[PATCH 2/3] libio: Update tst-fmemopen2.c

[Adhemerval Zanella <azanella at linux dot vnet dot ibm dot com>]

This patch updates tst-fmemopen2 to check for fmemopen with NULL buffer
inputs and also refactor the code a bit.

--

	* stdio-common/tst-fmemopen2.c (do_test): Add test for NULL and zero
	length buffers.

---

diff --git a/stdio-common/tst-fmemopen2.c b/stdio-common/tst-fmemopen2.c
index c2a4baa..652c412 100644
--- a/stdio-common/tst-fmemopen2.c
+++ b/stdio-common/tst-fmemopen2.c
@@ -5,64 +5,196 @@
 
 
 static int
-do_test (void)
+do_test_with_buffer (void)
 {
   int result = 0;
   char buf[100];
-  FILE *fp = fmemopen (buf, sizeof (buf), "w");
+  const size_t nbuf = sizeof (buf);
+
+  FILE *fp = fmemopen (buf, nbuf, "w");
   if (fp == NULL)
     {
-      puts ("fmemopen failed");
-      return 0;
+      printf ("%s: fmemopen failed\n", __FUNCTION__);
+      return 1;
     }
+
   static const char str[] = "hello world";
-#define nstr (sizeof (str) - 1)
+  const size_t nstr = sizeof (str) - 1;
   fputs (str, fp);
   off_t o = ftello (fp);
   if (o != nstr)
     {
-      printf ("first ftello returned %ld, expected %zu\n", o, nstr);
+      printf ("%s: first ftello returned %ld, expected %zu\n",
+	      __FUNCTION__, o, nstr);
       result = 1;
     }
+
   rewind (fp);
   o = ftello (fp);
   if (o != 0)
     {
-      printf ("second ftello returned %ld, expected 0\n", o);
+      printf ("%s: second ftello returned %ld, expected 0\n",
+	      __FUNCTION__, o);
       result = 1;
     }
   if (fseeko (fp, 0, SEEK_END) != 0)
     {
-      puts ("fseeko failed");
-      return 1;
+      printf ("%s: fseeko failed\n", __FUNCTION__);
+      result = 1;
     }
   o = ftello (fp);
   if (o != nstr)
     {
-      printf ("third ftello returned %ld, expected %zu\n", o, nstr);
+      printf ("%s: third ftello returned %ld, expected %zu\n",
+	      __FUNCTION__, o, nbuf);
       result = 1;
     }
+
   rewind (fp);
   static const char str2[] = "just hello";
-#define nstr2 (sizeof (str2) - 1)
+  const size_t nstr2 = sizeof (str2) - 1;
   assert (nstr2 < nstr);
   fputs (str2, fp);
   o = ftello (fp);
   if (o != nstr2)
     {
-      printf ("fourth ftello returned %ld, expected %zu\n", o, nstr2);
+      printf ("%s: fourth ftello returned %ld, expected %zu\n",
+	      __FUNCTION__, o, nstr2);
       result = 1;
     }
   fclose (fp);
+
   static const char str3[] = "just hellod";
   if (strcmp (buf, str3) != 0)
     {
-      printf ("final string is \"%s\", expected \"%s\"\n",
-              buf, str3);
+      printf ("%s: final string is \"%s\", expected \"%s\"\n",
+              __FUNCTION__, buf, str3);
       result = 1;
     }
   return result;
 }
 
+static int
+do_test_without_buffer (void)
+{
+  int result = 0;
+  const size_t nbuf = 100;
+
+  FILE *fp = fmemopen (NULL, nbuf, "w");
+  if (fp == NULL)
+    {
+      printf ("%s: fmemopen failed\n", __FUNCTION__);
+      return 1;
+    }
+
+  static const char str[] = "hello world";
+  const size_t nstr = sizeof (str) - 1;
+
+  fputs (str, fp);
+  off_t o = ftello (fp);
+  if (o != nstr)
+    {
+      printf ("%s: first ftello returned %ld, expected %zu\n",
+	      __FUNCTION__, o, nstr);
+      result = 1;
+    }
+  if (fseeko (fp, 0, SEEK_END) != 0)
+    {
+      printf ("%s: fseeko failed\n", __FUNCTION__);
+      result = 1;
+    }
+  o = ftello (fp);
+  if (o != nstr)
+    {
+      printf ("%s: second ftello returned %ld, expected %zu\n",
+	      __FUNCTION__, o, nbuf);
+      result = 1;
+    }
+  rewind (fp);
+  static const char str2[] = "just hello";
+  const size_t nstr2 = sizeof (str2) - 1;
+  assert (nstr2 < nstr);
+  fputs (str2, fp);
+  o = ftello (fp);
+  if (o != nstr2)
+    {
+      printf ("%s: third ftello returned %ld, expected %zu\n",
+	      __FUNCTION__, o, nstr2);
+      result = 1;
+    }
+  fclose (fp);
+
+  return result;
+}
+
+static int
+do_test_length_zero (void)
+{
+  int result = 0;
+  FILE *fp;
+  char buf[] = "";
+  const size_t nbuf = 0;
+  int r;
+
+  fp = fmemopen (buf, nbuf, "r");
+  if (fp == NULL)
+    {
+      printf ("%s: fmemopen failed\n", __FUNCTION__);
+      return 1;
+    }
+
+  /* Reading any data on a zero-length buffer should return EOF  */
+  if ((r = fgetc (fp)) != EOF)
+    {
+      printf ("%s: fgetc on a zero-lenght returned: %d\n",
+	      __FUNCTION__, r);
+      result = 1;
+    }
+  off_t o = ftello (fp);
+  if (o != 0)
+    {
+      printf ("%s: first ftello returned %ld, expected 0\n",
+	      __FUNCTION__, o);
+      result = 1;
+    }
+  fclose (fp);
+
+  /* Writing any data shall start at current position and shall not pass
+     current buffer size beyond the size in fmemopen call.  */
+  fp = fmemopen (buf, nbuf, "w");
+  if (fp == NULL)
+    {
+      printf ("%s: second fmemopen failed\n", __FUNCTION__);
+      return 1;
+    }
+
+  static const char str[] = "hello world";
+  /* Because of buffering, fputs call itself don't fail, however the final
+     buffer should be not changed because of lenght 0 passed in fmemopen
+     call.  */
+  fputs (str, fp);
+  fclose (fp);
+
+  if (strcmp (buf, "") != 0)
+    {
+      printf ("%s: strcmp (%s, "") failed\n", __FUNCTION__, buf);
+      return 1;
+    }
+
+  return result;
+}
+
+static int
+do_test (void)
+{
+  int ret = 0;
+
+  ret += do_test_with_buffer ();
+  ret += do_test_without_buffer ();
+  ret += do_test_length_zero ();
+
+  return ret;
+}
+
 #define TEST_FUNCTION do_test ()
 #include "../test-skeleton.c"