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[PATCH 09/19] tree-diff.c: reserve space in "base" for pathname concatenation

From
Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Date
Dec 13, 2010, 09:46 UTC
Message-ID
<1292233616-27692-10-git-send-email-pclouds@gmail.com>
In-Reply-To
<1292233616-27692-1-git-send-email-pclouds@gmail.com>

This patch make sure that "base" parameter is writable. The callees are free to modify it as long as base remains the same before entering and after leaving the callee.

This avoids quite a bit of malloc and memcpy().
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 tree-diff.c |   87 +++++++++++++++++++++++++++-------------------------------
 1 files changed, 41 insertions(+), 46 deletions(-)
diff --git a/tree-diff.c b/tree-diff.c
index 50d7e6d..a870f6c 100644
--- a/tree-diff.c
+++ b/tree-diff.c
@@ -6,34 +6,17 @@
 #include "diffcore.h"
 #include "tree.h"
 
-static char *malloc_base(const char *base, int baselen, const char *path, int pathlen)
-{
-	char *newbase = xmalloc(baselen + pathlen + 2);
-	memcpy(newbase, base, baselen);
-	memcpy(newbase + baselen, path, pathlen);
-	memcpy(newbase + baselen + pathlen, "/", 2);
-	return newbase;
-}
+static void show_entry(struct diff_options *opt, const char *prefix,
+		       struct tree_desc *desc, char *base, int baselen);
 
-static char *malloc_fullname(const char *base, int baselen, const char *path, int pathlen)
-{
-	char *fullname = xmalloc(baselen + pathlen + 1);
-	memcpy(fullname, base, baselen);
-	memcpy(fullname + baselen, path, pathlen);
-	fullname[baselen + pathlen] = 0;
-	return fullname;
-}
-
-static void show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc,
-		       const char *base, int baselen);
-
-static int compare_tree_entry(struct tree_desc *t1, struct tree_desc *t2, const char *base, int baselen, struct diff_options *opt)
+static int compare_tree_entry(struct tree_desc *t1, struct tree_desc *t2,
+			      char *base, int baselen,
+			      struct diff_options *opt)
 {
 	unsigned mode1, mode2;
 	const char *path1, *path2;
 	const unsigned char *sha1, *sha2;
 	int cmp, pathlen1, pathlen2;
-	char *fullname;
 
 	sha1 = tree_entry_extract(t1, &path1, &mode1);
 	sha2 = tree_entry_extract(t2, &path2, &mode2);
@@ -64,26 +47,31 @@ static int compare_tree_entry(struct tree_desc *t1, struct tree_desc *t2, const
 
 	if (DIFF_OPT_TST(opt, RECURSIVE) && S_ISDIR(mode1)) {
 		int retval;
-		char *newbase = malloc_base(base, baselen, path1, pathlen1);
+
+		memcpy(base + baselen, path1, pathlen1);
+		memcpy(base + baselen + pathlen1, "/", 2);
+
 		if (DIFF_OPT_TST(opt, TREE_IN_RECURSIVE)) {
-			newbase[baselen + pathlen1] = 0;
+			base[baselen + pathlen1] = 0;
 			opt->change(opt, mode1, mode2,
-				    sha1, sha2, newbase, 0, 0);
-			newbase[baselen + pathlen1] = '/';
+				    sha1, sha2, base, 0, 0);
+			base[baselen + pathlen1] = '/';
 		}
-		retval = diff_tree_sha1(sha1, sha2, newbase, opt);
-		free(newbase);
+		retval = diff_tree_sha1(sha1, sha2, base, opt);
+		base[baselen] = 0;
 		return retval;
 	}
 
-	fullname = malloc_fullname(base, baselen, path1, pathlen1);
-	opt->change(opt, mode1, mode2, sha1, sha2, fullname, 0, 0);
-	free(fullname);
+	memcpy(base + baselen, path1, pathlen1);
+	base[baselen + pathlen1] = 0;
+	opt->change(opt, mode1, mode2, sha1, sha2, base, 0, 0);
+	base[baselen] = 0;
 	return 0;
 }
 
