#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>

#define TEST(r, f, x, m) ( \
((r) = (f)) == (x) || \
(printf(__FILE__ ":%d: %s failed (" m ")\n", __LINE__, #f, r, x), err++, 0) )

#define TEST_E(f) ( (errno = 0), (f) || \
(printf(__FILE__ ":%d: %s failed (errno = %d)\n", __LINE__, #f, errno), err++, 0) )

#define TEST_S(s, x, m) ( \
!strcmp((s),(x)) || \
(printf(__FILE__ ":%d: [%s] != [%s] (%s)\n", __LINE__, s, x, m), err++, 0) )

#define TEST_M(s, x, n, m) ( \
!memcmp((s),(x),(n)) || \
(printf(__FILE__ ":%d: [%s] != [%s] (%s)\n", __LINE__, s, x, m), err++, 0) )

int test_memstream(void)
{
	int err = 0;
	FILE *f;
	char *s;
	size_t l;
	int i;

	s = 0;
	TEST_E(f = open_memstream(&s, &l));
	TEST_E(putc('a', f) == 'a');
	TEST_E(putc('b', f) == 'b');
	TEST_E(putc('c', f) == 'c');
	TEST_E(!fflush(f));
	fclose(f);
	if (s) TEST_S(s, "abc", "wrong output");
	free(s);

	s = 0;
	TEST_E(f = open_memstream(&s, &l));
	TEST_E(fseek(f,1,SEEK_CUR)>=0);
	TEST_E(putc('q', f) == 'q');
	TEST_E(!fflush(f));
	if (s) TEST_M(s, "\0q", 3, "wrong output");
	TEST(i, fseek(f,-3,SEEK_CUR), -1, "invalid seek allowed");
	TEST(i, errno, EINVAL, "%d != %d");
	TEST(i, ftell(f), 2, "%d != %d");
	TEST_E(fseek(f,-2,SEEK_CUR)>=0);
	TEST_E(putc('e', f) == 'e');
	TEST_E(!fflush(f));
	if (s) TEST_S(s, "eq", "wrong output");
	fclose(f);
	free(s);

	return err;
}