busybox/util-linux/mount.c

553 lines
14 KiB
C

/* vi: set sw=4 ts=4: */
/*
* Mini mount implementation for busybox
*
* Copyright (C) 1995, 1996 by Bruce Perens <bruce@pixar.com>.
* Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
* Copyright (C) 2005-2006 by Rob Landley <rob@landley.net>
*
* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*/
/* todo:
* bb_getopt_ulflags();
*/
/* Design notes: There is no spec for mount. Remind me to write one.
mount_main() calls singlemount() which calls mount_it_now().
mount_main() can loop through /etc/fstab for mount -a
singlemount() can loop through /etc/filesystems for fstype detection.
mount_it_now() does the actual mount.
*/
#include "busybox.h"
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <mntent.h>
#include <ctype.h>
#include <fcntl.h> // for CONFIG_FEATURE_MOUNT_LOOP
#include <sys/ioctl.h> // for CONFIG_FEATURE_MOUNT_LOOP
// These two aren't always defined in old headers
#ifndef MS_BIND
#define MS_BIND 4096
#endif
#ifndef MS_MOVE
#define MS_MOVE 8192
#endif
#ifndef MS_SILENT
#define MS_SILENT 32768
#endif
// Not real flags, but we want to be able to check for this.
#define MOUNT_NOAUTO (1<<29)
#define MOUNT_SWAP (1<<30)
/* Standard mount options (from -o options or --options), with corresponding
* flags */
struct {
const char *name;
long flags;
} static const mount_options[] = {
// NOP flags.
{"loop", 0},
{"defaults", 0},
{"quiet", 0},
// vfs flags
{"ro", MS_RDONLY},
{"rw", ~MS_RDONLY},
{"nosuid", MS_NOSUID},
{"suid", ~MS_NOSUID},
{"dev", ~MS_NODEV},
{"nodev", MS_NODEV},
{"exec", ~MS_NOEXEC},
{"noexec", MS_NOEXEC},
{"sync", MS_SYNCHRONOUS},
{"async", ~MS_SYNCHRONOUS},
{"atime", ~MS_NOATIME},
{"noatime", MS_NOATIME},
{"diratime", ~MS_NODIRATIME},
{"nodiratime", MS_NODIRATIME},
{"loud", ~MS_SILENT},
// action flags
{"remount", MS_REMOUNT},
{"bind", MS_BIND},
{"move", MS_MOVE},
{"noauto",MOUNT_NOAUTO},
{"swap",MOUNT_SWAP}
};
/* Append mount options to string */
static void append_mount_options(char **oldopts, char *newopts)
{
if(*oldopts && **oldopts) {
char *temp=bb_xasprintf("%s,%s",*oldopts,newopts);
free(*oldopts);
*oldopts=temp;
} else {
if (ENABLE_FEATURE_CLEAN_UP) free(*oldopts);
*oldopts = bb_xstrdup(newopts);
}
}
/* Use the mount_options list to parse options into flags.
* Return list of unrecognized options in *strflags if strflags!=NULL */
static int parse_mount_options(char *options, char **unrecognized)
{
int flags = MS_SILENT;
// Loop through options
for (;;) {
int i;
char *comma = strchr(options, ',');
if (comma) *comma = 0;
// Find this option in mount_options
for (i = 0; i < (sizeof(mount_options) / sizeof(*mount_options)); i++) {
if (!strcasecmp(mount_options[i].name, options)) {
long fl = mount_options[i].flags;
if(fl < 0) flags &= fl;
else flags |= fl;
break;
}
}
// If unrecognized not NULL, append unrecognized mount options */
if (unrecognized
&& i == (sizeof(mount_options) / sizeof(*mount_options)))
{
// Add it to strflags, to pass on to kernel
i = *unrecognized ? strlen(*unrecognized) : 0;
*unrecognized = xrealloc(*unrecognized, i+strlen(options)+2);
// Comma separated if it's not the first one
if (i) (*unrecognized)[i++] = ',';
strcpy((*unrecognized)+i, options);
}
// Advance to next option, or finish
if(comma) {
*comma = ',';
options = ++comma;
} else break;
}
return flags;
}
// Return a list of all block device backed filesystems
static llist_t *get_block_backed_filesystems(void)
{
char *fs, *buf,
*filesystems[] = {"/etc/filesystems", "/proc/filesystems", 0};
llist_t *list = 0;
int i;
FILE *f;
for(i = 0; filesystems[i]; i++) {
if(!(f = fopen(filesystems[i], "r"))) continue;
for(fs = buf = 0; (fs = buf = bb_get_chomped_line_from_file(f));
free(buf))
{
if(!strncmp(buf,"nodev",5) && isspace(buf[5])) continue;
while(isspace(*fs)) fs++;
if(*fs=='#' || *fs=='*') continue;
if(!*fs) continue;
llist_add_to_end(&list,bb_xstrdup(fs));
}
if (ENABLE_FEATURE_CLEAN_UP) fclose(f);
}
return list;
}
llist_t *fslist = 0;
#if ENABLE_FEATURE_CLEAN_UP
static void delete_block_backed_filesystems(void)
{
llist_free(fslist, free);
}
#else
void delete_block_backed_filesystems(void);
#endif
#if ENABLE_FEATURE_MTAB_SUPPORT
static int useMtab;
static int fakeIt;
#else
#define useMtab 0
#define fakeIt 0
#endif
// Perform actual mount of specific filesystem at specific location.
