Add "git_path()" and "head_ref()" helper functions.

"git_path()" returns a static pathname pointer into the git directory
using a printf-like format specifier.

"head_ref()" works like "for_each_ref()", except for just the HEAD.

cache.h

@@ -158,6 +158,7 @@ extern void rollback_index_file(struct cache_file *);
 #define TYPE_CHANGED    0x0040
 
 /* Return a statically allocated filename matching the sha1 signature */
+extern char *git_path(const char *fmt, ...);
 extern char *sha1_file_name(const unsigned char *sha1);
 
 /* Read and unpack a sha1 file into memory, write memory to a sha1 file */

fetch-pack.c

@@ -72,13 +72,9 @@ static int find_common(int fd[2], unsigned char *result_sha1, unsigned char *rem
 
 static int get_old_sha1(const char *refname, unsigned char *sha1)
 {
-	static char pathname[PATH_MAX];
-	const char *git_dir;
 	int fd, ret;
 
-	git_dir = gitenv(GIT_DIR_ENVIRONMENT) ? : DEFAULT_GIT_DIR_ENVIRONMENT;
-	snprintf(pathname, sizeof(pathname), "%s/%s", git_dir, refname);
-	fd = open(pathname, O_RDONLY);
+	fd = open(git_path("%s", refname), O_RDONLY);
 	ret = -1;
 	if (fd >= 0) {
 		char buffer[60];

refs.c

@@ -68,6 +68,15 @@ static int do_for_each_ref(const char *base, int (*fn)(const char *path, const u
 	return retval;
 }
 
+int head_ref(int (*fn)(const char *path, const unsigned char *sha1))
+{
+	unsigned char sha1[20];
+	const char *headpath = git_path("HEAD");
+	if (!read_ref(headpath, sha1))
+		fn(headpath, sha1);
+	return do_for_each_ref(get_refs_directory(), fn);
+}
+
 int for_each_ref(int (*fn)(const char *path, const unsigned char *sha1))
 {
 	return do_for_each_ref(get_refs_directory(), fn);

refs.h

@@ -5,6 +5,7 @@
  * Calls the specified function for each ref file until it returns nonzero,
  * and returns the value
  */
+extern int head_ref(int (*fn)(const char *path, const unsigned char *sha1));
 extern int for_each_ref(int (*fn)(const char *path, const unsigned char *sha1));
 
 /** Reads the refs file specified into sha1 **/

send-pack.c

@@ -92,12 +92,9 @@ static int pack_objects(int fd, struct ref *refs)
 static int read_ref(const char *ref, unsigned char *sha1)
 {
 	int fd, ret;
-	static char pathname[PATH_MAX];
 	char buffer[60];
-	const char *git_dir = gitenv(GIT_DIR_ENVIRONMENT) ? : DEFAULT_GIT_DIR_ENVIRONMENT;
 
-	snprintf(pathname, sizeof(pathname), "%s/%s", git_dir, ref);
-	fd = open(pathname, O_RDONLY);
+	fd = open(git_path("%s", ref), O_RDONLY);
 	if (fd < 0)
 		return -1;
 	ret = -1;

sha1_file.c

@@ -102,9 +102,30 @@ char *get_index_file(void)
 	return git_index_file;
 }
 
-int get_sha1(const char *str, unsigned char *sha1)
+char *git_path(const char *fmt, ...)
 {
 	static char pathname[PATH_MAX];
+	va_list args;
+	int len;
+
+	if (!git_dir)
+		setup_git_env();
+	len = strlen(git_dir);
+	if (len == 1 && *git_dir == '.')
+		len = 0;
+	if (len > PATH_MAX-100)
+		return "pad-path";
+	memcpy(pathname, git_dir, len);
+	if (len && git_dir[len-1] != '/')
+		pathname[len++] = '/';
+	va_start(args, fmt);
+	vsnprintf(pathname + len, sizeof(pathname) - len, fmt, args);
+	va_end(args);
+	return pathname;
+}
+
+int get_sha1(const char *str, unsigned char *sha1)
+{
 	static const char *prefix[] = {
 		"",
 		"refs",
@@ -118,11 +139,8 @@ int get_sha1(const char *str, unsigned char *sha1)
 	if (!get_sha1_hex(str, sha1))
 		return 0;
 
-	if (!git_dir)
-		setup_git_env();
 	for (p = prefix; *p; p++) {
-		snprintf(pathname, sizeof(pathname), "%s/%s/%s",
-			 git_dir, *p, str);
+		char * pathname = git_path("%s/%s", *p, str);
 		if (!get_sha1_file(pathname, sha1))
 			return 0;
 	}

upload-pack.c

@@ -153,6 +153,7 @@ static int send_ref(const char *refname, const unsigned char *sha1)
 
 static int upload_pack(void)
 {
+	head_ref(send_ref);
 	for_each_ref(send_ref);
 	packet_flush(1);
 	nr_needs = receive_needs();