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 GPLv2, see file LICENSE in this source tree.
9 //usage:#define mkswap_trivial_usage
10 //usage: "[-L LBL] BLOCKDEV [KBYTES]"
11 //usage:#define mkswap_full_usage "\n\n"
12 //usage: "Prepare BLOCKDEV to be used as swap partition\n"
13 //usage: "\n -L LBL Label"
16 #include "common_bufsiz.h"
19 static void mkswap_selinux_setcontext(int fd, const char *path)
23 if (!is_selinux_enabled())
26 xfstat(fd, &stbuf, path);
27 if (S_ISREG(stbuf.st_mode)) {
28 security_context_t newcon;
29 security_context_t oldcon = NULL;
32 if (fgetfilecon(fd, &oldcon) < 0) {
35 if (matchpathcon(path, stbuf.st_mode, &oldcon) < 0)
38 context = context_new(oldcon);
39 if (!context || context_type_set(context, "swapfile_t"))
41 newcon = context_str(context);
44 /* fsetfilecon_raw is hidden */
45 if (strcmp(oldcon, newcon) != 0 && fsetfilecon(fd, newcon) < 0)
47 if (ENABLE_FEATURE_CLEAN_UP) {
48 context_free(context);
54 bb_perror_msg_and_die("SELinux relabeling failed");
57 # define mkswap_selinux_setcontext(fd, path) ((void)0)
60 /* from Linux 2.6.23 */
62 * Magic header for a swap area. ... Note that the first
63 * kilobyte is reserved for boot loader or disk label stuff.
65 struct swap_header_v1 {
66 /* char bootbits[1024]; Space for disklabel etc. */
67 uint32_t version; /* second kbyte, word 0 */
68 uint32_t last_page; /* 1 */
69 uint32_t nr_badpages; /* 2 */
70 char sws_uuid[16]; /* 3,4,5,6 */
71 char sws_volume[16]; /* 7,8,9,10 */
72 uint32_t padding[117]; /* 11..127 */
73 uint32_t badpages[1]; /* 128 */
74 /* total 129 32-bit words in 2nd kilobyte */
78 #define hdr ((struct swap_header_v1*)bb_common_bufsiz1)
79 #define INIT_G() do { setup_common_bufsiz(); } while (0)
82 char swap_header_v1_wrong[sizeof(*hdr) != (NWORDS * 4) ? -1 : 1];
83 char 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 UNUSED_PARAM, char **argv)
95 const char *label = "";
99 opt_complementary = "-1"; /* at least one param */
100 /* TODO: -p PAGESZ, -U UUID */
101 getopt32(argv, "L:", &label);
104 fd = xopen(argv[0], O_WRONLY);
106 /* Figure out how big the device is */
107 len = get_volume_size_in_bytes(fd, argv[1], 1024, /*extend:*/ 1);
108 pagesize = getpagesize();
111 /* Announce our intentions */
112 printf("Setting up swapspace version 1, size = %"OFF_FMT"u bytes\n", len);
113 mkswap_selinux_setcontext(fd, argv[0]);
115 /* hdr is zero-filled so far. Clear the first kbyte, or else
116 * mkswap-ing former FAT partition does NOT erase its signature.
118 * util-linux-ng 2.17.2 claims to erase it only if it does not see
119 * a partition table and is not run on whole disk. -f forces it.
121 xwrite(fd, hdr, 1024);
123 /* Fill the header. */
125 hdr->last_page = (uoff_t)len / pagesize;
127 if (ENABLE_FEATURE_MKSWAP_UUID) {
128 char uuid_string[32];
129 generate_uuid((void*)hdr->sws_uuid);
130 bin2hex(uuid_string, hdr->sws_uuid, 16);
131 /* f.e. UUID=dfd9c173-be52-4d27-99a5-c34c6c2ff55f */
132 printf("UUID=%.8s" "-%.4s-%.4s-%.4s-%.12s\n",
140 safe_strncpy(hdr->sws_volume, label, 16);
142 /* Write the header. Sync to disk because some kernel versions check
143 * signature on disk (not in cache) during swapon. */
144 xwrite(fd, hdr, NWORDS * 4);
145 xlseek(fd, pagesize - 10, SEEK_SET);
146 xwrite(fd, SWAPSPACE2, 10);
149 if (ENABLE_FEATURE_CLEAN_UP)