diff mbox series

[20/23] pack-write: fix return parameter of `write_rev_file_order()`

Message ID 2f3e17915d750c0ded8bf4f2f57106b81e9d8b3b.1727687410.git.ps@pks.im (mailing list archive)
State Accepted
Commit 2f0ee051ddaf880daac06773b56f077c4012a1c7
Headers show
Series Memory leak fixes (pt.8) | expand

Commit Message

Patrick Steinhardt Sept. 30, 2024, 9:14 a.m. UTC
While the return parameter of `write_rev_file_order()` is a string
constant, the function may indeed return an allocated string when its
first parameter is a `NULL` pointer. This makes for a confusing calling
convention, where callers need to be aware of these intricate ownership
rules and cast away the constness to free the string in some cases.

Adapt the function and its caller `write_rev_file()` to always return an
allocated string and adapt callers to always free the return value.

Note that this requires us to also adapt `rename_tmp_packfile()`, which
compares the pointers to packfile data with each other. Now that the
path of the reverse index file gets allocated unconditionally the check
will always fail. This is fixed by using strcmp(3P) instead, which also
feels way less fragile.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
---
 builtin/index-pack.c              |  7 +++---
 midx-write.c                      |  3 ++-
 pack-write.c                      | 42 +++++++++++++++++--------------
 pack.h                            |  4 +--
 t/t5327-multi-pack-bitmaps-rev.sh |  1 +
 5 files changed, 31 insertions(+), 26 deletions(-)
diff mbox series

Patch

diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index e228c56ff2..9d23b41b3a 100644
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -1505,7 +1505,7 @@  static void rename_tmp_packfile(const char **final_name,
 				struct strbuf *name, unsigned char *hash,
 				const char *ext, int make_read_only_if_same)
 {
-	if (*final_name != curr_name) {
+	if (!*final_name || strcmp(*final_name, curr_name)) {
 		if (!*final_name)
 			*final_name = odb_pack_name(name, hash, ext);
 		if (finalize_object_file(curr_name, *final_name))
@@ -1726,7 +1726,7 @@  int cmd_index_pack(int argc,
 {
 	int i, fix_thin_pack = 0, verify = 0, stat_only = 0, rev_index;
 	const char *curr_index;
-	const char *curr_rev_index = NULL;
+	char *curr_rev_index = NULL;
 	const char *index_name = NULL, *pack_name = NULL, *rev_index_name = NULL;
 	const char *keep_msg = NULL;
 	const char *promisor_msg = NULL;
@@ -1968,8 +1968,7 @@  int cmd_index_pack(int argc,
 		free((void *) curr_pack);
 	if (!index_name)
 		free((void *) curr_index);
-	if (!rev_index_name)
-		free((void *) curr_rev_index);
+	free(curr_rev_index);
 
 	/*
 	 * Let the caller know this pack is not self contained
diff --git a/midx-write.c b/midx-write.c
index 625c7d3137..b3a5f6c516 100644
--- a/midx-write.c
+++ b/midx-write.c
@@ -649,7 +649,7 @@  static void write_midx_reverse_index(char *midx_name, unsigned char *midx_hash,
 				     struct write_midx_context *ctx)
 {
 	struct strbuf buf = STRBUF_INIT;
-	const char *tmp_file;
+	char *tmp_file;
 
 	trace2_region_enter("midx", "write_midx_reverse_index", the_repository);
 
@@ -662,6 +662,7 @@  static void write_midx_reverse_index(char *midx_name, unsigned char *midx_hash,
 		die(_("cannot store reverse index file"));
 
 	strbuf_release(&buf);
+	free(tmp_file);
 
 	trace2_region_leave("midx", "write_midx_reverse_index", the_repository);
 }
diff --git a/pack-write.c b/pack-write.c
index 27965672f1..9961149e65 100644
--- a/pack-write.c
+++ b/pack-write.c
@@ -212,15 +212,15 @@  static void write_rev_trailer(struct hashfile *f, const unsigned char *hash)
 	hashwrite(f, hash, the_hash_algo->rawsz);
 }
 
-const char *write_rev_file(const char *rev_name,
-			   struct pack_idx_entry **objects,
-			   uint32_t nr_objects,
-			   const unsigned char *hash,
-			   unsigned flags)
+char *write_rev_file(const char *rev_name,
+		     struct pack_idx_entry **objects,
+		     uint32_t nr_objects,
+		     const unsigned char *hash,
+		     unsigned flags)
 {
 	uint32_t *pack_order;
 	uint32_t i;
-	const char *ret;
+	char *ret;
 
 	if (!(flags & WRITE_REV) && !(flags & WRITE_REV_VERIFY))
 		return NULL;
@@ -238,13 +238,14 @@  const char *write_rev_file(const char *rev_name,
 	return ret;
 }
 
