1 files changed, 105 insertions, 21 deletions

diff --git a/sha1_file.c b/sha1_file.c
index ec957db5e1..71063890ff 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -129,8 +129,10 @@ enum scld_error safe_create_leading_directories(char *path)
 		*slash = '\0';
 		if (!stat(path, &st)) {
 			/* path exists */
-			if (!S_ISDIR(st.st_mode))
+			if (!S_ISDIR(st.st_mode)) {
+				errno = ENOTDIR;
 				ret = SCLD_EXISTS;
+			}
 		} else if (mkdir(path, 0777)) {
 			if (errno == EEXIST &&
 			    !stat(path, &st) && S_ISDIR(st.st_mode))
@@ -158,13 +160,85 @@ enum scld_error safe_create_leading_directories(char *path)
 
 enum scld_error safe_create_leading_directories_const(const char *path)
 {
+	int save_errno;
 	/* path points to cache entries, so xstrdup before messing with it */
 	char *buf = xstrdup(path);
 	enum scld_error result = safe_create_leading_directories(buf);
+
+	save_errno = errno;
 	free(buf);
+	errno = save_errno;
 	return result;
 }
 
+int raceproof_create_file(const char *path, create_file_fn fn, void *cb)
+{
+	/*
+	 * The number of times we will try to remove empty directories
+	 * in the way of path. This is only 1 because if another
+	 * process is racily creating directories that conflict with
+	 * us, we don't want to fight against them.
+	 */
+	int remove_directories_remaining = 1;
+
+	/*
+	 * The number of times that we will try to create the
+	 * directories containing path. We are willing to attempt this
+	 * more than once, because another process could be trying to
+	 * clean up empty directories at the same time as we are
+	 * trying to create them.
+	 */
+	int create_directories_remaining = 3;
+
+	/* A scratch copy of path, filled lazily if we need it: */
+	struct strbuf path_copy = STRBUF_INIT;
+
+	int ret, save_errno;
+
+	/* Sanity check: */
+	assert(*path);
+
+retry_fn:
+	ret = fn(path, cb);
+	save_errno = errno;
+	if (!ret)
+		goto out;
+
+	if (errno == EISDIR && remove_directories_remaining-- > 0) {
+		/*
+		 * A directory is in the way. Maybe it is empty; try
+		 * to remove it:
+		 */
+		if (!path_copy.len)
+			strbuf_addstr(&path_copy, path);
+
+		if (!remove_dir_recursively(&path_copy, REMOVE_DIR_EMPTY_ONLY))
+			goto retry_fn;
+	} else if (errno == ENOENT && create_directories_remaining-- > 0) {
+		/*
+		 * Maybe the containing directory didn't exist, or
+		 * maybe it was just deleted by a process that is
+		 * racing with us to clean up empty directories. Try
+		 * to create it:
+		 */
+		enum scld_error scld_result;
+
+		if (!path_copy.len)
+			strbuf_addstr(&path_copy, path);
+
+		do {
+			scld_result = safe_create_leading_directories(path_copy.buf);
+			if (scld_result == SCLD_OK)
+				goto retry_fn;
+		} while (scld_result == SCLD_VANISHED && create_directories_remaining-- > 0);
+	}
+
+out:
+	strbuf_release(&path_copy);
+	errno = save_errno;
+	return ret;
+}
+
 static void fill_sha1_path(struct strbuf *buf, const unsigned char *sha1)
 {
 	int i;
@@ -203,31 +277,26 @@ static const char *alt_sha1_path(struct alternate_object_database *alt,
 	return buf->buf;
 }
 
-/*
- * Return the name of the pack or index file with the specified sha1
- * in its filename.  *base and *name are scratch space that must be
- * provided by the caller.  which should be "pack" or "idx".
- */
-static char *sha1_get_pack_name(const unsigned char *sha1,
-				struct strbuf *buf,
-				const char *which)
+ char *odb_pack_name(struct strbuf *buf,
+		     const unsigned char *sha1,
+		     const char *ext)
 {
 	strbuf_reset(buf);
 	strbuf_addf(buf, "%s/pack/pack-%s.%s", get_object_directory(),
-		    sha1_to_hex(sha1), which);
+		    sha1_to_hex(sha1), ext);
 	return buf->buf;
 }
 
