summaryrefslogtreecommitdiff
path: root/util-linux/swaponoff.c (plain)
blob: 2a9b74dc02bb1b18f743563d66aaf294d6bff7d7
1/* vi: set sw=4 ts=4: */
2/*
3 * Mini swapon/swapoff implementation for busybox
4 *
5 * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
6 *
7 * Licensed under GPLv2, see file LICENSE in this source tree.
8 */
9//config:config SWAPON
10//config: bool "swapon"
11//config: default y
12//config: select PLATFORM_LINUX
13//config: help
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.
20//config:
21//config:config FEATURE_SWAPON_DISCARD
22//config: bool "Support discard option -d"
23//config: default y
24//config: depends on SWAPON
25//config: help
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.
29//config:
30//config:config FEATURE_SWAPON_PRI
31//config: bool "Support priority option -p"
32//config: default y
33//config: depends on SWAPON
34//config: help
35//config: Enable support for setting swap device priority in swapon.
36//config:
37//config:config SWAPOFF
38//config: bool "swapoff"
39//config: default y
40//config: select PLATFORM_LINUX
41//config: help
42//config: This option enables the 'swapoff' utility.
43
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))
46
47//kbuild:lib-$(CONFIG_SWAPON) += swaponoff.o
48//kbuild:lib-$(CONFIG_SWAPOFF) += swaponoff.o
49
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)"
58//usage: )
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"
62//usage: )
63//usage:
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"
69
70#include "libbb.h"
71#include "common_bufsiz.h"
72#include <mntent.h>
73#include <android.h>
74#ifndef __BIONIC__
75# include <sys/swap.h>
76#endif
77
78#if ENABLE_FEATURE_MOUNT_LABEL
79# include "volume_id.h"
80#else
81# define resolve_mount_spec(fsname) ((void)0)
82#endif
83
84#ifndef MNTTYPE_SWAP
85# define MNTTYPE_SWAP "swap"
86#endif
87
88#if ENABLE_FEATURE_SWAPON_DISCARD
89#ifndef SWAP_FLAG_DISCARD
90#define SWAP_FLAG_DISCARD 0x10000
91#endif
92#ifndef SWAP_FLAG_DISCARD_ONCE
93#define SWAP_FLAG_DISCARD_ONCE 0x20000
94#endif
95#ifndef SWAP_FLAG_DISCARD_PAGES
96#define SWAP_FLAG_DISCARD_PAGES 0x40000
97#endif
98#define SWAP_FLAG_DISCARD_MASK \
99 (SWAP_FLAG_DISCARD | SWAP_FLAG_DISCARD_ONCE | SWAP_FLAG_DISCARD_PAGES)
100#endif
101
102
103#if ENABLE_FEATURE_SWAPON_DISCARD || ENABLE_FEATURE_SWAPON_PRI
104struct globals {
105 int flags;
106} FIX_ALIASING;
107#define G (*(struct globals*)bb_common_bufsiz1)
108#define g_flags (G.flags)
109#define save_g_flags() int save_g_flags = g_flags
110#define restore_g_flags() g_flags = save_g_flags
111#else
112#define g_flags 0
113#define save_g_flags() ((void)0)
114#define restore_g_flags() ((void)0)
115#endif
116#define INIT_G() do { setup_common_bufsiz(); } while (0)
117
118#if ENABLE_SWAPOFF
119# if ENABLE_SWAPON
120# define do_swapoff (applet_name[5] == 'f')
121# else
122# define do_swapoff 1
123# endif
124#else
125# define do_swapoff 0
126#endif
127
128/* Command line options */
129enum {
130 OPTBIT_a, /* -a all */
131 OPTBIT_e, /* -e ifexists */
132 IF_FEATURE_SWAPON_DISCARD( OPTBIT_d ,) /* -d discard */
133 IF_FEATURE_SWAPON_PRI ( OPTBIT_p ,) /* -p priority */
134 OPT_a = 1 << OPTBIT_a,
135 OPT_e = 1 << OPTBIT_e,
136 OPT_d = IF_FEATURE_SWAPON_DISCARD((1 << OPTBIT_d)) + 0,
137 OPT_p = IF_FEATURE_SWAPON_PRI ((1 << OPTBIT_p)) + 0,
138};
139
140#define OPT_ALL (option_mask32 & OPT_a)
141#define OPT_DISCARD (option_mask32 & OPT_d)
142#define OPT_IFEXISTS (option_mask32 & OPT_e)
143#define OPT_PRIO (option_mask32 & OPT_p)
144
145static int swap_enable_disable(char *device)
146{
147 int err = 0;
148 int quiet = 0;
149
150 resolve_mount_spec(&device);
151
152 if (do_swapoff) {
153 err = swapoff(device);
154 /* Don't complain on OPT_ALL if not a swap device or if it doesn't exist */
155 quiet = (OPT_ALL && (errno == EINVAL || errno == ENOENT));
156 } else {
157 /* swapon */
158 struct stat st;
159 err = stat(device, &st);
160 if (!err) {
161 if (ENABLE_DESKTOP && S_ISREG(st.st_mode)) {
162 if (st.st_blocks * (off_t)512 < st.st_size) {
163 bb_error_msg("%s: file has holes", device);
164 return 1;
165 }
166 }
167 err = swapon(device, g_flags);
168 /* Don't complain on swapon -a if device is already in use */
