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
  10 //usage:#define swapon_trivial_usage
  11 //usage:       "[-a] [-e]" IF_FEATURE_SWAPON_DISCARD(" [-d[POL]]") IF_FEATURE_SWAPON_PRI(" [-p PRI]") " [DEVICE]"
  12 //usage:#define swapon_full_usage "\n\n"
  13 //usage:       "Start swapping on DEVICE\n"
  14 //usage:     "\n        -a      Start swapping on all swap devices"
  15 //usage:        IF_FEATURE_SWAPON_DISCARD(
  16 //usage:     "\n        -d[POL] Discard blocks at swapon (POL=once),"
  17 //usage:     "\n                as freed (POL=pages), or both (POL omitted)"
  18 //usage:        )
  19 //usage:     "\n        -e      Silently skip devices that do not exist"
  20 //usage:        IF_FEATURE_SWAPON_PRI(
  21 //usage:     "\n        -p PRI  Set swap device priority"
  22 //usage:        )
  23 //usage:
  24 //usage:#define swapoff_trivial_usage
  25 //usage:       "[-a] [DEVICE]"
  26 //usage:#define swapoff_full_usage "\n\n"
  27 //usage:       "Stop swapping on DEVICE\n"
  28 //usage:     "\n        -a      Stop swapping on all swap devices"
  29
  30 #include "libbb.h"
  31 #include "common_bufsiz.h"
  32 #include <mntent.h>
  33 #ifndef __BIONIC__
  34 # include <sys/swap.h>
  35 #endif
  36
  37 #if ENABLE_FEATURE_MOUNT_LABEL
  38 # include "volume_id.h"
  39 #else
  40 # define resolve_mount_spec(fsname) ((void)0)
  41 #endif
  42
  43 #ifndef MNTTYPE_SWAP
  44 # define MNTTYPE_SWAP "swap"
  45 #endif
  46
  47 #if ENABLE_FEATURE_SWAPON_DISCARD
  48 #ifndef SWAP_FLAG_DISCARD
  49 #define SWAP_FLAG_DISCARD 0x10000
  50 #endif
  51 #ifndef SWAP_FLAG_DISCARD_ONCE
  52 #define SWAP_FLAG_DISCARD_ONCE 0x20000
  53 #endif
  54 #ifndef SWAP_FLAG_DISCARD_PAGES
  55 #define SWAP_FLAG_DISCARD_PAGES 0x40000
  56 #endif
  57 #define SWAP_FLAG_DISCARD_MASK \
  58         (SWAP_FLAG_DISCARD | SWAP_FLAG_DISCARD_ONCE | SWAP_FLAG_DISCARD_PAGES)
  59 #endif
  60
  61
  62 #if ENABLE_FEATURE_SWAPON_DISCARD || ENABLE_FEATURE_SWAPON_PRI
  63 struct globals {
  64         int flags;
  65 } FIX_ALIASING;
  66 #define G (*(struct globals*)bb_common_bufsiz1)
  67 #define g_flags (G.flags)
  68 #define save_g_flags()    int save_g_flags = g_flags
  69 #define restore_g_flags() g_flags = save_g_flags
  70 #else
  71 #define g_flags 0
  72 #define save_g_flags()    ((void)0)
  73 #define restore_g_flags() ((void)0)
  74 #endif
  75 #define INIT_G() do { setup_common_bufsiz(); } while (0)
  76
  77 #define do_swapoff   (applet_name[5] == 'f')
  78
  79 /* Command line options */
  80 enum {
  81         OPTBIT_a,                              /* -a all      */
  82         OPTBIT_e,                              /* -e ifexists */
  83         IF_FEATURE_SWAPON_DISCARD( OPTBIT_d ,) /* -d discard  */
  84         IF_FEATURE_SWAPON_PRI    ( OPTBIT_p ,) /* -p priority */
  85         OPT_a = 1 << OPTBIT_a,
  86         OPT_e = 1 << OPTBIT_e,
  87         OPT_d = IF_FEATURE_SWAPON_DISCARD((1 << OPTBIT_d)) + 0,
  88         OPT_p = IF_FEATURE_SWAPON_PRI    ((1 << OPTBIT_p)) + 0,
  89 };
  90
  91 #define OPT_ALL      (option_mask32 & OPT_a)
  92 #define OPT_DISCARD  (option_mask32 & OPT_d)
  93 #define OPT_IFEXISTS (option_mask32 & OPT_e)
  94 #define OPT_PRIO     (option_mask32 & OPT_p)
  95
  96 static int swap_enable_disable(char *device)
  97 {
  98         int err = 0;
  99         int quiet = 0;
 100
 101         resolve_mount_spec(&device);
 102
 103         if (do_swapoff) {
 104                 err = swapoff(device);
 105                 /* Don't complain on OPT_ALL if not a swap device or if it doesn't exist */
