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Workaround for non-compliant vsnprintf()

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This commit is contained in:
Sergey Lyubka 2013-08-02 11:00:21 +01:00
parent f815c315e7
commit 2de96bd54e
1 changed files with 24 additions and 1 deletions
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25
mongoose.c
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@ -1629,6 +1629,24 @@ int mg_write(struct mg_connection *conn, const void *buf, size_t len) {
return (int) total;
}
// Alternative alloc_vprintf() for non-compliant C runtimes
static int alloc_vprintf2(char **buf, const char *fmt, va_list ap) {
va_list ap_copy;
int size = MG_BUF_LEN;
int len = -1;
*buf = NULL;
while (len == -1) {
if (*buf) free(*buf);
*buf = malloc(size *= 4);
if (!*buf) break;
va_copy(ap_copy, ap);
len = vsnprintf(*buf, size, fmt, ap_copy);
}
return len;
}
// Print message to buffer. If buffer is large enough to hold the message,
// return buffer. If buffer is to small, allocate large enough buffer on heap,
// and return allocated buffer.
@ -1644,7 +1662,12 @@ static int alloc_vprintf(char **buf, size_t size, const char *fmt, va_list ap) {
va_copy(ap_copy, ap);
len = vsnprintf(NULL, 0, fmt, ap_copy);
if (len > (int) size &&
if (len < 0) {
// C runtime is not standard compliant, vsnprintf() returned -1.
// Switch to alternative code path that uses incremental allocations.
va_copy(ap_copy, ap);
len = alloc_vprintf2(buf, fmt, ap);
} else if (len > (int) size &&
(size = len + 1) > 0 &&
(*buf = (char *) malloc(size)) == NULL) {
len = -1; // Allocation failed, mark failure