Handle broken vsnprintf implementations in strbuf

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>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/strbuf.c b/strbuf.c
index f4201e160de2ccb9f2d9adef695c73a124e676d5..cbada946c4e73a403cb2d237f8aebfcda5c88ac4 100644 (file)
--- a/strbuf.c
+++ b/strbuf.c
@@ -111,12 +111,13 @@ 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 69fa05e6446355ed8e5bb7f560c83f61b9bc3aff..0d89dbe7794dcdfb8519e6d083f74bf792976c6a 100644 (file)
--- 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);