index-pack: use strip_suffix to avoid magic numbers

We also switch to using strbufs, which lets us avoid the
potentially dangerous combination of a manual malloc
followed by a strcpy.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index 46376b6..d4b77fd 100644 (file)
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -1505,7 +1505,8 @@ int cmd_index_pack(int argc, const char **argv, const char *prefix)
        const char *curr_index;
        const char *index_name = NULL, *pack_name = NULL;
        const char *keep_name = NULL, *keep_msg = NULL;
-       char *index_name_buf = NULL, *keep_name_buf = NULL;
+       struct strbuf index_name_buf = STRBUF_INIT,
+                     keep_name_buf = STRBUF_INIT;
        struct pack_idx_entry **idx_objects;
        struct pack_idx_option opts;
        unsigned char pack_sha1[20];
@@ -1602,24 +1603,22 @@ int cmd_index_pack(int argc, const char **argv, const char *prefix)
        if (fix_thin_pack && !from_stdin)
                die(_("--fix-thin cannot be used without --stdin"));
        if (!index_name && pack_name) {
-               int len = strlen(pack_name);
-               if (!ends_with(pack_name, ".pack"))
+               size_t len;
+               if (!strip_suffix(pack_name, ".pack", &len))
                        die(_("packfile name '%s' does not end with '.pack'"),
                            pack_name);
-               index_name_buf = xmalloc(len);
-               memcpy(index_name_buf, pack_name, len - 5);
-               strcpy(index_name_buf + len - 5, ".idx");
-               index_name = index_name_buf;
+               strbuf_add(&index_name_buf, pack_name, len);
+               strbuf_addstr(&index_name_buf, ".idx");
+               index_name = index_name_buf.buf;
        }
        if (keep_msg && !keep_name && pack_name) {
-               int len = strlen(pack_name);
-               if (!ends_with(pack_name, ".pack"))
+               size_t len;
+               if (!strip_suffix(pack_name, ".pack", &len))
                        die(_("packfile name '%s' does not end with '.pack'"),
                            pack_name);
-               keep_name_buf = xmalloc(len);
-               memcpy(keep_name_buf, pack_name, len - 5);
-               strcpy(keep_name_buf + len - 5, ".keep");
-               keep_name = keep_name_buf;
+               strbuf_add(&keep_name_buf, pack_name, len);
+               strbuf_addstr(&keep_name_buf, ".idx");
+               keep_name = keep_name_buf.buf;
        }
        if (verify) {
                if (!index_name)
@@ -1667,8 +1666,8 @@ int cmd_index_pack(int argc, const char **argv, const char *prefix)
        else
                close(input_fd);
        free(objects);
-       free(index_name_buf);
-       free(keep_name_buf);
+       strbuf_release(&index_name_buf);
+       strbuf_release(&keep_name_buf);
        if (pack_name == NULL)
                free((void *) curr_pack);
        if (index_name == NULL)