finish_tmp_packfile(): a helper function

Factor out a small logic out of the private write_pack_file() function
in builtin/pack-objects.c.

This changes the order of finishing multi-pack generation slightly. The
code used to

 - adjust shared perm of temporary packfile
 - rename temporary packfile to the final name
 - update mtime of the packfile under the final name
 - adjust shared perm of temporary idxfile
 - rename temporary idxfile to the final name

but because the helper does not want to do the mtime thing, the updated
code does that step first and then all the rest.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/pack-objects.c

@@ -617,20 +617,8 @@ static void write_pack_file(void)
 
 		if (!pack_to_stdout) {
 			struct stat st;
-			const char *idx_tmp_name;
 			char tmpname[PATH_MAX];
 
-			idx_tmp_name = write_idx_file(NULL, written_list, nr_written,
-						      &pack_idx_opts, sha1);
-
-			snprintf(tmpname, sizeof(tmpname), "%s-%s.pack",
-				 base_name, sha1_to_hex(sha1));
-			free_pack_by_name(tmpname);
-			if (adjust_shared_perm(pack_tmp_name))
-				die_errno("unable to make temporary pack file readable");
-			if (rename(pack_tmp_name, tmpname))
-				die_errno("unable to rename temporary pack file");
-
 			/*
 			 * Packs are runtime accessed in their mtime
 			 * order since newer packs are more likely to contain
@@ -638,28 +626,27 @@ static void write_pack_file(void)
 			 * packs then we should modify the mtime of later ones
 			 * to preserve this property.
 			 */
-			if (stat(tmpname, &st) < 0) {
+			if (stat(pack_tmp_name, &st) < 0) {
 				warning("failed to stat %s: %s",
-					tmpname, strerror(errno));
+					pack_tmp_name, strerror(errno));
 			} else if (!last_mtime) {
 				last_mtime = st.st_mtime;
 			} else {
 				struct utimbuf utb;
 				utb.actime = st.st_atime;
 				utb.modtime = --last_mtime;
-				if (utime(tmpname, &utb) < 0)
+				if (utime(pack_tmp_name, &utb) < 0)
 					warning("failed utime() on %s: %s",
 						tmpname, strerror(errno));
 			}
 
-			snprintf(tmpname, sizeof(tmpname), "%s-%s.idx",
-				 base_name, sha1_to_hex(sha1));
-			if (adjust_shared_perm(idx_tmp_name))
-				die_errno("unable to make temporary index file readable");
-			if (rename(idx_tmp_name, tmpname))
-				die_errno("unable to rename temporary index file");
-
-			free((void *) idx_tmp_name);
+			/* Enough space for "-<sha-1>.pack"? */
+			if (sizeof(tmpname) <= strlen(base_name) + 50)
+				die("pack base name '%s' too long", base_name);
+			snprintf(tmpname, sizeof(tmpname), "%s-", base_name);
+			finish_tmp_packfile(tmpname, pack_tmp_name,
+					    written_list, nr_written,
+					    &pack_idx_opts, sha1);
 			free(pack_tmp_name);
 			puts(sha1_to_hex(sha1));
 		}

pack-write.c

@@ -338,3 +338,34 @@ struct sha1file *create_tmp_packfile(char **pack_tmp_name)
 	*pack_tmp_name = xstrdup(tmpname);
 	return sha1fd(fd, *pack_tmp_name);
 }
+
+void finish_tmp_packfile(char *name_buffer,
+			 const char *pack_tmp_name,
+			 struct pack_idx_entry **written_list,
+			 uint32_t nr_written,
+			 struct pack_idx_option *pack_idx_opts,
+			 unsigned char sha1[])
+{
+	const char *idx_tmp_name;
+	char *end_of_name_prefix = strrchr(name_buffer, 0);
+
+	if (adjust_shared_perm(pack_tmp_name))
+		die_errno("unable to make temporary pack file readable");
+
+	idx_tmp_name = write_idx_file(NULL, written_list, nr_written,
+				      pack_idx_opts, sha1);
+	if (adjust_shared_perm(idx_tmp_name))
+		die_errno("unable to make temporary index file readable");
+
+	sprintf(end_of_name_prefix, "%s.pack", sha1_to_hex(sha1));
+	free_pack_by_name(name_buffer);
+
+	if (rename(pack_tmp_name, name_buffer))
+		die_errno("unable to rename temporary pack file");
+
+	sprintf(end_of_name_prefix, "%s.idx", sha1_to_hex(sha1));
+	if (rename(idx_tmp_name, name_buffer))
+		die_errno("unable to rename temporary index file");
+
+	free((void *)idx_tmp_name);
+}

pack.h

@@ -86,5 +86,6 @@ extern int encode_in_pack_object_header(enum object_type, uintmax_t, unsigned ch
 extern int read_pack_header(int fd, struct pack_header *);
 
 extern struct sha1file *create_tmp_packfile(char **pack_tmp_name);
+extern void finish_tmp_packfile(char *name_buffer, const char *pack_tmp_name, struct pack_idx_entry **written_list, uint32_t nr_written, struct pack_idx_option *pack_idx_opts, unsigned char sha1[]);
 
 #endif