v3, 31 partswrapper: implement xopen()

git-compat-util.h, wrapper.c

diff --git a/git-compat-util.h b/git-compat-util.h
index 0cc7ae8..bc77d77 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -719,6 +719,7 @@ extern void *xrealloc(void *ptr, size_t size);
 extern void *xcalloc(size_t nmemb, size_t size);
 extern void *xmmap(void *start, size_t length, int prot, int flags, int fd, off_t offset);
 extern void *xmmap_gently(void *start, size_t length, int prot, int flags, int fd, off_t offset);
+extern int xopen(const char *path, int flags, ...);
 extern ssize_t xread(int fd, void *buf, size_t len);
 extern ssize_t xwrite(int fd, const void *buf, size_t len);
 extern ssize_t xpread(int fd, void *buf, size_t len, off_t offset);
diff --git a/wrapper.c b/wrapper.c
index c1a663f..82658b3 100644
--- a/wrapper.c
+++ b/wrapper.c
@@ -189,6 +189,31 @@ void *xcalloc(size_t nmemb, size_t size)
 # endif
 #endif
 
+/**
+ * xopen() is the same as open(), but it die()s if the open() fails.
+ */
+int xopen(const char *path, int oflag, ...)
+{
+	mode_t mode = 0;
+	va_list ap;
+
+	va_start(ap, oflag);
+	if (oflag & O_CREAT)
+		mode = va_arg(ap, mode_t);
+	va_end(ap);
+
+	assert(path);
+
+	for (;;) {
+		int fd = open(path, oflag, mode);
+		if (fd >= 0)
+			return fd;
+		if (errno == EINTR)
+			continue;
+		die_errno(_("could not open '%s'"), path);
+	}
+}
+
 /*
  * xread() is the same a read(), but it automatically restarts read()
  * operations with a recoverable error (EAGAIN and EINTR). xread()

diff --git a/wrapper.c b/wrapper.c
index c867ca9..e451463 100644
--- a/wrapper.c
+++ b/wrapper.c
@@ -214,7 +214,13 @@ int xopen(const char *path, int oflag, ...)
             return fd;
         if (errno == EINTR)
             continue;
-        die_errno(_("could not open '%s'"), path);
+
+        if ((oflag & O_RDWR) == O_RDWR)
+            die_errno(_("could not open '%s' for reading and writing"), path);
+        else if ((oflag & O_WRONLY) == O_WRONLY)
+            die_errno(_("could not open '%s' for writing"), path);
+        else
+            die_errno(_("could not open '%s' for reading"), path);
     }
 }

@@ -351,7 +357,13 @@ FILE *xfopen(const char *path, const char *mode)
             return fp;
         if (errno == EINTR)
             continue;
-        die_errno(_("could not open '%s'"), path);
+
+        if (*mode && mode[1] == '+')
+            die_errno(_("could not open '%s' for reading and writing"), path);
+        else if (*mode == 'w' || *mode == 'a')
+            die_errno(_("could not open '%s' for writing"), path);
+        else
+            die_errno(_("could not open '%s' for reading"), path);
     }
 }

git-compat-util.h, wrapper.c

diff --git a/git-compat-util.h b/git-compat-util.h
index bc77d77..4e69110 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -724,6 +724,7 @@ extern ssize_t xread(int fd, void *buf, size_t len);
 extern ssize_t xwrite(int fd, const void *buf, size_t len);
 extern ssize_t xpread(int fd, void *buf, size_t len, off_t offset);
 extern int xdup(int fd);
+extern FILE *xfopen(const char *path, const char *mode);
 extern FILE *xfdopen(int fd, const char *mode);
 extern int xmkstemp(char *template);
 extern int xmkstemp_mode(char *template, int mode);
diff --git a/wrapper.c b/wrapper.c
index 82658b3..9692460 100644
--- a/wrapper.c
+++ b/wrapper.c
@@ -336,6 +336,24 @@ int xdup(int fd)
 	return ret;
 }
 
+/**
+ * xfopen() is the same as fopen(), but it die()s if the fopen() fails.
+ */
+FILE *xfopen(const char *path, const char *mode)
+{
+	assert(path);
+	assert(mode);
+
+	for (;;) {
+		FILE *fp = fopen(path, mode);
+		if (fp)
+			return fp;
+		if (errno == EINTR)
+			continue;
+		die_errno(_("could not open '%s'"), path);
+	}
+}
+
 FILE *xfdopen(int fd, const char *mode)
 {
 	FILE *stream = fdopen(fd, mode);

Makefile, builtin.h, builtin/am.c, git.c

diff --git a/Makefile b/Makefile
index 93e4fa2..ff9bdc0 100644
--- a/Makefile
+++ b/Makefile
@@ -811,6 +811,7 @@ LIB_OBJS += xdiff-interface.o
 LIB_OBJS += zlib.o
 
 BUILTIN_OBJS += builtin/add.o
+BUILTIN_OBJS += builtin/am.o
 BUILTIN_OBJS += builtin/annotate.o
 BUILTIN_OBJS += builtin/apply.o
 BUILTIN_OBJS += builtin/archive.o
diff --git a/builtin.h b/builtin.h
index ea3c834..f30cf00 100644
--- a/builtin.h
+++ b/builtin.h
@@ -30,6 +30,7 @@ extern int textconv_object(const char *path, unsigned mode, const unsigned char
 extern int is_builtin(const char *s);
 
 extern int cmd_add(int argc, const char **argv, const char *prefix);
+extern int cmd_am(int argc, const char **argv, const char *prefix);
 extern int cmd_annotate(int argc, const char **argv, const char *prefix);
 extern int cmd_apply(int argc, const char **argv, const char *prefix);
 extern int cmd_archive(int argc, const char **argv, const char *prefix);
diff --git a/builtin/am.c b/builtin/am.c
new file mode 100644
index 0000000..dbc8836
--- /dev/null
+++ b/builtin/am.c
@@ -0,0 +1,28 @@
+/*
+ * Builtin "git am"
+ *
+ * Based on git-am.sh by Junio C Hamano.
+ */
+#include "cache.h"
+#include "builtin.h"
+#include "exec_cmd.h"
+
+int cmd_am(int argc, const char **argv, const char *prefix)
+{
+	/*
+	 * FIXME: Once all the features of git-am.sh have been re-implemented
+	 * in builtin/am.c, this preamble can be removed.
+	 */
+	if (!getenv("_GIT_USE_BUILTIN_AM")) {
+		const char *path = mkpath("%s/git-am", git_exec_path());
+
+		if (sane_execvp(path, (char **)argv) < 0)
+			die_errno("could not exec %s", path);
+	} else {
+		prefix = setup_git_directory();
+		trace_repo_setup(prefix);
+		setup_work_tree();
+	}
+
+	return 0;
+}
diff --git a/git.c b/git.c
index e7a7713..a671535 100644
--- a/git.c
+++ b/git.c
@@ -370,6 +370,7 @@ static int run_builtin(struct cmd_struct *p, int argc, const char **argv)
 
 static struct cmd_struct commands[] = {
 	{ "add", cmd_add, RUN_SETUP | NEED_WORK_TREE },
+	{ "am", cmd_am, NO_SETUP },
 	{ "annotate", cmd_annotate, RUN_SETUP },
 	{ "apply", cmd_apply, RUN_SETUP_GENTLY },
 	{ "archive", cmd_archive },

diff --git a/builtin/am.c b/builtin/am.c
index dbc8836..af68c51 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -6,6 +6,158 @@
 #include "cache.h"
 #include "builtin.h"
 #include "exec_cmd.h"
+#include "parse-options.h"
+#include "dir.h"
+
+struct am_state {
+	/* state directory path */
+	struct strbuf dir;
+
+	/* current and last patch numbers, 1-indexed */
+	int cur;
+	int last;
+};
+
+/**
+ * Initializes am_state with the default values.
+ */
+static void am_state_init(struct am_state *state)
+{
+	memset(state, 0, sizeof(*state));
+
+	strbuf_init(&state->dir, 0);
+}
+
+/**
+ * Release memory allocated by an am_state.
+ */
+static void am_state_release(struct am_state *state)
+{
+	strbuf_release(&state->dir);
+}
+
+/**
+ * Returns path relative to the am_state directory.
+ */
+static inline const char *am_path(const struct am_state *state, const char *path)
+{
+	return mkpath("%s/%s", state->dir.buf, path);
+}
+
+/**
+ * Returns 1 if there is an am session in progress, 0 otherwise.
+ */
+static int am_in_progress(const struct am_state *state)
+{
+	struct stat st;
+
+	if (lstat(state->dir.buf, &st) < 0 || !S_ISDIR(st.st_mode))
+		return 0;
+	if (lstat(am_path(state, "last"), &st) || !S_ISREG(st.st_mode))
+		return 0;
+	if (lstat(am_path(state, "next"), &st) || !S_ISREG(st.st_mode))
+		return 0;
+	return 1;
+}
+
+/**
+ * Reads the contents of `file`. The third argument can be used to give a hint
+ * about the file size, to avoid reallocs. Returns number of bytes read on
+ * success, -1 if the file does not exist. If trim is set, trailing whitespace
+ * will be removed from the file contents.
+ */
+static int read_state_file(struct strbuf *sb, const char *file, size_t hint, int trim)
+{
+	strbuf_reset(sb);
+	if (strbuf_read_file(sb, file, hint) >= 0) {
+		if (trim)
+			strbuf_trim(sb);
+
+		return sb->len;
+	}
+
+	if (errno == ENOENT)
+		return -1;
+
+	die_errno(_("could not read '%s'"), file);
+}
+
+/**
+ * Loads state from disk.
+ */
+static void am_load(struct am_state *state)
+{
+	struct strbuf sb = STRBUF_INIT;
+
+	read_state_file(&sb, am_path(state, "next"), 8, 1);
+	state->cur = strtol(sb.buf, NULL, 10);
+
+	read_state_file(&sb, am_path(state, "last"), 8, 1);
+	state->last = strtol(sb.buf, NULL, 10);
+
+	strbuf_release(&sb);
+}
+
+/**
+ * Remove the am_state directory.
+ */
+static void am_destroy(const struct am_state *state)
+{
+	struct strbuf sb = STRBUF_INIT;
+
+	strbuf_addstr(&sb, state->dir.buf);
+	remove_dir_recursively(&sb, 0);
+	strbuf_release(&sb);
+}
+
+/**
+ * Setup a new am session for applying patches
+ */
+static void am_setup(struct am_state *state)
+{
+	if (mkdir(state->dir.buf, 0777) < 0 && errno != EEXIST)
+		die_errno(_("failed to create directory '%s'"), state->dir.buf);
+
+	write_file(am_path(state, "next"), 1, "%d", state->cur);
+
+	write_file(am_path(state, "last"), 1, "%d", state->last);
+}
+
+/**
+ * Increments the patch pointer, and cleans am_state for the application of the
+ * next patch.
+ */
+static void am_next(struct am_state *state)
+{
+	state->cur++;
+	write_file(am_path(state, "next"), 1, "%d", state->cur);
+}
+
+/**
+ * Applies all queued patches.
+ */
+static void am_run(struct am_state *state)
+{
+	while (state->cur <= state->last) {
+
+		/* TODO: Patch application not implemented yet */
+
+		am_next(state);
+	}
+
+	am_destroy(state);
+}
+
+static struct am_state state;
+
+static const char * const am_usage[] = {
+	N_("git am [options] [(<mbox>|<Maildir>)...]"),
+	NULL
+};
+
+static struct option am_options[] = {
+	OPT_END()
+};
 
 int cmd_am(int argc, const char **argv, const char *prefix)
 {
@@ -24,5 +176,21 @@ int cmd_am(int argc, const char **argv, const char *prefix)
 		setup_work_tree();
 	}
 
+	git_config(git_default_config, NULL);
+
+	am_state_init(&state);
+	strbuf_addstr(&state.dir, git_path("rebase-apply"));
+
+	argc = parse_options(argc, argv, prefix, am_options, am_usage, 0);
+
+	if (am_in_progress(&state))
+		am_load(&state);
+	else
+		am_setup(&state);
+
+	am_run(&state);
+
+	am_state_release(&state);
+
 	return 0;
 }

diff --git a/builtin/am.c b/builtin/am.c
index af68c51..e9a3687 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -8,6 +8,12 @@
 #include "exec_cmd.h"
 #include "parse-options.h"
 #include "dir.h"
+#include "run-command.h"
+
+enum patch_format {
+	PATCH_FORMAT_UNKNOWN = 0,
+	PATCH_FORMAT_MBOX
+};
 
 struct am_state {
 	/* state directory path */
@@ -16,6 +22,9 @@ struct am_state {
 	/* current and last patch numbers, 1-indexed */
 	int cur;
 	int last;
+
+	/* number of digits in patch filename */
+	int prec;
 };
 
 /**
@@ -26,6 +35,8 @@ static void am_state_init(struct am_state *state)
 	memset(state, 0, sizeof(*state));
 
 	strbuf_init(&state->dir, 0);
+
+	state->prec = 4;
 }
 
 /**
@@ -111,13 +122,69 @@ static void am_destroy(const struct am_state *state)
 }
 
 /**
+ * Splits out individual patches from `paths`, where each path is either a mbox
+ * file or a Maildir. Return 0 on success, -1 on failure.
+ */
+static int split_patches_mbox(struct am_state *state, struct string_list *paths)
+{
+	struct child_process cp = CHILD_PROCESS_INIT;
+	struct string_list_item *item;
+	struct strbuf last = STRBUF_INIT;
+
+	cp.git_cmd = 1;
+	argv_array_push(&cp.args, "mailsplit");
+	argv_array_pushf(&cp.args, "-d%d", state->prec);
+	argv_array_pushf(&cp.args, "-o%s", state->dir.buf);
+	argv_array_push(&cp.args, "-b");
+	argv_array_push(&cp.args, "--");
+
+	for_each_string_list_item(item, paths)
+		argv_array_push(&cp.args, item->string);
+
+	if (capture_command(&cp, &last, 8))
+		return -1;
+
+	state->cur = 1;
+	state->last = strtol(last.buf, NULL, 10);
+
+	return 0;
+}
+
+/**
+ * Splits out individual patches, of patch_format, contained within paths.
+ * These patches will be stored in the state directory, with each patch's
+ * filename being its index, padded to state->prec digits. state->cur will be
+ * set to the index of the first patch, and state->last will be set to the
+ * index of the last patch.
+ *
+ * Returns 0 on success, -1 on failure.
+ */
+static int split_patches(struct am_state *state, enum patch_format patch_format,
+		struct string_list *paths)
+{
+	switch (patch_format) {
+	case PATCH_FORMAT_MBOX:
+		return split_patches_mbox(state, paths);
+	default:
+		die("BUG: invalid patch_format");
+	}
+	return -1;
+}
+
+/**
  * Setup a new am session for applying patches
  */
-static void am_setup(struct am_state *state)
+static void am_setup(struct am_state *state, enum patch_format patch_format,
+		struct string_list *paths)
 {
 	if (mkdir(state->dir.buf, 0777) < 0 && errno != EEXIST)
 		die_errno(_("failed to create directory '%s'"), state->dir.buf);
 
+	if (split_patches(state, patch_format, paths) < 0) {
+		am_destroy(state);
+		die(_("Failed to split patches."));
+	}
+
 	write_file(am_path(state, "next"), 1, "%d", state->cur);
 
 	write_file(am_path(state, "last"), 1, "%d", state->last);
@@ -148,7 +215,23 @@ static void am_run(struct am_state *state)
 	am_destroy(state);
 }
 
