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