 /* A whole sub-tree went away or appeared */
-static void show_tree(struct diff_options *opt, const char *prefix, struct tree_desc *desc, const char *base, int baselen)
+static void show_tree(struct diff_options *opt, const char *prefix,
+		      struct tree_desc *desc, char *base, int baselen)
 {
 	int all_interesting = 0;
 	while (desc->size) {
@@ -105,8 +93,8 @@ static void show_tree(struct diff_options *opt, const char *prefix, struct tree_
 }
 
 /* A file entry went away or appeared */
-static void show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc,
-		       const char *base, int baselen)
+static void show_entry(struct diff_options *opt, const char *prefix,
+		       struct tree_desc *desc, char *base, int baselen)
 {
 	unsigned mode;
 	const char *path;
@@ -115,34 +103,38 @@ static void show_entry(struct diff_options *opt, const char *prefix, struct tree
 
 	if (DIFF_OPT_TST(opt, RECURSIVE) && S_ISDIR(mode)) {
 		enum object_type type;
-		char *newbase = malloc_base(base, baselen, path, pathlen);
 		struct tree_desc inner;
 		void *tree;
 		unsigned long size;
 
+		memcpy(base + baselen, path, pathlen);
+		memcpy(base + baselen + pathlen, "/", 2);
+
 		tree = read_sha1_file(sha1, &type, &size);
 		if (!tree || type != OBJ_TREE)
 			die("corrupt tree sha %s", sha1_to_hex(sha1));
 
 		if (DIFF_OPT_TST(opt, TREE_IN_RECURSIVE)) {
-			newbase[baselen + pathlen] = 0;
-			opt->add_remove(opt, *prefix, mode, sha1, newbase, 0);
-			newbase[baselen + pathlen] = '/';
+			base[baselen + pathlen] = 0;
+			opt->add_remove(opt, *prefix, mode, sha1, base, 0);
+			base[baselen + pathlen] = '/';
 		}
 
 		init_tree_desc(&inner, tree, size);
-		show_tree(opt, prefix, &inner, newbase, baselen + 1 + pathlen);
+		show_tree(opt, prefix, &inner, base, baselen + 1 + pathlen);
 
+		base[baselen] = 0;
 		free(tree);
-		free(newbase);
 	} else {
-		char *fullname = malloc_fullname(base, baselen, path, pathlen);
-		opt->add_remove(opt, prefix[0], mode, sha1, fullname, 0);
-		free(fullname);
+		memcpy(base + baselen, path, pathlen);
+		base[baselen + pathlen] = 0;
+		opt->add_remove(opt, prefix[0], mode, sha1, base, 0);
+		base[baselen] = 0;
 	}
 }
 
-static void skip_uninteresting(struct tree_desc *t, const char *base, int baselen, struct diff_options *opt)
+static void skip_uninteresting(struct tree_desc *t, char *base,
+			       int baselen, struct diff_options *opt)
 {
 	int all_interesting = 0;
 	while (t->size) {
@@ -166,10 +158,13 @@ static void skip_uninteresting(struct tree_desc *t, const char *base, int basele
 	}
 }
 
-int diff_tree(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
+int diff_tree(struct tree_desc *t1, struct tree_desc *t2,
+	      const char *base_, struct diff_options *opt)
 {
-	int baselen = strlen(base);
+	char base[PATH_MAX];
+	int baselen = strlen(base_);
 
+	memcpy(base, base_, baselen+1);
 	for (;;) {
 		if (DIFF_OPT_TST(opt, QUICK) &&
 		    DIFF_OPT_TST(opt, HAS_CHANGES))

