/* 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_test (void) { int i; FILE *f; char buf[10]; long offset, diff; int result = 0; f = fopen (temp_file, "rw"); rewind (f); for (i = 0; i < 3; i++) printf ("%c\n", getc (f)); offset = ftell (f); printf ("offset = %ld\n", offset); if (ungetc ('4', f) != '4') { printf ("ungetc failed\n"); abort (); } printf ("offset after ungetc = %ld\n", ftell (f)); i = fread ((void *) buf, 4, (size_t) 1, f); printf ("read %d (%c), offset = %ld\n", i, buf[0], ftell (f)); diff = ftell (f) - offset; if (diff != 3) { printf ("ftell did not update properly. got %ld, expected 3\n", diff); result = 1; } fclose (f); return result; }