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]" 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_PRI(
  16 //usage:     "\n        -p PRI  Set swap device priority"
  17 //usage:        )
  18 //usage:
  19 //usage:#define swapoff_trivial_usage
  20 //usage:       "[-a] [DEVICE]"
  21 //usage:#define swapoff_full_usage "\n\n"
  22 //usage:       "Stop swapping on DEVICE\n"
  23 //usage:     "\n        -a      Stop swapping on all swap devices"
  24
  25 #include "libbb.h"
  26 #include <mntent.h>
  27 #ifndef __BIONIC__
  28 # include <sys/swap.h>
  29 #endif
  30
  31 #if ENABLE_FEATURE_MOUNT_LABEL
  32 # include "volume_id.h"
  33 #else
  34 # define resolve_mount_spec(fsname) ((void)0)
  35 #endif
  36
  37 #ifndef MNTTYPE_SWAP
  38 # define MNTTYPE_SWAP "swap"
  39 #endif
  40
  41 #if ENABLE_FEATURE_SWAPON_PRI
  42 struct globals {
  43         int flags;
  44 } FIX_ALIASING;
  45 #define G (*(struct globals*)&bb_common_bufsiz1)
  46 #define g_flags (G.flags)
  47 #else
  48 #define g_flags 0
  49 #endif
  50 #define INIT_G() do { } while (0)
  51
  52 static int swap_enable_disable(char *device)
  53 {
  54         int status;
  55         struct stat st;
  56
  57         resolve_mount_spec(&device);
  58         xstat(device, &st);
  59
  60 #if ENABLE_DESKTOP
  61         /* test for holes */
  62         if (S_ISREG(st.st_mode))
  63                 if (st.st_blocks * (off_t)512 < st.st_size)
  64                         bb_error_msg("warning: swap file has holes");
  65 #endif
  66
  67         if (applet_name[5] == 'n')
  68                 status = swapon(device, g_flags);
  69         else
  70                 status = swapoff(device);
  71
  72         if (status != 0) {
  73                 bb_simple_perror_msg(device);
  74                 return 1;
  75         }
  76
  77         return 0;
  78 }
  79
  80 static int do_em_all(void)
  81 {
  82         struct mntent *m;
  83         FILE *f;
  84         int err;
  85
  86         f = setmntent("/etc/fstab", "r");
  87         if (f == NULL)
  88                 bb_perror_msg_and_die("/etc/fstab");
  89
  90         err = 0;
  91         while ((m = getmntent(f)) != NULL) {
  92                 if (strcmp(m->mnt_type, MNTTYPE_SWAP) == 0) {
  93                         /* swapon -a should ignore entries with noauto,
  94                          * but swapoff -a should process them */
  95                         if (applet_name[5] != 'n'
  96                          || hasmntopt(m, MNTOPT_NOAUTO) == NULL
  97                         ) {
  98 #if ENABLE_FEATURE_SWAPON_PRI
  99                                 char *p;
 100                                 g_flags = 0; /* each swap space might have different flags */
 101                                 p = hasmntopt(m, "pri");
 102                                 if (p) {
 103                                         /* Max allowed 32767 (==SWAP_FLAG_PRIO_MASK) */
 104                                         unsigned int swap_prio = MIN(bb_strtou(p + 4 , NULL, 10), SWAP_FLAG_PRIO_MASK);
 105                                         /* We want to allow "NNNN,foo", thus errno == EINVAL is allowed too */
 106                                         if (errno != ERANGE) {
 107                                                 g_flags = SWAP_FLAG_PREFER |
 108                                                         (swap_prio << SWAP_FLAG_PRIO_SHIFT);
 109                                         }
 110                                 }
 111 #endif
 112                                 err += swap_enable_disable(m->mnt_fsname);
 113                         }
 114                 }
 115         }
 116
 117         if (ENABLE_FEATURE_CLEAN_UP)
 118                 endmntent(f);
 119
 120         return err;
 121 }
 122
 123 int swap_on_off_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 124 int swap_on_off_main(int argc UNUSED_PARAM, char **argv)
 125 {
 126         int ret;
 127
 128         INIT_G();
 129
 130 #if !ENABLE_FEATURE_SWAPON_PRI
 131         ret = getopt32(argv, "a");
 132 #else
 133         if (applet_name[5] == 'n')
 134                 opt_complementary = "p+";
 135         ret = getopt32(argv, (applet_name[5] == 'n') ? "ap:" : "a", &g_flags);
 136
 137         if (ret & 2) { // -p
 138                 g_flags = SWAP_FLAG_PREFER |
 139                         ((g_flags & SWAP_FLAG_PRIO_MASK) << SWAP_FLAG_PRIO_SHIFT);
 140                 ret &= 1;
 141         }
 142 #endif
 143
 144         if (ret /* & 1: not needed */) // -a
 145                 return do_em_all();
 146
 147         argv += optind;
 148         if (!*argv)
 149                 bb_show_usage();
 150
 151         /* ret = 0; redundant */
 152         do {
 153                 ret += swap_enable_disable(*argv);
 154         } while (*++argv);
 155
 156         return ret;
 157 }