1 | /*
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2 | * ismounted.c --- Check to see if the filesystem was mounted
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3 | *
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4 | * Copyright (C) 1995,1996,1997,1998,1999,2000 Theodore Ts'o.
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5 | *
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6 | * %Begin-Header%
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7 | * This file may be redistributed under the terms of the GNU Public
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8 | * License.
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9 | * %End-Header%
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10 | */
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11 |
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12 | #include <stdio.h>
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13 | #if HAVE_UNISTD_H
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14 | #include <unistd.h>
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15 | #endif
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16 | #if HAVE_ERRNO_H
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17 | #include <errno.h>
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18 | #endif
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19 | #include <fcntl.h>
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20 | #ifdef HAVE_LINUX_FD_H
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21 | #include <linux/fd.h>
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22 | #endif
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23 | #ifdef HAVE_MNTENT_H
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24 | #include <mntent.h>
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25 | #endif
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26 | #ifdef HAVE_GETMNTINFO
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27 | #include <paths.h>
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28 | #include <sys/param.h>
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29 | #include <sys/mount.h>
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30 | #endif /* HAVE_GETMNTINFO */
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31 | #include <string.h>
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32 | #include <sys/stat.h>
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33 |
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34 | #include "ext2_fs.h"
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35 | #include "ext2fs.h"
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36 |
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37 | #ifdef HAVE_MNTENT_H
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38 | /*
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39 | * Helper function which checks a file in /etc/mtab format to see if a
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40 | * filesystem is mounted. Returns an error if the file doesn't exist
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41 | * or can't be opened.
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42 | */
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43 | static errcode_t check_mntent_file(const char *mtab_file, const char *file,
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44 | int *mount_flags, char *mtpt, int mtlen)
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45 | {
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46 | struct mntent *mnt;
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47 | struct stat st_buf;
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48 | errcode_t retval = 0;
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49 | dev_t file_dev=0, file_rdev=0;
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50 | ino_t file_ino=0;
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51 | FILE *f;
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52 | int fd;
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53 |
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54 | *mount_flags = 0;
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55 | if ((f = setmntent (mtab_file, "r")) == NULL)
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56 | return errno;
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57 | if (stat(file, &st_buf) == 0) {
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58 | if (S_ISBLK(st_buf.st_mode)) {
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59 | #ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */
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60 | file_rdev = st_buf.st_rdev;
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61 | #endif /* __GNU__ */
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62 | } else {
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63 | file_dev = st_buf.st_dev;
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64 | file_ino = st_buf.st_ino;
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65 | }
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66 | }
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67 | while ((mnt = getmntent (f)) != NULL) {
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68 | if (strcmp(file, mnt->mnt_fsname) == 0)
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69 | break;
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70 | if (stat(mnt->mnt_fsname, &st_buf) == 0) {
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71 | if (S_ISBLK(st_buf.st_mode)) {
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72 | #ifndef __GNU__
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73 | if (file_rdev && (file_rdev == st_buf.st_rdev))
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74 | break;
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75 | #endif /* __GNU__ */
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76 | } else {
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77 | if (file_dev && ((file_dev == st_buf.st_dev) &&
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78 | (file_ino == st_buf.st_ino)))
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79 | break;
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80 | }
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81 | }
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82 | }
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83 |
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84 | if (mnt == 0) {
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85 | #ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */
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86 | /*
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87 | * Do an extra check to see if this is the root device. We
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88 | * can't trust /etc/mtab, and /proc/mounts will only list
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89 | * /dev/root for the root filesystem. Argh. Instead we
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90 | * check if the given device has the same major/minor number
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91 | * as the device that the root directory is on.
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92 | */
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93 | if (file_rdev && stat("/", &st_buf) == 0) {
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94 | if (st_buf.st_dev == file_rdev) {
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95 | *mount_flags = EXT2_MF_MOUNTED;
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96 | if (mtpt)
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97 | strncpy(mtpt, "/", mtlen);
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98 | goto is_root;
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99 | }
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100 | }
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101 | #endif /* __GNU__ */
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102 | goto errout;
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103 | }
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104 | #ifndef __GNU__ /* The GNU hurd is deficient; what else is new? */
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105 | /* Validate the entry in case /etc/mtab is out of date */
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106 | /*
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107 | * We need to be paranoid, because some broken distributions
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108 | * (read: Slackware) don't initialize /etc/mtab before checking
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109 | * all of the non-root filesystems on the disk.
