
+extern int cmd_line_log_walk(struct rev_info *rev);
+
 #endif
diff --git a/revision.c b/revision.c
index 7e82efd..25c9a94 100644
--- a/revision.c
+++ b/revision.c
@@ -1637,6 +1637,12 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, struct s
 	if (revs->combine_merges)
 		revs->ignore_merges = 0;
 	revs->diffopt.abbrev = revs->abbrev;
+
+	if (revs->line_level_traverse) {
+		revs->limited = 1;
+		revs->topo_order = 1;
+	}
+
 	if (diff_setup_done(&revs->diffopt) < 0)
 		die("diff_setup_done failed");
 

builtin/log.c, line.c, revision.h

diff --git a/builtin/log.c b/builtin/log.c
index 0aa982b..9799c1c 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -86,6 +86,7 @@ static void cmd_log_init(int argc, const char **argv, const char *prefix,
 {
 	int i;
 	int decoration_given = 0;
+	static int full_line_diff = 0;
 	struct userformat_want w;
 	const char *path = NULL, *pathspec = NULL;
 	static struct diff_line_range *range = NULL, *r = NULL;
@@ -93,6 +94,7 @@ static void cmd_log_init(int argc, const char **argv, const char *prefix,
 	static struct line_opt_callback_data line_cb = {&range, &ctx, NULL};
 	static const struct option options[] = {
 		OPT_CALLBACK('L', NULL, &line_cb, "n,m", "Process only line range n,m, counting from 1", log_line_range_callback),
+		OPT_BOOLEAN(0, "full-line-diff", &full_line_diff, "Always print the interesting range even if the current commit does not change any line of it"),
 		OPT_END()
 	};
 
@@ -225,6 +227,7 @@ parse_done:
 	/* Test whether line level history is asked for */
 	if (range && range->nr > 0) {
 		setup_line(rev, range);
+		rev->full_line_diff = full_line_diff;
 	}
 }
 
diff --git a/line.c b/line.c
index c17659a..5317fe5 100644
--- a/line.c
+++ b/line.c
@@ -1116,6 +1116,13 @@ static void diff_flush_filepair(struct rev_info *rev, struct diff_line_range *ra
 	 * no sensible rang->pair since there is no diff run.
 	 */
 	if (one == NULL) {
+		if (rev->full_line_diff) {
+			chunk.two = two->data;
+			chunk.two_end = two->data + two->size;
+			chunk.ltwo = 1;
+			chunk.range = range;
+			diff_flush_chunks(&rev->diffopt, &chunk);
+		}
 		return;
 	}
 
@@ -1226,7 +1233,7 @@ static void line_log_flush(struct rev_info *rev, struct commit *c)
 		return flush_nontrivial_merge(rev, nontrivial);
 
 	while (range) {
-		if (range->diff)
+		if (range->diff || (range->nr && rev->full_line_diff))
 			diff_flush_filepair(rev, range);
 		range = range->next;
 	}
@@ -1261,7 +1268,7 @@ int cmd_line_log_walk(struct rev_info *rev)
 			assign_parents_range(rev, commit);
 		}
 
-		if (commit->object.flags & NEED_PRINT) {
+		if (commit->object.flags & NEED_PRINT || rev->full_line_diff) {
 			line_log_flush(rev, commit);
 		}
 
diff --git a/revision.h b/revision.h
index 2627ec4..e4b6adf 100644
--- a/revision.h
+++ b/revision.h
@@ -72,7 +72,8 @@ struct rev_info {
 			bisect:1,
 			ancestry_path:1,
 			first_parent_only:1,
-			line_level_traverse:1;
+			line_level_traverse:1,
+			full_line_diff:1;
 
