[PATCH] Handle broken vsnprintf implementations in strbuf
- From
Shawn O. Pearce <spearce@spearce.org>
- Date
- Nov 13, 2007, 08:22 UTC
- Message-ID
- <20071113082244.GA12565@spearce.org>
Solaris 9's vsnprintf implementation returns -1 if we pass it a buffer of length 0. The only way to get it to give us the actual length necessary for the formatted string is to grow the buffer out to have at least 1 byte available in the strbuf and then ask it to compute the length.
If the available space is 0 I'm growing it out by 64 to ensure we will get an accurate length estimate from all implementations. Some callers may need to grow the strbuf again but 64 should be a reasonable enough initial growth.
We also no longer silently fail to append to the string when we are faced with a broken vsnprintf implementation. On Solaris 9 this silent failure caused me to no longer be able to execute "git clone" as we tried to exec the empty string rather than "git-clone".
Signed-off-by: Shawn O. Pearce <spearce@spearce.org> --- strbuf.c | 7 ++++--- trace.c | 4 ++-- 2 files changed, 6 insertions(+), 5 deletions(-)
diff --git a/strbuf.c b/strbuf.c index dbd8c4b..b9b194b 100644 --- a/strbuf.c +++ b/strbuf.c @@ -118,12 +118,13 @@ void strbuf_addf(struct strbuf *sb, const char *fmt, ...) int len; va_list ap; + if (!strbuf_avail(sb)) + strbuf_grow(sb, 64); va_start(ap, fmt); len = vsnprintf(sb->buf + sb->len, sb->alloc - sb->len, fmt, ap); va_end(ap); - if (len < 0) { - len = 0; - } + if (len < 0) + die("your vsnprintf is broken"); if (len > strbuf_avail(sb)) { strbuf_grow(sb, len); va_start(ap, fmt); diff --git a/trace.c b/trace.c index 69fa05e..0d89dbe 100644 --- a/trace.c +++ b/trace.c @@ -72,7 +72,7 @@ void trace_printf(const char *fmt, ...) if (!fd) return; - strbuf_init(&buf, 0); + strbuf_init(&buf, 64); va_start(ap, fmt); len = vsnprintf(buf.buf, strbuf_avail(&buf), fmt, ap); va_end(ap); @@ -103,7 +103,7 @@ void trace_argv_printf(const char **argv, int count, const char *fmt, ...) if (!fd) return; - strbuf_init(&buf, 0); + strbuf_init(&buf, 64); va_start(ap, fmt); len = vsnprintf(buf.buf, strbuf_avail(&buf), fmt, ap); va_end(ap);
-- 1.5.3.5.1661.gcbf0