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
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
|
#include <assert.h>
#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
static void create_file(const char *path, const char *buffer, int mode) {
int fd = open(path, O_WRONLY | O_CREAT | O_EXCL, mode);
assert(fd >= 0);
int err = write(fd, buffer, sizeof(char) * strlen(buffer));
assert(err == (sizeof(char) * strlen(buffer)));
close(fd);
}
void setup() {
create_file("file.txt", "cd", 0666);
}
void cleanup() {
unlink("file.txt");
}
void test() {
FILE *file;
int err;
char buffer[256];
file = fopen("file.txt", "r");
assert(file);
// pushing EOF always returns EOF
rewind(file);
err = ungetc(EOF, file);
assert(err == EOF);
// ungetc should return itself
err = ungetc('a', file);
assert(err == (int)'a');
// push two chars and make sure they're read back in
// the correct order (both by fgetc and fread)
rewind(file);
ungetc('b', file);
ungetc('a', file);
err = fgetc(file);
assert(err == (int)'a');
int r = fread(buffer, sizeof(char), sizeof(buffer), file);
assert(r == 3);
buffer[3] = 0;
assert(!strcmp(buffer, "bcd"));
// rewind and fseek should reset anything that's been
// pushed to the stream
ungetc('a', file);
rewind(file);
err = fgetc(file);
assert(err == (int)'c');
ungetc('a', file);
fseek(file, 0, SEEK_SET);
err = fgetc(file);
assert(err == (int)'c');
// fgetc, when nothing is left, should return EOF
fseek(file, 0, SEEK_END);
err = fgetc(file);
assert(err == EOF);
err = feof(file);
assert(err);
// ungetc should reset the EOF indicator
ungetc('e', file);
err = feof(file);
assert(!err);
fclose(file);
puts("success");
}
int main() {
atexit(cleanup);
signal(SIGABRT, cleanup);
setup();
test();
return EXIT_SUCCESS;
}
|