 106                 quiet = (OPT_ALL && (errno == EINVAL || errno == ENOENT));
 107         } else {
 108                 /* swapon */
 109                 struct stat st;
 110                 err = stat(device, &st);
 111                 if (!err) {
 112                         if (ENABLE_DESKTOP && S_ISREG(st.st_mode)) {
 113                                 if (st.st_blocks * (off_t)512 < st.st_size) {
 114                                         bb_error_msg("%s: file has holes", device);
 115                                         return 1;
 116                                 }
 117                         }
 118                         err = swapon(device, g_flags);
 119                         /* Don't complain on swapon -a if device is already in use */
 120                         quiet = (OPT_ALL && errno == EBUSY);
 121                 }
 122                 /* Don't complain if file does not exist with -e option */
 123                 if (err && OPT_IFEXISTS && errno == ENOENT)
 124                         err = 0;
 125         }
 126
 127         if (err && !quiet) {
 128                 bb_simple_perror_msg(device);
 129                 return 1;
 130         }
 131         return 0;
 132 }
 133
 134 #if ENABLE_FEATURE_SWAPON_DISCARD
 135 static void set_discard_flag(char *s)
 136 {
 137         /* Unset the flag first to allow fstab options to override */
 138         /* options set on the command line */
 139         g_flags = (g_flags & ~SWAP_FLAG_DISCARD_MASK) | SWAP_FLAG_DISCARD;
 140
 141         if (!s) /* No optional policy value on the commandline */
 142                 return;
 143         /* Skip prepended '=' */
 144         if (*s == '=')
 145                 s++;
 146         /* For fstab parsing: remove other appended options */
 147         *strchrnul(s, ',') = '\0';
 148
 149         if (strcmp(s, "once") == 0)
 150                 g_flags |= SWAP_FLAG_DISCARD_ONCE;
 151         if  (strcmp(s, "pages") == 0)
 152                 g_flags |= SWAP_FLAG_DISCARD_PAGES;
 153 }
 154 #else
 155 #define set_discard_flag(s) ((void)0)
 156 #endif
 157
 158 #if ENABLE_FEATURE_SWAPON_PRI
 159 static void set_priority_flag(char *s)
 160 {
 161         unsigned prio;
 162
 163         /* For fstab parsing: remove other appended options */
 164         *strchrnul(s, ',') = '\0';
 165         /* Max allowed 32767 (== SWAP_FLAG_PRIO_MASK) */
 166         prio = bb_strtou(s, NULL, 10);
 167         if (!errno) {
 168                 /* Unset the flag first to allow fstab options to override */
 169                 /* options set on the command line */
 170                 g_flags = (g_flags & ~SWAP_FLAG_PRIO_MASK) | SWAP_FLAG_PREFER |
 171                                         MIN(prio, SWAP_FLAG_PRIO_MASK);
 172         }
 173 }
 174 #else
 175 #define set_priority_flag(s) ((void)0)
 176 #endif
 177
 178 static int do_em_all_in_fstab(void)
 179 {
 180         struct mntent *m;
 181         int err = 0;
 182         FILE *f = xfopen_for_read("/etc/fstab");
 183
 184         while ((m = getmntent(f)) != NULL) {
 185                 if (strcmp(m->mnt_type, MNTTYPE_SWAP) == 0) {
 186                         /* swapon -a should ignore entries with noauto,
 187                          * but swapoff -a should process them
 188                          */
 189                         if (do_swapoff || hasmntopt(m, MNTOPT_NOAUTO) == NULL) {
 190                                 /* each swap space might have different flags */
 191                                 /* save global flags for the next round */
