1 /* vi: set sw=4 ts=4: */
2 /* mkswap.c - format swap device (Linux v1 only)
4 * Copyright 2006 Rob Landley <rob@landley.net>
6 * Licensed under GPL version 2, see file LICENSE in this tarball for details.
12 static void mkswap_selinux_setcontext(int fd, const char *path)
16 if (!is_selinux_enabled())
19 if (fstat(fd, &stbuf) < 0)
20 bb_perror_msg_and_die("fstat failed");
21 if (S_ISREG(stbuf.st_mode)) {
22 security_context_t newcon;
23 security_context_t oldcon = NULL;
26 if (fgetfilecon_raw(fd, &oldcon) < 0) {
29 if (matchpathcon(path, stbuf.st_mode, &oldcon) < 0)
32 context = context_new(oldcon);
33 if (!context || context_type_set(context, "swapfile_t"))
35 newcon = context_str(context);
38 if (strcmp(oldcon, newcon) != 0 && fsetfilecon_raw(fd, newcon) < 0)
40 if (ENABLE_FEATURE_CLEAN_UP) {
41 context_free(context);
47 bb_perror_msg_and_die("SELinux relabeling failed");
50 #define mkswap_selinux_setcontext(fd, path) ((void)0)
53 #if 0 /* from Linux 2.6.23 */
55 * Magic header for a swap area. The first part of the union is
56 * what the swap magic looks like for the old (limited to 128MB)
57 * swap area format, the second part of the union adds - in the
58 * old reserved area - some extra information. Note that the first
59 * kilobyte is reserved for boot loader or disk label stuff...
63 char reserved[PAGE_SIZE - 10];
64 char magic[10]; /* SWAP-SPACE or SWAPSPACE2 */
67 char bootbits[1024]; /* Space for disklabel etc. */
68 __u32 version; /* second kbyte, word 0 */
69 __u32 last_page; /* 1 */
70 __u32 nr_badpages; /* 2 */
71 unsigned char sws_uuid[16]; /* 3,4,5,6 */
72 unsigned char sws_volume[16]; /* 7,8,9,10 */
73 __u32 padding[117]; /* 11..127 */
74 __u32 badpages[1]; /* 128, total 129 32-bit words */
80 #define hdr ((uint32_t*)(&bb_common_bufsiz1))
82 struct BUG_bufsiz1_is_too_small {
83 char BUG_bufsiz1_is_too_small[COMMON_BUFSIZE < (NWORDS * 4) ? -1 : 1];
86 /* Stored without terminating NUL */
87 static const char SWAPSPACE2[sizeof("SWAPSPACE2")-1] ALIGN1 = "SWAPSPACE2";
89 int mkswap_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
90 int mkswap_main(int argc, char **argv)
95 // No options supported.
97 if (argc != 2) bb_show_usage();
99 // Figure out how big the device is and announce our intentions.
101 fd = xopen(argv[1], O_RDWR);
102 /* fdlength was reported to be unreliable - use seek */
103 len = xlseek(fd, 0, SEEK_END);
105 xlseek(fd, 0, SEEK_SET);
107 pagesize = getpagesize();
108 printf("Setting up swapspace version 1, size = %"OFF_FMT"u bytes\n",
110 mkswap_selinux_setcontext(fd, argv[1]);
112 // Make a header. hdr is zero-filled so far...
114 hdr[1] = (len / pagesize) - 1;
116 // Write the header. Sync to disk because some kernel versions check
117 // signature on disk (not in cache) during swapon.
119 xlseek(fd, 1024, SEEK_SET);
120 xwrite(fd, hdr, NWORDS * 4);
121 xlseek(fd, pagesize - 10, SEEK_SET);
122 xwrite(fd, SWAPSPACE2, 10);
125 if (ENABLE_FEATURE_CLEAN_UP) close(fd);