Changeset 544 for trunk/src/slib.c

Timestamp:

Feb 17, 2019, 2:41:49 PM (6 years ago)

Author:

katerina

Message:

Fix for ticket #436 (new gcc compiler options, including LTO).

File:

• trunk/src/slib.c (modified) (2 diffs)

trunk/src/slib.c

@@ -588 +588 @@
 /*
  * Have memset in a different translation unit (i.e. this) to prevent 
- * it to get optimized away
+ * it to get optimized away ...not safe with link-time optimisation...
  */
-void *sl_memset(void *s, int c, size_t n)
-{
-  return memset(s, c,n);
+void * sl_memset(void *s, int c, size_t n)
+{
+  /* See:
+   * https://www.usenix.org/sites/default/files/conference/protected-files/usenixsecurity17_slides_zhaomo_yang.pdf
+   */
+#if defined(HAVE_EXPLICIT_MEMSET)
+  return explicit_memset(s, c, n);
+#elif defined(HAVE_EXPLICIT_BZERO)
+  if (c == 0) {
+    explicit_bzero(s, n);
+    return s;
+  } else {
+    return memset(s, c, n);
+  }
+#elif defined(__GNUC__)
+  memset(s, c, n);
+  __asm__  __volatile__ ("" ::"r"(s): "memory"); /* compiler barrier */
+  return s;
+#else
+  if (c == 0) {
+    size_t i;
+    volatile unsigned char * t_s = (volatile unsigned char *)s;
+    for (i=0; i<n; ++i)
+      t_s[i] = 0;
+    return s;
+  } else {
+    return memset(s, c, n);
+  }
+#endif  
 }
 
@@ -1071 +1097 @@
   if (a != NULL && b != NULL)
     return (strcmp(a, b));
+  else if (a == NULL && b != NULL)
+    return (-1);
+  else if (a != NULL && b == NULL)
+    return (1);
+  else
+    return (-7); /* default to not equal */
+}
+
+/* Does not report sign. */
+int sl_ts_strncmp(const char * a, const char * b, size_t n)
+{
+#ifdef SL_FAIL_ON_ERROR
+  SL_REQUIRE (a != NULL, _("a != NULL"));
+  SL_REQUIRE (b != NULL, _("b != NULL"));
+  SL_REQUIRE (n > 0, _("n > 0"));
+#endif
+
+  if (a != NULL && b != NULL)
+    {
+      const unsigned char *a1 = (const unsigned char *)a;
+      const unsigned char *b1 = (const unsigned char *)b;
+      size_t i;
+      int  retval=0;
+      /* The simple index based access is optimized best by the
+       * compiler (tested with gcc 7.3.0). */
+      for (i = 0; i < n; ++i)
+        {
+          if (a1[i] == '\0' || b1[i] == '\0')
+            break;
+          retval |= (a1[i] ^ b1[i]);
+        }
+      /* if (retval == 0) --> false (0) */ 
+      return (retval != 0);
+    }
   else if (a == NULL && b != NULL)
     return (-1);