+/**
+ * parse_options() callback that validates and sets opt->value to the
+ * PATCH_FORMAT_* enum value corresponding to `arg`.
+ */
+static int parse_opt_patchformat(const struct option *opt, const char *arg, int unset)
+{
+	int *opt_value = opt->value;
+
+	if (!strcmp(arg, "mbox"))
+		*opt_value = PATCH_FORMAT_MBOX;
+	else
+		return -1;
+	return 0;
+}
+
 static struct am_state state;
+static int opt_patch_format;
 
 static const char * const am_usage[] = {
 	N_("git am [options] [(<mbox>|<Maildir>)...]"),
@@ -156,6 +239,8 @@ static const char * const am_usage[] = {
 };
 
 static struct option am_options[] = {
+	OPT_CALLBACK(0, "patch-format", &opt_patch_format, N_("format"),
+		N_("format the patch(es) are in"), parse_opt_patchformat),
 	OPT_END()
 };
 
@@ -185,8 +270,21 @@ int cmd_am(int argc, const char **argv, const char *prefix)
 
 	if (am_in_progress(&state))
 		am_load(&state);
-	else
-		am_setup(&state);
+	else {
+		struct string_list paths = STRING_LIST_INIT_DUP;
+		int i;
+
+		for (i = 0; i < argc; i++) {
+			if (is_absolute_path(argv[i]) || !prefix)
+				string_list_append(&paths, argv[i]);
+			else
+				string_list_append(&paths, mkpath("%s/%s", prefix, argv[i]));
+		}
+
+		am_setup(&state, opt_patch_format, &paths);
+
+		string_list_clear(&paths, 0);
+	}
 
 	am_run(&state);
 

diff --git a/builtin/am.c b/builtin/am.c
index e9a3687..7b97ea8 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -121,6 +121,96 @@ static void am_destroy(const struct am_state *state)
 	strbuf_release(&sb);
 }
 
+/*
+ * Returns 1 if the file looks like a piece of email a-la RFC2822, 0 otherwise.
+ * We check this by grabbing all the non-indented lines and seeing if they look
+ * like they begin with valid header field names.
+ */
+static int is_email(const char *filename)
+{
+	struct strbuf sb = STRBUF_INIT;
+	FILE *fp = xfopen(filename, "r");
+	int ret = 1;
+
+	while (!strbuf_getline(&sb, fp, '\n')) {
+		const char *x;
+
+		strbuf_rtrim(&sb);
+
+		if (!sb.len)
+			break; /* End of header */
+
+		/* Ignore indented folded lines */
+		if (*sb.buf == '\t' || *sb.buf == ' ')
+			continue;
+
+		/* It's a header if it matches the regexp "^[!-9;-~]+:" */
+		for (x = sb.buf; *x; x++) {
+			if (('!' <= *x && *x <= '9') || (';' <= *x && *x <= '~'))
+				continue;
+			if (*x == ':' && x != sb.buf)
+				break;
+			ret = 0;
+			goto done;
+		}
+	}
+
+done:
+	fclose(fp);
+	strbuf_release(&sb);
+	return ret;
+}
+
+/**
+ * Attempts to detect the patch_format of the patches contained in `paths`,
+ * returning the PATCH_FORMAT_* enum value. Returns PATCH_FORMAT_UNKNOWN if
+ * detection fails.
+ */
+static int detect_patch_format(struct string_list *paths)
+{
+	enum patch_format ret = PATCH_FORMAT_UNKNOWN;
+	struct strbuf l1 = STRBUF_INIT;
+	struct strbuf l2 = STRBUF_INIT;
+	struct strbuf l3 = STRBUF_INIT;
+	FILE *fp;
+
+	/*
+	 * We default to mbox format if input is from stdin and for directories
+	 */
+	if (!paths->nr || !strcmp(paths->items->string, "-") ||
+	    is_directory(paths->items->string)) {
+		ret = PATCH_FORMAT_MBOX;
+		goto done;
+	}
+
+	/*
+	 * Otherwise, check the first 3 lines of the first patch, starting
+	 * from the first non-blank line, to try to detect its format.
+	 */
+	fp = xfopen(paths->items->string, "r");
+	while (!strbuf_getline(&l1, fp, '\n')) {
+		strbuf_trim(&l1);
+		if (l1.len)
+			break;
+	}
+	strbuf_getline(&l2, fp, '\n');
+	strbuf_trim(&l2);
+	strbuf_getline(&l3, fp, '\n');
+	strbuf_trim(&l3);
+	fclose(fp);
+
+	if (starts_with(l1.buf, "From ") || starts_with(l1.buf, "From: "))
+		ret = PATCH_FORMAT_MBOX;
+	else if (l1.len && l2.len && l3.len && is_email(paths->items->string))
+		ret = PATCH_FORMAT_MBOX;
+
+done:
+	strbuf_release(&l1);
+	strbuf_release(&l2);
+	strbuf_release(&l3);
+	return ret;
+}
+
 /**
  * Splits out individual patches from `paths`, where each path is either a mbox
  * file or a Maildir. Return 0 on success, -1 on failure.
@@ -177,6 +267,14 @@ static int split_patches(struct am_state *state, enum patch_format patch_format,
 static void am_setup(struct am_state *state, enum patch_format patch_format,
 		struct string_list *paths)
 {
+	if (!patch_format)
+		patch_format = detect_patch_format(paths);
+
+	if (!patch_format) {
+		fprintf_ln(stderr, _("Patch format detection failed."));
+		exit(128);
+	}
+
 	if (mkdir(state->dir.buf, 0777) < 0 && errno != EEXIST)
 		die_errno(_("failed to create directory '%s'"), state->dir.buf);
 

diff --git a/builtin/am.c b/builtin/am.c
index 7b97ea8..d6434e4 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -9,6 +9,23 @@
 #include "parse-options.h"
 #include "dir.h"
 #include "run-command.h"
+#include "quote.h"
+
+/**
+ * Returns 1 if the file is empty or does not exist, 0 otherwise.
+ */
+static int is_empty_file(const char *filename)
+{
+	struct stat st;
+
+	if (stat(filename, &st) < 0) {
+		if (errno == ENOENT)
+			return 1;
+		die_errno(_("could not stat %s"), filename);
+	}
+
+	return !st.st_size;
+}
 
 enum patch_format {
 	PATCH_FORMAT_UNKNOWN = 0,
@@ -23,6 +40,12 @@ struct am_state {
 	int cur;
 	int last;
 
+	/* commit message and metadata */
+	struct strbuf author_name;
+	struct strbuf author_email;
+	struct strbuf author_date;
+	struct strbuf msg;
+
 	/* number of digits in patch filename */
 	int prec;
 };
@@ -36,6 +59,11 @@ static void am_state_init(struct am_state *state)
 
 	strbuf_init(&state->dir, 0);
 
+	strbuf_init(&state->author_name, 0);
+	strbuf_init(&state->author_email, 0);
+	strbuf_init(&state->author_date, 0);
+	strbuf_init(&state->msg, 0);
+
 	state->prec = 4;
 }
 
@@ -45,6 +73,10 @@ static void am_state_init(struct am_state *state)
 static void am_state_release(struct am_state *state)
 {
 	strbuf_release(&state->dir);
+	strbuf_release(&state->author_name);
+	strbuf_release(&state->author_email);
+	strbuf_release(&state->author_date);
+	strbuf_release(&state->msg);
 }
 
 /**
@@ -94,6 +126,105 @@ static int read_state_file(struct strbuf *sb, const char *file, size_t hint, int
 }
 
 /**
+ * Reads a KEY=VALUE shell variable assignment from fp, and returns the VALUE
+ * in `value`. VALUE must be a quoted string, and the KEY must match `key`.
+ * Returns 0 on success, -1 on failure.
+ *
+ * This is used by read_author_script() to read the GIT_AUTHOR_* variables from
+ * the author-script.
+ */
+static int read_shell_var(struct strbuf *value, FILE *fp, const char *key)
+{
+	struct strbuf sb = STRBUF_INIT;
+	char *str;
+
+	if (strbuf_getline(&sb, fp, '\n'))
+		return -1;
+
+	if (!skip_prefix(sb.buf, key, (const char **)&str))
+		return -1;
+
+	if (!skip_prefix(str, "=", (const char **)&str))
+		return -1;
+
+	str = sq_dequote(str);
+	if (!str)
+		return -1;
+
+	strbuf_reset(value);
+	strbuf_addstr(value, str);
+
+	strbuf_release(&sb);
+
+	return 0;
+}
+
+/**
+ * Parses the "author script" `filename`, and sets state->author_name,
+ * state->author_email and state->author_date accordingly. We are strict with
+ * our parsing, as the author script is supposed to be eval'd, and loosely
+ * parsing it may not give the results the user expects.
+ *
+ * The author script is of the format:
+ *
+ *	GIT_AUTHOR_NAME='$author_name'
+ *	GIT_AUTHOR_EMAIL='$author_email'
+ *	GIT_AUTHOR_DATE='$author_date'
+ *
+ * where $author_name, $author_email and $author_date are quoted.
+ */
+static int read_author_script(struct am_state *state)
+{
+	const char *filename = am_path(state, "author-script");
+	FILE *fp = fopen(filename, "r");
+	if (!fp) {
+		if (errno == ENOENT)
+			return 0;
+		die_errno(_("could not open '%s' for reading"), filename);
+	}
+
+	if (read_shell_var(&state->author_name, fp, "GIT_AUTHOR_NAME"))
+		return -1;
+
+	if (read_shell_var(&state->author_email, fp, "GIT_AUTHOR_EMAIL"))
+		return -1;
+
+	if (read_shell_var(&state->author_date, fp, "GIT_AUTHOR_DATE"))
+		return -1;
+
+	if (fgetc(fp) != EOF)
+		return -1;
+
+	fclose(fp);
+	return 0;
+}
+
+/**
+ * Saves state->author_name, state->author_email and state->author_date in
+ * `filename` as an "author script", which is the format used by git-am.sh.
+ */
+static void write_author_script(const struct am_state *state)
+{
+	static const char fmt[] = "GIT_AUTHOR_NAME=%s\n"
+		"GIT_AUTHOR_EMAIL=%s\n"
+		"GIT_AUTHOR_DATE=%s\n";
+	struct strbuf author_name = STRBUF_INIT;
+	struct strbuf author_email = STRBUF_INIT;
+	struct strbuf author_date = STRBUF_INIT;
+
+	sq_quote_buf(&author_name, state->author_name.buf);
+	sq_quote_buf(&author_email, state->author_email.buf);
+	sq_quote_buf(&author_date, state->author_date.buf);
+
+	write_file(am_path(state, "author-script"), 1, fmt,
+			author_name.buf, author_email.buf, author_date.buf);
+
+	strbuf_release(&author_name);
+	strbuf_release(&author_email);
+	strbuf_release(&author_date);
+}
+
+/**
  * Loads state from disk.
  */
 static void am_load(struct am_state *state)
@@ -106,6 +237,11 @@ static void am_load(struct am_state *state)
 	read_state_file(&sb, am_path(state, "last"), 8, 1);
 	state->last = strtol(sb.buf, NULL, 10);
 
+	if (read_author_script(state) < 0)
+		die(_("could not parse author script"));
+
+	read_state_file(&state->msg, am_path(state, "final-commit"), 0, 0);
+
 	strbuf_release(&sb);
 }
 
@@ -296,6 +432,91 @@ static void am_next(struct am_state *state)
 {
 	state->cur++;
 	write_file(am_path(state, "next"), 1, "%d", state->cur);
+
+	strbuf_reset(&state->author_name);
+	strbuf_reset(&state->author_email);
+	strbuf_reset(&state->author_date);
+	unlink(am_path(state, "author-script"));
+
+	strbuf_reset(&state->msg);
+	unlink(am_path(state, "final-commit"));
+}
+
+/**
+ * Returns the filename of the current patch.
+ */
+static const char *msgnum(const struct am_state *state)
+{
+	static struct strbuf sb = STRBUF_INIT;
+
+	strbuf_reset(&sb);
+	strbuf_addf(&sb, "%0*d", state->prec, state->cur);
+
+	return sb.buf;
+}
+
+/**
+ * Parses `patch` using git-mailinfo. state->msg will be set to the patch
+ * message. state->author_name, state->author_email, state->author_date will be
+ * set to the patch author's name, email and date respectively. The patch's
+ * body will be written to "$state_dir/patch", where $state_dir is the state
+ * directory.
+ *
+ * Returns 1 if the patch should be skipped, 0 otherwise.
+ */
+static int parse_patch(struct am_state *state, const char *patch)
+{
+	FILE *fp;
+	struct child_process cp = CHILD_PROCESS_INIT;
+	struct strbuf sb = STRBUF_INIT;
+
+	cp.git_cmd = 1;
+	cp.in = xopen(patch, O_RDONLY, 0);
+	cp.out = xopen(am_path(state, "info"), O_WRONLY | O_CREAT, 0777);
+
+	argv_array_push(&cp.args, "mailinfo");
+	argv_array_push(&cp.args, am_path(state, "msg"));
+	argv_array_push(&cp.args, am_path(state, "patch"));
+
+	if (run_command(&cp) < 0)
+		die("could not parse patch");
+
+	close(cp.in);
+	close(cp.out);
+
+	/* Extract message and author information */
+	fp = xfopen(am_path(state, "info"), "r");
+	while (!strbuf_getline(&sb, fp, '\n')) {
+		const char *x;
+
+		if (skip_prefix(sb.buf, "Subject: ", &x)) {
+			if (state->msg.len)
+				strbuf_addch(&state->msg, '\n');
+			strbuf_addstr(&state->msg, x);
+		} else if (skip_prefix(sb.buf, "Author: ", &x))
+			strbuf_addstr(&state->author_name, x);
+		else if (skip_prefix(sb.buf, "Email: ", &x))
+			strbuf_addstr(&state->author_email, x);
+		else if (skip_prefix(sb.buf, "Date: ", &x))
+			strbuf_addstr(&state->author_date, x);
+	}
+	fclose(fp);
+
+	/* Skip pine's internal folder data */
+	if (!strcmp(state->author_name.buf, "Mail System Internal Data"))
+		return 1;
+
+	if (is_empty_file(am_path(state, "patch")))
+		die(_("Patch is empty. Was it split wrong?\n"
+		"If you would prefer to skip this patch, instead run \"git am --skip\".\n"
+		"To restore the original branch and stop patching run \"git am --abort\"."));
+
+	strbuf_addstr(&state->msg, "\n\n");
+	if (strbuf_read_file(&state->msg, am_path(state, "msg"), 0) < 0)
+		die_errno(_("could not read '%s'"), am_path(state, "msg"));
+	stripspace(&state->msg, 0);
+
+	return 0;
 }
 
 /**
@@ -304,9 +525,20 @@ static void am_next(struct am_state *state)
 static void am_run(struct am_state *state)
 {
 	while (state->cur <= state->last) {
+		const char *patch = am_path(state, msgnum(state));
+
+		if (!file_exists(patch))
+			goto next;
+
+		if (parse_patch(state, patch))
+			goto next; /* patch should be skipped */
+
+		write_author_script(state);
+		write_file(am_path(state, "final-commit"), 1, "%s", state->msg.buf);
 
 		/* TODO: Patch application not implemented yet */
 
+next:
 		am_next(state);
 	}
 

diff --git a/builtin/am.c b/builtin/am.c
index f55dd14..944e35a 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -98,10 +98,10 @@ struct am_state {
 	int last;
 