 	/* Diff flags */
 	unsigned int	diff:1,

t/t4301-log-line-single-history.sh, t/t4302-log-line-merge-history.sh

diff --git a/t/t4301-log-line-single-history.sh b/t/t4301-log-line-single-history.sh
new file mode 100755
index 0000000..9cf34f8
--- /dev/null
+++ b/t/t4301-log-line-single-history.sh
@@ -0,0 +1,342 @@
+#!/bin/sh
+#
+# Copyright (c) 2010 Bo Yang
+#
+
+test_description='Test git log -L with single line of history
+
+'
+. ./test-lib.sh
+. "$TEST_DIRECTORY"/diff-lib.sh
+
+echo >path0 'void func(){
+	int a = 0;
+	int b = 1;
+	int c;
+	c = a + b;
+}
+'
+
+echo >path1 'void output(){
+	printf("hello world");
+}
+'
+
+test_expect_success \
+    'add path0/path1 and commit.' \
+    'git add path0 path1 &&
+     git commit -m "Base commit"'
+
+echo >path0 'void func(){
+	int a = 10;
+	int b = 11;
+	int c;
+	c = a + b;
+}
+'
+
+echo >path1 'void output(){
+	const char *str = "hello world!";
+	printf("%s", str);
+}
+'
+
+test_expect_success \
+    'Change the 2,3 lines of path0 and path1.' \
+    'git add path0 path1 &&
+     git commit -m "Change 2,3 lines of path0 and path1"'
+
+echo >path0 'void func(){
+	int a = 10;
+	int b = 11;
+	int c;
+	c = 10 * (a + b);
+}
+'
+
+test_expect_success \
+	'Change the 5th line of path0.' \
+	'git add path0 &&
+	 git commit -m "Change the 5th line of path0"'
+
+echo >path0 'void func(){
+	int a = 10;
+	int b = 11;
+	printf("%d", a - b);
+}
+'
+
+test_expect_success \
+	'Final change of path0.' \
+	'git add path0 &&
+	 git commit -m "Final change of path0"'
+
+test_expect_success \
+    'Show the line level log of path0' \
+    'git log --pretty=format:%s%n%b -L /func/,/^}/ path0 > current-path0'
+
+test_expect_success \
+    'Show the line level log of path1' \
+    'git log --pretty=format:%s%n%b -L /output/,/^}/ path1 > current-path1'
+
+test_expect_success \
+	'Show the line level log of two files' \
+    'git log --pretty=format:%s%n%b -L /func/,/^}/ path0 -L /output/,/^}/ path1 > current-pathall'
+
+test_expect_success \
+	'Test the line number argument' \
+	'git log --pretty=format:%s%n%b -L 1,2 path0 > current-linenum'
+
+test_expect_success \
+	'Test the --full-line-diff option' \
+	'git log --pretty=format:%s%n%b --full-line-diff -L 1,2 path0 > current-always'
+
+cat >expected-path0 <<\EOF
+Final change of path0
+
+diff --git a/path0 b/path0
+index 44db133..1518c15 100644
+--- a/path0
++++ b/path0
+@@ -1,6 +1,5 @@
+ void func(){
+ 	int a = 10;
+ 	int b = 11;
+-	int c;
+-	c = 10 * (a + b);
++	printf("%d", a - b);
+ }
+
+Change the 5th line of path0
+
+diff --git a/path0 b/path0
+index 9ef1692..44db133 100644
+--- a/path0
++++ b/path0
+@@ -1,6 +1,6 @@
+ void func(){
+ 	int a = 10;
+ 	int b = 11;
+ 	int c;
+-	c = a + b;
++	c = 10 * (a + b);
+ }
+
+Change 2,3 lines of path0 and path1
+
+diff --git a/path0 b/path0
+index aabffdf..9ef1692 100644
+--- a/path0
++++ b/path0
+@@ -1,6 +1,6 @@
+ void func(){
+-	int a = 0;
+-	int b = 1;
++	int a = 10;
++	int b = 11;
+ 	int c;
+ 	c = a + b;
+ }
+
+Base commit
+
+diff --git a/path0 b/path0
+new file mode 100644
+index 0000000..aabffdf
+--- /dev/null
++++ b/path0
+@@ -0,0 +1,6 @@
++void func(){
++	int a = 0;
++	int b = 1;
++	int c;
++	c = a + b;
++}
+EOF
+
+cat >expected-path1 <<\EOF
+Change 2,3 lines of path0 and path1
+
+diff --git a/path1 b/path1
+index 997d841..1d711b5 100644
+--- a/path1
++++ b/path1
+@@ -1,3 +1,4 @@
+ void output(){
+-	printf("hello world");
++	const char *str = "hello world!";
++	printf("%s", str);
+ }
+
+Base commit
+
+diff --git a/path1 b/path1
+new file mode 100644
+index 0000000..997d841
+--- /dev/null
++++ b/path1
+@@ -0,0 +1,3 @@
++void output(){
++	printf("hello world");
++}
+EOF
+
+cat >expected-pathall <<\EOF
+Final change of path0
+
+diff --git a/path0 b/path0
+index 44db133..1518c15 100644
+--- a/path0
++++ b/path0
+@@ -1,6 +1,5 @@
+ void func(){
+ 	int a = 10;
+ 	int b = 11;
+-	int c;
+-	c = 10 * (a + b);
++	printf("%d", a - b);
+ }
+
+Change the 5th line of path0
+
+diff --git a/path0 b/path0
+index 9ef1692..44db133 100644
+--- a/path0
++++ b/path0
+@@ -1,6 +1,6 @@
+ void func(){
+ 	int a = 10;
+ 	int b = 11;
+ 	int c;
+-	c = a + b;
++	c = 10 * (a + b);
+ }
+
+Change 2,3 lines of path0 and path1
+
+diff --git a/path0 b/path0
+index aabffdf..9ef1692 100644
+--- a/path0
++++ b/path0
+@@ -1,6 +1,6 @@
+ void func(){
+-	int a = 0;
+-	int b = 1;
++	int a = 10;
++	int b = 11;
+ 	int c;
+ 	c = a + b;
+ }
+diff --git a/path1 b/path1
+index 997d841..1d711b5 100644
+--- a/path1
++++ b/path1
+@@ -1,3 +1,4 @@
+ void output(){
+-	printf("hello world");
++	const char *str = "hello world!";
++	printf("%s", str);
+ }
+
+Base commit
+
+diff --git a/path0 b/path0
+new file mode 100644
+index 0000000..aabffdf
+--- /dev/null
++++ b/path0
+@@ -0,0 +1,6 @@
++void func(){
++	int a = 0;
++	int b = 1;
++	int c;
++	c = a + b;
++}
+diff --git a/path1 b/path1
+new file mode 100644
+index 0000000..997d841
+--- /dev/null
++++ b/path1
+@@ -0,0 +1,3 @@
++void output(){
++	printf("hello world");
++}
+EOF
+
+cat >expected-linenum <<\EOF
+Change 2,3 lines of path0 and path1
+
+diff --git a/path0 b/path0
+index aabffdf..9ef1692 100644
+--- a/path0
++++ b/path0
+@@ -1,2 +1,2 @@
+ void func(){
+-	int a = 0;
++	int a = 10;
+
+Base commit
+
+diff --git a/path0 b/path0
+new file mode 100644
+index 0000000..aabffdf
+--- /dev/null
++++ b/path0
+@@ -0,0 +1,2 @@
++void func(){
++	int a = 0;
+EOF
+
+cat >expected-always <<\EOF
+Final change of path0
+
+diff --git a/path0 b/path0
+index 44db133..1518c15 100644
+--- a/path0
++++ b/path0
+@@ -1,2 +1,2 @@
+ void func(){
+ 	int a = 10;
+
+Change the 5th line of path0
+
+diff --git a/path0 b/path0
+index 9ef1692..44db133 100644
+--- a/path0
++++ b/path0
+@@ -1,2 +1,2 @@
+ void func(){
+ 	int a = 10;
+
+Change 2,3 lines of path0 and path1
+
+diff --git a/path0 b/path0
+index aabffdf..9ef1692 100644
+--- a/path0
++++ b/path0
+@@ -1,2 +1,2 @@
+ void func(){
+-	int a = 0;
++	int a = 10;
+
+Base commit
+
+diff --git a/path0 b/path0
+new file mode 100644
+index 0000000..aabffdf
+--- /dev/null
++++ b/path0
+@@ -0,0 +1,2 @@
++void func(){
++	int a = 0;
+EOF
+
+test_expect_success \
+    'validate the output.' \
+    'test_cmp current-path0 expected-path0 &&
+	 test_cmp current-path1 expected-path1 &&
+	 test_cmp current-pathall expected-pathall &&
+	 test_cmp current-linenum expected-linenum &&
+	 test_cmp current-always expected-always'
+
+test_done
diff --git a/t/t4302-log-line-merge-history.sh b/t/t4302-log-line-merge-history.sh
new file mode 100755
index 0000000..02e7439
--- /dev/null
+++ b/t/t4302-log-line-merge-history.sh
@@ -0,0 +1,114 @@
+#!/bin/sh
+#
+# Copyright (c) 2010 Bo Yang
+#
+
+test_description='Test git log -L with merge commit
+
+'
+. ./test-lib.sh
+. "$TEST_DIRECTORY"/diff-lib.sh
+
+echo >path0 'void func(){
+	printf("hello");
+}
+'
+
+test_expect_success \
+    'Add path0 and commit.' \
+    'git add path0 &&
+     git commit -m "Base commit"'
+
+echo >path0 'void func(){
+	printf("hello earth");
+}
+'
+
+test_expect_success \
+    'Change path0 in master.' \
+    'git add path0 &&
+     git commit -m "Change path0 in master"'
+
+test_expect_success \
+	'Make a new branch from the base commit' \
+	'git checkout -b feature master^'
+
+echo >path0 'void func(){
+	print("hello moon");
+}
+'
+
+test_expect_success \
+    'Change path0 in feature.' \
+    'git add path0 &&
+     git commit -m "Change path0 in feature"'
+
+test_expect_success \
+	'Merge the master to feature' \
+	'! git merge master'
+
+echo >path0 'void func(){
+	printf("hello earth and moon");
+}
+'
+
+test_expect_success \
+	'Resolve the conflict' \
+	'git add path0 &&
+	 git commit -m "Merge two branches"'
+
+test_expect_success \
+    'Show the line level log of path0' \
+    'git log --pretty=format:%s%n%b -L /func/,/^}/ path0 > current'
+
+cat >expected <<\EOF
+Merge two branches
+
+nontrivial merge found
+path0
+
+@@ 2,1 @@
+ 	printf("hello earth and moon");
+
+
+Change path0 in master
+
+diff --git a/path0 b/path0
+index f628dea..bef7fa3 100644
+--- a/path0
++++ b/path0
+@@ -1,3 +1,3 @@
+ void func(){
+-	printf("hello");
++	printf("hello earth");
+ }
+
+Change path0 in feature
+
+diff --git a/path0 b/path0
+index f628dea..a940ef6 100644
+--- a/path0
++++ b/path0
+@@ -1,3 +1,3 @@
+ void func(){
+-	printf("hello");
++	print("hello moon");
+ }
+
+Base commit
+
+diff --git a/path0 b/path0
+new file mode 100644
+index 0000000..f628dea
+--- /dev/null
++++ b/path0
+@@ -0,0 +1,3 @@
++void func(){
++	printf("hello");
++}
+EOF
+test_expect_success \
+    'validate the output.' \
+    'test_cmp current expected'
+
+test_done

