LXR busybox/util-linux/swaponoff.c

   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 (4.9 kb)"
  11//config:       default y
  12//config:       select PLATFORM_LINUX
  13//config:       help
  14//config:       Once you have created some swap space using 'mkswap', you also need
  15//config:       to enable your swap space with the 'swapon' utility. The 'swapoff'
  16//config:       utility is used, typically at system shutdown, to disable any swap
  17//config:       space. If you are not using any swap space, you can leave this
  18//config:       option disabled.
  19//config:
  20//config:config FEATURE_SWAPON_DISCARD
  21//config:       bool "Support discard option -d"
  22//config:       default y
  23//config:       depends on SWAPON
  24//config:       help
  25//config:       Enable support for discarding swap area blocks at swapon and/or as
  26//config:       the kernel frees them. This option enables both the -d option on
  27//config:       'swapon' and the 'discard' option for swap entries in /etc/fstab.
  28//config:
  29//config:config FEATURE_SWAPON_PRI
  30//config:       bool "Support priority option -p"
  31//config:       default y
  32//config:       depends on SWAPON
  33//config:       help
  34//config:       Enable support for setting swap device priority in swapon.
  35//config:
  36//config:config SWAPOFF
  37//config:       bool "swapoff (4.3 kb)"
  38//config:       default y
  39//config:       select PLATFORM_LINUX
  40//config:
  41//config:config FEATURE_SWAPONOFF_LABEL
  42//config:       bool "Support specifying devices by label or UUID"
  43//config:       default y
  44//config:       depends on SWAPON || SWAPOFF
  45//config:       select VOLUMEID
  46//config:       help
  47//config:       This allows for specifying a device by label or uuid, rather than by
  48//config:       name. This feature utilizes the same functionality as blkid/findfs.
  49
  50//                  APPLET_ODDNAME:name     main         location     suid_type     help
  51//applet:IF_SWAPON( APPLET_ODDNAME(swapon,  swap_on_off, BB_DIR_SBIN, BB_SUID_DROP, swapon))
  52//applet:IF_SWAPOFF(APPLET_ODDNAME(swapoff, swap_on_off, BB_DIR_SBIN, BB_SUID_DROP, swapoff))
  53
  54//kbuild:lib-$(CONFIG_SWAPON) += swaponoff.o
  55//kbuild:lib-$(CONFIG_SWAPOFF) += swaponoff.o
  56
  57//usage:#define swapon_trivial_usage
  58//usage:       "[-a] [-e]" IF_FEATURE_SWAPON_DISCARD(" [-d[POL]]") IF_FEATURE_SWAPON_PRI(" [-p PRI]") " [DEVICE]"
  59//usage:#define swapon_full_usage "\n\n"
  60//usage:       "Start swapping on DEVICE\n"
  61//usage:     "\n        -a      Start swapping on all swap devices"
  62//usage:        IF_FEATURE_SWAPON_DISCARD(
  63//usage:     "\n        -d[POL] Discard blocks at swapon (POL=once),"
  64//usage:     "\n                as freed (POL=pages), or both (POL omitted)"
  65//usage:        )
  66//usage:     "\n        -e      Silently skip devices that do not exist"
  67//usage:        IF_FEATURE_SWAPON_PRI(
  68//usage:     "\n        -p PRI  Set swap device priority"
  69//usage:        )
  70//usage:
  71//usage:#define swapoff_trivial_usage
  72//usage:       "[-a] [DEVICE]"
  73//usage:#define swapoff_full_usage "\n\n"
  74//usage:       "Stop swapping on DEVICE\n"
  75//usage:     "\n        -a      Stop swapping on all swap devices"
  76
  77#include "libbb.h"
  78#include "common_bufsiz.h"
  79#include <mntent.h>
  80#ifndef __BIONIC__
  81# include <sys/swap.h>
  82#endif
  83
  84#if ENABLE_FEATURE_SWAPONOFF_LABEL
  85# include "volume_id.h"
  86#else
  87# define resolve_mount_spec(fsname) ((void)0)
  88#endif
  89
  90#ifndef MNTTYPE_SWAP
  91# define MNTTYPE_SWAP "swap"
  92#endif
  93
  94#if ENABLE_FEATURE_SWAPON_DISCARD
  95#ifndef SWAP_FLAG_DISCARD
  96#define SWAP_FLAG_DISCARD 0x10000
  97#endif
  98#ifndef SWAP_FLAG_DISCARD_ONCE
  99#define SWAP_FLAG_DISCARD_ONCE 0x20000
 100#endif
 101#ifndef SWAP_FLAG_DISCARD_PAGES
 102#define SWAP_FLAG_DISCARD_PAGES 0x40000
 103#endif
 104#define SWAP_FLAG_DISCARD_MASK \
 105        (SWAP_FLAG_DISCARD | SWAP_FLAG_DISCARD_ONCE | SWAP_FLAG_DISCARD_PAGES)
 106#endif
 107
 108
 109#if ENABLE_FEATURE_SWAPON_DISCARD || ENABLE_FEATURE_SWAPON_PRI
 110struct globals {
 111        int flags;
 112} FIX_ALIASING;
 113#define G (*(struct globals*)bb_common_bufsiz1)