 	/* commit message and metadata */
-	struct strbuf author_name;
-	struct strbuf author_email;
-	struct strbuf author_date;
-	struct strbuf msg;
+	char *author_name;
+	char *author_email;
+	char *author_date;
+	char *msg;
 
 	/* number of digits in patch filename */
 	int prec;
@@ -148,10 +148,10 @@ static void am_state_init(struct am_state *state, const char *dir)
 
 	state->dir = xstrdup_or_null(dir);
 
-	strbuf_init(&state->author_name, 0);
-	strbuf_init(&state->author_email, 0);
-	strbuf_init(&state->author_date, 0);
-	strbuf_init(&state->msg, 0);
+	state->author_name = NULL;
+	state->author_email = NULL;
+	state->author_date = NULL;
+	state->msg = NULL;
 
 	state->prec = 4;
 
@@ -177,10 +177,17 @@ static void am_state_release(struct am_state *state)
 	if (state->dir)
 		free(state->dir);
 
-	strbuf_release(&state->author_name);
-	strbuf_release(&state->author_email);
-	strbuf_release(&state->author_date);
-	strbuf_release(&state->msg);
+	if (state->author_name)
+		free(state->author_name);
+
+	if (state->author_email)
+		free(state->author_email);
+
+	if (state->author_date)
+		free(state->author_date);
+
+	if (state->msg)
+		free(state->msg);
 
 	argv_array_clear(&state->git_apply_opts);
 }
@@ -250,37 +257,32 @@ static int read_state_file(struct strbuf *sb, const char *file, size_t hint, int
 }
 
 /**
- * Reads a KEY=VALUE shell variable assignment from fp, and returns the VALUE
- * in `value`. VALUE must be a quoted string, and the KEY must match `key`.
- * Returns 0 on success, -1 on failure.
+ * Reads a KEY=VALUE shell variable assignment from fp, returning the VALUE as
+ * a newly-allocated string. VALUE must be a quoted string, and the KEY must
+ * match `key`. Returns NULL on failure.
  *
  * This is used by read_author_script() to read the GIT_AUTHOR_* variables from
  * the author-script.
  */
-static int read_shell_var(struct strbuf *value, FILE *fp, const char *key)
+static char *read_shell_var(FILE *fp, const char *key)
 {
 	struct strbuf sb = STRBUF_INIT;
 	char *str;
 
 	if (strbuf_getline(&sb, fp, '\n'))
-		return -1;
+		return NULL;
 
 	if (!skip_prefix(sb.buf, key, (const char **)&str))
-		return -1;
+		return NULL;
 
 	if (!skip_prefix(str, "=", (const char **)&str))
-		return -1;
+		return NULL;
 
 	str = sq_dequote(str);
 	if (!str)
-		return -1;
-
-	strbuf_reset(value);
-	strbuf_addstr(value, str);
+		return NULL;
 
-	strbuf_release(&sb);
-
-	return 0;
+	return strbuf_detach(&sb, NULL);
 }
 
 /**
@@ -307,13 +309,25 @@ static int read_author_script(struct am_state *state)
 		die_errno(_("could not open '%s' for reading"), filename);
 	}
 
-	if (read_shell_var(&state->author_name, fp, "GIT_AUTHOR_NAME"))
+	if (state->author_name)
+		free(state->author_name);
+
+	state->author_name = read_shell_var(fp, "GIT_AUTHOR_NAME");
+	if (!state->author_name)
 		return -1;
 
-	if (read_shell_var(&state->author_email, fp, "GIT_AUTHOR_EMAIL"))
+	if (state->author_email)
+		free(state->author_email);
+
+	state->author_email = read_shell_var(fp, "GIT_AUTHOR_EMAIL");
+	if (!state->author_email)
 		return -1;
 
-	if (read_shell_var(&state->author_date, fp, "GIT_AUTHOR_DATE"))
+	if (state->author_date)
+		free(state->author_date);
+
+	state->author_date = read_shell_var(fp, "GIT_AUTHOR_DATE");
+	if (!state->author_date)
 		return -1;
 
 	if (fgetc(fp) != EOF)
@@ -336,9 +350,9 @@ static void write_author_script(const struct am_state *state)
 	struct strbuf author_email = STRBUF_INIT;
 	struct strbuf author_date = STRBUF_INIT;
 
-	sq_quote_buf(&author_name, state->author_name.buf);
-	sq_quote_buf(&author_email, state->author_email.buf);
-	sq_quote_buf(&author_date, state->author_date.buf);
+	sq_quote_buf(&author_name, state->author_name);
+	sq_quote_buf(&author_email, state->author_email);
+	sq_quote_buf(&author_date, state->author_date);
 
 	write_file(am_path(state, "author-script"), 1, fmt,
 			author_name.buf, author_email.buf, author_date.buf);
@@ -364,7 +378,10 @@ static void am_load(struct am_state *state)
 	if (read_author_script(state) < 0)
 		die(_("could not parse author script"));
 
-	read_state_file(&state->msg, am_path(state, "final-commit"), 0, 0);
+	read_state_file(&sb, am_path(state, "final-commit"), 0, 0);
+	if (state->msg)
+		free(state->msg);
+	state->msg = strbuf_detach(&sb, NULL);
 
 	read_state_file(&sb, am_path(state, "threeway"), 2, 1);
 	state->threeway = !strcmp(sb.buf, "t");
@@ -670,12 +687,24 @@ static void am_next(struct am_state *state)
 	state->cur++;
 	write_file(am_path(state, "next"), 1, "%d", state->cur);
 
-	strbuf_reset(&state->author_name);
-	strbuf_reset(&state->author_email);
-	strbuf_reset(&state->author_date);
+	if (state->author_name)
+		free(state->author_name);
+	state->author_name = NULL;
+
+	if (state->author_email)
+		free(state->author_email);
+	state->author_email = NULL;
+
+	if (state->author_date)
+		free(state->author_date);
+	state->author_date = NULL;
+
 	unlink(am_path(state, "author-script"));
 
-	strbuf_reset(&state->msg);
+	if (state->msg)
+		free(state->msg);
+	state->msg = NULL;
+
 	unlink(am_path(state, "final-commit"));
 
 	if (!get_sha1("HEAD", head))
@@ -762,6 +791,10 @@ static int parse_patch(struct am_state *state, const char *patch)
 	FILE *fp;
 	struct child_process cp = CHILD_PROCESS_INIT;
 	struct strbuf sb = STRBUF_INIT;
+	struct strbuf msg = STRBUF_INIT;
+	struct strbuf author_name = STRBUF_INIT;
+	struct strbuf author_date = STRBUF_INIT;
+	struct strbuf author_email = STRBUF_INIT;
 
 	cp.git_cmd = 1;
 	cp.in = xopen(patch, O_RDONLY, 0);
@@ -813,20 +846,32 @@ static int parse_patch(struct am_state *state, const char *patch)
 		const char *x;
 
 		if (skip_prefix(sb.buf, "Subject: ", &x)) {
-			if (state->msg.len)
-				strbuf_addch(&state->msg, '\n');
-			strbuf_addstr(&state->msg, x);
+			if (msg.len)
+				strbuf_addch(&msg, '\n');
+			strbuf_addstr(&msg, x);
 		} else if (skip_prefix(sb.buf, "Author: ", &x))
-			strbuf_addstr(&state->author_name, x);
+			strbuf_addstr(&author_name, x);
 		else if (skip_prefix(sb.buf, "Email: ", &x))
-			strbuf_addstr(&state->author_email, x);
+			strbuf_addstr(&author_email, x);
 		else if (skip_prefix(sb.buf, "Date: ", &x))
-			strbuf_addstr(&state->author_date, x);
+			strbuf_addstr(&author_date, x);
 	}
 	fclose(fp);
 
+	if (state->author_name)
+		free(state->author_name);
+	state->author_name = strbuf_detach(&author_name, NULL);
+
+	if (state->author_email)
+		free(state->author_email);
+	state->author_email = strbuf_detach(&author_email, NULL);
+
+	if (state->author_date)
+		free(state->author_date);
+	state->author_date = strbuf_detach(&author_date, NULL);
+
 	/* Skip pine's internal folder data */
-	if (!strcmp(state->author_name.buf, "Mail System Internal Data"))
+	if (!strcmp(state->author_name, "Mail System Internal Data"))
 		return 1;
 
 	if (is_empty_file(am_path(state, "patch")))
@@ -834,13 +879,17 @@ static int parse_patch(struct am_state *state, const char *patch)
 		"If you would prefer to skip this patch, instead run \"git am --skip\".\n"
 		"To restore the original branch and stop patching run \"git am --abort\"."));
 
-	strbuf_addstr(&state->msg, "\n\n");
-	if (strbuf_read_file(&state->msg, am_path(state, "msg"), 0) < 0)
+	strbuf_addstr(&msg, "\n\n");
+	if (strbuf_read_file(&msg, am_path(state, "msg"), 0) < 0)
 		die_errno(_("could not read '%s'"), am_path(state, "msg"));
-	stripspace(&state->msg, 0);
+	stripspace(&msg, 0);
 
 	if (state->sign)
-		append_signoff(&state->msg, 0, 0);
+		append_signoff(&msg, 0, 0);
+
+	if (state->msg)
+		free(state->msg);
+	state->msg = strbuf_detach(&msg, NULL);
 
 	return 0;
 }
@@ -876,6 +925,9 @@ static int get_patch_commit_sha1(unsigned char *commit_id, const char *patch)
 static void get_commit_info(struct am_state *state, struct commit *commit)
 {
 	const char *buf, *begin, *end;
+	struct strbuf author_name = STRBUF_INIT;
+	struct strbuf author_email = STRBUF_INIT;
+	struct strbuf author_date = STRBUF_INIT;
 
 	buf = logmsg_reencode(commit, NULL, get_commit_output_encoding());
 	begin = end = buf;
@@ -895,24 +947,36 @@ static void get_commit_info(struct am_state *state, struct commit *commit)
 			}
 
 			if (split.name_begin)
-				strbuf_add(&state->author_name,
-					split.name_begin,
+				strbuf_add(&author_name, split.name_begin,
 					split.name_end - split.name_begin);
 
 			if (split.mail_begin)
-				strbuf_add(&state->author_email,
-					split.mail_begin,
+				strbuf_add(&author_email, split.mail_begin,
 					split.mail_end - split.mail_begin);
 
 			date = show_ident_date(&split, DATE_NORMAL);
-			strbuf_addstr(&state->author_date, date);
+			strbuf_addstr(&author_date, date);
 		} else if (begin == end) {
 			end++;
 			break;
 		}
 	}
 
-	strbuf_addstr(&state->msg, end);
+	if (state->author_name)
+		free(state->author_name);
+	state->author_name = strbuf_detach(&author_name, NULL);
+
+	if (state->author_email)
+		free(state->author_email);
+	state->author_email = strbuf_detach(&author_email, NULL);
+
+	if (state->author_date)
+		free(state->author_date);
+	state->author_date = strbuf_detach(&author_date, NULL);
+
+	if (state->msg)
+		free(state->msg);
+	state->msg = xstrdup(end);
 }
 
 /**
@@ -1107,7 +1171,7 @@ static int fall_back_threeway(const struct am_state *state, const char *index_pa
 	init_merge_options(&o);
 
 	o.branch1 = "HEAD";
-	his_tree_name = xstrfmt("%.*s", linelen(state->msg.buf), state->msg.buf);
+	his_tree_name = xstrfmt("%.*s", linelen(state->msg), state->msg);
 	o.branch2 = his_tree_name;
 
 	if (state->quiet)
@@ -1147,15 +1211,15 @@ static void do_commit(const struct am_state *state)
 		say(state, stderr, _("applying to an empty history"));
 	}
 
-	author = fmt_ident(state->author_name.buf, state->author_email.buf,
-			state->ignore_date ? NULL : state->author_date.buf,
+	author = fmt_ident(state->author_name, state->author_email,
+			state->ignore_date ? NULL : state->author_date,
 			IDENT_STRICT);
 
 	if (state->committer_date_is_author_date)
 		setenv("GIT_COMMITTER_DATE",
-			state->ignore_date ? "" : state->author_date.buf, 1);
+			state->ignore_date ? "" : state->author_date, 1);
 
-	if (commit_tree(state->msg.buf, state->msg.len, tree, parents, commit,
+	if (commit_tree(state->msg, strlen(state->msg), tree, parents, commit,
 				author, state->sign_commit))
 		die(_("failed to write commit object"));
 
@@ -1163,8 +1227,8 @@ static void do_commit(const struct am_state *state)
 	if (!reflog_msg)
 		reflog_msg = "am";
 
-	strbuf_addf(&sb, "%s: %.*s", reflog_msg, linelen(state->msg.buf),
-			state->msg.buf);
+	strbuf_addf(&sb, "%s: %.*s", reflog_msg, linelen(state->msg),
+			state->msg);
 
 	update_ref(sb.buf, "HEAD", commit, ptr, 0, UPDATE_REFS_DIE_ON_ERR);
 
@@ -1191,7 +1255,7 @@ static void am_run(struct am_state *state)
 	strbuf_release(&sb);
 
 	while (state->cur <= state->last) {
-		const char *patch, *msg;
+		const char *patch;
 		int apply_status, skip;
 
 		patch = am_path(state, msgnum(state));
@@ -1208,10 +1272,10 @@ static void am_run(struct am_state *state)
 			goto next; /* patch should be skipped */
 
 		write_author_script(state);
-		write_file(am_path(state, "final-commit"), 1, "%s", state->msg.buf);
+		write_file(am_path(state, "final-commit"), 1, "%s", state->msg);
 
-		msg = state->msg.buf;
-		say(state, stdout, _("Applying: %.*s"), linelen(msg), msg);
+		say(state, stdout, _("Applying: %.*s"), linelen(state->msg),
+			state->msg);
 
 		apply_status = run_apply(state, NULL);
 
@@ -1235,9 +1299,8 @@ static void am_run(struct am_state *state)
 		if (apply_status) {
 			int advice_amworkdir = 1;
 
-			msg = state->msg.buf;
 			printf_ln(_("Patch failed at %s %.*s"), msgnum(state),
-					linelen(msg), msg);
+				linelen(state->msg), state->msg);
 
 			git_config_get_bool("advice.amworkdir", &advice_amworkdir);
 
@@ -1267,10 +1330,7 @@ next:
  */
 static void am_resolve(struct am_state *state)
 {
-	const char *msg;
-
-	msg = state->msg.buf;
-	say(state, stdout, _("Applying: %.*s"), linelen(msg), msg);
+	say(state, stdout, _("Applying: %.*s"), linelen(state->msg), state->msg);
 
 	if (!index_has_changes(NULL)) {
 		printf_ln(_("No changes - did you forget to use 'git add'?\n"

diff --git a/builtin/am.c b/builtin/am.c
index d6434e4..296a5fc 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -27,6 +27,18 @@ static int is_empty_file(const char *filename)
 	return !st.st_size;
 }
 
+/**
+ * Returns the first line of msg
+ */
+static const char *firstline(const char *msg)
+{
+	static struct strbuf sb = STRBUF_INIT;
+
+	strbuf_reset(&sb);
+	strbuf_add(&sb, msg, strchrnul(msg, '\n') - msg);
+	return sb.buf;
+}
+
 enum patch_format {
 	PATCH_FORMAT_UNKNOWN = 0,
 	PATCH_FORMAT_MBOX
@@ -519,6 +531,31 @@ static int parse_patch(struct am_state *state, const char *patch)
 	return 0;
 }
 
