Fix strncmp, fread and fwrite in jerry-libc.

JerryScript-DCO-1.0-Signed-off-by: Ruben Ayrapetyan r.ayrapetyan@samsung.com

jerry-libc/jerry-libc.c

@@ -197,6 +197,12 @@ int
 strncmp (const char *s1, const char *s2, size_t n)
 {
   size_t i;
+
+  if (n == 0)
+  {
+    return 0;
+  }
+
   if (s1 == NULL)
   {
     if (s2 != NULL)

jerry-libc/target/linux/jerry-libc-target.c

@@ -322,7 +322,7 @@ ftell (FILE * fp) /**< stream pointer */
 /**
  * fread
  *
- * @return number of bytes read
+ * @return number of elements read
  */
 size_t
 fread (void *ptr, /**< address of buffer to read to */
@@ -333,6 +333,11 @@ fread (void *ptr, /**< address of buffer to read to */
   long int ret;
   size_t bytes_read = 0;
 
+  if (size == 0)
+  {
+    return 0;
+  }
+
   do
   {
     ret = syscall_3 (__NR_read,
@@ -344,13 +349,13 @@ fread (void *ptr, /**< address of buffer to read to */
   }
   while (bytes_read != size * nmemb && ret != 0);
 
-  return bytes_read;
+  return bytes_read / size;
 } /* fread */
 
 /**
  * fwrite
  *
- * @return number of bytes written
+ * @return number of elements written
  */
 size_t
 fwrite (const void *ptr, /**< data to write */
@@ -360,6 +365,11 @@ fwrite (const void *ptr, /**< data to write */
 {
   size_t bytes_written = 0;
 
+  if (size == 0)
+  {
+    return 0;
+  }
+
   do
   {
     long int ret = syscall_3 (__NR_write,
@@ -371,7 +381,7 @@ fwrite (const void *ptr, /**< data to write */
   }
   while (bytes_written != size * nmemb);
 
-  return bytes_written;
+  return bytes_written / size;
 } /* fwrite */
 
 // FIXME