-const char *write_rev_file_order(const char *rev_name,
-				 uint32_t *pack_order,
-				 uint32_t nr_objects,
-				 const unsigned char *hash,
-				 unsigned flags)
+char *write_rev_file_order(const char *rev_name,
+			   uint32_t *pack_order,
+			   uint32_t nr_objects,
+			   const unsigned char *hash,
+			   unsigned flags)
 {
 	struct hashfile *f;
+	char *path;
 	int fd;
 
 	if ((flags & WRITE_REV) && (flags & WRITE_REV_VERIFY))
@@ -254,12 +255,13 @@  const char *write_rev_file_order(const char *rev_name,
 		if (!rev_name) {
 			struct strbuf tmp_file = STRBUF_INIT;
 			fd = odb_mkstemp(&tmp_file, "pack/tmp_rev_XXXXXX");
-			rev_name = strbuf_detach(&tmp_file, NULL);
+			path = strbuf_detach(&tmp_file, NULL);
 		} else {
 			unlink(rev_name);
 			fd = xopen(rev_name, O_CREAT|O_EXCL|O_WRONLY, 0600);
+			path = xstrdup(rev_name);
 		}
-		f = hashfd(fd, rev_name);
+		f = hashfd(fd, path);
 	} else if (flags & WRITE_REV_VERIFY) {
 		struct stat statbuf;
 		if (stat(rev_name, &statbuf)) {
@@ -270,22 +272,24 @@  const char *write_rev_file_order(const char *rev_name,
 				die_errno(_("could not stat: %s"), rev_name);
 		}
 		f = hashfd_check(rev_name);
-	} else
+		path = xstrdup(rev_name);
+	} else {
 		return NULL;
+	}
 
 	write_rev_header(f);
 
 	write_rev_index_positions(f, pack_order, nr_objects);
 	write_rev_trailer(f, hash);
 
-	if (rev_name && adjust_shared_perm(rev_name) < 0)
-		die(_("failed to make %s readable"), rev_name);
+	if (adjust_shared_perm(path) < 0)
+		die(_("failed to make %s readable"), path);
 
 	finalize_hashfile(f, NULL, FSYNC_COMPONENT_PACK_METADATA,
 			  CSUM_HASH_IN_STREAM | CSUM_CLOSE |
 			  ((flags & WRITE_IDX_VERIFY) ? 0 : CSUM_FSYNC));
 
-	return rev_name;
+	return path;
 }
 
 static void write_mtimes_header(struct hashfile *f)
@@ -549,7 +553,7 @@  void stage_tmp_packfiles(struct strbuf *name_buffer,
 			 unsigned char hash[],
 			 char **idx_tmp_name)
 {
-	const char *rev_tmp_name = NULL;
+	char *rev_tmp_name = NULL;
 	char *mtimes_tmp_name = NULL;
 
 	if (adjust_shared_perm(pack_tmp_name))
@@ -575,7 +579,7 @@  void stage_tmp_packfiles(struct strbuf *name_buffer,
 	if (mtimes_tmp_name)
 		rename_tmp_packfile(name_buffer, mtimes_tmp_name, "mtimes");
 
-	free((char *)rev_tmp_name);
+	free(rev_tmp_name);
 	free(mtimes_tmp_name);
 }
 
diff --git a/pack.h b/pack.h
index 3ab9e3f60c..02bbdfb19c 100644
--- a/pack.h
+++ b/pack.h
@@ -96,8 +96,8 @@  struct ref;
 
 void write_promisor_file(const char *promisor_name, struct ref **sought, int nr_sought);
 
-const char *write_rev_file(const char *rev_name, struct pack_idx_entry **objects, uint32_t nr_objects, const unsigned char *hash, unsigned flags);
-const char *write_rev_file_order(const char *rev_name, uint32_t *pack_order, uint32_t nr_objects, const unsigned char *hash, unsigned flags);
+char *write_rev_file(const char *rev_name, struct pack_idx_entry **objects, uint32_t nr_objects, const unsigned char *hash, unsigned flags);
+char *write_rev_file_order(const char *rev_name, uint32_t *pack_order, uint32_t nr_objects, const unsigned char *hash, unsigned flags);
 
 /*
  * The "hdr" output buffer should be at least this big, which will handle sizes
diff --git a/t/t5327-multi-pack-bitmaps-rev.sh b/t/t5327-multi-pack-bitmaps-rev.sh
index 9cac03a94b..994a8e6be4 100755
--- a/t/t5327-multi-pack-bitmaps-rev.sh
+++ b/t/t5327-multi-pack-bitmaps-rev.sh
@@ -2,6 +2,7 @@ 
 
 test_description='exercise basic multi-pack bitmap functionality (.rev files)'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 . "${TEST_DIRECTORY}/lib-bitmap.sh"