strbuf: add strbuf_vaddf

In a variable-args function, the code for writing into a strbuf is
non-trivial. We ended up cutting and pasting it in several places
because there was no vprintf-style function for strbufs (which in turn
was held up by a lack of va_copy).

Now that we have a fallback va_copy, we can add strbuf_vaddf, the
strbuf equivalent of vsprintf. And we can clean up the cut and paste
mess.

Signed-off-by: Jeff King <peff@peff.net>
Improved-by: Christian Couder <christian.couder@gmail.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 6 insertions, 26 deletions

diff --git a/trace.c b/trace.c
index 35d388dce4..eda3f6d721 100644
--- a/trace.c
+++ b/trace.c
@@ -64,28 +64,18 @@ static const char err_msg[] = "Could not trace into fd given by "
 
 void trace_printf(const char *fmt, ...)
 {
-	struct strbuf buf;
+	struct strbuf buf = STRBUF_INIT;
 	va_list ap;
-	int fd, len, need_close = 0;
+	int fd, need_close = 0;
 
 	fd = get_trace_fd(&need_close);
 	if (!fd)
 		return;
 
 	set_try_to_free_routine(NULL);	/* is never reset */
-	strbuf_init(&buf, 64);
 	va_start(ap, fmt);
-	len = vsnprintf(buf.buf, strbuf_avail(&buf), fmt, ap);
+	strbuf_vaddf(&buf, fmt, ap);
 	va_end(ap);
-	if (len >= strbuf_avail(&buf)) {
-		strbuf_grow(&buf, len - strbuf_avail(&buf) + 128);
-		va_start(ap, fmt);
-		len = vsnprintf(buf.buf, strbuf_avail(&buf), fmt, ap);
-		va_end(ap);
-		if (len >= strbuf_avail(&buf))
-			die("broken vsnprintf");
-	}
-	strbuf_setlen(&buf, len);
 
 	write_or_whine_pipe(fd, buf.buf, buf.len, err_msg);
 	strbuf_release(&buf);
@@ -96,28 +86,18 @@ void trace_printf(const char *fmt, ...)
 
 void trace_argv_printf(const char **argv, const char *fmt, ...)
 {
-	struct strbuf buf;
+	struct strbuf buf = STRBUF_INIT;
 	va_list ap;
-	int fd, len, need_close = 0;
+	int fd, need_close = 0;
 
 	fd = get_trace_fd(&need_close);
 	if (!fd)
 		return;
 
 	set_try_to_free_routine(NULL);	/* is never reset */
-	strbuf_init(&buf, 64);
 	va_start(ap, fmt);
-	len = vsnprintf(buf.buf, strbuf_avail(&buf), fmt, ap);
+	strbuf_vaddf(&buf, fmt, ap);
 	va_end(ap);
-	if (len >= strbuf_avail(&buf)) {
-		strbuf_grow(&buf, len - strbuf_avail(&buf) + 128);
-		va_start(ap, fmt);
-		len = vsnprintf(buf.buf, strbuf_avail(&buf), fmt, ap);
-		va_end(ap);
-		if (len >= strbuf_avail(&buf))
-			die("broken vsnprintf");
-	}
-	strbuf_setlen(&buf, len);
 
 	sq_quote_argv(&buf, argv, 0);
 	strbuf_addch(&buf, '\n');