1 files changed, 134 insertions, 0 deletions
diff --git a/gnulib-tests/test-fpurge.c b/gnulib-tests/test-fpurge.c
new file mode 100644
index 0000000..381b8a1
--- /dev/null
+++ b/gnulib-tests/test-fpurge.c
@@ -0,0 +1,134 @@
+/* Test of fpurge() function.
+   Copyright (C) 2007-2022 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+/* Written by Bruno Haible <bruno@clisp.org>, 2007.  */
+
+#include <config.h>
+
+/* None of the files accessed by this test are large, so disable the
+   fseek link warning if we are not using the gnulib fseek module.  */
+#define _GL_NO_LARGE_FILES
+#include <stdio.h>
+
+#include <string.h>
+
+#include "macros.h"
+
+#define TESTFILE "t-fpurge.tmp"
+
+int
+main (void)
+{
+  int check_filepos;
+
+  for (check_filepos = 0; check_filepos <= 1; check_filepos++)
+    {
+      FILE *fp;
+
+      /* Create a file with some contents.  */
+      fp = fopen (TESTFILE, "w");
+      if (fp == NULL)
+        goto skip;
+      if (fwrite ("foobarsh", 1, 8, fp) < 8)
+        goto skip;
+      if (fclose (fp))
+        goto skip;
+
+      /* The file's contents is now "foobarsh".  */
+
+      /* Open it in read-write mode.  */
+      fp = fopen (TESTFILE, "r+");
+      if (fp == NULL)
+        goto skip;
+      if (fseek (fp, 3, SEEK_CUR))
+        goto skip;
+      if (fwrite ("g", 1, 1, fp) < 1)
+        goto skip;
+      if (fflush (fp))
+        goto skip;
+      if (fwrite ("bz", 1, 2, fp) < 2)
+        goto skip;
+      /* Discard pending write.  */
+      ASSERT (fpurge (fp) == 0);
+      /* Verify that when discarding pending output, the file position is set
+         back to where it was before the write calls.  */
+      if (check_filepos)
+        ASSERT (ftell (fp) == 4);
+      ASSERT (fclose (fp) == 0);
+
+      /* Open it in read-only mode.  */
+      fp = fopen (TESTFILE, "r");
+      if (fp == NULL)
+        goto skip;
+      /* Verify that the pending writes before the fpurge were really
+         discarded.  */
+      {
+        char buf[8];
+        if (fread (buf, 1, 7, fp) < 7)
+          goto skip;
+        ASSERT (memcmp (buf, "foogars", 7) == 0);
+      }
+      /* Discard the buffered 'h'.  */
+      if (check_filepos)
+        ASSERT (ftell (fp) == 7);
+      ASSERT (fpurge (fp) == 0);
+      /* Verify that when discarding pending input, the file position is
+         advanced to match the end of the previously read input.  */
+      if (check_filepos)
+        ASSERT (ftell (fp) == 8);
+      ASSERT (getc (fp) == EOF);
+      ASSERT (fclose (fp) == 0);
+
+      /* The file's contents is now "foogarsh".  */
+
+      /* Ensure that purging a read does not corrupt subsequent writes.  */
+      fp = fopen (TESTFILE, "r+");
+      if (fp == NULL)
+        goto skip;
+      if (fseek (fp, -1, SEEK_END))
+        goto skip;
+      ASSERT (getc (fp) == 'h');
+      ASSERT (getc (fp) == EOF);
+      if (check_filepos)
+        ASSERT (ftell (fp) == 8);
+      ASSERT (fpurge (fp) == 0);
+      if (check_filepos)
+        ASSERT (ftell (fp) == 8);
+      ASSERT (putc ('!', fp) == '!');
+      if (check_filepos)
+        ASSERT (ftell (fp) == 9);
+      ASSERT (fclose (fp) == 0);
+      fp = fopen (TESTFILE, "r");
+      if (fp == NULL)
+        goto skip;
+      {
+        char buf[10];
+        ASSERT (fread (buf, 1, 10, fp) == 9);
+        ASSERT (memcmp (buf, "foogarsh!", 9) == 0);
+      }
+      ASSERT (fclose (fp) == 0);
+
+      /* The file's contents is now "foogarsh!".  */
+    }
+
+  remove (TESTFILE);
+  return 0;
+
+ skip:
+  fprintf (stderr, "Skipping test: prerequisite file operations failed.\n");
+  remove (TESTFILE);
+  return 77;
+}