blob: 954a1948dc4b3eb46ef812ef703c2bce99d03fdb
1 | /* vi: set sw=4 ts=4: */ |
2 | /* mkswap.c - format swap device (Linux v1 only) |
3 | * |
4 | * Copyright 2006 Rob Landley <rob@landley.net> |
5 | * |
6 | * Licensed under GPLv2, see file LICENSE in this source tree. |
7 | */ |
8 | //config:config MKSWAP |
9 | //config: bool "mkswap" |
10 | //config: default y |
11 | //config: help |
12 | //config: The mkswap utility is used to configure a file or disk partition as |
13 | //config: Linux swap space. This allows Linux to use the entire file or |
14 | //config: partition as if it were additional RAM, which can greatly increase |
15 | //config: the capability of low-memory machines. This additional memory is |
16 | //config: much slower than real RAM, but can be very helpful at preventing your |
17 | //config: applications being killed by the Linux out of memory (OOM) killer. |
18 | //config: Once you have created swap space using 'mkswap' you need to enable |
19 | //config: the swap space using the 'swapon' utility. |
20 | //config: |
21 | //config:config FEATURE_MKSWAP_UUID |
22 | //config: bool "UUID support" |
23 | //config: default y |
24 | //config: depends on MKSWAP |
25 | //config: help |
26 | //config: Generate swap spaces with universally unique identifiers. |
27 | |
28 | //applet:IF_MKSWAP(APPLET(mkswap, BB_DIR_SBIN, BB_SUID_DROP)) |
29 | |
30 | //kbuild:lib-$(CONFIG_MKSWAP) += mkswap.o |
31 | |
32 | //usage:#define mkswap_trivial_usage |
33 | //usage: "[-L LBL] BLOCKDEV [KBYTES]" |
34 | //usage:#define mkswap_full_usage "\n\n" |
35 | //usage: "Prepare BLOCKDEV to be used as swap partition\n" |
36 | //usage: "\n -L LBL Label" |
37 | |
38 | #include "libbb.h" |
39 | #include "common_bufsiz.h" |
40 | |
41 | #if ENABLE_SELINUX |
42 | static void mkswap_selinux_setcontext(int fd, const char *path) |
43 | { |
44 | struct stat stbuf; |
45 | |
46 | if (!is_selinux_enabled()) |
47 | return; |
48 | |
49 | xfstat(fd, &stbuf, path); |
50 | if (S_ISREG(stbuf.st_mode)) { |
51 | security_context_t newcon; |
52 | security_context_t oldcon = NULL; |
53 | context_t context; |
54 | |
55 | if (fgetfilecon(fd, &oldcon) < 0) { |
56 | if (errno != ENODATA) |
57 | goto error; |
58 | if (matchpathcon(path, stbuf.st_mode, &oldcon) < 0) |
59 | goto error; |
60 | } |
61 | context = context_new(oldcon); |
62 | if (!context || context_type_set(context, "swapfile_t")) |
63 | goto error; |
64 | newcon = context_str(context); |
65 | if (!newcon) |
66 | goto error; |
67 | /* fsetfilecon_raw is hidden */ |
68 | if (strcmp(oldcon, newcon) != 0 && fsetfilecon(fd, newcon) < 0) |
69 | goto error; |
70 | if (ENABLE_FEATURE_CLEAN_UP) { |
71 | context_free(context); |
72 | freecon(oldcon); |
73 | } |
74 | } |
75 | return; |
76 | error: |
77 | bb_perror_msg_and_die("SELinux relabeling failed"); |
78 | } |
79 | #else |
80 | # define mkswap_selinux_setcontext(fd, path) ((void)0) |
81 | #endif |
82 | |
83 | /* from Linux 2.6.23 */ |
84 | /* |
85 | * Magic header for a swap area. ... Note that the first |
86 | * kilobyte is reserved for boot loader or disk label stuff. |
87 | */ |
88 | struct swap_header_v1 { |