 114#define g_flags (G.flags)
 115#define save_g_flags()    int save_g_flags = g_flags
 116#define restore_g_flags() g_flags = save_g_flags
 117#else
 118#define g_flags 0
 119#define save_g_flags()    ((void)0)
 120#define restore_g_flags() ((void)0)
 121#endif
 122#define INIT_G() do { setup_common_bufsiz(); } while (0)
 123
 124#if ENABLE_SWAPOFF
 125# if ENABLE_SWAPON
 126#  define do_swapoff (applet_name[5] == 'f')
 127# else
 128#  define do_swapoff 1
 129# endif
 130#else
 131#  define do_swapoff 0
 132#endif
 133
 134/* Command line options */
 135enum {
 136        OPTBIT_a,                              /* -a all      */
 137        OPTBIT_e,                              /* -e ifexists */
 138        IF_FEATURE_SWAPON_DISCARD( OPTBIT_d ,) /* -d discard  */
 139        IF_FEATURE_SWAPON_PRI    ( OPTBIT_p ,) /* -p priority */
 140        OPT_a = 1 << OPTBIT_a,
 141        OPT_e = 1 << OPTBIT_e,
 142        OPT_d = IF_FEATURE_SWAPON_DISCARD((1 << OPTBIT_d)) + 0,
 143        OPT_p = IF_FEATURE_SWAPON_PRI    ((1 << OPTBIT_p)) + 0,
 144};
 145
 146#define OPT_ALL      (option_mask32 & OPT_a)
 147#define OPT_DISCARD  (option_mask32 & OPT_d)
 148#define OPT_IFEXISTS (option_mask32 & OPT_e)
 149#define OPT_PRIO     (option_mask32 & OPT_p)
 150
 151static int swap_enable_disable(char *device)
 152{
 153        int err = 0;
 154        int quiet = 0;
 155
 156        resolve_mount_spec(&device);
 157
 158        if (do_swapoff) {
 159                err = swapoff(device);
 160                /* Don't complain on OPT_ALL if not a swap device or if it doesn't exist */
 161                quiet = (OPT_ALL && (errno == EINVAL || errno == ENOENT));
 162        } else {
 163                /* swapon */
 164                struct stat st;
 165                err = stat(device, &st);
 166                if (!err) {
 167                        if (ENABLE_DESKTOP && S_ISREG(st.st_mode)) {
 168                                if (st.st_blocks * (off_t)512 < st.st_size) {
 169                                        bb_error_msg("%s: file has holes", device);
 170                                        return 1;
 171                                }
 172                        }
 173                        err = swapon(device, g_flags);
 174                        /* Don't complain on swapon -a if device is already in use */
 175                        quiet = (OPT_ALL && errno == EBUSY);
 176                }
 177                /* Don't complain if file does not exist with -e option */
 178                if (err && OPT_IFEXISTS && errno == ENOENT)
 179                        err = 0;
 180        }
 181
 182        if (err && !quiet) {
 183                bb_simple_perror_msg(device);
 184                return 1;
 185        }
 186        return 0;
 187}
 188
 189#if ENABLE_FEATURE_SWAPON_DISCARD
 190static void set_discard_flag(char *s)
 191{
 192        /* Unset the flag first to allow fstab options to override */
 193        /* options set on the command line */
 194        g_flags = (g_flags & ~SWAP_FLAG_DISCARD_MASK) | SWAP_FLAG_DISCARD;
 195
 196        if (!s) /* No optional policy value on the commandline */
 197                return;
 198        /* Skip prepended '=' */
 199        if (*s == '=')
 200                s++;
 201        /* For fstab parsing: remove other appended options */
 202        *strchrnul(s, ',') = '\0';
 203
 204        if (strcmp(s, "once") == 0)
 205                g_flags |= SWAP_FLAG_DISCARD_ONCE;
 206        if  (strcmp(s, "pages") == 0)
 207                g_flags |= SWAP_FLAG_DISCARD_PAGES;
 208}
 209#else
 210#define set_discard_flag(s) ((void)0)
 211#endif
 212
 213#if ENABLE_FEATURE_SWAPON_PRI
 214static void set_priority_flag(char *s)
 215{
 216        unsigned prio;
 217
 218        /* For fstab parsing: remove other appended options */
 219        *strchrnul(s, ',') = '\0';
 220        /* Max allowed 32767 (== SWAP_FLAG_PRIO_MASK) */
 221        prio = bb_strtou(s, NULL, 10);
 222        if (!errno) {
 223                /* Unset the flag first to allow fstab options to override */
 224                /* options set on the command line */
 225                g_flags = (g_flags & ~SWAP_FLAG_PRIO_MASK) | SWAP_FLAG_PREFER |
 226                                        MIN(prio, SWAP_FLAG_PRIO_MASK);
