Fix file descriptor position after fclose

fclose should leave the file descriptor position after the last read
or written byte.

1 files changed, 132 insertions, 0 deletions

diff --git a/libio/bug-fclose1.c b/libio/bug-fclose1.c
new file mode 100644
index 0000000..f1e09f5
--- /dev/null
+++ b/libio/bug-fclose1.c
@@ -0,0 +1,132 @@
+// BZ #12724
+
+static void do_prepare (void);
+#define PREPARE(argc, argv) do_prepare ()
+static int do_test (void);
+#define TEST_FUNCTION do_test()
+#include "../test-skeleton.c"
+
+
+static int fd;
+
+
+static void
+do_prepare (void)
+{
+  fd = create_temp_file ("bug-fclose1.", NULL);
+  if (fd == -1)
+    {
+      printf ("cannot create temporary file: %m\n");
+      exit (1);
+    }
+}
+
+
+static int
+do_test (void)
+{
+  static const char pattern[] = "hello world";
+
+  /* Prepare a seekable file.  */
+  if (write (fd, pattern, sizeof pattern) != sizeof pattern)
+    {
+      printf ("cannot write pattern: %m\n");
+      return 1;
+    }
+  if (lseek (fd, 1, SEEK_SET) != 1)
+    {
+      printf ("cannot seek after write: %m\n");
+      return 1;
+    }
+
+  /* Create an output stream visiting the file; when it is closed, all
+     other file descriptors visiting the file must see the new file
+     position.  */
+  int fd2 = dup (fd);
+  if (fd2 < 0)
+    {
+      printf ("cannot duplicate descriptor for writing: %m\n");
+      return 1;
+    }
+  FILE *f = fdopen (fd2, "w");
+  if (f == NULL)
+    {
+      printf ("first fdopen failed: %m\n");
+      return 1;
+    }
+  if (fputc (pattern[1], f) != pattern[1])
+    {
+      printf ("fputc failed: %m\n");
+      return 1;
+    }
+  if (fclose (f) != 0)
+    {
+      printf ("first fclose failed: %m\n");
+      return 1;
+    }
+  errno = 0;
+  if (lseek (fd2, 0, SEEK_CUR) != -1)
+    {
+      printf ("lseek after fclose after write did not fail\n");
+      return 1;
+    }
+  if (errno != EBADF)
+    {
+      printf ("lseek after fclose after write did not fail with EBADF: %m\n");
+      return 1;
+    }
+  off_t o = lseek (fd, 0, SEEK_CUR);
+  if (o != 2)
+    {
+      printf ("\
+lseek on original descriptor after first fclose returned %ld, expected 2\n",
+	      (long int) o);
+      return 1;
+    }
+
+  /* Likewise for an input stream.  */
+  fd2 = dup (fd);
+  if (fd2 < 0)
+     {
+      printf ("cannot duplicate descriptor for reading: %m\n");
+      return 1;
+    }
+  f = fdopen (fd2, "r");
+   if (f == NULL)
+    {
+      printf ("second fdopen failed: %m\n");
+      return 1;
+    }
+   char c = fgetc (f);
+   if (c != pattern[2])
+     {
+       printf ("getc returned %c, expected %c\n", c, pattern[2]);
+       return 1;
+     }
+  if (fclose (f) != 0)
+    {
+      printf ("second fclose failed: %m\n");
+      return 1;
+    }
+  errno = 0;
+  if (lseek (fd2, 0, SEEK_CUR) != -1)
+    {
+      printf ("lseek after fclose after read did not fail\n");
+      return 1;
+    }
+  if (errno != EBADF)
+    {
+      printf ("lseek after fclose after read did not fail with EBADF: %m\n");
+      return 1;
+    }
+  o = lseek (fd, 0, SEEK_CUR);
+  if (o != 3)
+    {
+      printf ("\
+lseek on original descriptor after second fclose returned %ld, expected 3\n",
+	      (long int) o);
+      return 1;
+    }
+
+  return 0;
+}