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110 | */
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111 | if (stat(mnt->mnt_dir, &st_buf) < 0) {
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112 | retval = errno;
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113 | if (retval == ENOENT) {
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114 | #ifdef DEBUG
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115 | printf("Bogus entry in %s! (%s does not exist)\n",
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116 | mtab_file, mnt->mnt_dir);
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117 | #endif /* DEBUG */
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118 | retval = 0;
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119 | }
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120 | goto errout;
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121 | }
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122 | if (file_rdev && (st_buf.st_dev != file_rdev)) {
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123 | #ifdef DEBUG
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124 | printf("Bogus entry in %s! (%s not mounted on %s)\n",
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125 | mtab_file, file, mnt->mnt_dir);
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126 | #endif /* DEBUG */
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127 | goto errout;
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128 | }
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129 | #endif /* __GNU__ */
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130 | *mount_flags = EXT2_MF_MOUNTED;
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131 |
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132 | #ifdef MNTOPT_RO
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133 | /* Check to see if the ro option is set */
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134 | if (hasmntopt(mnt, MNTOPT_RO))
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135 | *mount_flags |= EXT2_MF_READONLY;
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136 | #endif
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137 |
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138 | if (mtpt)
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139 | strncpy(mtpt, mnt->mnt_dir, mtlen);
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140 | /*
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141 | * Check to see if we're referring to the root filesystem.
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142 | * If so, do a manual check to see if we can open /etc/mtab
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143 | * read/write, since if the root is mounted read/only, the
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144 | * contents of /etc/mtab may not be accurate.
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145 | */
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146 | if (!strcmp(mnt->mnt_dir, "/")) {
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147 | is_root:
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148 | #define TEST_FILE "/.ismount-test-file"
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149 | *mount_flags |= EXT2_MF_ISROOT;
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150 | fd = open(TEST_FILE, O_RDWR|O_CREAT);
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151 | if (fd < 0) {
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152 | if (errno == EROFS)
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153 | *mount_flags |= EXT2_MF_READONLY;
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154 | } else
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155 | close(fd);
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156 | (void) unlink(TEST_FILE);
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157 | }
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158 | retval = 0;
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159 | errout:
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160 | endmntent (f);
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161 | return retval;
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162 | }
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163 |
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164 | static errcode_t check_mntent(const char *file, int *mount_flags,
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165 | char *mtpt, int mtlen)
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166 | {
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167 | errcode_t retval;
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168 |
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169 | #ifdef DEBUG
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170 | retval = check_mntent_file("/tmp/mtab", file, mount_flags,
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171 | mtpt, mtlen);
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172 | if (retval == 0)
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173 | return 0;
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174 | #endif /* DEBUG */
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175 | #ifdef __linux__
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176 | retval = check_mntent_file("/proc/mounts", file, mount_flags,
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177 | mtpt, mtlen);
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178 | if (retval == 0 && (*mount_flags != 0))
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179 | return 0;
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180 | #endif /* __linux__ */
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181 | #if defined(MOUNTED) || defined(_PATH_MOUNTED)
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182 | #ifndef MOUNTED
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183 | #define MOUNTED _PATH_MOUNTED
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184 | #endif /* MOUNTED */
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185 | retval = check_mntent_file(MOUNTED, file, mount_flags, mtpt, mtlen);
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186 | return retval;
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187 | #else
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188 | *mount_flags = 0;
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189 | return 0;
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190 | #endif /* defined(MOUNTED) || defined(_PATH_MOUNTED) */
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191 | }
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192 |
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193 | #else
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194 | #if defined(HAVE_GETMNTINFO)
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195 |
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196 | static errcode_t check_getmntinfo(const char *file, int *mount_flags,
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197 | char *mtpt, int mtlen)
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198 | {
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199 | struct statfs *mp;
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200 | int len, n;
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201 | const char *s1;
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202 | char *s2;
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203 |
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204 | n = getmntinfo(&mp, MNT_NOWAIT);
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205 | if (n == 0)
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206 | return errno;
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207 |
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208 | len = sizeof(_PATH_DEV) - 1;
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209 | s1 = file;
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210 | if (strncmp(_PATH_DEV, s1, len) == 0)
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211 | s1 += len;
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212 |
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213 | *mount_flags = 0;
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214 | while (--n >= 0) {
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215 | s2 = mp->f_mntfromname;
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216 | if (strncmp(_PATH_DEV, s2, len) == 0) {
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217 | s2 += len - 1;
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218 | *s2 = 'r';
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219 | }
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220 | if (strcmp(s1, s2) == 0 || strcmp(s1, &s2[1]) == 0) {
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221 | *mount_flags = EXT2_MF_MOUNTED;
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222 | break;
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223 | }
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224 | ++mp;
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225 | }
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226 | if (mtpt)
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227 | strncpy(mtpt, mp->f_mntonname, mtlen);
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228 | return 0;
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229 | }
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230 | #endif /* HAVE_GETMNTINFO */
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231 | #endif /* HAVE_MNTENT_H */
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232 |
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233 | /*
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234 | * Check to see if we're dealing with the swap device.
