ubase/mkswap.c

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C
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/* See LICENSE file for copyright and license details. */
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "util.h"
enum { SWAP_UUID_LENGTH = 16, SWAP_LABEL_LENGTH = 16 };
enum { SWAP_MIN_PAGES = 10 };
struct swap_hdr {
char bootbits[1024];
unsigned int version;
unsigned int last_page;
unsigned int nr_badpages;
unsigned char uuid[SWAP_UUID_LENGTH];
char volume_name[SWAP_LABEL_LENGTH];
unsigned int padding[117];
unsigned int badpages[1];
};
static void
usage(void)
{
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eprintf("usage: %s device\n", argv0);
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}
int
main(int argc, char *argv[])
{
int fd;
unsigned int pages;
long pagesize;
struct stat sb;
char *buf;
struct swap_hdr *hdr;
ARGBEGIN {
default:
usage();
} ARGEND;
if (argc < 1)
usage();
pagesize = sysconf(_SC_PAGESIZE);
if (pagesize <= 0) {
pagesize = sysconf(_SC_PAGE_SIZE);
if (pagesize <= 0)
enprintf(EXIT_FAILURE, "can't determine pagesize\n");
}
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fd = open(argv[0], O_RDWR);
if (fd < 0)
eprintf("open %s:", argv[0]);
if (fstat(fd, &sb) < 0)
eprintf("stat %s:", argv[0]);
buf = calloc(1, pagesize);
if (!buf)
eprintf("malloc:");
pages = sb.st_size / pagesize;
if (pages < SWAP_MIN_PAGES)
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enprintf(EXIT_FAILURE, "swap space needs to be at least %ldKiB\n",
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SWAP_MIN_PAGES * pagesize / 1024);
/* Fill up the swap header */
hdr = (struct swap_hdr *)buf;
hdr->version = 1;
hdr->last_page = pages - 1;
strncpy(buf + pagesize - 10, "SWAPSPACE2", 10);
printf("Setting up swapspace version 1, size = %luKiB\n",
(pages - 1) * pagesize / 1024);
/* Write out the signature page */
if (write(fd, buf, pagesize) != pagesize)
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enprintf(EXIT_FAILURE, "unable to write signature page\n");
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fsync(fd);
close(fd);
free(buf);
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return EXIT_SUCCESS;
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}