1 /* vi: set sw=4 ts=4: */
3 * Mini swapon/swapoff implementation for busybox
5 * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
7 * Licensed under GPLv2, see file LICENSE in this source tree.
10 //config: bool "swapon"
12 //config: select PLATFORM_LINUX
14 //config: This option enables the 'swapon' utility.
15 //config: Once you have created some swap space using 'mkswap', you also need
16 //config: to enable your swap space with the 'swapon' utility. The 'swapoff'
17 //config: utility is used, typically at system shutdown, to disable any swap
18 //config: space. If you are not using any swap space, you can leave this
19 //config: option disabled.
21 //config:config FEATURE_SWAPON_DISCARD
22 //config: bool "Support discard option -d"
24 //config: depends on SWAPON
26 //config: Enable support for discarding swap area blocks at swapon and/or as
27 //config: the kernel frees them. This option enables both the -d option on
28 //config: 'swapon' and the 'discard' option for swap entries in /etc/fstab.
30 //config:config FEATURE_SWAPON_PRI
31 //config: bool "Support priority option -p"
33 //config: depends on SWAPON
35 //config: Enable support for setting swap device priority in swapon.
37 //config:config SWAPOFF
38 //config: bool "swapoff"
40 //config: select PLATFORM_LINUX
42 //config: This option enables the 'swapoff' utility.
44 //applet:IF_SWAPON(APPLET_ODDNAME(swapon, swap_on_off, BB_DIR_SBIN, BB_SUID_DROP, swapon))
45 //applet:IF_SWAPOFF(APPLET_ODDNAME(swapoff, swap_on_off, BB_DIR_SBIN, BB_SUID_DROP, swapoff))
47 //kbuild:lib-$(CONFIG_SWAPON) += swaponoff.o
48 //kbuild:lib-$(CONFIG_SWAPOFF) += swaponoff.o
50 //usage:#define swapon_trivial_usage
51 //usage: "[-a] [-e]" IF_FEATURE_SWAPON_DISCARD(" [-d[POL]]") IF_FEATURE_SWAPON_PRI(" [-p PRI]") " [DEVICE]"
52 //usage:#define swapon_full_usage "\n\n"
53 //usage: "Start swapping on DEVICE\n"
54 //usage: "\n -a Start swapping on all swap devices"
55 //usage: IF_FEATURE_SWAPON_DISCARD(
56 //usage: "\n -d[POL] Discard blocks at swapon (POL=once),"
57 //usage: "\n as freed (POL=pages), or both (POL omitted)"
59 //usage: "\n -e Silently skip devices that do not exist"
60 //usage: IF_FEATURE_SWAPON_PRI(
61 //usage: "\n -p PRI Set swap device priority"
64 //usage:#define swapoff_trivial_usage
65 //usage: "[-a] [DEVICE]"
66 //usage:#define swapoff_full_usage "\n\n"
67 //usage: "Stop swapping on DEVICE\n"
68 //usage: "\n -a Stop swapping on all swap devices"
71 #include "common_bufsiz.h"
74 # include <sys/swap.h>
77 #if ENABLE_FEATURE_MOUNT_LABEL
78 # include "volume_id.h"
80 # define resolve_mount_spec(fsname) ((void)0)
84 # define MNTTYPE_SWAP "swap"
87 #if ENABLE_FEATURE_SWAPON_DISCARD
88 #ifndef SWAP_FLAG_DISCARD
89 #define SWAP_FLAG_DISCARD 0x10000
91 #ifndef SWAP_FLAG_DISCARD_ONCE
92 #define SWAP_FLAG_DISCARD_ONCE 0x20000
94 #ifndef SWAP_FLAG_DISCARD_PAGES
95 #define SWAP_FLAG_DISCARD_PAGES 0x40000
97 #define SWAP_FLAG_DISCARD_MASK \
98 (SWAP_FLAG_DISCARD | SWAP_FLAG_DISCARD_ONCE | SWAP_FLAG_DISCARD_PAGES)
102 #if ENABLE_FEATURE_SWAPON_DISCARD || ENABLE_FEATURE_SWAPON_PRI
106 #define G (*(struct globals*)bb_common_bufsiz1)
107 #define g_flags (G.flags)
108 #define save_g_flags() int save_g_flags = g_flags
109 #define restore_g_flags() g_flags = save_g_flags
112 #define save_g_flags() ((void)0)
113 #define restore_g_flags() ((void)0)
115 #define INIT_G() do { setup_common_bufsiz(); } while (0)
119 # define do_swapoff (applet_name[5] == 'f')
121 # define do_swapoff 1
124 # define do_swapoff 0
127 /* Command line options */
129 OPTBIT_a, /* -a all */
130 OPTBIT_e, /* -e ifexists */
131 IF_FEATURE_SWAPON_DISCARD( OPTBIT_d ,) /* -d discard */
132 IF_FEATURE_SWAPON_PRI ( OPTBIT_p ,) /* -p priority */
133 OPT_a = 1 << OPTBIT_a,
134 OPT_e = 1 << OPTBIT_e,
135 OPT_d = IF_FEATURE_SWAPON_DISCARD((1 << OPTBIT_d)) + 0,
136 OPT_p = IF_FEATURE_SWAPON_PRI ((1 << OPTBIT_p)) + 0,
139 #define OPT_ALL (option_mask32 & OPT_a)
