1/* See LICENSE file for copyright and license details. */
 2
 3#include <sys/stat.h>
 4
 5#include <fcntl.h>
 6#include <stdio.h>
 7#include <stdlib.h>
 8#include <string.h>
 9#include <unistd.h>
10
11#include "util.h"
12
13#define SWAP_UUID_LENGTH  16
14#define SWAP_LABEL_LENGTH 16
15#define SWAP_MIN_PAGES    10
16
17struct swap_hdr {
18  char          bootbits[1024];
19  unsigned int  version;
20  unsigned int  last_page;
21  unsigned int  nr_badpages;
22  unsigned char uuid[SWAP_UUID_LENGTH];
23  char          volume_name[SWAP_LABEL_LENGTH];
24  unsigned int  padding[117];
25  unsigned int  badpages[1];
26};
27
28static void
29usage(void)
30{
31  eprintf("usage: %s device\n", argv0);
32}
33
34// ?man mkswap: set up a swap area
35// ?man arguments: device
36// ?man initialize a linux swap area on a device or file
37int
38main(int argc, char *argv[])
39{
40  int              fd;
41  unsigned int     pages;
42  long             pagesize;
43  struct stat      sb;
44  char            *buf;
45  struct swap_hdr *hdr;
46
47  ARGBEGIN
48  {
49    default:
50      usage();
51  }
52  ARGEND;
53
54  if (argc < 1)
55    usage();
56
57  pagesize = sysconf(_SC_PAGESIZE);
58  if (pagesize <= 0) {
59    pagesize = sysconf(_SC_PAGE_SIZE);
60    if (pagesize <= 0)
61      eprintf("can't determine pagesize\n");
62  }
63
64  fd = open(argv[0], O_RDWR);
65  if (fd < 0)
66    eprintf("open %s:", argv[0]);
67  if (fstat(fd, &sb) < 0)
68    eprintf("stat %s:", argv[0]);
69
70  buf = ecalloc(1, pagesize);
71
72  pages = sb.st_size / pagesize;
73  if (pages < SWAP_MIN_PAGES)
74    eprintf("swap space needs to be at least %ldKiB\n", SWAP_MIN_PAGES * pagesize / 1024);
75
76  /* Fill up the swap header */
77  hdr            = (struct swap_hdr *)buf;
78  hdr->version   = 1;
79  hdr->last_page = pages - 1;
80  memcpy(buf + pagesize - 10, "SWAPSPACE2", 10);
81
82  printf("Setting up swapspace version 1, size = %luKiB\n", (pages - 1) * pagesize / 1024);
83
84  /* Write out the signature page */
85  if (write(fd, buf, pagesize) != pagesize)
86    eprintf("unable to write signature page\n");
87
88  fsync(fd);
89  close(fd);
90  free(buf);
91
92  return 0;
93}