ismounted.c revision cc86017b593ddfbd4d7a12ed8695e62998f30944
1/* 2 * ismounted.c --- Check to see if the filesystem was mounted 3 * 4 * Copyright (C) 1995,1996,1997,1998,1999,2000 Theodore Ts'o. 5 * 6 * %Begin-Header% 7 * This file may be redistributed under the terms of the GNU Public 8 * License. 9 * %End-Header% 10 */ 11 12#include <stdio.h> 13#if HAVE_UNISTD_H 14#include <unistd.h> 15#endif 16#if HAVE_ERRNO_H 17#include <errno.h> 18#endif 19#include <fcntl.h> 20#ifdef HAVE_LINUX_FD_H 21#include <linux/fd.h> 22#endif 23#ifdef HAVE_MNTENT_H 24#include <mntent.h> 25#endif 26#ifdef HAVE_GETMNTINFO 27#include <paths.h> 28#include <sys/param.h> 29#include <sys/mount.h> 30#endif /* HAVE_GETMNTINFO */ 31#include <string.h> 32#include <sys/stat.h> 33 34#include "ext2_fs.h" 35#include "ext2fs.h" 36 37#ifdef HAVE_MNTENT_H 38/* 39 * Helper function which checks a file in /etc/mtab format to see if a 40 * filesystem is mounted. Returns an error if the file doesn't exist 41 * or can't be opened. 42 */ 43static errcode_t check_mntent_file(const char *mtab_file, const char *file, 44 int *mount_flags, char *mtpt, int mtlen) 45{ 46 FILE * f; 47 struct mntent * mnt; 48 int fd; 49 50 *mount_flags = 0; 51 if ((f = setmntent (mtab_file, "r")) == NULL) 52 return errno; 53 while ((mnt = getmntent (f)) != NULL) 54 if (strcmp(file, mnt->mnt_fsname) == 0) 55 break; 56 57 if (mnt == 0) { 58 struct stat st_root, st_file; 59 /* 60 * Do an extra check to see if this is the root device. We 61 * can't trust /etc/fstab, and /proc/mounts will only list 62 * /dev/root for the root filesystem. Argh. Instead we 63 * check if the given device has the same major/minor number 64 * as the device that the root directory is on. 65 */ 66 if (stat("/", &st_root) == 0 && stat(file, &st_file) == 0) { 67 if (st_root.st_dev == st_file.st_rdev) { 68 *mount_flags = EXT2_MF_MOUNTED; 69 if (mtpt) 70 strcpy(mtpt, "/"); 71 goto is_root; 72 } 73 } 74 endmntent (f); 75 return 0; 76 } 77 *mount_flags = EXT2_MF_MOUNTED; 78 79 /* Check to see if the ro option is set */ 80 if (hasmntopt(mnt, MNTOPT_RO)) 81 *mount_flags |= EXT2_MF_READONLY; 82 83 if (mtpt) 84 strncpy(mtpt, mnt->mnt_dir, mtlen); 85 /* 86 * Check to see if we're referring to the root filesystem. 87 * If so, do a manual check to see if we can open /etc/mtab 88 * read/write, since if the root is mounted read/only, the 89 * contents of /etc/mtab may not be accurate. 90 */ 91 if (!strcmp(mnt->mnt_dir, "/")) { 92is_root: 93 *mount_flags |= EXT2_MF_ISROOT; 94 fd = open(MOUNTED, O_RDWR); 95 if (fd < 0) { 96 if (errno == EROFS) 97 *mount_flags |= EXT2_MF_READONLY; 98 } else 99 close(fd); 100 } 101 endmntent (f); 102 return 0; 103} 104 105static errcode_t check_mntent(const char *file, int *mount_flags, 106 char *mtpt, int mtlen) 107{ 108 errcode_t retval; 109 110#ifdef __linux__ 111 retval = check_mntent_file("/proc/mounts", file, mount_flags, 112 mtpt, mtlen); 