+/*
+ * Applies current patch with git-apply. Returns 0 on success, -1 otherwise.
+ */
+static int run_apply(const struct am_state *state)
+{
+	struct child_process cp = CHILD_PROCESS_INIT;
+
+	cp.git_cmd = 1;
+
+	argv_array_push(&cp.args, "apply");
+
+	argv_array_push(&cp.args, "--index");
+
+	argv_array_push(&cp.args, am_path(state, "patch"));
+
+	if (run_command(&cp))
+		return -1;
+
+	/* Reload index as git-apply will have modified it. */
+	discard_cache();
+	read_cache();
+
+	return 0;
+}
+
 /**
  * Applies all queued patches.
  */
@@ -536,7 +573,25 @@ static void am_run(struct am_state *state)
 		write_author_script(state);
 		write_file(am_path(state, "final-commit"), 1, "%s", state->msg.buf);
 
-		/* TODO: Patch application not implemented yet */
+		printf_ln(_("Applying: %s"), firstline(state->msg.buf));
+
+		if (run_apply(state) < 0) {
+			int value;
+
+			printf_ln(_("Patch failed at %s %s"), msgnum(state),
+					firstline(state->msg.buf));
+
+			if (!git_config_get_bool("advice.amworkdir", &value) && !value)
+				printf_ln(_("The copy of the patch that failed is found in: %s"),
+						am_path(state, "patch"));
+
+			exit(128);
+		}
+
+		/*
+		 * TODO: After the patch has been applied to the index with
+		 * git-apply, we need to make commit as well.
+		 */
 
 next:
 		am_next(state);

diff --git a/builtin/am.c b/builtin/am.c
index 296a5fc..dfb6f7e 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -10,6 +10,9 @@
 #include "dir.h"
 #include "run-command.h"
 #include "quote.h"
+#include "cache-tree.h"
+#include "refs.h"
+#include "commit.h"
 
 /**
  * Returns 1 if the file is empty or does not exist, 0 otherwise.
@@ -557,6 +560,49 @@ static int run_apply(const struct am_state *state)
 }
 
 /**
+ * Commits the current index with state->msg as the commit message and
+ * state->author_name, state->author_email and state->author_date as the author
+ * information.
+ */
+static void do_commit(const struct am_state *state)
+{
+	unsigned char tree[GIT_SHA1_RAWSZ], parent[GIT_SHA1_RAWSZ],
+		      commit[GIT_SHA1_RAWSZ];
+	unsigned char *ptr;
+	struct commit_list *parents = NULL;
+	const char *reflog_msg, *author;
+	struct strbuf sb = STRBUF_INIT;
+
+	if (write_cache_as_tree(tree, 0, NULL))
+		die(_("git write-tree failed to write a tree"));
+
+	if (!get_sha1_commit("HEAD", parent)) {
+		ptr = parent;
+		commit_list_insert(lookup_commit(parent), &parents);
+	} else {
+		ptr = NULL;
+		fprintf_ln(stderr, _("applying to an empty history"));
+	}
+
+	author = fmt_ident(state->author_name.buf, state->author_email.buf,
+			state->author_date.buf, IDENT_STRICT);
+
+	if (commit_tree(state->msg.buf, state->msg.len, tree, parents, commit,
+				author, NULL))
+		die(_("failed to write commit object"));
+
+	reflog_msg = getenv("GIT_REFLOG_ACTION");
+	if (!reflog_msg)
+		reflog_msg = "am";
+
+	strbuf_addf(&sb, "%s: %s", reflog_msg, firstline(state->msg.buf));
+
+	update_ref(sb.buf, "HEAD", commit, ptr, 0, UPDATE_REFS_DIE_ON_ERR);
+
+	strbuf_release(&sb);
+}
+
+/**
  * Applies all queued patches.
  */
 static void am_run(struct am_state *state)
@@ -588,10 +634,7 @@ static void am_run(struct am_state *state)
 			exit(128);
 		}
 
-		/*
-		 * TODO: After the patch has been applied to the index with
-		 * git-apply, we need to make commit as well.
-		 */
+		do_commit(state);
 
 next:
 		am_next(state);

diff --git a/builtin/am.c b/builtin/am.c
index dfb6f7e..a7efe85 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -13,6 +13,7 @@
 #include "cache-tree.h"
 #include "refs.h"
 #include "commit.h"
+#include "lockfile.h"
 
 /**
  * Returns 1 if the file is empty or does not exist, 0 otherwise.
@@ -471,6 +472,20 @@ static const char *msgnum(const struct am_state *state)
 }
 
 /**
+ * Refresh and write index.
+ */
+static void refresh_and_write_cache(void)
+{
+	static struct lock_file lock_file;
+
+	hold_locked_index(&lock_file, 1);
+	refresh_cache(REFRESH_QUIET);
+	if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
+		die(_("unable to write index file"));
+	rollback_lock_file(&lock_file);
+}
+
+/**
  * Parses `patch` using git-mailinfo. state->msg will be set to the patch
  * message. state->author_name, state->author_email, state->author_date will be
  * set to the patch author's name, email and date respectively. The patch's
@@ -607,6 +622,8 @@ static void do_commit(const struct am_state *state)
  */
 static void am_run(struct am_state *state)
 {
+	refresh_and_write_cache();
+
 	while (state->cur <= state->last) {
 		const char *patch = am_path(state, msgnum(state));
 
@@ -696,6 +713,9 @@ int cmd_am(int argc, const char **argv, const char *prefix)
 
 	argc = parse_options(argc, argv, prefix, am_options, am_usage, 0);
 
+	if (read_index_preload(&the_index, NULL) < 0)
+		die(_("failed to read the index"));
+
 	if (am_in_progress(&state))
 		am_load(&state);
 	else {

diff --git a/builtin/am.c b/builtin/am.c
index a7efe85..9d6ab2a 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -14,6 +14,8 @@
 #include "refs.h"
 #include "commit.h"
 #include "lockfile.h"
+#include "diff.h"
+#include "diffcore.h"
 
 /**
  * Returns 1 if the file is empty or does not exist, 0 otherwise.
@@ -486,6 +488,43 @@ static void refresh_and_write_cache(void)
 }
 
 /**
+ * Returns 1 if the index differs from HEAD, 0 otherwise. When on an unborn
+ * branch, returns 1 if there are entries in the index, 0 otherwise. If an
+ * strbuf is provided, the space-separated list of files that differ will be
+ * appended to it.
+ */
+static int index_has_changes(struct strbuf *sb)
+{
+	unsigned char head[GIT_SHA1_RAWSZ];
+	int i;
+
+	if (!get_sha1_tree("HEAD", head)) {
+		struct diff_options opt;
+
+		diff_setup(&opt);
+		DIFF_OPT_SET(&opt, EXIT_WITH_STATUS);
+		if (!sb)
+			DIFF_OPT_SET(&opt, QUICK);
+		do_diff_cache(head, &opt);
+		diffcore_std(&opt);
+		for (i = 0; sb && i < diff_queued_diff.nr; i++) {
+			if (i)
+				strbuf_addch(sb, ' ');
+			strbuf_addstr(sb, diff_queued_diff.queue[i]->two->path);
+		}
+		diff_flush(&opt);
+		return DIFF_OPT_TST(&opt, HAS_CHANGES) != 0;
+	} else {
+		for (i = 0; sb && i < active_nr; i++) {
+			if (i)
+				strbuf_addch(sb, ' ');
+			strbuf_addstr(sb, active_cache[i]->name);
+		}
+		return !!active_nr;
+	}
+}
+
+/**
  * Parses `patch` using git-mailinfo. state->msg will be set to the patch
  * message. state->author_name, state->author_email, state->author_date will be
  * set to the patch author's name, email and date respectively. The patch's
@@ -622,8 +661,15 @@ static void do_commit(const struct am_state *state)
  */
 static void am_run(struct am_state *state)
 {
+	struct strbuf sb = STRBUF_INIT;
+
 	refresh_and_write_cache();
 
+	if (index_has_changes(&sb))
+		die(_("Dirty index: cannot apply patches (dirty: %s)"), sb.buf);
+
+	strbuf_release(&sb);
+
 	while (state->cur <= state->last) {
 		const char *patch = am_path(state, msgnum(state));
 

diff --git a/builtin/am.c b/builtin/am.c
index 9d6ab2a..4381164 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -707,6 +707,34 @@ next:
 }
 
 /**
+ * Resume the current am session after patch application failure. The user did
+ * all the hard work, and we do not have to do any patch application. Just
+ * trust and commit what the user has in the index and working tree.
+ */
+static void am_resolve(struct am_state *state)
+{
+	printf_ln(_("Applying: %s"), firstline(state->msg.buf));
+
+	if (!index_has_changes(NULL)) {
+		printf_ln(_("No changes - did you forget to use 'git add'?\n"
+			"If there is nothing left to stage, chances are that something else\n"
+			"already introduced the same changes; you might want to skip this patch."));
+		exit(128);
+	}
+
+	if (unmerged_cache()) {
+		printf_ln(_("You still have unmerged paths in your index.\n"
+			"Did you forget to use 'git add'?"));
+		exit(128);
+	}
+
+	do_commit(state);
+
+	am_next(state);
+	am_run(state);
+}
+
+/**
  * parse_options() callback that validates and sets opt->value to the
  * PATCH_FORMAT_* enum value corresponding to `arg`.
  */
@@ -721,17 +749,30 @@ static int parse_opt_patchformat(const struct option *opt, const char *arg, int
 	return 0;
 }
 
+enum resume_mode {
+	RESUME_FALSE = 0,
+	RESUME_RESOLVED
+};
+
 static struct am_state state;
 static int opt_patch_format;
+static enum resume_mode opt_resume;
 
 static const char * const am_usage[] = {
 	N_("git am [options] [(<mbox>|<Maildir>)...]"),
+	N_("git am [options] --continue"),
 	NULL
 };
 
 static struct option am_options[] = {
 	OPT_CALLBACK(0, "patch-format", &opt_patch_format, N_("format"),
 		N_("format the patch(es) are in"), parse_opt_patchformat),
+	OPT_CMDMODE(0, "continue", &opt_resume,
+		N_("continue applying patches after resolving a conflict"),
+		RESUME_RESOLVED),
+	OPT_CMDMODE('r', "resolved", &opt_resume,
+		N_("synonyms for --continue"),
+		RESUME_RESOLVED),
 	OPT_END()
 };
 
@@ -768,6 +809,9 @@ int cmd_am(int argc, const char **argv, const char *prefix)
 		struct string_list paths = STRING_LIST_INIT_DUP;
 		int i;
 
+		if (opt_resume)
+			die(_("Resolve operation not in progress, we are not resuming."));
+
 		for (i = 0; i < argc; i++) {
 			if (is_absolute_path(argv[i]) || !prefix)
 				string_list_append(&paths, argv[i]);
@@ -780,7 +824,16 @@ int cmd_am(int argc, const char **argv, const char *prefix)
 		string_list_clear(&paths, 0);
 	}
 
-	am_run(&state);
+	switch (opt_resume) {
+	case RESUME_FALSE:
+		am_run(&state);
+		break;
+	case RESUME_RESOLVED:
+		am_resolve(&state);
+		break;
+	default:
+		die("BUG: invalid resume value");
+	}
 
 	am_state_release(&state);
 

diff --git a/builtin/am.c b/builtin/am.c
index 4381164..0d7af19 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -16,6 +16,8 @@
 #include "lockfile.h"
 #include "diff.h"
 #include "diffcore.h"
+#include "unpack-trees.h"
+#include "branch.h"
 
 /**
  * Returns 1 if the file is empty or does not exist, 0 otherwise.
@@ -735,6 +737,114 @@ static void am_resolve(struct am_state *state)
 }
 
 /**
+ * Performs a checkout fast-forward from `head` to `remote`. If `reset` is
+ * true, any unmerged entries will be discarded. Returns 0 on success, -1 on
+ * failure.
+ */
+static int fast_forward_to(struct tree *head, struct tree *remote, int reset)
+{
+	struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
+	struct unpack_trees_options opts;
+	struct tree_desc t[2];
+
+	if (parse_tree(head) || parse_tree(remote))
+		return -1;
+
+	hold_locked_index(lock_file, 1);
+
+	refresh_cache(REFRESH_QUIET);
+
+	memset(&opts, 0, sizeof(opts));
+	opts.head_idx = 1;
+	opts.src_index = &the_index;
+	opts.dst_index = &the_index;
+	opts.update = 1;
+	opts.merge = 1;
+	opts.reset = reset;
+	opts.fn = twoway_merge;
+	init_tree_desc(&t[0], head->buffer, head->size);
+	init_tree_desc(&t[1], remote->buffer, remote->size);
+
+	if (unpack_trees(2, t, &opts)) {
+		rollback_lock_file(lock_file);
+		return -1;
+	}
+
+	if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
+		die(_("unable to write new index file"));
+
+	return 0;
+}
+
+/**
+ * Clean the index without touching entries that are not modified between
+ * `head` and `remote`.
+ */
+static int clean_index(const unsigned char *head, const unsigned char *remote)
+{
+	struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
+	struct tree *head_tree, *remote_tree, *index_tree;
+	unsigned char index[GIT_SHA1_RAWSZ];
+	struct pathspec pathspec;
+
+	head_tree = parse_tree_indirect(head);
+	if (!head_tree)
+		return error(_("Could not parse object '%s'."), sha1_to_hex(head));
+
+	remote_tree = parse_tree_indirect(remote);
+	if (!remote_tree)
+		return error(_("Could not parse object '%s'."), sha1_to_hex(remote));
+
+	read_cache_unmerged();
+
+	if (fast_forward_to(head_tree, head_tree, 1))
+		return -1;
+
+	if (write_cache_as_tree(index, 0, NULL))
+		return -1;
+
+	index_tree = parse_tree_indirect(index);
+	if (!index_tree)
+		return error(_("Could not parse object '%s'."), sha1_to_hex(index));
+
+	if (fast_forward_to(index_tree, remote_tree, 0))
+		return -1;
+
+	memset(&pathspec, 0, sizeof(pathspec));
+
+	hold_locked_index(lock_file, 1);
+
+	if (read_tree(remote_tree, 0, &pathspec)) {
+		rollback_lock_file(lock_file);
+		return -1;
+	}
+
+	if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
+		die(_("unable to write new index file"));
+
+	remove_branch_state();
+
+	return 0;
+}
+
+/**
+ * Resume the current am session by skipping the current patch.
+ */
+static void am_skip(struct am_state *state)
+{
+	unsigned char head[GIT_SHA1_RAWSZ];
+
+	if (get_sha1("HEAD", head))
+		hashcpy(head, EMPTY_TREE_SHA1_BIN);
+
+	if (clean_index(head, head))
+		die(_("failed to clean index"));
+
+	am_next(state);
+	am_run(state);
+}
+
+/**
  * parse_options() callback that validates and sets opt->value to the
  * PATCH_FORMAT_* enum value corresponding to `arg`.
  */
@@ -751,7 +861,8 @@ static int parse_opt_patchformat(const struct option *opt, const char *arg, int
 
 enum resume_mode {
 	RESUME_FALSE = 0,
-	RESUME_RESOLVED
+	RESUME_RESOLVED,
+	RESUME_SKIP
 };
 
 static struct am_state state;
@@ -760,7 +871,7 @@ static enum resume_mode opt_resume;
 
 static const char * const am_usage[] = {
 	N_("git am [options] [(<mbox>|<Maildir>)...]"),
-	N_("git am [options] --continue"),
+	N_("git am [options] (--continue | --skip)"),
 	NULL
 };
 
