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mkfs-x6.c
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mkfs-x6.c
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/*
* file: mkfs-x6.c
* description: create empty file system for cs5600/cs7600 file sys. assignment
*/
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <fcntl.h>
#include <sys/select.h>
#include <ctype.h>
#include <time.h>
#include <assert.h>
#include "fs7600.h"
char *disk;
/* handle K/M
*/
int parseint(char *s)
{
int n = strtol(s, &s, 0);
if (tolower(*s) == 'k')
return n * 1024;
if (tolower(*s) == 'm')
return n * 1024 * 1024;
return n;
}
#define DIV_ROUND_UP(n, m) ((n) + (m) - 1) / (m)
/* usage: mkfs-x6 [-size #] file.img
* If file doesn't exist, create with size '#' (K and M suffixes allowed)
*/
int main(int argc, char **argv)
{
int i, fd = -1, size = 0;
if (!strcmp(argv[1], "-size") && argc >= 3) {
size = parseint(argv[2]);
argv += 2;
argc -= 2;
}
if (argc == 2) {
fd = open(argv[1], O_WRONLY | O_CREAT, 0777);
if (fd >= 0 && size == 0) {
struct stat sb;
fstat(fd, &sb);
size = sb.st_size;
}
}
if (fd < 0) {
printf("usage: mkfs-x6 [-size #] file.img\n");
exit(1);
}
if (size % FS_BLOCK_SIZE != 0)
printf("WARNING: disk size not a multiple of block size: %d (0x%x)\n",
size, size);
int n_blks = size / FS_BLOCK_SIZE;
int n_map_blks = DIV_ROUND_UP(n_blks, 8*FS_BLOCK_SIZE);
int n_inos = n_blks / 4;
int n_ino_map_blks = DIV_ROUND_UP(n_inos, 8*FS_BLOCK_SIZE);
int n_ino_blks = DIV_ROUND_UP(n_inos*sizeof(struct fs7600_inode),
FS_BLOCK_SIZE);
disk = malloc(n_blks * FS_BLOCK_SIZE);
memset(disk, 0, n_blks * FS_BLOCK_SIZE);
struct fs7600_super *sb = (void*)disk;
int inode_map_base = 1;
fd_set *inode_map = (void*)(disk + inode_map_base*FS_BLOCK_SIZE);
int block_map_base = inode_map_base + n_ino_map_blks;
fd_set *block_map = (void*)(disk + block_map_base*FS_BLOCK_SIZE);
int inode_base = block_map_base + n_map_blks;
struct fs7600_inode *inodes = (void*)(disk + inode_base*FS_BLOCK_SIZE);
int rootdir_base = inode_base + n_ino_blks;
struct fs7600_dirent *de = (void*)(disk + rootdir_base*FS_BLOCK_SIZE);
/* superblock */
*sb = (struct fs7600_super){.magic = FS7600_MAGIC, .inode_map_sz = n_ino_map_blks,
.inode_region_sz = n_ino_blks,
.block_map_sz = n_map_blks,
.num_blocks = n_blks, .root_inode = 1};
/* bitmaps */
FD_SET(0, inode_map);
FD_SET(1, inode_map);
for (i = 0; i <= rootdir_base; i++)
FD_SET(i, block_map);
int t = time(NULL);
inodes[1] = (struct fs7600_inode){.uid = 1001, .gid = 125, .mode = 0040777,
.ctime = t, .mtime = t, .size = 1024,
.direct = {rootdir_base, 0, 0, 0, 0, 0},
.indir_1 = 0, .indir_2 = 0};
/* remember (from /usr/include/i386-linux-gnu/bits/stat.h)
* S_IFDIR = 0040000 - directory
* S_IFREG = 0100000 - regular file
*/
/* block 0 - superblock [layout for 1MB file]
* 1 - inode map
* 2 - block map
* 3,4,5,6 - inodes
* 7 - root directory (inode 1)
*/
assert(size == n_blks* FS_BLOCK_SIZE);
write(fd, disk, size);
close(fd);
return 0;
}