113 if (retval == 0) 114 return 0; 115#endif 116 retval = check_mntent_file(MOUNTED, file, mount_flags, mtpt, mtlen); 117 return retval; 118} 119 120#endif 121 122#ifdef HAVE_GETMNTINFO 123static errcode_t check_getmntinfo(const char *file, int *mount_flags, 124 char *mtpt, int mtlen) 125{ 126 struct statfs *mp; 127 int len, n; 128 const char *s1; 129 char *s2; 130 131 n = getmntinfo(&mp, MNT_NOWAIT); 132 if (n == 0) 133 return errno; 134 135 len = sizeof(_PATH_DEV) - 1; 136 s1 = file; 137 if (strncmp(_PATH_DEV, s1, len) == 0) 138 s1 += len; 139 140 *mount_flags = 0; 141 while (--n >= 0) { 142 s2 = mp->f_mntfromname; 143 if (strncmp(_PATH_DEV, s2, len) == 0) { 144 s2 += len - 1; 145 *s2 = 'r'; 146 } 147 if (strcmp(s1, s2) == 0 || strcmp(s1, &s2[1]) == 0) { 148 *mount_flags = EXT2_MF_MOUNTED; 149 break; 150 } 151 ++mp; 152 } 153 if (mtpt) 154 strncpy(mtpt, mp->f_mntonname, mtlen); 155 return 0; 156} 157#endif /* HAVE_GETMNTINFO */ 158 159/* 160 * ext2fs_check_mount_point() returns 1 if the device is mounted, 0 161 * otherwise. If mtpt is non-NULL, the directory where the device is 162 * mounted is copied to where mtpt is pointing, up to mtlen 163 * characters. 164 */ 165#ifdef __TURBOC__ 166 #pragma argsused 167#endif 168errcode_t ext2fs_check_mount_point(const char *device, int *mount_flags, 169 char *mtpt, int mtlen) 170{ 171#ifdef HAVE_MNTENT_H 172 return check_mntent(device, mount_flags, mtpt, mtlen); 173#else 174#ifdef HAVE_GETMNTINFO 175 return check_getmntinfo(device, mount_flags, mtpt, mtlen); 176#else 177 *mount_flags = 0; 178 return 0; 179#endif /* HAVE_GETMNTINFO */ 180#endif /* HAVE_MNTENT_H */ 181} 182 183/* 184 * ext2fs_check_if_mounted() sets the mount_flags EXT2_MF_MOUNTED and 185 * EXT2_MF_READONLY 186 * 187 */ 188#ifdef __TURBOC__ 189 #pragma argsused 190#endif 191errcode_t ext2fs_check_if_mounted(const char *file, int *mount_flags) 192{ 193#ifdef HAVE_MNTENT_H 194 return check_mntent(file, mount_flags, NULL, 0); 195#else 196#ifdef HAVE_GETMNTINFO 197 return check_getmntinfo(file, mount_flags, NULL, 0); 198#else 199 *mount_flags = 0; 200 return 0; 201#endif /* HAVE_GETMNTINFO */ 202#endif /* HAVE_MNTENT_H */ 203} 204 205#ifdef DEBUG 206int main(int argc, char **argv) 207{ 208 blk_t blocks; 209 int retval, mount_flags; 210 211 if (argc < 2) { 212 fprintf(stderr, "Usage: %s device\n", argv[0]); 213 exit(1); 214 } 215 216 retval = ext2fs_check_if_mounted(argv[1], &mount_flags); 217 if (retval) { 218 com_err(argv[0], retval, 219 "while calling ext2fs_check_if_mounted"); 220 exit(1); 221 } 222 printf("Device %s reports flags %02x\n", argv[1], mount_flags); 223 if (mount_flags & EXT2_MF_MOUNTED) 224 printf("\t%s is mounted.\n", argv[1]); 225 226 if (mount_flags & EXT2_MF_READONLY) 227 printf("\t%s is read-only.\n", argv[1]); 228 229 if (mount_flags & EXT2_MF_ISROOT) 230 printf("\t%s is the root filesystem.\n", argv[1]); 231 232 exit(0); 233} 234#endif 235