140 #define OPT_DISCARD (option_mask32 & OPT_d)
141 #define OPT_IFEXISTS (option_mask32 & OPT_e)
142 #define OPT_PRIO (option_mask32 & OPT_p)
144 static int swap_enable_disable(char *device)
149 resolve_mount_spec(&device);
152 err = swapoff(device);
153 /* Don't complain on OPT_ALL if not a swap device or if it doesn't exist */
154 quiet = (OPT_ALL && (errno == EINVAL || errno == ENOENT));
158 err = stat(device, &st);
160 if (ENABLE_DESKTOP && S_ISREG(st.st_mode)) {
161 if (st.st_blocks * (off_t)512 < st.st_size) {
162 bb_error_msg("%s: file has holes", device);
166 err = swapon(device, g_flags);
167 /* Don't complain on swapon -a if device is already in use */
168 quiet = (OPT_ALL && errno == EBUSY);
170 /* Don't complain if file does not exist with -e option */
171 if (err && OPT_IFEXISTS && errno == ENOENT)
176 bb_simple_perror_msg(device);
182 #if ENABLE_FEATURE_SWAPON_DISCARD
183 static void set_discard_flag(char *s)
185 /* Unset the flag first to allow fstab options to override */
186 /* options set on the command line */
187 g_flags = (g_flags & ~SWAP_FLAG_DISCARD_MASK) | SWAP_FLAG_DISCARD;
189 if (!s) /* No optional policy value on the commandline */
191 /* Skip prepended '=' */
194 /* For fstab parsing: remove other appended options */
195 *strchrnul(s, ',') = '\0';
197 if (strcmp(s, "once") == 0)
198 g_flags |= SWAP_FLAG_DISCARD_ONCE;
199 if (strcmp(s, "pages") == 0)
200 g_flags |= SWAP_FLAG_DISCARD_PAGES;
203 #define set_discard_flag(s) ((void)0)
206 #if ENABLE_FEATURE_SWAPON_PRI
207 static void set_priority_flag(char *s)
211 /* For fstab parsing: remove other appended options */
212 *strchrnul(s, ',') = '\0';
213 /* Max allowed 32767 (== SWAP_FLAG_PRIO_MASK) */
214 prio = bb_strtou(s, NULL, 10);
216 /* Unset the flag first to allow fstab options to override */
217 /* options set on the command line */
218 g_flags = (g_flags & ~SWAP_FLAG_PRIO_MASK) | SWAP_FLAG_PREFER |
219 MIN(prio, SWAP_FLAG_PRIO_MASK);
223 #define set_priority_flag(s) ((void)0)
226 static int do_em_all_in_fstab(void)
230 FILE *f = xfopen_for_read("/etc/fstab");
232 while ((m = getmntent(f)) != NULL) {
233 if (strcmp(m->mnt_type, MNTTYPE_SWAP) == 0) {
234 /* swapon -a should ignore entries with noauto,
235 * but swapoff -a should process them
237 if (do_swapoff || hasmntopt(m, MNTOPT_NOAUTO) == NULL) {
238 /* each swap space might have different flags */
239 /* save global flags for the next round */
241 if (ENABLE_FEATURE_SWAPON_DISCARD) {
242 char *p = hasmntopt(m, "discard");
244 /* move to '=' or to end of string */
249 if (ENABLE_FEATURE_SWAPON_PRI) {
250 char *p = hasmntopt(m, "pri");
252 set_priority_flag(p + 4);
255 err |= swap_enable_disable(m->mnt_fsname);
261 if (ENABLE_FEATURE_CLEAN_UP)
267 static int do_all_in_proc_swaps(void)
271 FILE *f = fopen_for_read("/proc/swaps");
272 /* Don't complain if missing */
274 while ((line = xmalloc_fgetline(f)) != NULL) {
275 if (line[0] == '/') {
276 *strchrnul(line, ' ') = '\0';
277 err |= swap_enable_disable(line);
281 if (ENABLE_FEATURE_CLEAN_UP)
288 #define OPTSTR_SWAPON "ae" \
289 IF_FEATURE_SWAPON_DISCARD("d::") \
290 IF_FEATURE_SWAPON_PRI("p:")
292 int swap_on_off_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
293 int swap_on_off_main(int argc UNUSED_PARAM, char **argv)
295 IF_FEATURE_SWAPON_PRI(char *prio;)
296 IF_FEATURE_SWAPON_DISCARD(char *discard = NULL;)
301 getopt32(argv, do_swapoff ? "ae" : OPTSTR_SWAPON
302 IF_FEATURE_SWAPON_DISCARD(, &discard)
303 IF_FEATURE_SWAPON_PRI(, &prio)
309 set_discard_flag(discard);
312 set_priority_flag(prio);
316 /* swapoff -a does also /proc/swaps */
318 ret = do_all_in_proc_swaps();
319 ret |= do_em_all_in_fstab();
321 /* if not -a we need at least one arg */
324 /* Unset -a now to allow for more messages in swap_enable_disable */
325 option_mask32 = option_mask32 & ~OPT_a;
326 /* Now process devices on the commandline if any */
328 ret |= swap_enable_disable(*argv++);