@@ -773,6 +884,9 @@ static struct option am_options[] = {
 	OPT_CMDMODE('r', "resolved", &opt_resume,
 		N_("synonyms for --continue"),
 		RESUME_RESOLVED),
+	OPT_CMDMODE(0, "skip", &opt_resume,
+		N_("skip the current patch"),
+		RESUME_SKIP),
 	OPT_END()
 };
 
@@ -831,6 +945,9 @@ int cmd_am(int argc, const char **argv, const char *prefix)
 	case RESUME_RESOLVED:
 		am_resolve(&state);
 		break;
+	case RESUME_SKIP:
+		am_skip(&state);
+		break;
 	default:
 		die("BUG: invalid resume value");
 	}

diff --git a/builtin/am.c b/builtin/am.c
index 0d7af19..7053b8f 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -423,6 +423,8 @@ static int split_patches(struct am_state *state, enum patch_format patch_format,
 static void am_setup(struct am_state *state, enum patch_format patch_format,
 		struct string_list *paths)
 {
+	unsigned char curr_head[GIT_SHA1_RAWSZ];
+
 	if (!patch_format)
 		patch_format = detect_patch_format(paths);
 
@@ -442,6 +444,14 @@ static void am_setup(struct am_state *state, enum patch_format patch_format,
 	write_file(am_path(state, "next"), 1, "%d", state->cur);
 
 	write_file(am_path(state, "last"), 1, "%d", state->last);
+
+	if (!get_sha1("HEAD", curr_head)) {
+		write_file(am_path(state, "abort-safety"), 1, "%s", sha1_to_hex(curr_head));
+		update_ref("am", "ORIG_HEAD", curr_head, NULL, 0, UPDATE_REFS_DIE_ON_ERR);
+	} else {
+		write_file(am_path(state, "abort-safety"), 1, "%s", "");
+		delete_ref("ORIG_HEAD", NULL, 0);
+	}
 }
 
 /**
@@ -450,6 +460,8 @@ static void am_setup(struct am_state *state, enum patch_format patch_format,
  */
 static void am_next(struct am_state *state)
 {
+	unsigned char head[GIT_SHA1_RAWSZ];
+
 	state->cur++;
 	write_file(am_path(state, "next"), 1, "%d", state->cur);
 
@@ -460,6 +472,11 @@ static void am_next(struct am_state *state)
 
 	strbuf_reset(&state->msg);
 	unlink(am_path(state, "final-commit"));
+
+	if (!get_sha1("HEAD", head))
+		write_file(am_path(state, "abort-safety"), 1, "%s", sha1_to_hex(head));
+	else
+		write_file(am_path(state, "abort-safety"), 1, "%s", "");
 }
 
 /**
@@ -665,10 +682,14 @@ static void am_run(struct am_state *state)
 {
 	struct strbuf sb = STRBUF_INIT;
 
+	unlink(am_path(state, "dirtyindex"));
+
 	refresh_and_write_cache();
 
-	if (index_has_changes(&sb))
+	if (index_has_changes(&sb)) {
+		write_file(am_path(state, "dirtyindex"), 1, "t");
 		die(_("Dirty index: cannot apply patches (dirty: %s)"), sb.buf);
+	}
 
 	strbuf_release(&sb);
 
@@ -844,6 +865,67 @@ static void am_skip(struct am_state *state)
 	am_run(state);
 }
 
+static int safe_to_abort(const struct am_state *state)
+{
+	struct strbuf sb = STRBUF_INIT;
+	unsigned char abort_safety[GIT_SHA1_RAWSZ], head[GIT_SHA1_RAWSZ];
+
+	if (file_exists(am_path(state, "dirtyindex")))
+		return 0;
+
+	if (read_state_file(&sb, am_path(state, "abort-safety"), 40, 1) > 0) {
+		if (get_sha1_hex(sb.buf, abort_safety))
+			die(_("could not parse %s"), am_path(state, "abort_safety"));
+	} else
+		hashclr(abort_safety);
+
+	if (get_sha1("HEAD", head))
+		hashclr(head);
+
+	if (!hashcmp(head, abort_safety))
+		return 1;
+
+	error(_("You seem to have moved HEAD since the last 'am' failure.\n"
+		"Not rewinding to ORIG_HEAD"));
+
+	return 0;
+}
+
+/**
+ * Aborts the current am session if it is safe to do so.
+ */
+static void am_abort(struct am_state *state)
+{
+	unsigned char curr_head[GIT_SHA1_RAWSZ], orig_head[GIT_SHA1_RAWSZ];
+	int has_curr_head, has_orig_head;
+	const char *curr_branch;
+
+	if (!safe_to_abort(state)) {
+		am_destroy(state);
+		return;
+	}
+
+	curr_branch = resolve_refdup("HEAD", 0, curr_head, NULL);
+	has_curr_head = !is_null_sha1(curr_head);
+	if (!has_curr_head)
+		hashcpy(curr_head, EMPTY_TREE_SHA1_BIN);
+
+	has_orig_head = !get_sha1("ORIG_HEAD", orig_head);
+	if (!has_orig_head)
+		hashcpy(orig_head, EMPTY_TREE_SHA1_BIN);
+
+	clean_index(curr_head, orig_head);
+
+	if (has_orig_head)
+		update_ref("am --abort", "HEAD", orig_head,
+				has_curr_head ? curr_head : NULL, 0,
+				UPDATE_REFS_DIE_ON_ERR);
+	else if (curr_branch)
+		delete_ref(curr_branch, NULL, REF_NODEREF);
+
+	am_destroy(state);
+}
+
 /**
  * parse_options() callback that validates and sets opt->value to the
  * PATCH_FORMAT_* enum value corresponding to `arg`.
@@ -862,7 +944,8 @@ static int parse_opt_patchformat(const struct option *opt, const char *arg, int
 enum resume_mode {
 	RESUME_FALSE = 0,
 	RESUME_RESOLVED,
-	RESUME_SKIP
+	RESUME_SKIP,
+	RESUME_ABORT
 };
 
 static struct am_state state;
@@ -871,7 +954,7 @@ static enum resume_mode opt_resume;
 
 static const char * const am_usage[] = {
 	N_("git am [options] [(<mbox>|<Maildir>)...]"),
-	N_("git am [options] (--continue | --skip)"),
+	N_("git am [options] (--continue | --skip | --abort)"),
 	NULL
 };
 
@@ -887,6 +970,9 @@ static struct option am_options[] = {
 	OPT_CMDMODE(0, "skip", &opt_resume,
 		N_("skip the current patch"),
 		RESUME_SKIP),
+	OPT_CMDMODE(0, "abort", &opt_resume,
+		N_("restore the original branch and abort the patching operation."),
+		RESUME_ABORT),
 	OPT_END()
 };
 
@@ -948,6 +1034,9 @@ int cmd_am(int argc, const char **argv, const char *prefix)
 	case RESUME_SKIP:
 		am_skip(&state);
 		break;
+	case RESUME_ABORT:
+		am_abort(&state);
+		break;
 	default:
 		die("BUG: invalid resume value");
 	}

diff --git a/builtin/am.c b/builtin/am.c
index 7053b8f..4adc487 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -1003,9 +1003,24 @@ int cmd_am(int argc, const char **argv, const char *prefix)
 	if (read_index_preload(&the_index, NULL) < 0)
 		die(_("failed to read the index"));
 
-	if (am_in_progress(&state))
+	if (am_in_progress(&state)) {
+		/*
+		 * Catch user error to feed us patches when there is a session
+		 * in progress:
+		 *
+		 * 1. mbox path(s) are provided on the command-line.
+		 * 2. stdin is not a tty: the user is trying to feed us a patch
+		 *    from standard input. This is somewhat unreliable -- stdin
+		 *    could be /dev/null for example and the caller did not
+		 *    intend to feed us a patch but wanted to continue
+		 *    unattended.
+		 */
+		if (argc || (!opt_resume && !isatty(0)))
+			die(_("previous rebase directory %s still exists but mbox given."),
+				state.dir.buf);
+
 		am_load(&state);
-	else {
+	} else {
 		struct string_list paths = STRING_LIST_INIT_DUP;
 		int i;
 

diff --git a/builtin/am.c b/builtin/am.c
index 4adc487..5f38264 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -68,6 +68,8 @@ struct am_state {
 
 	/* number of digits in patch filename */
 	int prec;
+
+	int quiet;
 };
 
 /**
@@ -75,6 +77,8 @@ struct am_state {
  */
 static void am_state_init(struct am_state *state)
 {
+	const char *quiet;
+
 	memset(state, 0, sizeof(*state));
 
 	strbuf_init(&state->dir, 0);
@@ -85,6 +89,10 @@ static void am_state_init(struct am_state *state)
 	strbuf_init(&state->msg, 0);
 
 	state->prec = 4;
+
+	quiet = getenv("GIT_QUIET");
+	if (quiet && *quiet)
+		state->quiet = 1;
 }
 
 /**
@@ -108,6 +116,22 @@ static inline const char *am_path(const struct am_state *state, const char *path
 }
 
 /**
+ * If state->quiet is false, calls fprintf(fp, fmt, ...), and appends a newline
+ * at the end.
+ */
+static void say(const struct am_state *state, FILE *fp, const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	if (!state->quiet) {
+		vfprintf(fp, fmt, ap);
+		putc('\n', fp);
+	}
+	va_end(ap);
+}
+
+/**
  * Returns 1 if there is an am session in progress, 0 otherwise.
  */
 static int am_in_progress(const struct am_state *state)
@@ -262,6 +286,9 @@ static void am_load(struct am_state *state)
 
 	read_state_file(&state->msg, am_path(state, "final-commit"), 0, 0);
 
+	read_state_file(&sb, am_path(state, "quiet"), 2, 1);
+	state->quiet = !strcmp(sb.buf, "t");
+
 	strbuf_release(&sb);
 }
 
@@ -445,6 +472,8 @@ static void am_setup(struct am_state *state, enum patch_format patch_format,
 
 	write_file(am_path(state, "last"), 1, "%d", state->last);
 
+	write_file(am_path(state, "quiet"), 1, state->quiet ? "t" : "f");
+
 	if (!get_sha1("HEAD", curr_head)) {
 		write_file(am_path(state, "abort-safety"), 1, "%s", sha1_to_hex(curr_head));
 		update_ref("am", "ORIG_HEAD", curr_head, NULL, 0, UPDATE_REFS_DIE_ON_ERR);
@@ -654,7 +683,7 @@ static void do_commit(const struct am_state *state)
 		commit_list_insert(lookup_commit(parent), &parents);
 	} else {
 		ptr = NULL;
-		fprintf_ln(stderr, _("applying to an empty history"));
+		say(state, stderr, _("applying to an empty history"));
 	}
 
 	author = fmt_ident(state->author_name.buf, state->author_email.buf,
@@ -705,7 +734,7 @@ static void am_run(struct am_state *state)
 		write_author_script(state);
 		write_file(am_path(state, "final-commit"), 1, "%s", state->msg.buf);
 
-		printf_ln(_("Applying: %s"), firstline(state->msg.buf));
+		say(state, stdout, _("Applying: %s"), firstline(state->msg.buf));
 
 		if (run_apply(state) < 0) {
 			int value;
@@ -736,7 +765,7 @@ next:
  */
 static void am_resolve(struct am_state *state)
 {
-	printf_ln(_("Applying: %s"), firstline(state->msg.buf));
+	say(state, stdout, _("Applying: %s"), firstline(state->msg.buf));
 
 	if (!index_has_changes(NULL)) {
 		printf_ln(_("No changes - did you forget to use 'git add'?\n"
@@ -959,6 +988,7 @@ static const char * const am_usage[] = {
 };
 
 static struct option am_options[] = {
+	OPT__QUIET(&state.quiet, N_("be quiet")),
 	OPT_CALLBACK(0, "patch-format", &opt_patch_format, N_("format"),
 		N_("format the patch(es) are in"), parse_opt_patchformat),
 	OPT_CMDMODE(0, "continue", &opt_resume,

diff --git a/builtin/am.c b/builtin/am.c
index 5f38264..1807d12 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -70,6 +70,9 @@ struct am_state {
 	int prec;
 
 	int quiet;
+
+	/* override error message when patch failure occurs */
+	const char *resolvemsg;
 };
 
 /**
@@ -636,6 +639,21 @@ static int parse_patch(struct am_state *state, const char *patch)
 	return 0;
 }
 
+/**
+ * Dies with a user-friendly message on how to proceed after resolving the
+ * problem. This message can be overridden with state->resolvemsg.
+ */
+static void NORETURN die_user_resolve(const struct am_state *state)
+{
+	if (state->resolvemsg)
+		printf_ln("%s", state->resolvemsg);
+	else
+		printf_ln(_("When you have resolved this problem, run \"git am --continue\".\n"
+			"If you prefer to skip this patch, run \"git am --skip\" instead.\n"
+			"To restore the original branch and stop patching, run \"git am --abort\"."));
+	exit(128);
+}
+
 /*
  * Applies current patch with git-apply. Returns 0 on success, -1 otherwise.
  */
@@ -746,7 +764,7 @@ static void am_run(struct am_state *state)
 				printf_ln(_("The copy of the patch that failed is found in: %s"),
 						am_path(state, "patch"));
 
-			exit(128);
+			die_user_resolve(state);
 		}
 
 		do_commit(state);
@@ -771,13 +789,13 @@ static void am_resolve(struct am_state *state)
 		printf_ln(_("No changes - did you forget to use 'git add'?\n"
 			"If there is nothing left to stage, chances are that something else\n"
 			"already introduced the same changes; you might want to skip this patch."));
-		exit(128);
+		die_user_resolve(state);
 	}
 
 	if (unmerged_cache()) {
 		printf_ln(_("You still have unmerged paths in your index.\n"
 			"Did you forget to use 'git add'?"));
-		exit(128);
+		die_user_resolve(state);
 	}
 
 	do_commit(state);
@@ -991,6 +1009,8 @@ static struct option am_options[] = {
 	OPT__QUIET(&state.quiet, N_("be quiet")),
 	OPT_CALLBACK(0, "patch-format", &opt_patch_format, N_("format"),
 		N_("format the patch(es) are in"), parse_opt_patchformat),
+	OPT_STRING(0, "resolvemsg", &state.resolvemsg, NULL,
+		N_("override error message when patch failure occurs")),
 	OPT_CMDMODE(0, "continue", &opt_resume,
 		N_("continue applying patches after resolving a conflict"),
 		RESUME_RESOLVED),

diff --git a/builtin/am.c b/builtin/am.c
index 1807d12..d45dd41 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -18,6 +18,7 @@
 #include "diffcore.h"
 #include "unpack-trees.h"
 #include "branch.h"
+#include "sequencer.h"
 
 /**
  * Returns 1 if the file is empty or does not exist, 0 otherwise.
@@ -71,6 +72,8 @@ struct am_state {
 
 	int quiet;
 
+	int sign;
+
 	/* override error message when patch failure occurs */
 	const char *resolvemsg;
 };
@@ -292,6 +295,9 @@ static void am_load(struct am_state *state)
 	read_state_file(&sb, am_path(state, "quiet"), 2, 1);
 	state->quiet = !strcmp(sb.buf, "t");
 
+	read_state_file(&sb, am_path(state, "sign"), 2, 1);
+	state->sign = !strcmp(sb.buf, "t");
+
 	strbuf_release(&sb);
 }
 
@@ -477,6 +483,8 @@ static void am_setup(struct am_state *state, enum patch_format patch_format,
 
 	write_file(am_path(state, "quiet"), 1, state->quiet ? "t" : "f");
 
