1 files changed, 94 insertions, 0 deletions
diff --git a/libio/bug-ungetc3.c b/libio/bug-ungetc3.c
new file mode 100644
index 0000000000..0c83c1161e
--- /dev/null
+++ b/libio/bug-ungetc3.c
@@ -0,0 +1,94 @@
+/* Test program for ungetc/ftell interaction bug.  */
+
+#include <stdio.h>
+
+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 const char pattern[] = "12345";
+static char *temp_file;
+
+static void
+do_prepare (void)
+{
+  int fd = create_temp_file ("bug-ungetc.", &temp_file);
+  if (fd == -1)
+    {
+      printf ("cannot create temporary file: %m\n");
+      exit (1);
+    }
+  write (fd, pattern, sizeof (pattern));
+  close (fd);
+}
+
+static int
+do_one_test (int mode)
+{
+  FILE *f;
+
+  f = fopen (temp_file, "r");
+  if (f == NULL)
+    {
+      printf ("could not open temporary file: %m\n");
+      return 1;
+    }
+
+  if (mode == 1 && ftell (f) != 0)
+    {
+      printf ("first ftell returned wrong position %ld\n", ftell (f));
+      return 1;
+    }
+
+  if (fgetc (f) != '1' || fgetc (f) != '2')
+    {
+      puts ("fgetc failed");
+      return 1;
+    }
+
+  if (mode == 2 && ftell (f) != 2)
+    {
+      printf ("second ftell returned wrong position %ld\n", ftell (f));
+      return 1;
+    }
+
+  if (ungetc ('6', f) != '6')
+    {
+      puts ("ungetc failed");
+      return 1;
+    }
+
+  if (ftell (f) != 1)
+    {
+      printf ("third ftell returned wrong position %ld\n", ftell (f));
+      return 1;
+    }
+
+  if (fgetc (f) != '6')
+    {
+      puts ("fgetc failed");
+      return 1;
+    }
+
+  if (ftell (f) != 2)
+    {
+      printf ("fourth ftell returned wrong position %ld\n", ftell (f));
+      return 1;
+    }
+
+  fclose (f);
+
+  return 0;
+}
+
+static int
+do_test (void)
+{
+  int mode;
+  for (mode = 0; mode <= 2; mode++)
+    if (do_one_test (mode))
+      return 1;
+  return 0;
+}