Use the same move_temp_to_file in git-http-fetch.

The http commit walker cannot use the same temporary file
creation code because it needs to use predictable temporary
filename for partial fetch continuation purposes, but the code
to move the temporary file to the final location should be
usable from the ordinary object creation codepath.

Export move_temp_to_file from sha1_file.c and use it, while
losing the custom relink_or_rename function from http-fetch.c.

Also the temporary object file creation part needs to make sure
the leading path exists, in preparation of the really lazy
fan-out directory creation.

Signed-off-by: Junio C Hamano <junkio@cox.net>

cache.h

@@ -223,6 +223,7 @@ extern int read_tree(void *buffer, unsigned long size, int stage, const char **p
 extern int write_sha1_from_fd(const unsigned char *sha1, int fd, char *buffer,
 			      size_t bufsize, size_t *bufposn);
 extern int write_sha1_to_fd(int fd, const unsigned char *sha1);
+extern int move_temp_to_file(const char *tmpfile, char *filename);
 
 extern int has_sha1_pack(const unsigned char *sha1);
 extern int has_sha1_file(const unsigned char *sha1);

http-fetch.c

@@ -138,25 +138,6 @@ static size_t fwrite_sha1_file(void *ptr, size_t eltsize, size_t nmemb,
 	return size;
 }
 
-int relink_or_rename(char *old, char *new) {
-	int ret;
-
-	ret = link(old, new);
-	if (ret < 0) {
-		/* Same Coda hack as in write_sha1_file(sha1_file.c) */
-		ret = errno;
-		if (ret == EXDEV && !rename(old, new))
-			return 0;
-	}
-	unlink(old);
-	if (ret) {
-		if (ret != EEXIST)
-			return ret;
-	}
-
-	return 0;
-}
-
 #ifdef USE_CURL_MULTI
 void process_curl_messages();
 void process_request_queue();
@@ -295,6 +276,20 @@ void start_request(struct transfer_request *request)
 
 	request->local = open(request->tmpfile,
 			      O_WRONLY | O_CREAT | O_EXCL, 0666);
+	/* This could have failed due to the "lazy directory creation";
+	 * try to mkdir the last path component.
+	 */
+	if (request->local < 0 && errno == ENOENT) {
+		char *dir = strrchr(request->tmpfile, '/');
+		if (dir) {
+			*dir = 0;
+			mkdir(request->tmpfile, 0777);
+			*dir = '/';
+		}
+		request->local = open(request->tmpfile,
+				      O_WRONLY | O_CREAT | O_EXCL, 0666);
+	}
+
 	if (request->local < 0) {
 		request->state = ABORTED;
 		error("Couldn't create temporary file %s for %s: %s\n",
@@ -408,7 +403,7 @@ void finish_request(struct transfer_request *request)
 		return;
 	}
 	request->rename =
-		relink_or_rename(request->tmpfile, request->filename);
+		move_temp_to_file(request->tmpfile, request->filename);
 
 	if (request->rename == 0)
 		pull_say("got %s\n", sha1_to_hex(request->sha1));
@@ -542,7 +537,6 @@ static int fetch_index(struct alt_base *repo, unsigned char *sha1)
 	char *filename;
 	char *url;
 	char tmpfile[PATH_MAX];
-	int ret;
 	long prev_posn = 0;
 	char range[RANGE_HEADER_SIZE];
 	struct curl_slist *range_header = NULL;
@@ -599,12 +593,7 @@ static int fetch_index(struct alt_base *repo, unsigned char *sha1)
 
 	fclose(indexfile);
 
-	ret = relink_or_rename(tmpfile, filename);
-	if (ret)
-		return error("unable to write index filename %s: %s",
-			     filename, strerror(ret));
-
-	return 0;
+	return move_temp_to_file(tmpfile, filename);
 }
 
 static int setup_index(struct alt_base *repo, unsigned char *sha1)
@@ -869,10 +858,9 @@ static int fetch_pack(struct alt_base *repo, unsigned char *sha1)
 
 	fclose(packfile);
 
-	ret = relink_or_rename(tmpfile, filename);
+	ret = move_temp_to_file(tmpfile, filename);
 	if (ret)
-		return error("unable to write pack filename %s: %s",
-			     filename, strerror(ret));
+		return ret;
 
 	lst = &repo->packs;
 	while (*lst != target)

sha1_file.c

@@ -1287,7 +1287,7 @@ static int link_temp_to_file(const char *tmpfile, char *filename)
 /*
  * Move the just written object into its final resting place
  */
-static int move_temp_to_file(const char *tmpfile, char *filename)
+int move_temp_to_file(const char *tmpfile, char *filename)
 {
 	int ret = link_temp_to_file(tmpfile, filename);
 	if (ret) {