+	write_file(am_path(state, "sign"), 1, state->sign ? "t" : "f");
+
 	if (!get_sha1("HEAD", curr_head)) {
 		write_file(am_path(state, "abort-safety"), 1, "%s", sha1_to_hex(curr_head));
 		update_ref("am", "ORIG_HEAD", curr_head, NULL, 0, UPDATE_REFS_DIE_ON_ERR);
@@ -636,6 +644,9 @@ static int parse_patch(struct am_state *state, const char *patch)
 		die_errno(_("could not read '%s'"), am_path(state, "msg"));
 	stripspace(&state->msg, 0);
 
+	if (state->sign)
+		append_signoff(&state->msg, 0, 0);
+
 	return 0;
 }
 
@@ -1007,6 +1018,8 @@ static const char * const am_usage[] = {
 
 static struct option am_options[] = {
 	OPT__QUIET(&state.quiet, N_("be quiet")),
+	OPT_BOOL('s', "signoff", &state.sign,
+		N_("add a Signed-off-by line to the commit message")),
 	OPT_CALLBACK(0, "patch-format", &opt_patch_format, N_("format"),
 		N_("format the patch(es) are in"), parse_opt_patchformat),
 	OPT_STRING(0, "resolvemsg", &state.resolvemsg, NULL,

cache-tree.c, cache-tree.h

diff --git a/cache-tree.c b/cache-tree.c
index 32772b9..feace8b 100644
--- a/cache-tree.c
+++ b/cache-tree.c
@@ -592,7 +592,7 @@ static struct cache_tree *cache_tree_find(struct cache_tree *it, const char *pat
 	return it;
 }
 
-int write_cache_as_tree(unsigned char *sha1, int flags, const char *prefix)
+int write_index_as_tree(unsigned char *sha1, struct index_state *index_state, const char *index_path, int flags, const char *prefix)
 {
 	int entries, was_valid, newfd;
 	struct lock_file *lock_file;
@@ -603,23 +603,23 @@ int write_cache_as_tree(unsigned char *sha1, int flags, const char *prefix)
 	 */
 	lock_file = xcalloc(1, sizeof(struct lock_file));
 
-	newfd = hold_locked_index(lock_file, 1);
+	newfd = hold_lock_file_for_update(lock_file, index_path, LOCK_DIE_ON_ERROR);
 
-	entries = read_cache();
+	entries = read_index_from(index_state, index_path);
 	if (entries < 0)
 		return WRITE_TREE_UNREADABLE_INDEX;
 	if (flags & WRITE_TREE_IGNORE_CACHE_TREE)
-		cache_tree_free(&(active_cache_tree));
+		cache_tree_free(&index_state->cache_tree);
 
-	if (!active_cache_tree)
-		active_cache_tree = cache_tree();
+	if (!index_state->cache_tree)
+		index_state->cache_tree = cache_tree();
 
-	was_valid = cache_tree_fully_valid(active_cache_tree);
+	was_valid = cache_tree_fully_valid(index_state->cache_tree);
 	if (!was_valid) {
-		if (cache_tree_update(&the_index, flags) < 0)
+		if (cache_tree_update(index_state, flags) < 0)
 			return WRITE_TREE_UNMERGED_INDEX;
 		if (0 <= newfd) {
-			if (!write_locked_index(&the_index, lock_file, COMMIT_LOCK))
+			if (!write_locked_index(index_state, lock_file, COMMIT_LOCK))
 				newfd = -1;
 		}
 		/* Not being able to write is fine -- we are only interested
@@ -631,14 +631,14 @@ int write_cache_as_tree(unsigned char *sha1, int flags, const char *prefix)
 	}
 
 	if (prefix) {
-		struct cache_tree *subtree =
-			cache_tree_find(active_cache_tree, prefix);
+		struct cache_tree *subtree;
+		subtree = cache_tree_find(index_state->cache_tree, prefix);
 		if (!subtree)
 			return WRITE_TREE_PREFIX_ERROR;
 		hashcpy(sha1, subtree->sha1);
 	}
 	else
-		hashcpy(sha1, active_cache_tree->sha1);
+		hashcpy(sha1, index_state->cache_tree->sha1);
 
 	if (0 <= newfd)
 		rollback_lock_file(lock_file);
@@ -646,6 +646,11 @@ int write_cache_as_tree(unsigned char *sha1, int flags, const char *prefix)
 	return 0;
 }
 
+int write_cache_as_tree(unsigned char *sha1, int flags, const char *prefix)
+{
+	return write_index_as_tree(sha1, &the_index, get_index_file(), flags, prefix);
+}
+
 static void prime_cache_tree_rec(struct cache_tree *it, struct tree *tree)
 {
 	struct tree_desc desc;
diff --git a/cache-tree.h b/cache-tree.h
index aa7b3e4..41c5746 100644
--- a/cache-tree.h
+++ b/cache-tree.h
@@ -46,6 +46,7 @@ int update_main_cache_tree(int);
 #define WRITE_TREE_UNMERGED_INDEX (-2)
 #define WRITE_TREE_PREFIX_ERROR (-3)
 
+int write_index_as_tree(unsigned char *sha1, struct index_state *index_state, const char *index_path, int flags, const char *prefix);
 int write_cache_as_tree(unsigned char *sha1, int flags, const char *prefix);
 void prime_cache_tree(struct index_state *, struct tree *);
 

diff --git a/builtin/am.c b/builtin/am.c
index d45dd41..e154c87 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -19,6 +19,8 @@
 #include "unpack-trees.h"
 #include "branch.h"
 #include "sequencer.h"
+#include "revision.h"
+#include "merge-recursive.h"
 
 /**
  * Returns 1 if the file is empty or does not exist, 0 otherwise.
@@ -70,6 +72,8 @@ struct am_state {
 	/* number of digits in patch filename */
 	int prec;
 
+	int threeway;
+
 	int quiet;
 
 	int sign;
@@ -292,6 +296,9 @@ static void am_load(struct am_state *state)
 
 	read_state_file(&state->msg, am_path(state, "final-commit"), 0, 0);
 
+	read_state_file(&sb, am_path(state, "threeway"), 2, 1);
+	state->threeway = !strcmp(sb.buf, "t");
+
 	read_state_file(&sb, am_path(state, "quiet"), 2, 1);
 	state->quiet = !strcmp(sb.buf, "t");
 
@@ -481,6 +488,8 @@ static void am_setup(struct am_state *state, enum patch_format patch_format,
 
 	write_file(am_path(state, "last"), 1, "%d", state->last);
 
+	write_file(am_path(state, "threeway"), 1, state->threeway ? "t" : "f");
+
 	write_file(am_path(state, "quiet"), 1, state->quiet ? "t" : "f");
 
 	write_file(am_path(state, "sign"), 1, state->sign ? "t" : "f");
@@ -666,17 +675,33 @@ static void NORETURN die_user_resolve(const struct am_state *state)
 }
 
 /*
- * Applies current patch with git-apply. Returns 0 on success, -1 otherwise.
+ * Applies current patch with git-apply. Returns 0 on success, -1 otherwise. If
+ * index_file is not NULL, the patch will be applied to that index.
  */
-static int run_apply(const struct am_state *state)
+static int run_apply(const struct am_state *state, const char *index_file)
 {
 	struct child_process cp = CHILD_PROCESS_INIT;
 
 	cp.git_cmd = 1;
 
+	if (index_file)
+		argv_array_pushf(&cp.env_array, "GIT_INDEX_FILE=%s", index_file);
+
+	/*
+	 * If we are allowed to fall back on 3-way merge, don't give false
+	 * errors during the initial attempt.
+	 */
+	if (state->threeway && !index_file) {
+		cp.no_stdout = 1;
+		cp.no_stderr = 1;
+	}
+
 	argv_array_push(&cp.args, "apply");
 
-	argv_array_push(&cp.args, "--index");
+	if (index_file)
+		argv_array_push(&cp.args, "--cached");
+	else
+		argv_array_push(&cp.args, "--index");
 
 	argv_array_push(&cp.args, am_path(state, "patch"));
 
@@ -685,8 +710,100 @@ static int run_apply(const struct am_state *state)
 
 	/* Reload index as git-apply will have modified it. */
 	discard_cache();
+	read_cache_from(index_file ? index_file : get_index_file());
+
+	return 0;
+}
+
+/**
+ * Builds a index that contains just the blobs needed for a 3way merge.
+ */
+static int build_fake_ancestor(const struct am_state *state, const char *index_file)
+{
+	struct child_process cp = CHILD_PROCESS_INIT;
+
+	cp.git_cmd = 1;
+	argv_array_push(&cp.args, "apply");
+	argv_array_pushf(&cp.args, "--build-fake-ancestor=%s", index_file);
+	argv_array_push(&cp.args, am_path(state, "patch"));
+
+	if (run_command(&cp))
+		return -1;
+
+	return 0;
+}
+
+/**
+ * Attempt a threeway merge, using index_path as the temporary index.
+ */
+static int fall_back_threeway(const struct am_state *state, const char *index_path)
+{
+	unsigned char orig_tree[GIT_SHA1_RAWSZ], his_tree[GIT_SHA1_RAWSZ],
+		      our_tree[GIT_SHA1_RAWSZ];
+	const unsigned char *bases[1] = {orig_tree};
+	struct merge_options o;
+	struct commit *result;
+
+	if (get_sha1("HEAD", our_tree) < 0)
+		hashcpy(our_tree, EMPTY_TREE_SHA1_BIN);
+
+	if (build_fake_ancestor(state, index_path))
+		return error("could not build fake ancestor");
+
+	discard_cache();
+	read_cache_from(index_path);
+
+	if (write_index_as_tree(orig_tree, &the_index, index_path, 0, NULL))
+		return error(_("Repository lacks necessary blobs to fall back on 3-way merge."));
+
+	say(state, stdout, _("Using index info to reconstruct a base tree..."));
+
+	if (!state->quiet) {
+		/*
+		 * List paths that needed 3-way fallback, so that the user can
+		 * review them with extra care to spot mismerges.
+		 */
+		struct rev_info rev_info;
+		const char *diff_filter_str = "--diff-filter=AM";
+
+		init_revisions(&rev_info, NULL);
+		rev_info.diffopt.output_format = DIFF_FORMAT_NAME_STATUS;
+		diff_opt_parse(&rev_info.diffopt, &diff_filter_str, 1);
+		add_pending_sha1(&rev_info, "HEAD", our_tree, 0);
+		diff_setup_done(&rev_info.diffopt);
+		run_diff_index(&rev_info, 1);
+	}
+
+	if (run_apply(state, index_path))
+		return error(_("Did you hand edit your patch?\n"
+				"It does not apply to blobs recorded in its index."));
+
+	if (write_index_as_tree(his_tree, &the_index, index_path, 0, NULL))
+		return error("could not write tree");
+
+	say(state, stdout, _("Falling back to patching base and 3-way merge..."));
+
+	discard_cache();
 	read_cache();
 
+	/*
+	 * This is not so wrong. Depending on which base we picked, orig_tree
+	 * may be wildly different from ours, but his_tree has the same set of
+	 * wildly different changes in parts the patch did not touch, so
+	 * recursive ends up canceling them, saying that we reverted all those
+	 * changes.
+	 */
+
+	init_merge_options(&o);
+
+	o.branch1 = "HEAD";
+	o.branch2 = firstline(state->msg.buf);
+	if (state->quiet)
+		o.verbosity = 0;
+
+	if (merge_recursive_generic(&o, our_tree, his_tree, 1, bases, &result))
+		return error(_("Failed to merge in the changes."));
+
 	return 0;
 }
 
@@ -753,6 +870,7 @@ static void am_run(struct am_state *state)
 
 	while (state->cur <= state->last) {
 		const char *patch = am_path(state, msgnum(state));
+		int apply_status;
 
 		if (!file_exists(patch))
 			goto next;
@@ -765,7 +883,26 @@ static void am_run(struct am_state *state)
 
 		say(state, stdout, _("Applying: %s"), firstline(state->msg.buf));
 
-		if (run_apply(state) < 0) {
+		apply_status = run_apply(state, NULL);
+
+		if (apply_status && state->threeway) {
+			struct strbuf sb = STRBUF_INIT;
+
+			strbuf_addstr(&sb, am_path(state, "patch-merge-index"));
+			apply_status = fall_back_threeway(state, sb.buf);
+			strbuf_release(&sb);
+
+			/*
+			 * Applying the patch to an earlier tree and merging
+			 * the result may have produced the same tree as ours.
+			 */
+			if (!apply_status && !index_has_changes(NULL)) {
+				say(state, stdout, _("No changes -- Patch already applied."));
+				goto next;
+			}
+		}
+
+		if (apply_status) {
 			int value;
 
 			printf_ln(_("Patch failed at %s %s"), msgnum(state),
@@ -1017,6 +1154,8 @@ static const char * const am_usage[] = {
 };
 
 static struct option am_options[] = {
+	OPT_BOOL('3', "3way", &state.threeway,
+		N_("allow fall back on 3way merging if needed")),
 	OPT__QUIET(&state.quiet, N_("be quiet")),
 	OPT_BOOL('s', "signoff", &state.sign,
 		N_("add a Signed-off-by line to the commit message")),

diff --git a/builtin/am.c b/builtin/am.c
index e154c87..9afa3bb 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -80,6 +80,8 @@ struct am_state {
 
 	/* override error message when patch failure occurs */
 	const char *resolvemsg;
+
+	int rebasing;
 };
 
 /**
@@ -305,6 +307,8 @@ static void am_load(struct am_state *state)
 	read_state_file(&sb, am_path(state, "sign"), 2, 1);
 	state->sign = !strcmp(sb.buf, "t");
 
+	state->rebasing = !!file_exists(am_path(state, "rebasing"));
+
 	strbuf_release(&sb);
 }
 
@@ -484,6 +488,9 @@ static void am_setup(struct am_state *state, enum patch_format patch_format,
 		die(_("Failed to split patches."));
 	}
 
+	if (state->rebasing)
+		state->threeway = 1;
+
 	write_file(am_path(state, "next"), 1, "%d", state->cur);
 
 	write_file(am_path(state, "last"), 1, "%d", state->last);
@@ -494,12 +501,20 @@ static void am_setup(struct am_state *state, enum patch_format patch_format,
 
 	write_file(am_path(state, "sign"), 1, state->sign ? "t" : "f");
 
+	if (state->rebasing)
+		write_file(am_path(state, "rebasing"), 1, "%s", "");
+	else
+		write_file(am_path(state, "applying"), 1, "%s", "");
+
 	if (!get_sha1("HEAD", curr_head)) {
 		write_file(am_path(state, "abort-safety"), 1, "%s", sha1_to_hex(curr_head));
-		update_ref("am", "ORIG_HEAD", curr_head, NULL, 0, UPDATE_REFS_DIE_ON_ERR);
+		if (!state->rebasing)
+			update_ref("am", "ORIG_HEAD", curr_head, NULL, 0,
+					UPDATE_REFS_DIE_ON_ERR);
 	} else {
 		write_file(am_path(state, "abort-safety"), 1, "%s", "");
-		delete_ref("ORIG_HEAD", NULL, 0);
+		if (!state->rebasing)
+			delete_ref("ORIG_HEAD", NULL, 0);
 	}
 }
 
