From c6887522fe1021e135164b26bef86d5cd6edeef1 Mon Sep 17 00:00:00 2001
From: goldsimon <goldsimon@gmx.de>
Date: Sat, 23 Dec 2017 20:35:18 +0100
Subject: [PATCH] Fixed lwip_itoa (bug #51729) and added unit tests for it

---
 src/core/def.c             | 14 +++----
 test/unit/core/test_def.c  | 81 ++++++++++++++++++++++++++++++++++++++
 test/unit/core/test_def.h  |  8 ++++
 test/unit/lwip_unittests.c |  2 +
 4 files changed, 96 insertions(+), 9 deletions(-)
 create mode 100644 test/unit/core/test_def.c
 create mode 100644 test/unit/core/test_def.h

diff --git a/src/core/def.c b/src/core/def.c
index c483aa68..e37501ae 100644
--- a/src/core/def.c
+++ b/src/core/def.c
@@ -201,7 +201,8 @@ lwip_itoa(char *result, size_t bufsize, int number)
   char *tmp = result;
   size_t res_left = bufsize;
   size_t result_len;
-  int n = (number > 0) ? number : -number;
+  int pos = number >= 0;
+  int n = pos ? number : -number;
 
   /* handle invalid bufsize */
   if (bufsize < 2) {
@@ -217,21 +218,16 @@ lwip_itoa(char *result, size_t bufsize, int number)
   /* create the string in a temporary buffer since we don't know how long
      it will get */
   tmp = &result[bufsize - 2];
-  if (n == 0) {
-    *tmp = '0';
-    tmp--;
-    result_len++;
-  }
-  while ((n != 0) && (result_len < (bufsize - 1))) {
+  do {
     char val = (char)('0' + (n % 10));
     *tmp = val;
     tmp--;
     n = n / 10;
     result_len++;
-  }
+  } while ((n != 0) && (result_len <= bufsize));
 
   /* output sign first */
-  if (number < 0) {
+  if (!pos) {
     *res = '-';
     res++;
     res_left--;
diff --git a/test/unit/core/test_def.c b/test/unit/core/test_def.c
new file mode 100644
index 00000000..e8ec63a6
--- /dev/null
+++ b/test/unit/core/test_def.c
@@ -0,0 +1,81 @@
+#include "test_def.h"
+
+#include "lwip/def.h"
+
+#define MAGIC_UNTOUCHED_BYTE  0xfa
+#define TEST_BUFSIZE          32
+#define GUARD_SIZE            4
+
+/* Setups/teardown functions */
+
+static void
+def_setup(void)
+{
+}
+
+static void
+def_teardown(void)
+{
+}
+
+static void
+def_check_range_untouched(const char *buf, size_t len)
+{
+  size_t i;
+
+  for (i = 0; i < len; i++) {
+    fail_unless(buf[i] == (char)MAGIC_UNTOUCHED_BYTE);
+  }
+}
+
+static void test_def_itoa(int number, const char *expected)
+{
+  char buf[TEST_BUFSIZE];
+  char *test_buf = &buf[GUARD_SIZE];
+
+  size_t exp_len = strlen(expected);
+  fail_unless(exp_len + 1 < (TEST_BUFSIZE - (2 * GUARD_SIZE)));
+
+  memset(buf, MAGIC_UNTOUCHED_BYTE, sizeof(buf));
+  lwip_itoa(test_buf, exp_len + 1, number);
+  def_check_range_untouched(buf, GUARD_SIZE);
+  fail_unless(test_buf[exp_len] == 0);
+  fail_unless(!memcmp(test_buf, expected, exp_len));
+  def_check_range_untouched(&test_buf[exp_len + 1], TEST_BUFSIZE - GUARD_SIZE - exp_len - 1);
+
+  /* check with too small buffer */
+  memset(buf, MAGIC_UNTOUCHED_BYTE, sizeof(buf));
+  lwip_itoa(test_buf, exp_len, number);
+
+  /* check with too large buffer */
+  memset(buf, MAGIC_UNTOUCHED_BYTE, sizeof(buf));
+  lwip_itoa(test_buf, exp_len + 4, number);
+  def_check_range_untouched(buf, GUARD_SIZE);
+  fail_unless(test_buf[exp_len] == 0);
+  fail_unless(!memcmp(test_buf, expected, exp_len));
+  def_check_range_untouched(&test_buf[exp_len + 4], TEST_BUFSIZE - GUARD_SIZE - exp_len - 4);
+}
+
+START_TEST(test_def_lwip_itoa)
+{
+  LWIP_UNUSED_ARG(_i);
+
+  test_def_itoa(0, "0");
+  test_def_itoa(1, "1");
+  test_def_itoa(-1, "-1");
+  test_def_itoa(15, "15");
+  test_def_itoa(-15, "-15");
+  test_def_itoa(156, "156");
+  test_def_itoa(-156, "-156");
+}
+END_TEST
+
+/** Create the suite including all tests for this module */
+Suite *
+def_suite(void)
+{
+  testfunc tests[] = {
+    TESTFUNC(test_def_lwip_itoa)
+  };
+  return create_suite("DEF", tests, sizeof(tests)/sizeof(testfunc), def_setup, def_teardown);
+}
diff --git a/test/unit/core/test_def.h b/test/unit/core/test_def.h
new file mode 100644
index 00000000..73160512
--- /dev/null
+++ b/test/unit/core/test_def.h
@@ -0,0 +1,8 @@
+#ifndef LWIP_HDR_TEST_DEF_H
+#define LWIP_HDR_TEST_DEF_H
+
+#include "../lwip_check.h"
+
+Suite *def_suite(void);
+
+#endif
diff --git a/test/unit/lwip_unittests.c b/test/unit/lwip_unittests.c
index b371764f..d9e65d54 100644
--- a/test/unit/lwip_unittests.c
+++ b/test/unit/lwip_unittests.c
@@ -4,6 +4,7 @@
 #include "udp/test_udp.h"
 #include "tcp/test_tcp.h"
 #include "tcp/test_tcp_oos.h"
+#include "core/test_def.h"
 #include "core/test_mem.h"
 #include "core/test_pbuf.h"
 #include "etharp/test_etharp.h"
@@ -62,6 +63,7 @@ int main(void)
     udp_suite,
     tcp_suite,
     tcp_oos_suite,
+    def_suite,
     mem_suite,
     pbuf_suite,
     etharp_suite,