From c9036f3ac091a31f25ae10e10384a885fb5e9a82 Mon Sep 17 00:00:00 2001
From: Sergey Lyubka <valenok@gmail.com>
Date: Wed, 5 Feb 2014 12:33:36 +0000
Subject: [PATCH] Added workaround for non-compliant runtimes in
alloc_vprintf()
---
mongoose.c | 37 ++++++++++++++++++++++++-------------
unit_test.c | 25 +++++++++++++++++++++++++
2 files changed, 49 insertions(+), 13 deletions(-)
diff --git a/mongoose.c b/mongoose.c
index a186418de..01cd72ca9 100644
--- a/mongoose.c
+++ b/mongoose.c
@@ -731,21 +731,32 @@ static int alloc_vprintf(char **buf, size_t size, const char *fmt, va_list ap) {
va_list ap_copy;
int len;
- // Windows is not standard-compliant, and vsnprintf() returns -1 if
- // buffer is too small. Also, older versions of msvcrt.dll do not have
- // _vscprintf(). However, if size is 0, vsnprintf() behaves correctly.
- // Therefore, we make two passes: on first pass, get required message length.
- // On second pass, actually print the message.
va_copy(ap_copy, ap);
- len = vsnprintf(NULL, 0, fmt, ap_copy);
+ len = vsnprintf(*buf, size, fmt, ap_copy);
+ va_end(ap_copy);
- if (len > (int) size &&
- (size = len + 1) > 0 &&
- (*buf = (char *) malloc(size)) == NULL) {
- len = -1; // Allocation failed, mark failure
- } else {
- va_copy(ap_copy, ap);
- vsnprintf(*buf, size, fmt, ap_copy);
+ if (len < 0) {
+ // eCos and Windows are not standard-compliant and return -1 when
+ // the buffer is too small. Keep allocating larger buffers until we
+ // succeed or out of memory.
+ *buf = NULL;
+ while (len < 0) {
+ if (*buf) free(*buf);
+ size *= 2;
+ if ((*buf = (char *) malloc(size)) == NULL) break;
+ va_copy(ap_copy, ap);
+ len = vsnprintf(*buf, size, fmt, ap_copy);
+ va_end(ap_copy);
+ }
+ } else if (len > (int) size) {
+ // Standard-compliant code path. Allocate a buffer that is large enough.
+ if ((*buf = (char *) malloc(len + 1)) == NULL) {
+ len = -1;
+ } else {
+ va_copy(ap_copy, ap);
+ len = vsnprintf(*buf, len + 1, fmt, ap_copy);
+ va_end(ap_copy);
+ }
}
return len;
diff --git a/unit_test.c b/unit_test.c
index b3d034492..3f9a39ed4 100644
--- a/unit_test.c
+++ b/unit_test.c
@@ -613,6 +613,30 @@ static const char *test_rewrites(void) {
return NULL;
}
+static int avt(char **buf, size_t buf_size, const char *fmt, ...) {
+ int result;
+ va_list ap;
+ va_start(ap, fmt);
+ result = alloc_vprintf(buf, buf_size, fmt, ap);
+ va_end(ap);
+ return result;
+}
+
+static const char *test_alloc_vprintf(void) {
+ char buf[5], *p = buf;
+
+ ASSERT(avt(&p, sizeof(buf), "%d", 123) == 3);
+ ASSERT(p == buf);
+ ASSERT(strcmp(p, "123") == 0);
+
+ ASSERT(avt(&p, sizeof(buf), "%d", 123456789) == 9);
+ ASSERT(p != buf);
+ ASSERT(strcmp(p, "123456789") == 0);
+ free(p);
+
+ return NULL;
+}
+
static const char *run_all_tests(void) {
RUN_TEST(test_should_keep_alive);
RUN_TEST(test_match_prefix);
@@ -630,6 +654,7 @@ static const char *run_all_tests(void) {
RUN_TEST(test_mg_connect);
RUN_TEST(test_mg_set_option);
RUN_TEST(test_rewrites);
+ RUN_TEST(test_alloc_vprintf);
#ifdef MONGOOSE_USE_SSL
RUN_TEST(test_ssl);
#endif
--
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