X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=tests%2Ftest-fwriting.c;h=a16213046373790b0cdf636d419641f14154cba2;hb=b2b1b4208042f959acc8cbc9ec1da0cac0445492;hp=24279f313ae4c493a0a83d0ce95d9a1bc4f0eac5;hpb=a8f956440539cf954fb92e2396cc58e2a111455f;p=gnulib.git

diff --git a/tests/test-fwriting.c b/tests/test-fwriting.c
index 24279f313..a16213046 100644
--- a/tests/test-fwriting.c
+++ b/tests/test-fwriting.c
@@ -21,9 +21,19 @@
 
 #include "fwriting.h"
 
+#include <stdio.h>
 #include <stdlib.h>
 
-#define ASSERT(expr) if (!(expr)) abort ();
+#define ASSERT(expr) \
+  do									     \
+    {									     \
+      if (!(expr))							     \
+        {								     \
+          fprintf (stderr, "%s:%d: assertion failed\n", __FILE__, __LINE__); \
+          abort ();							     \
+        }								     \
+    }									     \
+  while (0)
 
 #define TESTFILE "t-fwriting.tmp"
 
@@ -57,6 +67,11 @@ main ()
   if (fgetc (fp) != 'b')
     goto skip;
   ASSERT (!fwriting (fp));
+  fflush (fp);
+  ASSERT (!fwriting (fp));
+  if (fgetc (fp) != 'a')
+    goto skip;
+  ASSERT (!fwriting (fp));
   if (fseek (fp, 0, SEEK_END))
     goto skip;
   ASSERT (!fwriting (fp));
@@ -68,6 +83,7 @@ main ()
      fwriting is only deterministic after input or output, but this
      test case should be portable even on open, after reposition, and
      after fflush.  */
+  /* First a scenario with only fgetc, fseek, fputc.  */
   fp = fopen (TESTFILE, "r+");
   if (fp == NULL)
     goto skip;
@@ -81,14 +97,59 @@ main ()
   if (fgetc (fp) != 'b')
     goto skip;
   ASSERT (!fwriting (fp));
+  /* This fseek call is necessary when switching from reading to writing.
+     See the description of fopen(), ISO C 99 7.19.5.3.(6).  */
   if (fseek (fp, 0, SEEK_CUR) != 0)
     goto skip;
+  ASSERT (!fwriting (fp));
+  if (fputc ('x', fp) != 'x')
+    goto skip;
+  ASSERT (fwriting (fp));
+  if (fseek (fp, 0, SEEK_END))
+    goto skip;
+  /* freading (fp) is undefined here, because on some implementations (e.g.
+     glibc) fseek causes a buffer to be read.
+     fwriting (fp) is undefined as well.  */
+  if (fclose (fp))
+    goto skip;
+
+  /* Open it in read-write mode.  POSIX requires a reposition (fseek,
+     fsetpos, rewind) or fflush when transitioning from write to read,
+     fwriting is only deterministic after input or output, but this
+     test case should be portable even on open, after reposition, and
+     after fflush.  */
+  /* Here a scenario that includes fflush.  */
+  fp = fopen (TESTFILE, "r+");
+  if (fp == NULL)
+    goto skip;
+  ASSERT (!fwriting (fp));
+  if (fgetc (fp) != 'f')
+    goto skip;
+  ASSERT (!fwriting (fp));
+  if (fseek (fp, 2, SEEK_CUR))
+    goto skip;
+  ASSERT (!fwriting (fp));
+  if (fgetc (fp) != 'b')
+    goto skip;
+  ASSERT (!fwriting (fp));
+  fflush (fp);
+  ASSERT (!fwriting (fp));
+  if (fgetc (fp) != 'x')
+    goto skip;
+  ASSERT (!fwriting (fp));
+  /* This fseek call is necessary when switching from reading to writing.
+     See the description of fopen(), ISO C 99 7.19.5.3.(6).  */
+  if (fseek (fp, 0, SEEK_CUR) != 0)
+    goto skip;
+  ASSERT (!fwriting (fp));
   if (fputc ('z', fp) != 'z')
     goto skip;
   ASSERT (fwriting (fp));
   if (fseek (fp, 0, SEEK_END))
     goto skip;
-  /* fwriting (fp) is undefined here, but freading is false.  */
+  /* freading (fp) is undefined here, because on some implementations (e.g.
+     glibc) fseek causes a buffer to be read.
+     fwriting (fp) is undefined as well.  */
   if (fclose (fp))
     goto skip;