Documentation/blame-options.txt, Documentation/git-log.txt, Documentation/line-range-format.txt

diff --git a/Documentation/blame-options.txt b/Documentation/blame-options.txt
index 16e3c68..3526835 100644
--- a/Documentation/blame-options.txt
+++ b/Documentation/blame-options.txt
@@ -13,24 +13,7 @@
 	Annotate only the given line range.  <start> and <end> can take
 	one of these forms:
 
-	- number
-+
-If <start> or <end> is a number, it specifies an
-absolute line number (lines count from 1).
-+
-
-- /regex/
-+
-This form will use the first line matching the given
-POSIX regex.  If <end> is a regex, it will search
-starting at the line given by <start>.
-+
-
-- +offset or -offset
-+
-This is only valid for <end> and will specify a number
-of lines before or after the line given by <start>.
-+
+include::line-range-format.txt[]
 
 -l::
 	Show long rev (Default: off).
diff --git a/Documentation/git-log.txt b/Documentation/git-log.txt
index e970664..6f712e7 100644
--- a/Documentation/git-log.txt
+++ b/Documentation/git-log.txt
@@ -9,6 +9,7 @@ git-log - Show commit logs
 SYNOPSIS
 --------
 'git log' [<options>] [<since>..<until>] [[\--] <path>...]
+'git log' [<options>] -L n,m <path>
 
 DESCRIPTION
 -----------
@@ -19,6 +20,9 @@ command to control what is shown and how, and options applicable to
 the 'git diff-*' commands to control how the changes
 each commit introduces are shown.
 
+With '-L' option, the command will help to trace the history of user specified
+line ranges. It can trace multiple ranges coming from multiple files.
+
 
 OPTIONS
 -------
@@ -63,6 +67,17 @@ OPTIONS
 	Note that only message is considered, if also a diff is shown
 	its size is not included.
 
+-L <start>,<end>::
+	The line range.  <start> and <end> can take one of these forms:
+
+include::line-range-format.txt[]
+You can also specify this option more than once before each path.
+
+
+--full-line-diff::
+	Always print the interesting range even if the current commit
+	does not change any line of the range.
+
 [\--] <path>...::
 	Show only commits that affect any of the specified paths. To
 	prevent confusion with options and branch names, paths may need
diff --git a/Documentation/line-range-format.txt b/Documentation/line-range-format.txt
new file mode 100644
index 0000000..265bc23
--- /dev/null
+++ b/Documentation/line-range-format.txt
@@ -0,0 +1,18 @@
+- number
++
+If <start> or <end> is a number, it specifies an
+absolute line number (lines count from 1).
++
+
+- /regex/
++
+This form will use the first line matching the given
+POSIX regex.  If <end> is a regex, it will search
+starting at the line given by <start>.
++
+
+- +offset or -offset
++
+This is only valid for <end> and will specify a number
+of lines before or after the line given by <start>.
++

revision.c, revision.h

diff --git a/revision.c b/revision.c
index 25c9a94..fb08978 100644
--- a/revision.c
+++ b/revision.c
@@ -1893,12 +1893,6 @@ int prepare_revision_walk(struct rev_info *revs)
 	return 0;
 }
 
-enum rewrite_result {
-	rewrite_one_ok,
-	rewrite_one_noparents,
-	rewrite_one_error
-};
-
 static enum rewrite_result rewrite_one(struct rev_info *revs, struct commit **pp)
 {
 	struct commit_list *cache = NULL;
@@ -1920,12 +1914,13 @@ static enum rewrite_result rewrite_one(struct rev_info *revs, struct commit **pp
 	}
 }
 
-static int rewrite_parents(struct rev_info *revs, struct commit *commit)
+int rewrite_parents(struct rev_info *revs, struct commit *commit,
+	rewrite_parent_fn_t rewrite_parent)
 {
 	struct commit_list **pp = &commit->parents;
 	while (*pp) {
 		struct commit_list *parent = *pp;
-		switch (rewrite_one(revs, &parent->item)) {
+		switch (rewrite_parent(revs, &parent->item)) {
 		case rewrite_one_ok:
 			break;
 		case rewrite_one_noparents:
@@ -1993,7 +1988,7 @@ enum commit_action simplify_commit(struct rev_info *revs, struct commit *commit)
 	if (action == commit_show &&
 	    !revs->show_all &&
 	    revs->prune && revs->dense && want_ancestry(revs)) {
-		if (rewrite_parents(revs, commit) < 0)
+		if (rewrite_parents(revs, commit, rewrite_one) < 0)
 			return commit_error;
 	}
 	return action;
diff --git a/revision.h b/revision.h
index e4b6adf..e625c3d 100644
--- a/revision.h
+++ b/revision.h
@@ -200,4 +200,14 @@ enum commit_action {
 extern enum commit_action get_commit_action(struct rev_info *revs, struct commit *commit);
 extern enum commit_action simplify_commit(struct rev_info *revs, struct commit *commit);
 
+enum rewrite_result {
+	rewrite_one_ok,
+	rewrite_one_noparents,
+	rewrite_one_error
+};
+
+typedef enum rewrite_result (*rewrite_parent_fn_t)(struct rev_info *revs, struct commit **pp);
+
+extern int rewrite_parents(struct rev_info *revs, struct commit *commit,
+	rewrite_parent_fn_t rewrite_parent);
 #endif

line.c, line.h, revision.c

diff --git a/line.c b/line.c
index 5317fe5..cc8be97 100644
--- a/line.c
+++ b/line.c
@@ -10,6 +10,9 @@
 #include "xdiff-interface.h"
 #include "strbuf.h"
 #include "log-tree.h"
+#include "graph.h"
+
+static int limited = 0;
 
 static void cleanup(struct diff_line_range *r)
 {
@@ -1249,12 +1252,12 @@ int cmd_line_log_walk(struct rev_info *rev)
 		die("revision walk prepare failed");
 
 	list = rev->commits;
-	if (list) {
+	if (list && !limited) {
 		list->item->object.flags |= RANGE_UPDATE;
 		list = list->next;
 	}
 	/* Clear the flags */
-	while (list) {
+	while (list && !limited) {
 		list->item->object.flags &= ~(RANGE_UPDATE | EVIL_MERGE | NEED_PRINT);
 		list = list->next;
 	}
@@ -1268,7 +1271,9 @@ int cmd_line_log_walk(struct rev_info *rev)
 			assign_parents_range(rev, commit);
 		}
 
-		if (commit->object.flags & NEED_PRINT || rev->full_line_diff) {
+		if (commit->object.flags & NEED_PRINT || rev->full_line_diff || rev->graph) {
+			if (rev->graph)
+				graph_update(rev->graph, commit);
 			line_log_flush(rev, commit);
 		}
 
@@ -1293,3 +1298,86 @@ int cmd_line_log_walk(struct rev_info *rev)
 	return 0;
 }
 