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235 | */
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236 | static int is_swap_device(const char *file)
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237 | {
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238 | FILE *f;
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239 | char buf[1024], *cp;
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240 | dev_t file_dev;
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241 | struct stat st_buf;
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242 | int ret = 0;
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243 |
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244 | file_dev = 0;
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245 | #ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */
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246 | if ((stat(file, &st_buf) == 0) &&
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247 | S_ISBLK(st_buf.st_mode))
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248 | file_dev = st_buf.st_rdev;
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249 | #endif /* __GNU__ */
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250 |
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251 | if (!(f = fopen("/proc/swaps", "r")))
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252 | return 0;
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253 | /* Skip the first line */
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254 | fgets(buf, sizeof(buf), f);
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255 | while (!feof(f)) {
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256 | if (!fgets(buf, sizeof(buf), f))
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257 | break;
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258 | if ((cp = strchr(buf, ' ')) != NULL)
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259 | *cp = 0;
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260 | if ((cp = strchr(buf, '\t')) != NULL)
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261 | *cp = 0;
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262 | if (strcmp(buf, file) == 0) {
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263 | ret++;
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264 | break;
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265 | }
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266 | #ifndef __GNU__
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267 | if (file_dev && (stat(buf, &st_buf) == 0) &&
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268 | S_ISBLK(st_buf.st_mode) &&
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269 | file_dev == st_buf.st_rdev) {
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270 | ret++;
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271 | break;
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272 | }
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273 | #endif /* __GNU__ */
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274 | }
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275 | fclose(f);
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276 | return ret;
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277 | }
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278 |
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279 |
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280 | /*
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281 | * ext2fs_check_mount_point() returns 1 if the device is mounted, 0
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282 | * otherwise. If mtpt is non-NULL, the directory where the device is
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283 | * mounted is copied to where mtpt is pointing, up to mtlen
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284 | * characters.
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285 | */
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286 | #ifdef __TURBOC__
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287 | # pragma argsused
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288 | #endif
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289 | errcode_t ext2fs_check_mount_point(const char *device, int *mount_flags,
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290 | char *mtpt, int mtlen)
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291 | {
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292 | if (is_swap_device(device)) {
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293 | *mount_flags = EXT2_MF_MOUNTED | EXT2_MF_SWAP;
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294 | strncpy(mtpt, "<swap>", mtlen);
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295 | return 0;
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296 | }
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297 | #ifdef HAVE_MNTENT_H
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298 | return check_mntent(device, mount_flags, mtpt, mtlen);
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299 | #else
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300 | #ifdef HAVE_GETMNTINFO
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301 | return check_getmntinfo(device, mount_flags, mtpt, mtlen);
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302 | #else
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303 | #ifdef __GNUC__
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304 | #warning "Can't use getmntent or getmntinfo to check for mounted filesystems!"
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305 | #endif
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306 | *mount_flags = 0;
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307 | return 0;
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308 | #endif /* HAVE_GETMNTINFO */
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309 | #endif /* HAVE_MNTENT_H */
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310 | }
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311 |
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312 | /*
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313 | * ext2fs_check_if_mounted() sets the mount_flags EXT2_MF_MOUNTED,
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314 | * EXT2_MF_READONLY, and EXT2_MF_ROOT
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315 | *
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316 | */
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317 | errcode_t ext2fs_check_if_mounted(const char *file, int *mount_flags)
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318 | {
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319 | return ext2fs_check_mount_point(file, mount_flags, NULL, 0);
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320 | }
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321 |
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322 | #ifdef DEBUG
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323 | int main(int argc, char **argv)
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324 | {
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325 | int retval, mount_flags;
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326 | char mntpt[80];
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327 |
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328 | if (argc < 2) {
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329 | fprintf(stderr, "Usage: %s device\n", argv[0]);
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330 | exit(1);
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331 | }
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332 |
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333 | mntpt[0] = 0;
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334 | retval = ext2fs_check_mount_point(argv[1], &mount_flags,
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335 | mntpt, sizeof(mntpt));
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336 | if (retval) {
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337 | com_err(argv[0], retval,
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338 | "while calling ext2fs_check_if_mounted");
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339 | exit(1);
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340 | }
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341 | printf("Device %s reports flags %02x\n", argv[1], mount_flags);
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342 | if (mount_flags & EXT2_MF_BUSY)
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343 | printf("\t%s is apparently in use.\n", argv[1]);
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344 | if (mount_flags & EXT2_MF_MOUNTED)
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345 | printf("\t%s is mounted.\n", argv[1]);
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346 | if (mount_flags & EXT2_MF_SWAP)
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347 | printf("\t%s is a swap device.\n", argv[1]);
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348 | if (mount_flags & EXT2_MF_READONLY)
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349 | printf("\t%s is read-only.\n", argv[1]);
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350 | if (mount_flags & EXT2_MF_ISROOT)
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351 | printf("\t%s is the root filesystem.\n", argv[1]);
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352 | if (mntpt[0])
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353 | printf("\t%s is mounted on %s.\n", argv[1], mntpt);
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354 | exit(0);
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355 | }
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356 | #endif /* DEBUG */
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