builtin-branch: use strbuf in rename_branch()

In case the length of branch name is greather then PATH_MAX-11, we write
to unallocated memory otherwise.

Signed-off-by: Miklos Vajna <vmiklos@frugalware.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 21 insertions, 18 deletions

diff --git a/builtin-branch.c b/builtin-branch.c
index c8a8e2a..494cbac 100644
--- a/builtin-branch.c
+++ b/builtin-branch.c
@@ -424,42 +424,45 @@ static void print_ref_list(int kinds, int detached, int verbose, int abbrev, str
 
 static void rename_branch(const char *oldname, const char *newname, int force)
 {
-	char oldref[PATH_MAX], newref[PATH_MAX], logmsg[PATH_MAX*2 + 100];
+	struct strbuf oldref = STRBUF_INIT, newref = STRBUF_INIT, logmsg = STRBUF_INIT;
 	unsigned char sha1[20];
-	char oldsection[PATH_MAX], newsection[PATH_MAX];
+	struct strbuf oldsection = STRBUF_INIT, newsection = STRBUF_INIT;
 
 	if (!oldname)
 		die("cannot rename the current branch while not on any.");
 
-	if (snprintf(oldref, sizeof(oldref), "refs/heads/%s", oldname) > sizeof(oldref))
-		die("Old branchname too long");
+	strbuf_addf(&oldref, "refs/heads/%s", oldname);
 
-	if (check_ref_format(oldref))
-		die("Invalid branch name: %s", oldref);
+	if (check_ref_format(oldref.buf))
+		die("Invalid branch name: %s", oldref.buf);
 
-	if (snprintf(newref, sizeof(newref), "refs/heads/%s", newname) > sizeof(newref))
-		die("New branchname too long");
+	strbuf_addf(&newref, "refs/heads/%s", newname);
 
-	if (check_ref_format(newref))
-		die("Invalid branch name: %s", newref);
+	if (check_ref_format(newref.buf))
+		die("Invalid branch name: %s", newref.buf);
 
-	if (resolve_ref(newref, sha1, 1, NULL) && !force)
+	if (resolve_ref(newref.buf, sha1, 1, NULL) && !force)
 		die("A branch named '%s' already exists.", newname);
 
-	snprintf(logmsg, sizeof(logmsg), "Branch: renamed %s to %s",
-		 oldref, newref);
+	strbuf_addf(&logmsg, "Branch: renamed %s to %s",
+		 oldref.buf, newref.buf);
 
-	if (rename_ref(oldref, newref, logmsg))
+	if (rename_ref(oldref.buf, newref.buf, logmsg.buf))
 		die("Branch rename failed");
+	strbuf_release(&logmsg);
 
 	/* no need to pass logmsg here as HEAD didn't really move */
-	if (!strcmp(oldname, head) && create_symref("HEAD", newref, NULL))
+	if (!strcmp(oldname, head) && create_symref("HEAD", newref.buf, NULL))
 		die("Branch renamed to %s, but HEAD is not updated!", newname);
 
-	snprintf(oldsection, sizeof(oldsection), "branch.%s", oldref + 11);
-	snprintf(newsection, sizeof(newsection), "branch.%s", newref + 11);
-	if (git_config_rename_section(oldsection, newsection) < 0)
+	strbuf_addf(&oldsection, "branch.%s", oldref.buf + 11);
+	strbuf_release(&oldref);
+	strbuf_addf(&newsection, "branch.%s", newref.buf + 11);
+	strbuf_release(&newref);
+	if (git_config_rename_section(oldsection.buf, newsection.buf) < 0)
 		die("Branch is renamed, but update of config-file failed");
+	strbuf_release(&oldsection);
+	strbuf_release(&newsection);
 }
 
 static int opt_parse_with_commit(const struct option *opt, const char *arg, int unset)