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glibc/libio/bug-ungetc.c
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/* 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; | |
} |