1 files changed, 94 insertions, 0 deletions
diff --git a/libio/bug-fseek.c b/libio/bug-fseek.c
new file mode 100644
index 0000000000..d8cd712f6a
--- /dev/null
+++ b/libio/bug-fseek.c
@@ -0,0 +1,94 @@
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+
+static char *fname;
+
+
+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 void
+do_prepare (void)
+{
+  static const char pattern[] = "12345678901234567890";
+  int fd = create_temp_file ("bug-fseek.", &fname);
+  if (fd == -1)
+    {
+      printf ("cannot create temporary file: %m\n");
+      exit (1);
+    }
+
+  if (write (fd, pattern, sizeof (pattern)) != sizeof (pattern))
+    {
+      perror ("short write");
+      abort ();
+    }
+  close (fd);
+}
+
+
+
+static int
+do_test (void)
+{
+  FILE *f;
+  int result = 0;
+  char buf[10];
+
+
+  if ((f = fopen (fname, "r")) == (FILE *) NULL)
+    {
+      perror ("fopen(\"r\")");
+    }
+
+  fread (buf, 3, 1, f);
+  errno = 0;
+  if (fseek (f, -10, SEEK_CUR) == 0)
+    {
+      printf ("fseek() for r to before start of file worked!\n");
+      result = 1;
+    }
+  else if (errno != EINVAL)
+    {
+      printf ("\
+fseek() for r to before start of file did not set errno to EINVAL.  \
+Got %d instead\n",
+	 errno);
+      result = 1;
+    }
+
+  fclose (f);
+
+
+  if ((f = fopen (fname, "r+")) == (FILE *) NULL)
+    {
+      perror ("fopen(\"r+\")");
+    }
+
+  fread (buf, 3, 1, f);
+  errno = 0;
+  if (fseek (f, -10, SEEK_CUR) == 0)
+    {
+      printf ("fseek() for r+ to before start of file worked!\n");
+      result = 1;
+    }
+  else if (errno != EINVAL)
+    {
+      printf ("\
+fseek() for r+ to before start of file did not set errno to EINVAL.  \
+Got %d instead\n",
+	 errno);
+      result = 1;
+    }
+
+  fclose (f);
+
+  return result;
+}