@@ -921,7 +936,8 @@ next:
 		am_next(state);
 	}
 
-	am_destroy(state);
+	if (!state->rebasing)
+		am_destroy(state);
 }
 
 /**
@@ -1175,6 +1191,8 @@ static struct option am_options[] = {
 	OPT_CMDMODE(0, "abort", &opt_resume,
 		N_("restore the original branch and abort the patching operation."),
 		RESUME_ABORT),
+	OPT_HIDDEN_BOOL(0, "rebasing", &state.rebasing,
+		N_("(internal use for git-rebase)")),
 	OPT_END()
 };
 

diff --git a/builtin/am.c b/builtin/am.c
index 9afa3bb..0d7e37c 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -21,6 +21,8 @@
 #include "sequencer.h"
 #include "revision.h"
 #include "merge-recursive.h"
+#include "revision.h"
+#include "log-tree.h"
 
 /**
  * Returns 1 if the file is empty or does not exist, 0 otherwise.
@@ -50,6 +52,30 @@ static const char *firstline(const char *msg)
 	return sb.buf;
 }
 
+/**
+ * Iterate over lines, each terminated by c, in a string, without modifying the
+ * string itself. begin will be set to the beginning of the line, while end
+ * will be set to the line termination or null character at the end of the line
+ * or string. On the first call, begin and end must be initialized to the
+ * string to be iterated over. E.g.:
+ *
+ *	const char *begin, *end, *str = "1\n2\n3";
+ *	begin = end = str;
+ *	while (!getbufline(&begin, &end, '\n'))
+ *		...
+ */
+static int getbufline(const char **begin, const char **end, int c)
+{
+	if (!**end)
+		return EOF;
+	else if (**end == c)
+		*begin = *end + 1;
+	else
+		*begin = *end;
+	*end = strchrnul(*begin, c);
+	return 0;
+}
+
 enum patch_format {
 	PATCH_FORMAT_UNKNOWN = 0,
 	PATCH_FORMAT_MBOX
@@ -675,6 +701,126 @@ static int parse_patch(struct am_state *state, const char *patch)
 }
 
 /**
+ * Sets commit_id to the commit hash where the patch was generated from.
+ * Returns 0 on success, -1 on failure.
+ */
+static int get_patch_commit_sha1(unsigned char *commit_id, const char *patch)
+{
+	struct strbuf sb = STRBUF_INIT;
+	FILE *fp = xfopen(patch, "r");
+	const char *x;
+
+	if (strbuf_getline(&sb, fp, '\n'))
+		return -1;
+
+	if (!skip_prefix(sb.buf, "From ", &x))
+		return -1;
+
+	if (get_sha1_hex(x, commit_id) < 0)
+		return -1;
+
+	strbuf_release(&sb);
+	fclose(fp);
+	return 0;
+}
+
+/**
+ * Sets state->msg, state->author_name, state->author_email, state->author_date
+ * to the commit's respective info.
+ */
+static void get_commit_info(struct am_state *state, struct commit *commit)
+{
+	const char *buf, *begin, *end;
+
+	buf = logmsg_reencode(commit, NULL, get_commit_output_encoding());
+	begin = end = buf;
+
+	while (!getbufline(&begin, &end, '\n')) {
+		const char *x;
+
+		if (skip_prefix(begin, "author ", &x)) {
+			struct ident_split split;
+			const char *date;
+
+			if (split_ident_line(&split, x, end - x) < 0) {
+				struct strbuf sb = STRBUF_INIT;
+
+				strbuf_add(&sb, x, end - x);
+				die(_("invalid ident line: %s"), sb.buf);
+			}
+
+			if (split.name_begin)
+				strbuf_add(&state->author_name,
+					split.name_begin,
+					split.name_end - split.name_begin);
+
+			if (split.mail_begin)
+				strbuf_add(&state->author_email,
+					split.mail_begin,
+					split.mail_end - split.mail_begin);
+
+			date = show_ident_date(&split, DATE_NORMAL);
+			strbuf_addstr(&state->author_date, date);
+		} else if (begin == end) {
+			end++;
+			break;
+		}
+	}
+
+	strbuf_addstr(&state->msg, end);
+}
+
+/**
+ * Writes commit as a patch to $state_dir/patch.
+ */
+static void write_commit_patch(const struct am_state *state, struct commit *commit)
+{
+	struct rev_info rev_info;
+	FILE *fp;
+
+	fp = xfopen(am_path(state, "patch"), "w");
+	init_revisions(&rev_info, NULL);
+	rev_info.diff = 1;
+	rev_info.abbrev = 0;
+	rev_info.disable_stdin = 1;
+	rev_info.show_root_diff = 1;
+	rev_info.diffopt.output_format = DIFF_FORMAT_PATCH;
+	rev_info.no_commit_id = 1;
+	DIFF_OPT_SET(&rev_info.diffopt, BINARY);
+	DIFF_OPT_SET(&rev_info.diffopt, FULL_INDEX);
+	rev_info.diffopt.use_color = 0;
+	rev_info.diffopt.file = fp;
+	rev_info.diffopt.close_file = 1;
+	add_pending_object(&rev_info, &commit->object, "");
+	diff_setup_done(&rev_info.diffopt);
+	log_tree_commit(&rev_info, commit);
+}
+
+/**
+ * Like parse_patch(), but parses the patch by looking up its commit ID
+ * directly. This is used in --rebasing mode to bypass git-mailinfo's munging
+ * of patches.
+ *
+ * Will always return 0 as the patch should never be skipped.
+ */
+static int parse_patch_rebase(struct am_state *state, const char *patch)
+{
+	struct commit *commit;
+	unsigned char commit_sha1[GIT_SHA1_RAWSZ];
+
+	if (get_patch_commit_sha1(commit_sha1, patch) < 0)
+		die(_("could not parse %s"), patch);
+
+	commit = lookup_commit_or_die(commit_sha1, patch);
+
+	get_commit_info(state, commit);
+
+	write_commit_patch(state, commit);
+
+	return 0;
+}
+
+/**
  * Dies with a user-friendly message on how to proceed after resolving the
  * problem. This message can be overridden with state->resolvemsg.
  */
@@ -885,12 +1031,17 @@ static void am_run(struct am_state *state)
 
 	while (state->cur <= state->last) {
 		const char *patch = am_path(state, msgnum(state));
-		int apply_status;
+		int apply_status, skip;
 
 		if (!file_exists(patch))
 			goto next;
 
-		if (parse_patch(state, patch))
+		if (state->rebasing)
+			skip = parse_patch_rebase(state, patch);
+		else
+			skip = parse_patch(state, patch);
+
+		if (skip)
 			goto next; /* patch should be skipped */
 
 		write_author_script(state);

diff --git a/builtin/am.c b/builtin/am.c
index 0d7e37c..bbef91f 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -1395,6 +1395,21 @@ int cmd_am(int argc, const char **argv, const char *prefix)
 		struct string_list paths = STRING_LIST_INIT_DUP;
 		int i;
 
+		/*
+		 * Possible stray dotest directory in the independent-run case.
+		 */
+		if (file_exists(state.dir.buf) && !state.rebasing) {
+			if (opt_resume == RESUME_ABORT) {
+				am_destroy(&state);
+				am_state_release(&state);
+				return 0;
+			}
+
+			die(_("Stray %s directory found.\n"
+				"Use \"git am --abort\" to remove it."),
+				state.dir.buf);
+		}
+
 		if (opt_resume)
 			die(_("Resolve operation not in progress, we are not resuming."));
 

diff --git a/builtin/am.c b/builtin/am.c
index bbef91f..b73549f 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -81,6 +81,12 @@ enum patch_format {
 	PATCH_FORMAT_MBOX
 };
 
+enum keep_type {
+	KEEP_FALSE = 0,
+	KEEP_TRUE,      /* pass -k flag to git-mailinfo */
+	KEEP_NON_PATCH  /* pass -b flag to git-mailinfo */
+};
+
 struct am_state {
 	/* state directory path */
 	struct strbuf dir;
@@ -104,6 +110,9 @@ struct am_state {
 
 	int sign;
 
+	/* one of the enum keep_type values */
+	int keep;
+
 	/* override error message when patch failure occurs */
 	const char *resolvemsg;
 
@@ -333,6 +342,14 @@ static void am_load(struct am_state *state)
 	read_state_file(&sb, am_path(state, "sign"), 2, 1);
 	state->sign = !strcmp(sb.buf, "t");
 
+	read_state_file(&sb, am_path(state, "keep"), 2, 1);
+	if (!strcmp(sb.buf, "t"))
+		state->keep = KEEP_TRUE;
+	else if (!strcmp(sb.buf, "b"))
+		state->keep = KEEP_NON_PATCH;
+	else
+		state->keep = KEEP_FALSE;
+
 	state->rebasing = !!file_exists(am_path(state, "rebasing"));
 
 	strbuf_release(&sb);
@@ -497,6 +514,7 @@ static void am_setup(struct am_state *state, enum patch_format patch_format,
 		struct string_list *paths)
 {
 	unsigned char curr_head[GIT_SHA1_RAWSZ];
+	const char *str;
 
 	if (!patch_format)
 		patch_format = detect_patch_format(paths);
@@ -527,6 +545,21 @@ static void am_setup(struct am_state *state, enum patch_format patch_format,
 
 	write_file(am_path(state, "sign"), 1, state->sign ? "t" : "f");
 
+	switch (state->keep) {
+	case KEEP_FALSE:
+		str = "f";
+		break;
+	case KEEP_TRUE:
+		str = "t";
+		break;
+	case KEEP_NON_PATCH:
+		str = "b";
+		break;
+	default:
+		die("BUG: invalid value for state->keep");
+	}
+	write_file(am_path(state, "keep"), 1, "%s", str);
+
 	if (state->rebasing)
 		write_file(am_path(state, "rebasing"), 1, "%s", "");
 	else
@@ -653,6 +686,20 @@ static int parse_patch(struct am_state *state, const char *patch)
 	cp.out = xopen(am_path(state, "info"), O_WRONLY | O_CREAT, 0777);
 
 	argv_array_push(&cp.args, "mailinfo");
+
+	switch (state->keep) {
+	case KEEP_FALSE:
+		break;
+	case KEEP_TRUE:
+		argv_array_push(&cp.args, "-k");
+		break;
+	case KEEP_NON_PATCH:
+		argv_array_push(&cp.args, "-b");
+		break;
+	default:
+		die("BUG: invalid value for state->keep");
+	}
+
 	argv_array_push(&cp.args, am_path(state, "msg"));
 	argv_array_push(&cp.args, am_path(state, "patch"));
 
@@ -1326,6 +1373,10 @@ static struct option am_options[] = {
 	OPT__QUIET(&state.quiet, N_("be quiet")),
 	OPT_BOOL('s', "signoff", &state.sign,
 		N_("add a Signed-off-by line to the commit message")),
+	OPT_SET_INT('k', "keep", &state.keep,
+		N_("pass -k flag to git-mailinfo"), KEEP_TRUE),
+	OPT_SET_INT(0, "keep-non-patch", &state.keep,
+		N_("pass -b flag to git-mailinfo"), KEEP_NON_PATCH),
 	OPT_CALLBACK(0, "patch-format", &opt_patch_format, N_("format"),
 		N_("format the patch(es) are in"), parse_opt_patchformat),
 	OPT_STRING(0, "resolvemsg", &state.resolvemsg, NULL,

diff --git a/builtin/am.c b/builtin/am.c
index b73549f..4cec380 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -113,6 +113,9 @@ struct am_state {
 	/* one of the enum keep_type values */
 	int keep;
 
+	/* pass -m flag to git-mailinfo */
+	int message_id;
+
 	/* override error message when patch failure occurs */
 	const char *resolvemsg;
 
@@ -140,6 +143,8 @@ static void am_state_init(struct am_state *state)
 	quiet = getenv("GIT_QUIET");
 	if (quiet && *quiet)
 		state->quiet = 1;
+
+	git_config_get_bool("am.messageid", &state->message_id);
 }
 
 /**
@@ -350,6 +355,9 @@ static void am_load(struct am_state *state)
 	else
 		state->keep = KEEP_FALSE;
 
+	read_state_file(&sb, am_path(state, "messageid"), 2, 1);
+	state->message_id = !strcmp(sb.buf, "t");
+
 	state->rebasing = !!file_exists(am_path(state, "rebasing"));
 
 	strbuf_release(&sb);
@@ -560,6 +568,8 @@ static void am_setup(struct am_state *state, enum patch_format patch_format,
 	}
 	write_file(am_path(state, "keep"), 1, "%s", str);
 
+	write_file(am_path(state, "messageid"), 1, state->message_id ? "t" : "f");
+
 	if (state->rebasing)
 		write_file(am_path(state, "rebasing"), 1, "%s", "");
 	else
@@ -700,6 +710,9 @@ static int parse_patch(struct am_state *state, const char *patch)
 		die("BUG: invalid value for state->keep");
 	}
 
+	if (state->message_id)
+		argv_array_push(&cp.args, "-m");
+
 	argv_array_push(&cp.args, am_path(state, "msg"));
 	argv_array_push(&cp.args, am_path(state, "patch"));
 
@@ -1377,6 +1390,8 @@ static struct option am_options[] = {
 		N_("pass -k flag to git-mailinfo"), KEEP_TRUE),
 	OPT_SET_INT(0, "keep-non-patch", &state.keep,
 		N_("pass -b flag to git-mailinfo"), KEEP_NON_PATCH),
+	OPT_BOOL('m', "message-id", &state.message_id,
+		N_("pass -m flag to git-mailinfo")),
 	OPT_CALLBACK(0, "patch-format", &opt_patch_format, N_("format"),
 		N_("format the patch(es) are in"), parse_opt_patchformat),
 	OPT_STRING(0, "resolvemsg", &state.resolvemsg, NULL,

diff --git a/builtin/am.c b/builtin/am.c
index 4cec380..1991f36 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -469,7 +469,8 @@ done:
  * Splits out individual patches from `paths`, where each path is either a mbox
  * file or a Maildir. Return 0 on success, -1 on failure.
  */
-static int split_patches_mbox(struct am_state *state, struct string_list *paths)
+static int split_patches_mbox(struct am_state *state, struct string_list *paths,
+		int keep_cr)
 {
 	struct child_process cp = CHILD_PROCESS_INIT;
 	struct string_list_item *item;
@@ -480,6 +481,8 @@ static int split_patches_mbox(struct am_state *state, struct string_list *paths)
 	argv_array_pushf(&cp.args, "-d%d", state->prec);
 	argv_array_pushf(&cp.args, "-o%s", state->dir.buf);
 	argv_array_push(&cp.args, "-b");
+	if (keep_cr)
+		argv_array_push(&cp.args, "--keep-cr");
 	argv_array_push(&cp.args, "--");
 
 	for_each_string_list_item(item, paths)
@@ -501,14 +504,22 @@ static int split_patches_mbox(struct am_state *state, struct string_list *paths)
  * set to the index of the first patch, and state->last will be set to the
  * index of the last patch.
  *
+ * Set keep_cr to 0 to convert all lines ending with \r\n to end with \n, 1
+ * to disable this behavior, -1 to use the default configured setting.
+ *
  * Returns 0 on success, -1 on failure.
  */
 static int split_patches(struct am_state *state, enum patch_format patch_format,
-		struct string_list *paths)
+		struct string_list *paths, int keep_cr)
 {
+	if (keep_cr < 0) {
+		keep_cr = 0;
+		git_config_get_bool("am.keepcr", &keep_cr);
+	}
+
 	switch (patch_format) {
 	case PATCH_FORMAT_MBOX:
-		return split_patches_mbox(state, paths);
+		return split_patches_mbox(state, paths, keep_cr);
 	default:
 		die("BUG: invalid patch_format");
 	}
@@ -519,7 +530,7 @@ static int split_patches(struct am_state *state, enum patch_format patch_format,
  * Setup a new am session for applying patches
  */
 static void am_setup(struct am_state *state, enum patch_format patch_format,
-		struct string_list *paths)
+		struct string_list *paths, int keep_cr)
 {
 	unsigned char curr_head[GIT_SHA1_RAWSZ];
 	const char *str;
@@ -535,7 +546,7 @@ static void am_setup(struct am_state *state, enum patch_format patch_format,
 	if (mkdir(state->dir.buf, 0777) < 0 && errno != EEXIST)
 		die_errno(_("failed to create directory '%s'"), state->dir.buf);
 
