1 /* Test program for ungetc/ftell interaction bug. */
2
3 #include <stdio.h>
4
5 static void do_prepare (void);
6 #define PREPARE(argc, argv) do_prepare ()
7 static int do_test (void);
8 #define TEST_FUNCTION do_test ()
9 #include <test-skeleton.c>
10
11 static const char pattern[] = "12345";
12 static char *temp_file;
13
14 static void
do_prepare(void)15 do_prepare (void)
16 {
17 int fd = create_temp_file ("bug-ungetc.", &temp_file);
18 if (fd == -1)
19 {
20 printf ("cannot create temporary file: %m\n");
21 exit (1);
22 }
23 write (fd, pattern, sizeof (pattern));
24 close (fd);
25 }
26
27 static int
do_test(void)28 do_test (void)
29 {
30 int i;
31 FILE *f;
32 char buf[10];
33 long offset, diff;
34 int result = 0;
35
36 f = fopen (temp_file, "rw");
37
38 rewind (f);
39 for (i = 0; i < 3; i++)
40 printf ("%c\n", getc (f));
41 offset = ftell (f);
42 printf ("offset = %ld\n", offset);
43 if (ungetc ('4', f) != '4')
44 {
45 printf ("ungetc failed\n");
46 abort ();
47 }
48 printf ("offset after ungetc = %ld\n", ftell (f));
49
50 i = fread ((void *) buf, 4, (size_t) 1, f);
51 printf ("read %d (%c), offset = %ld\n", i, buf[0], ftell (f));
52 diff = ftell (f) - offset;
53 if (diff != 3)
54 {
55 printf ("ftell did not update properly. got %ld, expected 3\n", diff);
56 result = 1;
57 }
58 fclose (f);
59
60 return result;
61 }
62