-- 
1.7.3.3.476.g10a82
Previous: Junio C HamanoNext: Junio C Hamano
Message 16 of 45 in “nd/struct-pathspec (or pathspec unification [1])”
  1. 00/19 nd/struct-pathspec (or pathspec unification [1])Nguyễn Thái Ngọc Duy, Dec 13, 2010
  2. 01/19 Add struct pathspecNguyễn Thái Ngọc Duy, Dec 13, 2010
  3. Thiago FarinaDec 13, 2010
  4. Nguyen Thai Ngoc DuyDec 14, 2010
  5. 02/19 diff-no-index: use diff_tree_setup_paths()Nguyễn Thái Ngọc Duy, Dec 13, 2010
  6. 03/19 pathspec: cache string length when initializing pathspecNguyễn Thái Ngọc Duy, Dec 13, 2010
  7. 04/19 Convert struct diff_options to use struct pathspecNguyễn Thái Ngọc Duy, Dec 13, 2010
  8. Junio C HamanoDec 13, 2010
  9. Nguyen Thai Ngoc DuyDec 14, 2010
  10. 05/19 tree_entry_interesting(): remove dependency on struct diff_optionsNguyễn Thái Ngọc Duy, Dec 13, 2010
  11. Junio C HamanoDec 13, 2010
  12. 06/19 Move tree_entry_interesting() to tree-walk.c and export itNguyễn Thái Ngọc Duy, Dec 13, 2010
  13. 07/19 glossary: define pathspecNguyễn Thái Ngọc Duy, Dec 13, 2010
  14. 08/19 pathspec: mark wildcard pathspecs from the beginningNguyễn Thái Ngọc Duy, Dec 13, 2010
  15. Junio C HamanoDec 13, 2010
  16. 09/19 tree-diff.c: reserve space in "base" for pathname concatenationNguyễn Thái Ngọc Duy, Dec 13, 2010
  17. Junio C HamanoDec 13, 2010
  18. Nguyen Thai Ngoc DuyDec 14, 2010
  19. Junio C HamanoDec 14, 2010
  20. Nguyen Thai Ngoc DuyDec 14, 2010
  21. Johannes SixtDec 14, 2010
  22. Nguyen Thai Ngoc DuyDec 14, 2010
  23. Johannes SixtDec 14, 2010
  24. Nguyen Thai Ngoc DuyDec 14, 2010
  25. Junio C HamanoDec 14, 2010
  26. 10/19 tree_entry_interesting(): factor out most matching logicNguyễn Thái Ngọc Duy, Dec 13, 2010
  27. Junio C HamanoDec 13, 2010
  28. 11/19 tree_entry_interesting: support depth limitNguyễn Thái Ngọc Duy, Dec 13, 2010
  29. Junio C HamanoDec 13, 2010
  30. Nguyen Thai Ngoc DuyDec 14, 2010
  31. 12/19 tree_entry_interesting(): support wildcard matchingNguyễn Thái Ngọc Duy, Dec 13, 2010
  32. Junio C HamanoDec 13, 2010
  33. Nguyen Thai Ngoc DuyDec 14, 2010
  34. 13/19 tree_entry_interesting(): optimize fnmatch when base is matchedNguyễn Thái Ngọc Duy, Dec 13, 2010
  35. Junio C HamanoDec 13, 2010
  36. 14/19 Convert ce_path_match() use to match_pathspec()Nguyễn Thái Ngọc Duy, Dec 13, 2010
  37. Junio C HamanoDec 13, 2010
  38. Nguyen Thai Ngoc DuyDec 14, 2010
  39. 15/19 pathspec: add match_pathspec_depth()Nguyễn Thái Ngọc Duy, Dec 13, 2010
  40. Junio C HamanoDec 13, 2010
  41. Nguyen Thai Ngoc DuyDec 14, 2010
  42. 16/19 grep: convert to use struct pathspecNguyễn Thái Ngọc Duy, Dec 13, 2010
  43. 17/19 grep: use match_pathspec_depth() for cache/worktree greppingNguyễn Thái Ngọc Duy, Dec 13, 2010
  44. 18/19 grep: use preallocated buffer for grep_tree()Nguyễn Thái Ngọc Duy, Dec 13, 2010
  45. 19/19 grep: drop pathspec_matches() in favor of tree_entry_interesting()Nguyễn Thái Ngọc Duy, Dec 13, 2010

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