+static enum rewrite_result rewrite_one(struct rev_info *rev, struct commit **pp)
+{
+	struct diff_line_range *r = NULL;
+	struct commit *p;
+	while (1) {
+		p = *pp;
+		if (p->object.flags & RANGE_UPDATE)
+			assign_parents_range(rev, p);
+		if (p->parents && p->parents->next)
+			return rewrite_one_ok;
+		if (p->object.flags & NEED_PRINT)
+			return rewrite_one_ok;
+		if (!p->parents)
+			return rewrite_one_noparents;
+
+		r = lookup_line_range(rev, p);
+		if (!r)
+			return rewrite_one_noparents;
+		*pp = p->parents->item;
+	}
+}
+
+/* The rev->commits must be sorted in topologically order */
+void limit_list_line(struct rev_info *rev)
+{
+	struct commit_list *list = rev->commits;
+	struct commit_list *commits = xmalloc(sizeof(struct commit_list));
+	struct commit_list *out = commits, *prev = commits;
+	struct commit *c;
+	struct diff_line_range *r;
+
+	if (list) {
+		list->item->object.flags |= RANGE_UPDATE;
+		list = list->next;
+	}
+	/* Clear the flags */
+	while (list) {
+		list->item->object.flags &= ~(RANGE_UPDATE | EVIL_MERGE | NEED_PRINT);
+		list = list->next;
+	}
+
+	list = rev->commits;
+	while (list) {
+		c = list->item;
+
+		if (c->object.flags & RANGE_UPDATE)
+			assign_parents_range(rev, c);
+
+		if (c->object.flags & NEED_PRINT ||
+			(c->parents && c->parents->next)) {
+			if (rewrite_parents(rev, c, rewrite_one))
+				die("Can't rewrite parent for commit %s",
+					sha1_to_hex(c->object.sha1));
+			commits->item = c;
+			commits->next = xmalloc(sizeof(struct commit_list));
+			prev = commits;
+			commits = commits->next;
+		} else {
+			r = lookup_line_range(rev, c);
+			if (r) {
+				cleanup(r);
+				r = NULL;
+				add_line_range(rev, c, r);
+			}
+		}
+
+		list = list->next;
+	}
+
+	prev->next = NULL;
+	free(commits);
+
+	list = rev->commits;
+	while (list) {
+		struct commit_list *l = list;
+		list = list->next;
+		free(l);
+	}
+
+	rev->commits = out;
+	limited = 1;
+}
+
diff --git a/line.h b/line.h
index 3f5c827..a2083ec 100644
--- a/line.h
+++ b/line.h
@@ -136,4 +136,6 @@ const char *parse_loc(const char *spec, nth_line_fn_t nth_line,
 
 extern int cmd_line_log_walk(struct rev_info *rev);
 
+extern void limit_list_line(struct rev_info *rev);
+
 #endif
diff --git a/revision.c b/revision.c
index fb08978..a6527ca 100644
--- a/revision.c
+++ b/revision.c
@@ -13,6 +13,7 @@
 #include "decorate.h"
 #include "log-tree.h"
 #include "string-list.h"
+#include "line.h"
 
 volatile show_early_output_fn_t show_early_output;
 
@@ -1886,6 +1887,8 @@ int prepare_revision_walk(struct rev_info *revs)
 			return -1;
 	if (revs->topo_order)
 		sort_in_topological_order(&revs->commits, revs->lifo);
+	if (revs->rewrite_parents && revs->line_level_traverse)
+		limit_list_line(revs);
 	if (revs->simplify_merges)
 		simplify_merges(revs);
 	if (revs->children.name)

diff --git a/line.c b/line.c
index cc8be97..c8c9ad3 100644
--- a/line.c
+++ b/line.c
@@ -1007,6 +1007,13 @@ static void flush_lines(struct diff_options *opt, const char **ptr, const char *
 	const char *p = *ptr;
 	struct strbuf buf = STRBUF_INIT;
 	const char *reset;
+	char *line_prefix = "";
+	struct strbuf *msgbuf;
+
+	if (opt && opt->output_prefix) {
+		msgbuf = opt->output_prefix(opt, opt->output_prefix_data);
+		line_prefix = msgbuf->buf;
+	}
 
 	if (*color)
 		reset = diff_get_color_opt(opt, DIFF_RESET);
@@ -1029,7 +1036,7 @@ static void flush_lines(struct diff_options *opt, const char **ptr, const char *
 
 	while (*ptr < end && *lno <= elno) {
 		if (**ptr == '\n') {
-			fprintf(opt->file, "%s", buf.buf);
+			fprintf(opt->file, "%s%s", line_prefix, buf.buf);
 			if (*ptr - p) {
 				fwrite(p, *ptr - p, 1, opt->file);
 			}
@@ -1040,7 +1047,7 @@ static void flush_lines(struct diff_options *opt, const char **ptr, const char *
 		(*ptr)++;
 	}
 	if (*lno <= elno) {
-		fprintf(opt->file, "%s", buf.buf);
+		fprintf(opt->file, "%s%s", line_prefix, buf.buf);
 		if (*ptr - p) {
 			fwrite(p, *ptr - p, 1, opt->file);
 		}
@@ -1083,8 +1090,15 @@ static void diff_flush_chunks(struct diff_options *opt, struct line_chunk *chunk
 	struct diff_line_range *range = chunk->range;
 	const char *set = diff_get_color_opt(opt, DIFF_FRAGINFO);
 	const char *reset = diff_get_color_opt(opt, DIFF_RESET);
+	char *line_prefix = "";
+	struct strbuf *msgbuf;
 	int i;
 
+	if (opt && opt->output_prefix) {
+		msgbuf = opt->output_prefix(opt, opt->output_prefix_data);
+		line_prefix = msgbuf->buf;
+	}
+
 	for (i = 0; i < range->nr; i++) {
 		struct range *r = range->ranges + i;
 		long lenp = r->pend - r->pstart + 1, pstart = r->pstart;
@@ -1092,8 +1106,8 @@ static void diff_flush_chunks(struct diff_options *opt, struct line_chunk *chunk
 		if (pstart == 0)
 			lenp = 0;
 
-		fprintf(opt->file, "%s@@ -%ld,%ld +%ld,%ld @@%s\n",
-			set, pstart, lenp, r->start, len, reset);
+		fprintf(opt->file, "%s%s@@ -%ld,%ld +%ld,%ld @@%s\n",
+			line_prefix, set, pstart, lenp, r->start, len, reset);
 
 		diff_flush_range(opt, chunk, r);
 	}
@@ -1112,6 +1126,13 @@ static void diff_flush_filepair(struct rev_info *rev, struct diff_line_range *ra
 	const char *reset = diff_get_color_opt(opt, DIFF_RESET);
 	struct line_chunk chunk;
 	int must_show_header;
+	char *line_prefix = "";
+	struct strbuf *msgbuf;
+
+	if (opt && opt->output_prefix) {
+		msgbuf = opt->output_prefix(opt, opt->output_prefix_data);
+		line_prefix = msgbuf->buf;
+	}
 
 	/*
 	 * the ranges that touch no different file, in this case
@@ -1153,21 +1174,26 @@ static void diff_flush_filepair(struct rev_info *rev, struct diff_line_range *ra
 	b_two = quote_two(b_prefix, name_b + (*name_b == '/'));
 	lbl[0] = DIFF_FILE_VALID(one) ? a_one : "/dev/null";
 	lbl[1] = DIFF_FILE_VALID(two) ? b_two : "/dev/null";
-	strbuf_addf(&header, "%sdiff --git %s %s%s\n", set, a_one, b_two, reset);
+	strbuf_addf(&header, "%s%sdiff --git %s %s%s\n", line_prefix,
+			set, a_one, b_two, reset);
 	if (lbl[0][0] == '/') {
-		strbuf_addf(&header, "%snew file mode %06o%s\n", set, two->mode, reset);
+		strbuf_addf(&header, "%s%snew file mode %06o%s\n",
+			line_prefix, set, two->mode, reset);
 	} else if (lbl[1][0] == '/') {
-		strbuf_addf(&header, "%sdeleted file mode %06o%s\n", set, one->mode, reset);
+		strbuf_addf(&header, "%s%sdeleted file mode %06o%s\n",
+			line_prefix, set, one->mode, reset);
 	} else if (one->mode != two->mode) {
-			strbuf_addf(&header, "%sold mode %06o%s\n", set, one->mode, reset);
-			strbuf_addf(&header, "%snew mode %06o%s\n", set, two->mode, reset);
+			strbuf_addf(&header, "%s%sold mode %06o%s\n",
+				line_prefix, set, one->mode, reset);
+			strbuf_addf(&header, "%s%snew mode %06o%s\n",
+				line_prefix, set, two->mode, reset);
 	}
 
 	fprintf(opt->file, "%s%s", header.buf, meta.buf);
 	strbuf_release(&meta);
 	strbuf_release(&header);
-	fprintf(opt->file, "%s--- %s%s\n", set, lbl[0], reset);
-	fprintf(opt->file, "%s+++ %s%s\n", set, lbl[1], reset);
+	fprintf(opt->file, "%s%s--- %s%s\n", line_prefix, set, lbl[0], reset);
+	fprintf(opt->file, "%s%s+++ %s%s\n", line_prefix, set, lbl[1], reset);
 	free((void *)a_one);
 	free((void *)b_two);
 