169 quiet = (OPT_ALL && errno == EBUSY);
170 }
171 /* Don't complain if file does not exist with -e option */
172 if (err && OPT_IFEXISTS && errno == ENOENT)
173 err = 0;
174 }
175
176 if (err && !quiet) {
177 bb_simple_perror_msg(device);
178 return 1;
179 }
180 return 0;
181}
182
183#if ENABLE_FEATURE_SWAPON_DISCARD
184static void set_discard_flag(char *s)
185{
186 /* Unset the flag first to allow fstab options to override */
187 /* options set on the command line */
188 g_flags = (g_flags & ~SWAP_FLAG_DISCARD_MASK) | SWAP_FLAG_DISCARD;
189
190 if (!s) /* No optional policy value on the commandline */
191 return;
192 /* Skip prepended '=' */
193 if (*s == '=')
194 s++;
195 /* For fstab parsing: remove other appended options */
196 *strchrnul(s, ',') = '\0';
197
198 if (strcmp(s, "once") == 0)
199 g_flags |= SWAP_FLAG_DISCARD_ONCE;
200 if (strcmp(s, "pages") == 0)
201 g_flags |= SWAP_FLAG_DISCARD_PAGES;
202}
203#else
204#define set_discard_flag(s) ((void)0)
205#endif
206
207#if ENABLE_FEATURE_SWAPON_PRI
208static void set_priority_flag(char *s)
209{
210 unsigned prio;
211
212 /* For fstab parsing: remove other appended options */
213 *strchrnul(s, ',') = '\0';
214 /* Max allowed 32767 (== SWAP_FLAG_PRIO_MASK) */
215 prio = bb_strtou(s, NULL, 10);
216 if (!errno) {
217 /* Unset the flag first to allow fstab options to override */
218 /* options set on the command line */
219 g_flags = (g_flags & ~SWAP_FLAG_PRIO_MASK) | SWAP_FLAG_PREFER |
220 MIN(prio, SWAP_FLAG_PRIO_MASK);
221 }
222}
223#else
224#define set_priority_flag(s) ((void)0)
225#endif
226
227static int do_em_all_in_fstab(void)
228{
229 struct mntent *m;
230 int err = 0;
231 FILE *f = xfopen_for_read("/etc/fstab");
232
233 while ((m = getmntent(f)) != NULL) {
234 if (strcmp(m->mnt_type, MNTTYPE_SWAP) == 0) {
235 /* swapon -a should ignore entries with noauto,
236 * but swapoff -a should process them
237 */
238 if (do_swapoff || hasmntopt(m, MNTOPT_NOAUTO) == NULL) {
239 /* each swap space might have different flags */
240 /* save global flags for the next round */
241 save_g_flags();
242 if (ENABLE_FEATURE_SWAPON_DISCARD) {
243 char *p = hasmntopt(m, "discard");
244 if (p) {
245 /* move to '=' or to end of string */
246 p += 7;
247 set_discard_flag(p);
248 }
249 }
250 if (ENABLE_FEATURE_SWAPON_PRI) {
251 char *p = hasmntopt(m, "pri");
252 if (p) {
253 set_priority_flag(p + 4);
254 }
255 }
256 err |= swap_enable_disable(m->mnt_fsname);
257 restore_g_flags();
258 }
259 }
260 }
261
262 if (ENABLE_FEATURE_CLEAN_UP)
263 endmntent(f);
264
265 return err;
266}
267
268static int do_all_in_proc_swaps(void)
269{
270 char *line;
271 int err = 0;
272 FILE *f = fopen_for_read("/proc/swaps");
273 /* Don't complain if missing */
274 if (f) {
275 while ((line = xmalloc_fgetline(f)) != NULL) {
276 if (line[0] == '/') {
277 *strchrnul(line, ' ') = '\0';
278 err |= swap_enable_disable(line);
279 }
280 free(line);
281 }
282 if (ENABLE_FEATURE_CLEAN_UP)
283 fclose(f);
284 }
285
286 return err;
287}
288
289#define OPTSTR_SWAPON "ae" \
290 IF_FEATURE_SWAPON_DISCARD("d::") \
291 IF_FEATURE_SWAPON_PRI("p:")
292
293int swap_on_off_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
294int swap_on_off_main(int argc UNUSED_PARAM, char **argv)
295{
296 IF_FEATURE_SWAPON_PRI(char *prio;)
297 IF_FEATURE_SWAPON_DISCARD(char *discard = NULL;)
298 int ret = 0;
299
300 INIT_G();
301
302 getopt32(argv, do_swapoff ? "ae" : OPTSTR_SWAPON
303 IF_FEATURE_SWAPON_DISCARD(, &discard)
304 IF_FEATURE_SWAPON_PRI(, &prio)
305 );
306
307 argv += optind;
308
309 if (OPT_DISCARD) {
310 set_discard_flag(discard);
311 }
312 if (OPT_PRIO) {
313 set_priority_flag(prio);
314 }
315
316 if (OPT_ALL) {
317 /* swapoff -a does also /proc/swaps */
318 if (do_swapoff)
319 ret = do_all_in_proc_swaps();
320 ret |= do_em_all_in_fstab();
321 } else if (!*argv) {
322 /* if not -a we need at least one arg */
323 bb_show_usage();
324 }
325 /* Unset -a now to allow for more messages in swap_enable_disable */
326 option_mask32 = option_mask32 & ~OPT_a;
327 /* Now process devices on the commandline if any */
328 while (*argv) {
329 ret |= swap_enable_disable(*argv++);
330 }
331 return ret;
332}
333
generated by cgit at 2024-05-15 04:17:30 (GMT)