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	mkswap.c - ubase - suckless linux base utils
	git clone git://git.suckless.org/ubase
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	---
	mkswap.c (1739B)
	---
	1 /* See LICENSE file for copyright and license details. */
	2 #include <sys/stat.h>
	3
	4 #include <fcntl.h>
	5 #include <stdio.h>
	6 #include <stdlib.h>
	7 #include <string.h>
	8 #include <unistd.h>
	9
	10 #include "util.h"
	11
	12 #define SWAP_UUID_LENGTH 16
	13 #define SWAP_LABEL_LENGTH 16
	14 #define SWAP_MIN_PAGES 10
	15
	16 struct swap_hdr {
	17 char bootbits[1024];
	18 unsigned int version;
	19 unsigned int last_page;
	20 unsigned int nr_badpages;
	21 unsigned char uuid[SWAP_UUID_LENGTH];
	22 char volume_name[SWAP_LABEL_LENGTH];
	23 unsigned int padding[117];
	24 unsigned int badpages[1];
	25 };
	26
	27 static void
	28 usage(void)
	29 {
	30 eprintf("usage: %s device\n", argv0);
	31 }
	32
	33 int
	34 main(int argc, char *argv[])
	35 {
	36 int fd;
	37 unsigned int pages;
	38 long pagesize;
	39 struct stat sb;
	40 char *buf;
	41 struct swap_hdr *hdr;
	42
	43 ARGBEGIN {
	44 default:
	45 usage();
	46 } ARGEND;
	47
	48 if (argc < 1)
	49 usage();
	50
	51 pagesize = sysconf(_SC_PAGESIZE);
	52 if (pagesize <= 0) {
	53 pagesize = sysconf(_SC_PAGE_SIZE);
	54 if (pagesize <= 0)
	55 eprintf("can't determine pagesize\n");
	56 }
	57
	58 fd = open(argv[0], O_RDWR);
	59 if (fd < 0)
	60 eprintf("open %s:", argv[0]);
	61 if (fstat(fd, &sb) < 0)
	62 eprintf("stat %s:", argv[0]);
	63
	64 buf = ecalloc(1, pagesize);
	65
	66 pages = sb.st_size / pagesize;
	67 if (pages < SWAP_MIN_PAGES)
	68 eprintf("swap space needs to be at least %ldKiB\n",
	69 SWAP_MIN_PAGES * pagesize / 1024);
	70
	71 /* Fill up the swap header */
	72 hdr = (struct swap_hdr *)buf;
	73 hdr->version = 1;
	74 hdr->last_page = pages - 1;
	75 strncpy(buf + pagesize - 10, "SWAPSPACE2", 10);
	76
	77 printf("Setting up swapspace version 1, size = %luKiB\n",
	78 (pages - 1) * pagesize / 1024);
	79
	80 /* Write out the signature page */
	81 if (write(fd, buf, pagesize) != pagesize)
	82 eprintf("unable to write signature page\n");
	83
	84 fsync(fd);
	85 close(fd);
	86 free(buf);
	87
	88 return 0;
	89 }