@@ -1189,8 +1215,15 @@ static void flush_nontrivial_merge(struct rev_info *rev, struct diff_line_range
 	const char *frag = diff_get_color_opt(opt, DIFF_FRAGINFO);
 	const char *meta = diff_get_color_opt(opt, DIFF_METAINFO);
 	const char *new = diff_get_color_opt(opt, DIFF_FILE_NEW);
+	char *line_prefix = "";
+	struct strbuf *msgbuf;
 
-	fprintf(opt->file, "%s%s%s\n", meta, EVIL_MERGE_STR, reset);
+	if (opt && opt->output_prefix) {
+		msgbuf = opt->output_prefix(opt, opt->output_prefix_data);
+		line_prefix = msgbuf->buf;
+	}
+
+	fprintf(opt->file, "%s%s%s%s\n", line_prefix, meta, EVIL_MERGE_STR, reset);
 
 	while (range) {
 		if (range->nr) {
@@ -1198,15 +1231,17 @@ static void flush_nontrivial_merge(struct rev_info *rev, struct diff_line_range
 			const char *ptr = range->spec->data;
 			const char *end = range->spec->data + range->spec->size;
 			int i = 0;
-			fprintf(opt->file, "%s%s%s\n\n", meta, range->spec->path, reset);
+			fprintf(opt->file, "%s%s%s%s\n%s\n", line_prefix,
+				meta, range->spec->path, reset, line_prefix);
 			for (; i < range->nr; i++) {
 				struct range *r = range->ranges + i;
-				fprintf(opt->file, "%s@@ %ld,%ld @@%s\n", frag, r->start,
+				fprintf(opt->file, "%s%s@@ %ld,%ld @@%s\n",
+					line_prefix, frag, r->start,
 					r->end - r->start + 1, reset);
 				flush_lines(opt, &ptr, end, r->start, r->end,
 					&lno, new, ' ');
 			}
-			fprintf(opt->file, "\n");
+			fprintf(opt->file, "%s\n", line_prefix);
 		}
 		range = range->next;
 	}
@@ -1217,6 +1252,9 @@ static void line_log_flush(struct rev_info *rev, struct commit *c)
 	struct diff_line_range *range = lookup_line_range(rev, c);
 	struct diff_line_range *nontrivial = lookup_decoration(&rev->nontrivial_merge, &c->object);
 	struct log_info log;
+	struct diff_options *opt = &rev->diffopt;
+	char *line_prefix = "";
+	struct strbuf *msgbuf;
 
 	if (range == NULL)
 		return;
@@ -1226,11 +1264,12 @@ static void line_log_flush(struct rev_info *rev, struct commit *c)
 	rev->loginfo = &log;
 	show_log(rev);
 	rev->loginfo = NULL;
-	/*
-	 * Add a new line after each commit message, of course we should
-	 * add --graph alignment later when the patches comes to master.
-	 */
-	fprintf(rev->diffopt.file, "\n");
+
+	if (opt && opt->output_prefix) {
+		msgbuf = opt->output_prefix(opt, opt->output_prefix_data);
+		line_prefix = msgbuf->buf;
+	}
+	fprintf(rev->diffopt.file, "%s\n", line_prefix);
 
 	if (c->object.flags & EVIL_MERGE)
 		return flush_nontrivial_merge(rev, nontrivial);

Documentation/git-log.txt, t/t4301-log-line-single-history.sh, t/t4302-log-line-merge-history.sh

diff --git a/Documentation/git-log.txt b/Documentation/git-log.txt
index 6f712e7..1beb243 100644
--- a/Documentation/git-log.txt
+++ b/Documentation/git-log.txt
@@ -77,6 +77,8 @@ You can also specify this option more than once before each path.
 --full-line-diff::
 	Always print the interesting range even if the current commit
 	does not change any line of the range.
+	Note that this option will take no effect when '--graph' is
+	also given.
 
 [\--] <path>...::
 	Show only commits that affect any of the specified paths. To
diff --git a/t/t4301-log-line-single-history.sh b/t/t4301-log-line-single-history.sh
index 9cf34f8..812a41e 100755
--- a/t/t4301-log-line-single-history.sh
+++ b/t/t4301-log-line-single-history.sh
@@ -339,4 +339,229 @@ test_expect_success \
 	 test_cmp current-linenum expected-linenum &&
 	 test_cmp current-always expected-always'
 
