[PATCH 07/19] ui-log.c: use a strbuf for refs

[John Keeping]

This avoids using a fixed-size buffer in fmt() for a user-supplied ref
string.

Signed-off-by: John Keeping <john at keeping.me.uk>
---
 ui-log.c | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/ui-log.c b/ui-log.c
index d75d7bf..7c3308c 100644
--- a/ui-log.c
+++ b/ui-log.c
@@ -244,15 +244,18 @@ static void print_commit(struct commit *commit, struct rev_info *revs)
 	cgit_free_commitinfo(info);
 }
 
-static const char *disambiguate_ref(const char *ref)
+static const char *disambiguate_ref(const char *ref, int *must_free_result)
 {
 	unsigned char sha1[20];
-	const char *longref;
+	struct strbuf longref = STRBUF_INIT;
 
-	longref = fmt("refs/heads/%s", ref);
-	if (get_sha1(longref, sha1) == 0)
-		return longref;
+	strbuf_addf(&longref, "refs/heads/%s", ref);
+	if (get_sha1(longref.buf, sha1) == 0) {
+		*must_free_result = 1;
+		return strbuf_detach(&longref, NULL);
+	}
 
+	*must_free_result = 0;
 	return ref;
 }
 
@@ -285,6 +288,7 @@ void cgit_print_log(const char *tip, int ofs, int cnt, char *grep, char *pattern
 	struct commit *commit;
 	struct vector vec = VECTOR_INIT(char *);
 	int i, columns = commit_graph ? 4 : 3;
+	int must_free_tip = 0;
 	char *arg;
 
 	/* First argv is NULL */
@@ -292,7 +296,7 @@ void cgit_print_log(const char *tip, int ofs, int cnt, char *grep, char *pattern
 
 	if (!tip)
 		tip = ctx.qry.head;
-	tip = disambiguate_ref(tip);
+	tip = disambiguate_ref(tip, &must_free_tip);
 	vector_push(&vec, &tip, 0);
 
 	if (grep && pattern && *pattern) {
@@ -430,4 +434,8 @@ void cgit_print_log(const char *tip, int ofs, int cnt, char *grep, char *pattern
 			      ctx.qry.vpath, 0, NULL, NULL, ctx.qry.showmsg);
 		html("</td></tr>\n");
 	}
+
+	/* If we allocated tip then it is safe to cast away const. */
+	if (must_free_tip)
+		free((char*) tip);
 }
-- 
1.8.2.692.g17a9715