1 | /* vi: set sw=4 ts=4: */
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2 | /*
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3 | * Mini umount implementation for busybox
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4 | *
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5 | * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
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6 | * Copyright (C) 2005 by Rob Landley <rob@landley.net>
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7 | *
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8 | * This program is licensed under the GNU General Public license (GPL)
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9 | * version 2 or later, see http://www.fsf.org/licensing/licenses/gpl.html
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10 | * or the file "LICENSE" in the busybox source tarball for the full text.
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11 | *
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12 | */
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13 |
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14 | #include "busybox.h"
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15 | #include <mntent.h>
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16 | #include <errno.h>
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17 | #include <getopt.h>
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18 |
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19 | #define OPTION_STRING "flDnravd"
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20 | #define OPT_FORCE 1
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21 | #define OPT_LAZY 2
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22 | #define OPT_DONTFREELOOP 4
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23 | #define OPT_NO_MTAB 8
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24 | #define OPT_REMOUNT 16
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25 | #define OPT_ALL (ENABLE_FEATURE_UMOUNT_ALL ? 32 : 0)
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26 |
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27 | int umount_main(int argc, char **argv)
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28 | {
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29 | int doForce;
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30 | char path[2*PATH_MAX];
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31 | struct mntent me;
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32 | FILE *fp;
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33 | int status = EXIT_SUCCESS;
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34 | unsigned long opt;
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35 | struct mtab_list {
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36 | char *dir;
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37 | char *device;
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38 | struct mtab_list *next;
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39 | } *mtl, *m;
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40 |
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41 | /* Parse any options */
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42 |
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43 | opt = bb_getopt_ulflags(argc, argv, OPTION_STRING);
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44 |
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45 | argc -= optind;
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46 | argv += optind;
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47 |
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48 | doForce = MAX((opt & OPT_FORCE), (opt & OPT_LAZY));
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49 |
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50 | /* Get a list of mount points from mtab. We read them all in now mostly
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51 | * for umount -a (so we don't have to worry about the list changing while
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52 | * we iterate over it, or about getting stuck in a loop on the same failing
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53 | * entry. Notice that this also naturally reverses the list so that -a
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54 | * umounts the most recent entries first. */
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55 |
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56 | m = mtl = 0;
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57 |
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58 | /* If we're umounting all, then m points to the start of the list and
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59 | * the argument list should be empty (which will match all). */
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60 |
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61 | if (!(fp = setmntent(bb_path_mtab_file, "r"))) {
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62 | if (opt & OPT_ALL)
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63 | bb_error_msg_and_die("Cannot open %s", bb_path_mtab_file);
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64 | } else while (getmntent_r(fp,&me,path,sizeof(path))) {
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65 | m = xmalloc(sizeof(struct mtab_list));
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66 | m->next = mtl;
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67 | m->device = bb_xstrdup(me.mnt_fsname);
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68 | m->dir = bb_xstrdup(me.mnt_dir);
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69 | mtl = m;
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70 | }
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71 | endmntent(fp);
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72 |
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73 | /* If we're not mounting all, we need at least one argument. */
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74 | if (!(opt & OPT_ALL)) {
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75 | m = 0;
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76 | if (!argc) bb_show_usage();
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77 | }
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78 |
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79 | // Loop through everything we're supposed to umount, and do so.
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80 | for (;;) {
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81 | int curstat;
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82 | char *zapit = *argv;
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83 |
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84 | // Do we already know what to umount this time through the loop?
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85 | if (m) safe_strncpy(path, m->dir, PATH_MAX);
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86 | // For umount -a, end of mtab means time to exit.
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87 | else if (opt & OPT_ALL) break;
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88 | // Get next command line argument (and look it up in mtab list)
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89 | else if (!argc--) break;
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90 | else {
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91 | argv++;
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92 | realpath(zapit, path);
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93 | for (m = mtl; m; m = m->next)
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94 | if (!strcmp(path, m->dir) || !strcmp(path, m->device))
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95 | break;
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96 | }
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97 | // If we couldn't find this sucker in /etc/mtab, punt by passing our
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98 | // command line argument straight to the umount syscall. Otherwise,
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99 | // umount the directory even if we were given the block device.
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100 | if (m) zapit = m->dir;
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101 |
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102 | // Let's ask the thing nicely to unmount.
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103 | curstat = umount(zapit);
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104 |
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105 | // Force the unmount, if necessary.
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106 | if (curstat && doForce) {
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107 | curstat = umount2(zapit, doForce);
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108 | if (curstat)
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109 | bb_error_msg_and_die("forced umount of %s failed!", zapit);
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110 | }
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111 |
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112 | // If still can't umount, maybe remount read-only?
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113 | if (curstat && (opt & OPT_REMOUNT) && errno == EBUSY && m) {
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114 | curstat = mount(m->device, zapit, NULL, MS_REMOUNT|MS_RDONLY, NULL);
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115 | bb_error_msg(curstat ? "Cannot remount %s read-only" :
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116 | "%s busy - remounted read-only", m->device);
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117 | }
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118 |
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119 | if (curstat) {
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120 | status = EXIT_FAILURE;
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121 | bb_perror_msg("Couldn't umount %s", zapit);
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122 | } else {
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123 | /* De-allocate the loop device. This ioctl should be ignored on
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124 | * any non-loop block devices. */
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125 | if (ENABLE_FEATURE_MOUNT_LOOP && !(opt & OPT_DONTFREELOOP) && m)
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126 | del_loop(m->device);
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127 | if (ENABLE_FEATURE_MTAB_SUPPORT && !(opt & OPT_NO_MTAB) && m)
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128 | erase_mtab(m->dir);
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129 | }
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130 |
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131 | // Find next matching mtab entry for -a or umount /dev
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132 | // Note this means that "umount /dev/blah" will unmount all instances
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133 | // of /dev/blah, not just the most recent.
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134 | while (m && (m = m->next))
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135 | if ((opt & OPT_ALL) || !strcmp(path,m->device))
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136 | break;
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137 | }
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138 |
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139 | // Free mtab list if necessary
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140 |
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141 | if (ENABLE_FEATURE_CLEAN_UP) {
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142 | while (mtl) {
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143 | m = mtl->next;
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144 | free(mtl->device);
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145 | free(mtl->dir);
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146 | free(mtl);
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147 | mtl=m;
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148 | }
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149 | }
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150 |
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151 | return status;
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152 | }
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