+# Rerun all log with graph
+test_expect_success \
+    'Show the line level log of path0 with --graph' \
+    'git log --pretty=format:%s%n%b --graph -L /func/,/^}/ path0 > current-path0-graph'
+
+test_expect_success \
+    'Show the line level log of path1 with --graph' \
+    'git log --pretty=format:%s%n%b --graph -L /output/,/^}/ path1 > current-path1-graph'
+
+test_expect_success \
+    'Show the line level log of two files with --graph' \
+    'git log --pretty=format:%s%n%b --graph -L /func/,/^}/ path0 --graph -L /output/,/^}/ path1 > current-pathall-graph'
+
+test_expect_success \
+    'Test the line number argument with --graph' \
+    'git log --pretty=format:%s%n%b --graph -L 1,2 path0 > current-linenum-graph'
+
+test_expect_success \
+	'Test the --full-line-diff option with --graph option' \
+	'git log --pretty=format:%s%n%b --full-line-diff --graph -L 1,2 path0 > current-always-graph'
+
+cat > expected-path0-graph <<\EOF
+* Final change of path0
+| 
+| diff --git a/path0 b/path0
+| index 44db133..1518c15 100644
+| --- a/path0
+| +++ b/path0
+| @@ -1,6 +1,5 @@
+|  void func(){
+|  	int a = 10;
+|  	int b = 11;
+| -	int c;
+| -	c = 10 * (a + b);
+| +	printf("%d", a - b);
+|  }
+|  
+* Change the 5th line of path0
+| 
+| diff --git a/path0 b/path0
+| index 9ef1692..44db133 100644
+| --- a/path0
+| +++ b/path0
+| @@ -1,6 +1,6 @@
+|  void func(){
+|  	int a = 10;
+|  	int b = 11;
+|  	int c;
+| -	c = a + b;
+| +	c = 10 * (a + b);
+|  }
+|  
+* Change 2,3 lines of path0 and path1
+| 
+| diff --git a/path0 b/path0
+| index aabffdf..9ef1692 100644
+| --- a/path0
+| +++ b/path0
+| @@ -1,6 +1,6 @@
+|  void func(){
+| -	int a = 0;
+| -	int b = 1;
+| +	int a = 10;
+| +	int b = 11;
+|  	int c;
+|  	c = a + b;
+|  }
+|  
+* Base commit
+  
+  diff --git a/path0 b/path0
+  new file mode 100644
+  index 0000000..aabffdf
+  --- /dev/null
+  +++ b/path0
+  @@ -0,0 +1,6 @@
+  +void func(){
+  +	int a = 0;
+  +	int b = 1;
+  +	int c;
+  +	c = a + b;
+  +}
+EOF
+
+cat > expected-path1-graph <<\EOF
+* Change 2,3 lines of path0 and path1
+| 
+| diff --git a/path1 b/path1
+| index 997d841..1d711b5 100644
+| --- a/path1
+| +++ b/path1
+| @@ -1,3 +1,4 @@
+|  void output(){
+| -	printf("hello world");
+| +	const char *str = "hello world!";
+| +	printf("%s", str);
+|  }
+|  
+* Base commit
+  
+  diff --git a/path1 b/path1
+  new file mode 100644
+  index 0000000..997d841
+  --- /dev/null
+  +++ b/path1
+  @@ -0,0 +1,3 @@
+  +void output(){
+  +	printf("hello world");
+  +}
+EOF
+
+cat > expected-pathall-graph <<\EOF
+* Final change of path0
+| 
+| diff --git a/path0 b/path0
+| index 44db133..1518c15 100644
+| --- a/path0
+| +++ b/path0
+| @@ -1,6 +1,5 @@
+|  void func(){
+|  	int a = 10;
+|  	int b = 11;
+| -	int c;
+| -	c = 10 * (a + b);
+| +	printf("%d", a - b);
+|  }
+|  
+* Change the 5th line of path0
+| 
+| diff --git a/path0 b/path0
+| index 9ef1692..44db133 100644
+| --- a/path0
+| +++ b/path0
+| @@ -1,6 +1,6 @@
+|  void func(){
+|  	int a = 10;
+|  	int b = 11;
+|  	int c;
+| -	c = a + b;
+| +	c = 10 * (a + b);
+|  }
+|  
+* Change 2,3 lines of path0 and path1
+| 
+| diff --git a/path0 b/path0
+| index aabffdf..9ef1692 100644
+| --- a/path0
+| +++ b/path0
+| @@ -1,6 +1,6 @@
+|  void func(){
+| -	int a = 0;
+| -	int b = 1;
+| +	int a = 10;
+| +	int b = 11;
+|  	int c;
+|  	c = a + b;
+|  }
+| diff --git a/path1 b/path1
+| index 997d841..1d711b5 100644
+| --- a/path1
+| +++ b/path1
+| @@ -1,3 +1,4 @@
+|  void output(){
+| -	printf("hello world");
+| +	const char *str = "hello world!";
+| +	printf("%s", str);
+|  }
+|  
+* Base commit
+  
+  diff --git a/path0 b/path0
+  new file mode 100644
+  index 0000000..aabffdf
+  --- /dev/null
+  +++ b/path0
+  @@ -0,0 +1,6 @@
+  +void func(){
+  +	int a = 0;
+  +	int b = 1;
+  +	int c;
+  +	c = a + b;
+  +}
+  diff --git a/path1 b/path1
+  new file mode 100644
+  index 0000000..997d841
+  --- /dev/null
+  +++ b/path1
+  @@ -0,0 +1,3 @@
+  +void output(){
+  +	printf("hello world");
+  +}
+EOF
+
+cat > expected-linenum-graph <<\EOF
+* Change 2,3 lines of path0 and path1
+| 
+| diff --git a/path0 b/path0
+| index aabffdf..9ef1692 100644
+| --- a/path0
+| +++ b/path0
+| @@ -1,2 +1,2 @@
+|  void func(){
+| -	int a = 0;
+| +	int a = 10;
+|  
+* Base commit
+  
+  diff --git a/path0 b/path0
+  new file mode 100644
+  index 0000000..aabffdf
+  --- /dev/null
+  +++ b/path0
+  @@ -0,0 +1,2 @@
+  +void func(){
+  +	int a = 0;
+EOF
+
+test_expect_success \
+    'validate the output.' \
+    'test_cmp current-path0-graph expected-path0-graph &&
+	 test_cmp current-path1-graph expected-path1-graph &&
+	 test_cmp current-pathall-graph expected-pathall-graph &&
+	 test_cmp current-linenum-graph expected-linenum-graph &&
+	 test_cmp current-always-graph expected-linenum-graph'
+
 test_done
diff --git a/t/t4302-log-line-merge-history.sh b/t/t4302-log-line-merge-history.sh
index 02e7439..cd417d3 100755
--- a/t/t4302-log-line-merge-history.sh
+++ b/t/t4302-log-line-merge-history.sh
@@ -107,8 +107,57 @@ index 0000000..f628dea
 +	printf("hello");
 +}
 EOF
+
+cat > expected-graph <<\EOF
+*   Merge two branches
+|\  
+| | 
+| | nontrivial merge found
+| | path0
+| | 
+| | @@ 2,1 @@
+| |  	printf("hello earth and moon");
+| | 
+| |   
+| * Change path0 in master
+| | 
+| | diff --git a/path0 b/path0
+| | index f628dea..bef7fa3 100644
+| | --- a/path0
+| | +++ b/path0
+| | @@ -2,1 +2,1 @@
+| | -	printf("hello");
+| | +	printf("hello earth");
+| |   
+* | Change path0 in feature
+|/  
+|   
+|   diff --git a/path0 b/path0
+|   index f628dea..a940ef6 100644
+|   --- a/path0
+|   +++ b/path0
+|   @@ -2,1 +2,1 @@
+|   -	printf("hello");
+|   +	print("hello moon");
+|  
+* Base commit
+  
+  diff --git a/path0 b/path0
+  new file mode 100644
+  index 0000000..f628dea
+  --- /dev/null
+  +++ b/path0
+  @@ -0,0 +2,1 @@
+  +	printf("hello");
+EOF
+
+test_expect_success \
+    'Show the line log of the 2 line of path0 with graph' \
+    'git log --pretty=format:%s%n%b --graph -L 2,+1 path0 > current-graph'
+
 test_expect_success \
     'validate the output.' \
-    'test_cmp current expected'
+    'test_cmp current expected &&
+     test_cmp current-graph expected-graph'
 
 test_done

diff --git a/line.c b/line.c
index c8c9ad3..ca8980d 100644
--- a/line.c
+++ b/line.c
@@ -975,13 +975,15 @@ static void assign_parents_range(struct rev_info *rev, struct commit *commit)
 		parents = parents->next;
 	}
 
+	/* Never print out any diff for a merge commit */
+	commit->object.flags &= ~NEED_PRINT;
 	/*
 	 * yes, this must be an evil merge.
 	 */
 	range = copy;
 	while (range) {
 		if (range->nr) {
-			commit->object.flags |= NEED_PRINT | EVIL_MERGE;
+			commit->object.flags |= EVIL_MERGE;
 			nontrivial = 1;
 		}
 		range = range->next;
@@ -1256,7 +1258,8 @@ static void line_log_flush(struct rev_info *rev, struct commit *c)
 	char *line_prefix = "";
 	struct strbuf *msgbuf;
 
-	if (range == NULL)
+	if (range == NULL || ! (c->object.flags & EVIL_MERGE ||
+							c->object.flags & NEED_PRINT))
 		return;
 
 	log.commit = c;
@@ -1310,7 +1313,9 @@ int cmd_line_log_walk(struct rev_info *rev)
 			assign_parents_range(rev, commit);
 		}
 
-		if (commit->object.flags & NEED_PRINT || rev->full_line_diff || rev->graph) {
+		if (commit->object.flags & NEED_PRINT ||
+			commit->object.flags & EVIL_MERGE ||
+			rev->full_line_diff || rev->graph) {
 			if (rev->graph)
 				graph_update(rev->graph, commit);
 			line_log_flush(rev, commit);

graph.c, graph.h

diff --git a/graph.c b/graph.c
index ac7c605..824e055 100644
--- a/graph.c
+++ b/graph.c
@@ -4,21 +4,9 @@
 #include "graph.h"
 #include "diff.h"
 #include "revision.h"
-
 /* Internal API */
 
