1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
|
#include <stdio.h>
#include <assert.h>
#ifdef USE_HOST_LIBC
#define TEST_FILE "ungetc-host-libc.tmp"
#else
#define TEST_FILE "ungetc.tmp"
#endif
void test(int buffering) {
FILE *f = fopen(TEST_FILE, "w");
for(int c = '0'; c <= '9'; c++) {
fputc(c, f);
}
fclose(f);
f = fopen(TEST_FILE, "r");
if (!buffering) {
setbuf(f, NULL);
}
assert(ungetc('x', f) == 'x');
assert(fgetc(f) == 'x');
// Test pushing back the same character
for (int c = '0'; c <= '9'; c++) {
assert(fgetc(f) == c);
assert(ungetc(c, f) == c);
assert(fgetc(f) == c);
}
assert(fgetc(f) == EOF);
assert(ungetc(EOF, f) == EOF);
// Even though the spec does not guarantee it, we should be able to
// ungetc more than one character.
assert(ungetc('x', f) == 'x');
assert(ungetc('y', f) == 'y');
assert(fgetc(f) == 'y');
assert(fgetc(f) == 'x');
// Seeking should discard the effects of ungetc.
assert(ungetc('x', f) == 'x');
rewind(f);
// Test pushing back a different character
for (int c = '0'; c <= '9'; c++) {
assert(fgetc(f) == c);
assert(ungetc(c - '0' + 'a', f) == c - '0' + 'a');
assert(fgetc(f) == c - '0' + 'a');
}
#ifndef USE_HOST_LIBC
// Too many ungetcs should fail.
int eof = 0;
for (int i = 0; i < 100; i++) {
if (ungetc('x', f) == EOF) {
eof = 1;
break;
}
}
assert(eof);
#endif
fclose(f);
// TODO: Test with other operations, like fread.
}
int main() {
fprintf(stderr, "with buffering...\n");
test(1);
fprintf(stderr, "without buffering...\n");
test(0);
}
|