-	if (split_patches(state, patch_format, paths) < 0) {
+	if (split_patches(state, patch_format, paths, keep_cr) < 0) {
 		am_destroy(state);
 		die(_("Failed to split patches."));
 	}
@@ -1371,6 +1382,7 @@ enum resume_mode {
 };
 
 static struct am_state state;
+static int opt_keep_cr = -1;
 static int opt_patch_format;
 static enum resume_mode opt_resume;
 
@@ -1392,6 +1404,12 @@ static struct option am_options[] = {
 		N_("pass -b flag to git-mailinfo"), KEEP_NON_PATCH),
 	OPT_BOOL('m', "message-id", &state.message_id,
 		N_("pass -m flag to git-mailinfo")),
+	{ OPTION_SET_INT, 0, "keep-cr", &opt_keep_cr, NULL,
+	  N_("pass --keep-cr flag to git-mailsplit for mbox format"),
+	  PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, 1},
+	{ OPTION_SET_INT, 0, "no-keep-cr", &opt_keep_cr, NULL,
+	  N_("do not pass --keep-cr flag to git-mailsplit independent of am.keepcr"),
+	  PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, 0},
 	OPT_CALLBACK(0, "patch-format", &opt_patch_format, N_("format"),
 		N_("format the patch(es) are in"), parse_opt_patchformat),
 	OPT_STRING(0, "resolvemsg", &state.resolvemsg, NULL,
@@ -1486,7 +1504,7 @@ int cmd_am(int argc, const char **argv, const char *prefix)
 				string_list_append(&paths, mkpath("%s/%s", prefix, argv[i]));
 		}
 
-		am_setup(&state, opt_patch_format, &paths);
+		am_setup(&state, opt_patch_format, &paths, opt_keep_cr);
 
 		string_list_clear(&paths, 0);
 	}

diff --git a/builtin/am.c b/builtin/am.c
index 1991f36..42efce1 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -87,6 +87,12 @@ enum keep_type {
 	KEEP_NON_PATCH  /* pass -b flag to git-mailinfo */
 };
 
+enum scissors_type {
+	SCISSORS_UNSET = -1,
+	SCISSORS_TRUE,  /* pass --scissors to git-mailinfo */
+	SCISSORS_FALSE  /* pass --no-scissors to git-mailinfo */
+};
+
 struct am_state {
 	/* state directory path */
 	struct strbuf dir;
@@ -116,6 +122,9 @@ struct am_state {
 	/* pass -m flag to git-mailinfo */
 	int message_id;
 
+	/* one of the enum scissors_type values */
+	int scissors;
+
 	/* override error message when patch failure occurs */
 	const char *resolvemsg;
 
@@ -145,6 +154,8 @@ static void am_state_init(struct am_state *state)
 		state->quiet = 1;
 
 	git_config_get_bool("am.messageid", &state->message_id);
+
+	state->scissors = SCISSORS_UNSET;
 }
 
 /**
@@ -358,6 +369,14 @@ static void am_load(struct am_state *state)
 	read_state_file(&sb, am_path(state, "messageid"), 2, 1);
 	state->message_id = !strcmp(sb.buf, "t");
 
+	read_state_file(&sb, am_path(state, "scissors"), 2, 1);
+	if (!strcmp(sb.buf, "t"))
+		state->scissors = SCISSORS_TRUE;
+	else if (!strcmp(sb.buf, "f"))
+		state->scissors = SCISSORS_FALSE;
+	else
+		state->scissors = SCISSORS_UNSET;
+
 	state->rebasing = !!file_exists(am_path(state, "rebasing"));
 
 	strbuf_release(&sb);
@@ -581,6 +600,21 @@ static void am_setup(struct am_state *state, enum patch_format patch_format,
 
 	write_file(am_path(state, "messageid"), 1, state->message_id ? "t" : "f");
 
+	switch (state->scissors) {
+	case SCISSORS_UNSET:
+		str = "";
+		break;
+	case SCISSORS_FALSE:
+		str = "f";
+		break;
+	case SCISSORS_TRUE:
+		str = "t";
+		break;
+	default:
+		die("BUG: invalid value for state->scissors");
+	}
+	write_file(am_path(state, "scissors"), 1, "%s", str);
+
 	if (state->rebasing)
 		write_file(am_path(state, "rebasing"), 1, "%s", "");
 	else
@@ -724,6 +758,19 @@ static int parse_patch(struct am_state *state, const char *patch)
 	if (state->message_id)
 		argv_array_push(&cp.args, "-m");
 
+	switch (state->scissors) {
+	case SCISSORS_UNSET:
+		break;
+	case SCISSORS_FALSE:
+		argv_array_push(&cp.args, "--no-scissors");
+		break;
+	case SCISSORS_TRUE:
+		argv_array_push(&cp.args, "--scissors");
+		break;
+	default:
+		die("BUG: invalid value for state->scissors");
+	}
+
 	argv_array_push(&cp.args, am_path(state, "msg"));
 	argv_array_push(&cp.args, am_path(state, "patch"));
 
@@ -1410,6 +1457,8 @@ static struct option am_options[] = {
 	{ OPTION_SET_INT, 0, "no-keep-cr", &opt_keep_cr, NULL,
 	  N_("do not pass --keep-cr flag to git-mailsplit independent of am.keepcr"),
 	  PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, 0},
+	OPT_BOOL('c', "scissors", &state.scissors,
+		N_("strip everything before a scissors line")),
 	OPT_CALLBACK(0, "patch-format", &opt_patch_format, N_("format"),
 		N_("format the patch(es) are in"), parse_opt_patchformat),
 	OPT_STRING(0, "resolvemsg", &state.resolvemsg, NULL,

diff --git a/builtin/am.c b/builtin/am.c
index 42efce1..3556765 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -125,6 +125,8 @@ struct am_state {
 	/* one of the enum scissors_type values */
 	int scissors;
 
+	struct argv_array git_apply_opts;
+
 	/* override error message when patch failure occurs */
 	const char *resolvemsg;
 
@@ -156,6 +158,8 @@ static void am_state_init(struct am_state *state)
 	git_config_get_bool("am.messageid", &state->message_id);
 
 	state->scissors = SCISSORS_UNSET;
+
+	argv_array_init(&state->git_apply_opts);
 }
 
 /**
@@ -168,6 +172,8 @@ static void am_state_release(struct am_state *state)
 	strbuf_release(&state->author_email);
 	strbuf_release(&state->author_date);
 	strbuf_release(&state->msg);
+
+	argv_array_clear(&state->git_apply_opts);
 }
 
 /**
@@ -377,6 +383,11 @@ static void am_load(struct am_state *state)
 	else
 		state->scissors = SCISSORS_UNSET;
 
+	read_state_file(&sb, am_path(state, "apply-opt"), 128, 1);
+	argv_array_clear(&state->git_apply_opts);
+	if (sq_dequote_to_argv_array(sb.buf, &state->git_apply_opts) < 0)
+		die(_("could not parse %s"), am_path(state, "apply-opt"));
+
 	state->rebasing = !!file_exists(am_path(state, "rebasing"));
 
 	strbuf_release(&sb);
@@ -553,6 +564,7 @@ static void am_setup(struct am_state *state, enum patch_format patch_format,
 {
 	unsigned char curr_head[GIT_SHA1_RAWSZ];
 	const char *str;
+	struct strbuf sb = STRBUF_INIT;
 
 	if (!patch_format)
 		patch_format = detect_patch_format(paths);
@@ -615,6 +627,10 @@ static void am_setup(struct am_state *state, enum patch_format patch_format,
 	}
 	write_file(am_path(state, "scissors"), 1, "%s", str);
 
+	sq_quote_argv(&sb, state->git_apply_opts.argv, 0);
+	write_file(am_path(state, "apply-opt"), 1, "%s", sb.buf);
+	strbuf_release(&sb);
+
 	if (state->rebasing)
 		write_file(am_path(state, "rebasing"), 1, "%s", "");
 	else
@@ -977,6 +993,8 @@ static int run_apply(const struct am_state *state, const char *index_file)
 
 	argv_array_push(&cp.args, "apply");
 
+	argv_array_pushv(&cp.args, state->git_apply_opts.argv);
+
 	if (index_file)
 		argv_array_push(&cp.args, "--cached");
 	else
@@ -1003,6 +1021,7 @@ static int build_fake_ancestor(const struct am_state *state, const char *index_f
 
 	cp.git_cmd = 1;
 	argv_array_push(&cp.args, "apply");
+	argv_array_pushv(&cp.args, state->git_apply_opts.argv);
 	argv_array_pushf(&cp.args, "--build-fake-ancestor=%s", index_file);
 	argv_array_push(&cp.args, am_path(state, "patch"));
 
@@ -1459,8 +1478,35 @@ static struct option am_options[] = {
 	  PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, 0},
 	OPT_BOOL('c', "scissors", &state.scissors,
 		N_("strip everything before a scissors line")),
+	OPT_PASSTHRU_ARGV(0, "whitespace", &state.git_apply_opts, N_("action"),
+		N_("pass it through git-apply"),
+		0),
+	OPT_PASSTHRU_ARGV(0, "ignore-space-change", &state.git_apply_opts, NULL,
+		N_("pass it through git-apply"),
+		PARSE_OPT_NOARG),
+	OPT_PASSTHRU_ARGV(0, "ignore-whitespace", &state.git_apply_opts, NULL,
+		N_("pass it through git-apply"),
+		PARSE_OPT_NOARG),
+	OPT_PASSTHRU_ARGV(0, "directory", &state.git_apply_opts, N_("root"),
+		N_("pass it through git-apply"),
+		0),
+	OPT_PASSTHRU_ARGV(0, "exclude", &state.git_apply_opts, N_("path"),
+		N_("pass it through git-apply"),
+		0),
+	OPT_PASSTHRU_ARGV(0, "include", &state.git_apply_opts, N_("path"),
+		N_("pass it through git-apply"),
+		0),
+	OPT_PASSTHRU_ARGV('C', NULL, &state.git_apply_opts, N_("n"),
+		N_("pass it through git-apply"),
+		0),
+	OPT_PASSTHRU_ARGV('p', NULL, &state.git_apply_opts, N_("num"),
+		N_("pass it through git-apply"),
+		0),
 	OPT_CALLBACK(0, "patch-format", &opt_patch_format, N_("format"),
 		N_("format the patch(es) are in"), parse_opt_patchformat),
+	OPT_PASSTHRU_ARGV(0, "reject", &state.git_apply_opts, NULL,
+		N_("pass it through git-apply"),
+		PARSE_OPT_NOARG),
 	OPT_STRING(0, "resolvemsg", &state.resolvemsg, NULL,
 		N_("override error message when patch failure occurs")),
 	OPT_CMDMODE(0, "continue", &opt_resume,

diff --git a/builtin/am.c b/builtin/am.c
index 3556765..6623b49 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -130,6 +130,8 @@ struct am_state {
 	/* override error message when patch failure occurs */
 	const char *resolvemsg;
 
+	int ignore_date;
+
 	int rebasing;
 };
 
@@ -1131,7 +1133,8 @@ static void do_commit(const struct am_state *state)
 	}
 
 	author = fmt_ident(state->author_name.buf, state->author_email.buf,
-			state->author_date.buf, IDENT_STRICT);
+			state->ignore_date ? NULL : state->author_date.buf,
+			IDENT_STRICT);
 
 	if (commit_tree(state->msg.buf, state->msg.len, tree, parents, commit,
 				author, NULL))
@@ -1521,6 +1524,8 @@ static struct option am_options[] = {
 	OPT_CMDMODE(0, "abort", &opt_resume,
 		N_("restore the original branch and abort the patching operation."),
 		RESUME_ABORT),
+	OPT_BOOL(0, "ignore-date", &state.ignore_date,
+		N_("use current timestamp for author date")),
 	OPT_HIDDEN_BOOL(0, "rebasing", &state.rebasing,
 		N_("(internal use for git-rebase)")),
 	OPT_END()

diff --git a/builtin/am.c b/builtin/am.c
index 6623b49..608a2da 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -130,6 +130,8 @@ struct am_state {
 	/* override error message when patch failure occurs */
 	const char *resolvemsg;
 
+	int committer_date_is_author_date;
+
 	int ignore_date;
 
 	int rebasing;
@@ -1136,6 +1138,10 @@ static void do_commit(const struct am_state *state)
 			state->ignore_date ? NULL : state->author_date.buf,
 			IDENT_STRICT);
 
+	if (state->committer_date_is_author_date)
+		setenv("GIT_COMMITTER_DATE",
+			state->ignore_date ? "" : state->author_date.buf, 1);
+
 	if (commit_tree(state->msg.buf, state->msg.len, tree, parents, commit,
 				author, NULL))
 		die(_("failed to write commit object"));
@@ -1524,6 +1530,9 @@ static struct option am_options[] = {
 	OPT_CMDMODE(0, "abort", &opt_resume,
 		N_("restore the original branch and abort the patching operation."),
 		RESUME_ABORT),
+	OPT_BOOL(0, "committer-date-is-author-date",
+		&state.committer_date_is_author_date,
+		N_("lie about committer date")),
 	OPT_BOOL(0, "ignore-date", &state.ignore_date,
 		N_("use current timestamp for author date")),
 	OPT_HIDDEN_BOOL(0, "rebasing", &state.rebasing,

diff --git a/builtin/am.c b/builtin/am.c
index 608a2da..91dae92 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -134,6 +134,8 @@ struct am_state {
 
 	int ignore_date;
 
+	const char *sign_commit;
+
 	int rebasing;
 };
 
@@ -143,6 +145,7 @@ struct am_state {
 static void am_state_init(struct am_state *state)
 {
 	const char *quiet;
+	int sign_commit;
 
 	memset(state, 0, sizeof(*state));
 
@@ -164,6 +167,9 @@ static void am_state_init(struct am_state *state)
 	state->scissors = SCISSORS_UNSET;
 
 	argv_array_init(&state->git_apply_opts);
+
+	if (!git_config_get_bool("commit.gpgsign", &sign_commit))
+		state->sign_commit = sign_commit ? "" : NULL;
 }
 
 /**
@@ -1143,7 +1149,7 @@ static void do_commit(const struct am_state *state)
 			state->ignore_date ? "" : state->author_date.buf, 1);
 
 	if (commit_tree(state->msg.buf, state->msg.len, tree, parents, commit,
-				author, NULL))
+				author, state->sign_commit))
 		die(_("failed to write commit object"));
 
 	reflog_msg = getenv("GIT_REFLOG_ACTION");
@@ -1535,6 +1541,9 @@ static struct option am_options[] = {
 		N_("lie about committer date")),
 	OPT_BOOL(0, "ignore-date", &state.ignore_date,
 		N_("use current timestamp for author date")),
+	{ OPTION_STRING, 'S', "gpg-sign", &state.sign_commit, N_("key-id"),
+	  N_("GPG-sign commits"),
+	  PARSE_OPT_OPTARG, NULL, (intptr_t) "" },
 	OPT_HIDDEN_BOOL(0, "rebasing", &state.rebasing,
 		N_("(internal use for git-rebase)")),
 	OPT_END()