 227        }
 228}
 229#else
 230#define set_priority_flag(s) ((void)0)
 231#endif
 232
 233static int do_em_all_in_fstab(void)
 234{
 235        struct mntent *m;
 236        int err = 0;
 237        FILE *f = xfopen_for_read("/etc/fstab");
 238
 239        while ((m = getmntent(f)) != NULL) {
 240                if (strcmp(m->mnt_type, MNTTYPE_SWAP) == 0) {
 241                        /* swapon -a should ignore entries with noauto,
 242                         * but swapoff -a should process them
 243                         */
 244                        if (do_swapoff || hasmntopt(m, MNTOPT_NOAUTO) == NULL) {
 245                                /* each swap space might have different flags */
 246                                /* save global flags for the next round */
 247                                save_g_flags();
 248                                if (ENABLE_FEATURE_SWAPON_DISCARD) {
 249                                        char *p = hasmntopt(m, "discard");
 250                                        if (p) {
 251                                                /* move to '=' or to end of string */
 252                                                p += 7;
 253                                                set_discard_flag(p);
 254                                        }
 255                                }
 256                                if (ENABLE_FEATURE_SWAPON_PRI) {
 257                                        char *p = hasmntopt(m, "pri");
 258                                        if (p) {
 259                                                set_priority_flag(p + 4);
 260                                        }
 261                                }
 262                                err |= swap_enable_disable(m->mnt_fsname);
 263                                restore_g_flags();
 264                        }
 265                }
 266        }
 267
 268        if (ENABLE_FEATURE_CLEAN_UP)
 269                endmntent(f);
 270
 271        return err;
 272}
 273
 274static int do_all_in_proc_swaps(void)
 275{
 276        char *line;
 277        int err = 0;
 278        FILE *f = fopen_for_read("/proc/swaps");
 279        /* Don't complain if missing */
 280        if (f) {
 281                while ((line = xmalloc_fgetline(f)) != NULL) {
 282                        if (line[0] == '/') {
 283                                *strchrnul(line, ' ') = '\0';
 284                                err |= swap_enable_disable(line);
 285                        }
 286                        free(line);
 287                }
 288                if (ENABLE_FEATURE_CLEAN_UP)
 289                        fclose(f);
 290        }
 291
 292        return err;
 293}
 294
 295#define OPTSTR_SWAPON "ae" \
 296        IF_FEATURE_SWAPON_DISCARD("d::") \
 297        IF_FEATURE_SWAPON_PRI("p:")
 298
 299int swap_on_off_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 300int swap_on_off_main(int argc UNUSED_PARAM, char **argv)
 301{
 302        IF_FEATURE_SWAPON_PRI(char *prio;)
 303        IF_FEATURE_SWAPON_DISCARD(char *discard = NULL;)
 304        int ret = 0;
 305
 306        INIT_G();
 307
 308        getopt32(argv, do_swapoff ? "ae" : OPTSTR_SWAPON
 309                        IF_FEATURE_SWAPON_DISCARD(, &discard)
 310                        IF_FEATURE_SWAPON_PRI(, &prio)
 311        );
 312
 313        argv += optind;
 314
 315        if (OPT_DISCARD) {
 316                set_discard_flag(discard);
 317        }
 318        if (OPT_PRIO) {
 319                set_priority_flag(prio);
 320        }
 321
 322        if (OPT_ALL) {
 323                /* swapoff -a does also /proc/swaps */
 324                if (do_swapoff)
 325                        ret = do_all_in_proc_swaps();
 326                ret |= do_em_all_in_fstab();
 327        } else if (!*argv) {
 328                /* if not -a we need at least one arg */
 329                bb_show_usage();
 330        }
 331        /* Unset -a now to allow for more messages in swap_enable_disable */
 332        option_mask32 = option_mask32 & ~OPT_a;
 333        /* Now process devices on the commandline if any */
 334        while (*argv) {
 335                ret |= swap_enable_disable(*argv++);
 336        }
 337        return ret;
 338}
 339