89 | /* char bootbits[1024]; Space for disklabel etc. */ |
90 | uint32_t version; /* second kbyte, word 0 */ |
91 | uint32_t last_page; /* 1 */ |
92 | uint32_t nr_badpages; /* 2 */ |
93 | char sws_uuid[16]; /* 3,4,5,6 */ |
94 | char sws_volume[16]; /* 7,8,9,10 */ |
95 | uint32_t padding[117]; /* 11..127 */ |
96 | uint32_t badpages[1]; /* 128 */ |
97 | /* total 129 32-bit words in 2nd kilobyte */ |
98 | } FIX_ALIASING; |
99 | |
100 | #define NWORDS 129 |
101 | #define hdr ((struct swap_header_v1*)bb_common_bufsiz1) |
102 | #define INIT_G() do { setup_common_bufsiz(); } while (0) |
103 | |
104 | struct BUG_sizes { |
105 | char swap_header_v1_wrong[sizeof(*hdr) != (NWORDS * 4) ? -1 : 1]; |
106 | char bufsiz1_is_too_small[COMMON_BUFSIZE < (NWORDS * 4) ? -1 : 1]; |
107 | }; |
108 | |
109 | /* Stored without terminating NUL */ |
110 | static const char SWAPSPACE2[sizeof("SWAPSPACE2")-1] ALIGN1 = "SWAPSPACE2"; |
111 | |
112 | int mkswap_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
113 | int mkswap_main(int argc UNUSED_PARAM, char **argv) |
114 | { |
115 | int fd; |
116 | unsigned pagesize; |
117 | off_t len; |
118 | const char *label = ""; |
119 | |
120 | INIT_G(); |
121 | |
122 | opt_complementary = "-1"; /* at least one param */ |
123 | /* TODO: -p PAGESZ, -U UUID */ |
124 | getopt32(argv, "L:", &label); |
125 | argv += optind; |
126 | |
127 | fd = xopen(argv[0], O_WRONLY); |
128 | |
129 | /* Figure out how big the device is */ |
130 | len = get_volume_size_in_bytes(fd, argv[1], 1024, /*extend:*/ 1); |
131 | pagesize = getpagesize(); |
132 | len -= pagesize; |
133 | |
134 | /* Announce our intentions */ |
135 | printf("Setting up swapspace version 1, size = %"OFF_FMT"u bytes\n", len); |
136 | mkswap_selinux_setcontext(fd, argv[0]); |
137 | |
138 | /* hdr is zero-filled so far. Clear the first kbyte, or else |
139 | * mkswap-ing former FAT partition does NOT erase its signature. |
140 | * |
141 | * util-linux-ng 2.17.2 claims to erase it only if it does not see |
142 | * a partition table and is not run on whole disk. -f forces it. |
143 | */ |
144 | xwrite(fd, hdr, 1024); |
145 | |
146 | /* Fill the header. */ |
147 | hdr->version = 1; |
148 | hdr->last_page = (uoff_t)len / pagesize; |
149 | |
150 | if (ENABLE_FEATURE_MKSWAP_UUID) { |
151 | char uuid_string[32]; |
152 | generate_uuid((void*)hdr->sws_uuid); |
153 | bin2hex(uuid_string, hdr->sws_uuid, 16); |
154 | /* f.e. UUID=dfd9c173-be52-4d27-99a5-c34c6c2ff55f */ |
155 | printf("UUID=%.8s" "-%.4s-%.4s-%.4s-%.12s\n", |
156 | uuid_string, |
157 | uuid_string+8, |
158 | uuid_string+8+4, |
159 | uuid_string+8+4+4, |
160 | uuid_string+8+4+4+4 |
161 | ); |
162 | } |
163 | safe_strncpy(hdr->sws_volume, label, 16); |
164 | |
165 | /* Write the header. Sync to disk because some kernel versions check |
166 | * signature on disk (not in cache) during swapon. */ |
167 | xwrite(fd, hdr, NWORDS * 4); |
168 | xlseek(fd, pagesize - 10, SEEK_SET); |
169 | xwrite(fd, SWAPSPACE2, 10); |
170 | fsync(fd); |
171 | |
172 | if (ENABLE_FEATURE_CLEAN_UP) |
173 | close(fd); |
174 | |
175 | return 0; |
176 | } |
177 |