 192                                 save_g_flags();
 193                                 if (ENABLE_FEATURE_SWAPON_DISCARD) {
 194                                         char *p = hasmntopt(m, "discard");
 195                                         if (p) {
 196                                                 /* move to '=' or to end of string */
 197                                                 p += 7;
 198                                                 set_discard_flag(p);
 199                                         }
 200                                 }
 201                                 if (ENABLE_FEATURE_SWAPON_PRI) {
 202                                         char *p = hasmntopt(m, "pri");
 203                                         if (p) {
 204                                                 set_priority_flag(p + 4);
 205                                         }
 206                                 }
 207                                 err |= swap_enable_disable(m->mnt_fsname);
 208                                 restore_g_flags();
 209                         }
 210                 }
 211         }
 212
 213         if (ENABLE_FEATURE_CLEAN_UP)
 214                 endmntent(f);
 215
 216         return err;
 217 }
 218
 219 static int do_all_in_proc_swaps(void)
 220 {
 221         char *line;
 222         int err = 0;
 223         FILE *f = fopen_for_read("/proc/swaps");
 224         /* Don't complain if missing */
 225         if (f) {
 226                 while ((line = xmalloc_fgetline(f)) != NULL) {
 227                         if (line[0] == '/') {
 228                                 *strchrnul(line, ' ') = '\0';
 229                                 err |= swap_enable_disable(line);
 230                         }
 231                         free(line);
 232                 }
 233                 if (ENABLE_FEATURE_CLEAN_UP)
 234                         fclose(f);
 235         }
 236
 237         return err;
 238 }
 239
 240 #define OPTSTR_SWAPON "ae" \
 241         IF_FEATURE_SWAPON_DISCARD("d::") \
 242         IF_FEATURE_SWAPON_PRI("p:")
 243
 244 int swap_on_off_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 245 int swap_on_off_main(int argc UNUSED_PARAM, char **argv)
 246 {
 247         IF_FEATURE_SWAPON_PRI(char *prio;)
 248         IF_FEATURE_SWAPON_DISCARD(char *discard = NULL;)
 249         int ret = 0;
 250
 251         INIT_G();
 252
 253         getopt32(argv, do_swapoff ? "ae" : OPTSTR_SWAPON
 254                         IF_FEATURE_SWAPON_DISCARD(, &discard)
 255                         IF_FEATURE_SWAPON_PRI(, &prio)
 256         );
 257
 258         argv += optind;
 259
 260         if (OPT_DISCARD) {
 261                 set_discard_flag(discard);
 262         }
 263         if (OPT_PRIO) {
 264                 set_priority_flag(prio);
 265         }
 266
 267         if (OPT_ALL) {
 268                 /* swapoff -a does also /proc/swaps */
 269                 if (do_swapoff)
 270                         ret = do_all_in_proc_swaps();
 271                 ret |= do_em_all_in_fstab();
 272         } else if (!*argv) {
 273                 /* if not -a we need at least one arg */
 274                 bb_show_usage();
 275         }
 276         /* Unset -a now to allow for more messages in swap_enable_disable */
 277         option_mask32 = option_mask32 & ~OPT_a;
 278         /* Now process devices on the commandline if any */
 279         while (*argv) {
 280                 ret |= swap_enable_disable(*argv++);
 281         }
 282         return ret;
 283 }