 /*
- * Output the next line for a graph.
- * This formats the next graph line into the specified strbuf.  It is not
- * terminated with a newline.
- *
- * Returns 1 if the line includes the current commit, and 0 otherwise.
- * graph_next_line() will return 1 exactly once for each time
- * graph_update() is called.
- */
-static int graph_next_line(struct git_graph *graph, struct strbuf *sb);
-
-/*
  * Output a padding line in the graph.
  * This is similar to graph_next_line().  However, it is guaranteed to
  * never print the current commit line.  Instead, if the commit line is
@@ -1143,7 +1131,7 @@ static void graph_output_collapsing_line(struct git_graph *graph, struct strbuf
 		graph_update_state(graph, GRAPH_PADDING);
 }
 
-static int graph_next_line(struct git_graph *graph, struct strbuf *sb)
+int graph_next_line(struct git_graph *graph, struct strbuf *sb)
 {
 	switch (graph->state) {
 	case GRAPH_PADDING:
diff --git a/graph.h b/graph.h
index b82ae87..5b3f059 100644
--- a/graph.h
+++ b/graph.h
@@ -32,6 +32,16 @@ void graph_update(struct git_graph *graph, struct commit *commit);
  */
 int graph_is_commit_finished(struct git_graph const *graph);
 
+/*
+ * Output the next line for a graph.
+ * This formats the next graph line into the specified strbuf.  It is not
+ * terminated with a newline.
+ *
+ * Returns 1 if the line includes the current commit, and 0 otherwise.
+ * graph_next_line() will return 1 exactly once for each time
+ * graph_update() is called.
+ */
+int graph_next_line(struct git_graph *graph, struct strbuf *sb);
 
 /*
  * graph_show_*: helper functions for printing to stdout

diff --git a/line.c b/line.c
index ca8980d..272f166 100644
--- a/line.c
+++ b/line.c
@@ -470,15 +470,15 @@ void add_line_range(struct rev_info *revs, struct commit *commit, struct diff_li
 {
 	struct diff_line_range *ret = NULL;
 
-	if (r != NULL) {
-		ret = lookup_decoration(&revs->line_range, &commit->object);
-		if (ret != NULL) {
-			diff_line_range_merge(ret, r);
-		} else {
-			add_decoration(&revs->line_range, &commit->object, r);
-		}
-		commit->object.flags |= RANGE_UPDATE;
+	ret = lookup_decoration(&revs->line_range, &commit->object);
+	if (ret != NULL && r != NULL) {
+		diff_line_range_merge(ret, r);
+	} else {
+		add_decoration(&revs->line_range, &commit->object, r);
 	}
+
+	if (r != NULL)
+		commit->object.flags |= RANGE_UPDATE;
 }
 
 struct diff_line_range *lookup_line_range(struct rev_info *revs, struct commit *commit)
@@ -544,8 +544,26 @@ void map_lines(long p_start, long p_end, long t_start, long t_end,
 		return;
 	}
 
-	if (start == t_start && end == t_end) {
+	if (start == t_start && end == t_end)
+	{
+		*o_start = p_start;
+		*o_end = p_end;
+		return;
+	}
+
+	if (start == t_start)
+	{
 		*o_start = p_start;
+		*o_end = p_start + (end - start);
+		if (*o_end > p_end)
+			*o_end = p_end;
+		return;
+	}
+
+	if (end == t_end) {
+		*o_start = p_end - (end - start);
+		if (*o_start < p_start)
+			*o_start = p_start;
 		*o_end = p_end;
 		return;
 	}
@@ -771,7 +789,7 @@ static void map_range_cb(void *data, long same, long p_next, long t_next)
 	d->tlno = t_next;
 }
 
-static void assign_range_to_parent(struct rev_info *rev, struct commit *c,
+static int assign_range_to_parent(struct rev_info *rev, struct commit *c,
 		struct commit *p, struct diff_line_range *r,
 		struct diff_options *opt, int map)
 {
@@ -917,20 +935,49 @@ static void assign_range_to_parent(struct rev_info *rev, struct commit *c,
 		}
 	}
 
+	if (!map)
+		goto out;
+
 	if (rr) {
 		assert(p);
 		add_line_range(rev, p, rr);
 	}
 
+	/* debug output */
+	/*
+	fprintf(stderr, "%8s..%8s:\n", sha1_to_hex(p->object.sha1), sha1_to_hex(c->object.sha1));
+	while (r) {
+		fprintf(stderr, "file: %s\n", r->spec->path);
+		int n = 0;
+		for (; n < r->nr; n++) {
+			fprintf(stderr, "%d-%d, ", r->ranges[n].start, r->ranges[n].end);
+		}
+		r = r->next;
+	}
+	fprintf(stderr, "\n");
+	while (rr) {
+		fprintf(stderr, "file: %s\n", rr->spec->path);
+		int n = 0;
+		for (; n < rr->nr; n++) {
+			fprintf(stderr, "%d-%d, ", rr->ranges[n].start, rr->ranges[n].end);
+		}
+		rr = rr->next;
+	}
+	fprintf(stderr, "\n");
+	*/
+
 	/* and the ranges of current commit c is updated */
 	c->object.flags &= ~RANGE_UPDATE;
 	if (diff)
 		c->object.flags |= NEED_PRINT;
 
+out:
 	if (tree1)
 		free(tree1);
 	if (tree2)
 		free(tree2);
+
+	return diff;
 }
 
 static void diff_update_parent_range(struct rev_info *rev, struct commit *commit)
@@ -967,16 +1014,46 @@ static void assign_parents_range(struct rev_info *rev, struct commit *commit)
 	 * be an evil merge.
 	 */
 	copy = diff_line_range_clone_deeply(r);
+	/* Never print out any diff for a merge commit */
+	commit->object.flags &= ~NEED_PRINT;
 	parents = commit->parents;
 	while (parents) {
 		struct commit *p = parents->item;
-		assign_range_to_parent(rev, commit, p, r, &rev->diffopt, 1);
+		int diff = 0;
+		diff = assign_range_to_parent(rev, commit, p, r, &rev->diffopt, 1);
+		/* Since all the ranges comes from this parent, we can ignore others */
+		if (diff == 0) {
+			/* parent rewriting code */
+			parents = commit->parents;
+			while (parents->item != p) {
+				struct commit_list *list = parents;
+				struct diff_line_range *line_range = NULL;
+				parents = parents->next;
+				line_range = lookup_line_range(rev, list->item);
+				add_line_range(rev, list->item, NULL);
+				free(line_range);
+				list->item->object.flags &= ~(RANGE_UPDATE | NEED_PRINT | EVIL_MERGE);
+				free(list);
+			}
+			commit->parents = parents;
+			parents = parents->next;
+			commit->parents->next = NULL;
+			while (parents) {
+				struct commit_list *list = parents;
+				struct diff_line_range *line_range = NULL;
+				parents = parents->next;
+				line_range = lookup_line_range(rev, list->item);
+				add_line_range(rev, list->item, NULL);
+				free(line_range);
+				list->item->object.flags &= ~(RANGE_UPDATE | NEED_PRINT | EVIL_MERGE);
+				free(list);
+			}
+			return;
+		}
 		assign_range_to_parent(rev, commit, p, copy, &rev->diffopt, 0);
 		parents = parents->next;
 	}
 
