glibc/stdio-common/tst-ungetc.c

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/* Test for ungetc bugs. */
#include <stdio.h>
#include <unistd.h>
#define assert(x) \
if (!(x)) \
{ \
fputs ("test failed: " #x "\n", stderr); \
retval = 1; \
goto the_end; \
}
int
main (int argc, char *argv[])
{
char *name;
FILE *fp = NULL;
int retval = 0;
int c;
char buffer[64];
name = tmpnam (NULL);
fp = fopen (name, "w");
assert (fp != NULL)
fputs ("bla", fp);
fclose (fp);
fp = NULL;
fp = fopen (name, "r");
assert (fp != NULL);
assert (ungetc ('z', fp) == 'z');
assert (getc (fp) == 'z');
assert (getc (fp) == 'b');
assert (getc (fp) == 'l');
assert (ungetc ('m', fp) == 'm');
assert (getc (fp) == 'm');
assert ((c = getc (fp)) == 'a');
assert (getc (fp) == EOF);
assert (ungetc (c, fp) == c);
assert (feof (fp) == 0);
assert (getc (fp) == c);
assert (getc (fp) == EOF);
fclose (fp);
fp = NULL;
fp = fopen (name, "r");
assert (fp != NULL);
assert (getc (fp) == 'b');
assert (getc (fp) == 'l');
assert (ungetc ('b', fp) == 'b');
assert (fread (buffer, 1, 64, fp) == 2);
assert (buffer[0] == 'b');
assert (buffer[1] == 'a');
the_end:
if (fp != NULL)
fclose (fp);
unlink (name);
return retval;
}