 char *sha1_pack_name(const unsigned char *sha1)
 {
 	static struct strbuf buf = STRBUF_INIT;
-	return sha1_get_pack_name(sha1, &buf, "pack");
+	return odb_pack_name(&buf, sha1, "pack");
 }
 
 char *sha1_pack_index_name(const unsigned char *sha1)
 {
 	static struct strbuf buf = STRBUF_INIT;
-	return sha1_get_pack_name(sha1, &buf, "idx");
+	return odb_pack_name(&buf, sha1, "idx");
 }
 
 struct alternate_object_database *alt_odb_list;
@@ -593,7 +662,7 @@ static int freshen_file(const char *fn)
  * either does not exist on disk, or has a stale mtime and may be subject to
  * pruning).
  */
-static int check_and_freshen_file(const char *fn, int freshen)
+int check_and_freshen_file(const char *fn, int freshen)
 {
 	if (access(fn, F_OK))
 		return 0;
@@ -2532,6 +2601,7 @@ void *unpack_entry(struct packed_git *p, off_t obj_offset,
 	while (delta_stack_nr) {
 		void *delta_data;
 		void *base = data;
+		void *external_base = NULL;
 		unsigned long delta_size, base_size = size;
 		int i;
 
@@ -2558,6 +2628,7 @@ void *unpack_entry(struct packed_git *p, off_t obj_offset,
 				      p->pack_name);
 				mark_bad_packed_object(p, base_sha1);
 				base = read_object(base_sha1, &type, &base_size);
+				external_base = base;
 			}
 		}
 
@@ -2576,6 +2647,7 @@ void *unpack_entry(struct packed_git *p, off_t obj_offset,
 			      "at offset %"PRIuMAX" from %s",
 			      (uintmax_t)curpos, p->pack_name);
 			data = NULL;
+			free(external_base);
 			continue;
 		}
 
@@ -2595,6 +2667,7 @@ void *unpack_entry(struct packed_git *p, off_t obj_offset,
 			error("failed to apply delta");
 
 		free(delta_data);
+		free(external_base);
 	}
 
 	*final_type = type;
@@ -2628,6 +2701,17 @@ const unsigned char *nth_packed_object_sha1(struct packed_git *p,
 	}
 }
 
+const struct object_id *nth_packed_object_oid(struct object_id *oid,
+					      struct packed_git *p,
+					      uint32_t n)
+{
+	const unsigned char *hash = nth_packed_object_sha1(p, n);
+	if (!hash)
+		return NULL;
+	hashcpy(oid->hash, hash);
+	return oid;
+}
+
 void check_pack_index_ptr(const struct packed_git *p, const void *vptr)
 {
 	const unsigned char *ptr = vptr;
@@ -3674,15 +3758,15 @@ static int for_each_file_in_obj_subdir(int subdir_nr,
 		strbuf_setlen(path, baselen);
 		strbuf_addf(path, "/%s", de->d_name);
 
-		if (strlen(de->d_name) == 38)  {
-			char hex[41];
-			unsigned char sha1[20];
+		if (strlen(de->d_name) == GIT_SHA1_HEXSZ - 2)  {
+			char hex[GIT_SHA1_HEXSZ+1];
+			struct object_id oid;
 
 			snprintf(hex, sizeof(hex), "%02x%s",
 				 subdir_nr, de->d_name);
-			if (!get_sha1_hex(hex, sha1)) {
+			if (!get_oid_hex(hex, &oid)) {
 				if (obj_cb) {
-					r = obj_cb(sha1, path->buf, data);
+					r = obj_cb(&oid, path->buf, data);
 					if (r)
 						break;
 				}
@@ -3788,13 +3872,13 @@ static int for_each_object_in_pack(struct packed_git *p, each_packed_object_fn c
 	int r = 0;
 
 	for (i = 0; i < p->num_objects; i++) {
-		const unsigned char *sha1 = nth_packed_object_sha1(p, i);
+		struct object_id oid;
 
-		if (!sha1)
+		if (!nth_packed_object_oid(&oid, p, i))
 			return error("unable to get sha1 of object %u in %s",
 				     i, p->pack_name);
 
-		r = cb(sha1, p, i, data);
+		r = cb(&oid, p, i, data);
 		if (r)
 			break;
 	}