-	/* Never print out any diff for a merge commit */
-	commit->object.flags &= ~NEED_PRINT;
 	/*
 	 * yes, this must be an evil merge.
 	 */
@@ -1262,6 +1339,8 @@ static void line_log_flush(struct rev_info *rev, struct commit *c)
 							c->object.flags & NEED_PRINT))
 		return;
 
+	if (rev->graph)
+		graph_update(rev->graph, c);
 	log.commit = c;
 	log.parent = NULL;
 	rev->loginfo = &log;
@@ -1275,12 +1354,21 @@ static void line_log_flush(struct rev_info *rev, struct commit *c)
 	fprintf(rev->diffopt.file, "%s\n", line_prefix);
 
 	if (c->object.flags & EVIL_MERGE)
-		return flush_nontrivial_merge(rev, nontrivial);
+		flush_nontrivial_merge(rev, nontrivial);
+	else {
+		while (range) {
+			if (range->diff || (range->nr && rev->full_line_diff))
+				diff_flush_filepair(rev, range);
+			range = range->next;
+		}
+	}
 
-	while (range) {
-		if (range->diff || (range->nr && rev->full_line_diff))
-			diff_flush_filepair(rev, range);
-		range = range->next;
+	while (rev->graph && !graph_is_commit_finished(rev->graph))
+	{
+		struct strbuf sb;
+		strbuf_init(&sb, 0);
+		graph_next_line(rev->graph, &sb);
+		fputs(sb.buf, opt->file);
 	}
 }
 
@@ -1316,8 +1404,6 @@ int cmd_line_log_walk(struct rev_info *rev)
 		if (commit->object.flags & NEED_PRINT ||
 			commit->object.flags & EVIL_MERGE ||
 			rev->full_line_diff || rev->graph) {
-			if (rev->graph)
-				graph_update(rev->graph, commit);
 			line_log_flush(rev, commit);
 		}
 
@@ -1350,8 +1436,6 @@ static enum rewrite_result rewrite_one(struct rev_info *rev, struct commit **pp)
 		p = *pp;
 		if (p->object.flags & RANGE_UPDATE)
 			assign_parents_range(rev, p);
-		if (p->parents && p->parents->next)
-			return rewrite_one_ok;
 		if (p->object.flags & NEED_PRINT)
 			return rewrite_one_ok;
 		if (!p->parents)

diff --git a/line.c b/line.c
index 272f166..bc9fc76 100644
--- a/line.c
+++ b/line.c
@@ -390,6 +390,7 @@ struct diff_line_range *diff_line_range_clone(struct diff_line_range *r)
 	struct diff_line_range *ret = xmalloc(sizeof(*ret));
 	int i = 0;
 
+	assert(r);
 	DIFF_LINE_RANGE_INIT(ret);
 	ret->ranges = xcalloc(r->nr, sizeof(struct range));
 	memcpy(ret->ranges, r->ranges, sizeof(struct range) * r->nr);
@@ -993,13 +994,21 @@ static void diff_update_parent_range(struct rev_info *rev, struct commit *commit
 	assign_range_to_parent(rev, commit, c, r, &rev->diffopt, 1);
 }
 
+struct commit_state {
+	struct diff_line_range *range;
+	struct object obj;
+};
+
 static void assign_parents_range(struct rev_info *rev, struct commit *commit)
 {
 	struct commit_list *parents = commit->parents;
 	struct diff_line_range *r = lookup_line_range(rev, commit);
 	struct diff_line_range *copy = NULL, *range = NULL;
+	struct decoration parents_state;
+	struct commit_state *state = NULL;
 	int nontrivial = 0;
 
+	memset(&parents_state, 0, sizeof(parents_state));
 	/*
 	 * If we are in linear history, update range and flush the patch if
 	 * necessary
@@ -1020,36 +1029,44 @@ static void assign_parents_range(struct rev_info *rev, struct commit *commit)
 	while (parents) {
 		struct commit *p = parents->item;
 		int diff = 0;
+		struct diff_line_range *origin_range = lookup_line_range(rev, p);
+		if (origin_range)
+			origin_range = diff_line_range_clone_deeply(origin_range);
+
+		state = xmalloc(sizeof(*state));
+		state->range = origin_range;
+		state->obj = p->object;
+		add_decoration(&parents_state, &p->object, state);
 		diff = assign_range_to_parent(rev, commit, p, r, &rev->diffopt, 1);
 		/* Since all the ranges comes from this parent, we can ignore others */
 		if (diff == 0) {
-			/* parent rewriting code */
+			/* restore the state of parents before this one */
 			parents = commit->parents;
 			while (parents->item != p) {
 				struct commit_list *list = parents;
 				struct diff_line_range *line_range = NULL;
 				parents = parents->next;
 				line_range = lookup_line_range(rev, list->item);
-				add_line_range(rev, list->item, NULL);
-				free(line_range);
-				list->item->object.flags &= ~(RANGE_UPDATE | NEED_PRINT | EVIL_MERGE);
+				cleanup(line_range);
+				state = lookup_decoration(&parents_state, &list->item->object);
+				add_decoration(&parents_state, &list->item->object, NULL);
+				add_line_range(rev, list->item, state->range);
+				list->item->object = state->obj;
+				free(state);
 				free(list);
 			}
+
 			commit->parents = parents;
 			parents = parents->next;
 			commit->parents->next = NULL;
 			while (parents) {
 				struct commit_list *list = parents;
-				struct diff_line_range *line_range = NULL;
 				parents = parents->next;
-				line_range = lookup_line_range(rev, list->item);
-				add_line_range(rev, list->item, NULL);
-				free(line_range);
-				list->item->object.flags &= ~(RANGE_UPDATE | NEED_PRINT | EVIL_MERGE);
 				free(list);
 			}
-			return;
+			goto out;
 		}
+		/* take the ranges from 'commit', try to detect nontrivial merge */
 		assign_range_to_parent(rev, commit, p, copy, &rev->diffopt, 0);
 		parents = parents->next;
 	}
@@ -1066,6 +1083,17 @@ static void assign_parents_range(struct rev_info *rev, struct commit *commit)
 		range = range->next;
 	}
 
+out:
+	parents = commit->parents;
+	while (parents) {
+		state = lookup_decoration(&parents_state, &parents->item->object);
+		if (state) {
+			cleanup(state->range);
+			free(state);
+		}
+		parents = parents->next;
+	}
+
 	if (nontrivial) {
 		add_decoration(&rev->nontrivial_merge, &commit->object, copy);
 	} else {

diff --git a/line.c b/line.c
index bc9fc76..5782003 100644
--- a/line.c
+++ b/line.c
@@ -1023,8 +1023,6 @@ static void assign_parents_range(struct rev_info *rev, struct commit *commit)
 	 * be an evil merge.
 	 */
 	copy = diff_line_range_clone_deeply(r);
-	/* Never print out any diff for a merge commit */
-	commit->object.flags &= ~NEED_PRINT;
 	parents = commit->parents;
 	while (parents) {
 		struct commit *p = parents->item;
@@ -1059,6 +1057,8 @@ static void assign_parents_range(struct rev_info *rev, struct commit *commit)
 			commit->parents = parents;
 			parents = parents->next;
 			commit->parents->next = NULL;
+
+			/* free the non-use commit_list */
 			while (parents) {
 				struct commit_list *list = parents;
 				parents = parents->next;
@@ -1084,6 +1084,9 @@ static void assign_parents_range(struct rev_info *rev, struct commit *commit)
 	}
 
 out:
+	/* Never print out any diff for a merge commit */
+	commit->object.flags &= ~NEED_PRINT;
+
 	parents = commit->parents;
 	while (parents) {
 		state = lookup_decoration(&parents_state, &parents->item->object);