finish_tmp_packfile():use strbuf for pathname construction

The old version fixes a maximum length on the buffer, which could be a problem
if one is not certain of the length of get_object_directory().
Using strbuf can avoid the protential bug.

Helped-by: Michael Haggerty <mhagger@alum.mit.edu>
Helped-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Sun He <sunheehnus@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/pack-objects.c

@@ -803,7 +803,7 @@ static void write_pack_file(void)
 
 		if (!pack_to_stdout) {
 			struct stat st;
-			char tmpname[PATH_MAX];
+			struct strbuf tmpname = STRBUF_INIT;
 
 			/*
 			 * Packs are runtime accessed in their mtime
@@ -826,23 +826,19 @@ static void write_pack_file(void)
 						pack_tmp_name, strerror(errno));
 			}
 
-			/* 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);
+			strbuf_addf(&tmpname, "%s-", base_name);
 
 			if (write_bitmap_index) {
 				bitmap_writer_set_checksum(sha1);
 				bitmap_writer_build_type_index(written_list, nr_written);
 			}
 
-			finish_tmp_packfile(tmpname, pack_tmp_name,
+			finish_tmp_packfile(&tmpname, pack_tmp_name,
 					    written_list, nr_written,
 					    &pack_idx_opts, sha1);
 
 			if (write_bitmap_index) {
-				char *end_of_name_prefix = strrchr(tmpname, 0);
-				sprintf(end_of_name_prefix, "%s.bitmap", sha1_to_hex(sha1));
+				strbuf_addf(&tmpname, "%s.bitmap", sha1_to_hex(sha1));
 
 				stop_progress(&progress_state);
 
@@ -851,10 +847,11 @@ static void write_pack_file(void)
 				bitmap_writer_select_commits(indexed_commits, indexed_commits_nr, -1);
 				bitmap_writer_build(&to_pack);
 				bitmap_writer_finish(written_list, nr_written,
-						     tmpname, write_bitmap_options);
+						     tmpname.buf, write_bitmap_options);
 				write_bitmap_index = 0;
 			}
 
+			strbuf_release(&tmpname);
 			free(pack_tmp_name);
 			puts(sha1_to_hex(sha1));
 		}

bulk-checkin.c

@@ -4,6 +4,7 @@
 #include "bulk-checkin.h"
 #include "csum-file.h"
 #include "pack.h"
+#include "strbuf.h"
 
 static int pack_compression_level = Z_DEFAULT_COMPRESSION;
 
@@ -23,7 +24,7 @@ static struct bulk_checkin_state {
 static void finish_bulk_checkin(struct bulk_checkin_state *state)
 {
 	unsigned char sha1[20];
-	char packname[PATH_MAX];
+	struct strbuf packname = STRBUF_INIT;
 	int i;
 
 	if (!state->f)
@@ -43,8 +44,8 @@ static void finish_bulk_checkin(struct bulk_checkin_state *state)
 		close(fd);
 	}
 
-	sprintf(packname, "%s/pack/pack-", get_object_directory());
-	finish_tmp_packfile(packname, state->pack_tmp_name,
+	strbuf_addf(&packname, "%s/pack/pack-", get_object_directory());
+	finish_tmp_packfile(&packname, state->pack_tmp_name,
 			    state->written, state->nr_written,
 			    &state->pack_idx_opts, sha1);
 	for (i = 0; i < state->nr_written; i++)
@@ -54,6 +55,7 @@ static void finish_bulk_checkin(struct bulk_checkin_state *state)
 	free(state->written);
 	memset(state, 0, sizeof(*state));
 
+	strbuf_release(&packname);
 	/* Make objects we just wrote available to ourselves */
 	reprepare_packed_git();
 }

pack-write.c

@@ -336,15 +336,15 @@ struct sha1file *create_tmp_packfile(char **pack_tmp_name)
 	return sha1fd(fd, *pack_tmp_name);
 }
 
-void finish_tmp_packfile(char *name_buffer,
+void finish_tmp_packfile(struct strbuf *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);
+	int basename_len = name_buffer->len;
 
 	if (adjust_shared_perm(pack_tmp_name))
 		die_errno("unable to make temporary pack file readable");
@@ -354,17 +354,19 @@ void finish_tmp_packfile(char *name_buffer,
 	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);
+	strbuf_addf(name_buffer, "%s.pack", sha1_to_hex(sha1));
+	free_pack_by_name(name_buffer->buf);
 
-	if (rename(pack_tmp_name, name_buffer))
+	if (rename(pack_tmp_name, name_buffer->buf))
 		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))
+	strbuf_setlen(name_buffer, basename_len);
+
+	strbuf_addf(name_buffer, "%s.idx", sha1_to_hex(sha1));
+	if (rename(idx_tmp_name, name_buffer->buf))
 		die_errno("unable to rename temporary index file");
 
-	*end_of_name_prefix = '\0';
+	strbuf_setlen(name_buffer, basename_len);
 
 	free((void *)idx_tmp_name);
 }

pack.h

@@ -91,6 +91,6 @@ 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[]);
+extern void finish_tmp_packfile(struct strbuf *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