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
|
#include "csapp.h"
#define BLKSZ 4096 /* block size */
#define NBLKS 8192 /* number of blocks written to a file */
#define WRAP 64
int main(void) {
int fd = Open("holes.bin", O_CREAT | O_TRUNC | O_WRONLY, 0644);
int usedblks = 0;
for (int i = 0; i < NBLKS; i++) {
if (i % WRAP == 0)
dprintf(STDERR_FILENO, "%04d ", i);
if (random() % 64) {
Lseek(fd, BLKSZ, SEEK_CUR);
Write(STDERR_FILENO, ".", 1);
} else {
char blk[BLKSZ];
for (int j = 0; j < BLKSZ; j++)
blk[j] = random();
Write(fd, blk, BLKSZ);
Write(STDERR_FILENO, "O", 1);
usedblks++;
}
if (i % WRAP == WRAP - 1)
Write(STDERR_FILENO, "\n", 1);
}
Close(fd);
dprintf(STDERR_FILENO, "Non-zero blocks: %d\n", usedblks);
return 0;
}
|
