1 /* mkswap.c - Format swap device.
2 *
3 * Copyright 2009 Rob Landley <rob@landley.net>
4
5 USE_MKSWAP(NEWTOY(mkswap, "<1>1", TOYFLAG_SBIN))
6
7 config MKSWAP
8 bool "mkswap"
9 default y
10 help
11 usage: mkswap DEVICE
12
13 Sets up a Linux swap area on a device or file.
14 */
15
16 #include "toys.h"
17
mkswap_main(void)18 void mkswap_main(void)
19 {
20 int fd = xopen(*toys.optargs, O_RDWR), pagesize = sysconf(_SC_PAGE_SIZE);
21 off_t len = fdlength(fd);
22 unsigned int pages = (len/pagesize)-1, *swap = (unsigned int *)toybuf;
23
24 // Write header. Note that older kernel versions checked signature
25 // on disk (not in cache) during swapon, so sync after writing.
26
27 swap[0] = 1;
28 swap[1] = pages;
29 xlseek(fd, 1024, SEEK_SET);
30 xwrite(fd, swap, 129*sizeof(unsigned int));
31 xlseek(fd, pagesize-10, SEEK_SET);
32 xwrite(fd, "SWAPSPACE2", 10);
33 fsync(fd);
34
35 if (CFG_TOYBOX_FREE) close(fd);
36
37 printf("Swapspace size: %luk\n", pages*(unsigned long)(pagesize/1024));
38 }
39