static int mount_it_now(struct mntent *mp, int vfsflags, char *filteropts)
{
int rc;
if (fakeIt) { return 0; }
// Mount, with fallback to read-only if necessary.
for(;;) {
rc = mount(mp->mnt_fsname, mp->mnt_dir, mp->mnt_type,
vfsflags, filteropts);
if(!rc || (vfsflags&MS_RDONLY) || (errno!=EACCES && errno!=EROFS))
break;
bb_error_msg("%s is write-protected, mounting read-only",
mp->mnt_fsname);
vfsflags |= MS_RDONLY;
}
// Abort entirely if permission denied.
if (rc && errno == EPERM)
bb_error_msg_and_die(bb_msg_perm_denied_are_you_root);
/* If the mount was successful, and we're maintaining an old-style
* mtab file by hand, add the new entry to it now. */
if(ENABLE_FEATURE_MTAB_SUPPORT && useMtab && !rc) {
FILE *mountTable = setmntent(bb_path_mtab_file, "a+");
int i;
if(!mountTable)
bb_error_msg("No %s\n",bb_path_mtab_file);
// Add vfs string flags
for(i=0; mount_options[i].flags != MS_REMOUNT; i++)
if (mount_options[i].flags > 0)
append_mount_options(&(mp->mnt_opts),
// Shut up about the darn const. It's not important. I don't care.
(char *)mount_options[i].name);
// Remove trailing / (if any) from directory we mounted on
i = strlen(mp->mnt_dir);
if(i>1 && mp->mnt_dir[i-1] == '/') mp->mnt_dir[i-1] = 0;
// Write and close.
if(!mp->mnt_type || !*mp->mnt_type) mp->mnt_type="--bind";
addmntent(mountTable, mp);
endmntent(mountTable);
if (ENABLE_FEATURE_CLEAN_UP)
if(strcmp(mp->mnt_type,"--bind")) mp->mnt_type = 0;
}
return rc;
}
// Mount one directory. Handles NFS, loopback, autobind, and filesystem type
// detection. Returns 0 for success, nonzero for failure.
static int singlemount(struct mntent *mp, int ignore_busy)
{
int rc = -1, vfsflags;
char *loopFile = 0, *filteropts = 0;
llist_t *fl = 0;
struct stat st;
vfsflags = parse_mount_options(mp->mnt_opts, &filteropts);
// Treat fstype "auto" as unspecified.
if (mp->mnt_type && !strcmp(mp->mnt_type,"auto")) mp->mnt_type = 0;
// Might this be an NFS filesystem?
if (ENABLE_FEATURE_MOUNT_NFS &&
(!mp->mnt_type || !strcmp(mp->mnt_type,"nfs")) &&
strchr(mp->mnt_fsname, ':') != NULL)
{
if (nfsmount(mp->mnt_fsname, mp->mnt_dir, &vfsflags, &filteropts, 1)) {
bb_perror_msg("nfsmount failed");
goto report_error;
} else {
// Strangely enough, nfsmount() doesn't actually mount() anything.
mp->mnt_type = "nfs";
rc = mount_it_now(mp, vfsflags, filteropts);
if (ENABLE_FEATURE_CLEAN_UP) free(filteropts);
goto report_error;
}
}
// Look at the file. (Not found isn't a failure for remount, or for
// a synthetic filesystem like proc or sysfs.)
if (lstat(mp->mnt_fsname, &st));
else if (!(vfsflags & (MS_REMOUNT | MS_BIND | MS_MOVE))) {
// Do we need to allocate a loopback device for it?
if (ENABLE_FEATURE_MOUNT_LOOP && S_ISREG(st.st_mode)) {
loopFile = bb_simplify_path(mp->mnt_fsname);
mp->mnt_fsname = 0;
switch(set_loop(&(mp->mnt_fsname), loopFile, 0)) {
case 0:
case 1:
break;
default:
bb_error_msg( errno == EPERM || errno == EACCES
? bb_msg_perm_denied_are_you_root
: "Couldn't setup loop device");
return errno;
}
// Autodetect bind mounts
} else if (S_ISDIR(st.st_mode) && !mp->mnt_type) vfsflags |= MS_BIND;
}
/* If we know the fstype (or don't need to), jump straight
* to the actual mount. */
if (mp->mnt_type || (vfsflags & (MS_REMOUNT | MS_BIND | MS_MOVE)))
rc = mount_it_now(mp, vfsflags, filteropts);
// Loop through filesystem types until mount succeeds or we run out
else {
/* Initialize list of block backed filesystems. This has to be
* done here so that during "mount -a", mounts after /proc shows up
* can autodetect. */
if (!fslist) {
fslist = get_block_backed_filesystems();
if (ENABLE_FEATURE_CLEAN_UP && fslist)
atexit(delete_block_backed_filesystems);
}
for (fl = fslist; fl; fl = fl->link) {
mp->mnt_type = fl->data;
if (!(rc = mount_it_now(mp,vfsflags, filteropts))) break;
mp->mnt_type = 0;
}
}
if (ENABLE_FEATURE_CLEAN_UP) free(filteropts);
// If mount failed, clean up loop file (if any).
if (ENABLE_FEATURE_MOUNT_LOOP && rc && loopFile) {
del_loop(mp->mnt_fsname);
if (ENABLE_FEATURE_CLEAN_UP) {
free(loopFile);
free(mp->mnt_fsname);
}
}
report_error:
if (rc && errno == EBUSY && ignore_busy) rc = 0;
if (rc < 0)
bb_perror_msg("Mounting %s on %s failed", mp->mnt_fsname, mp->mnt_dir);
return rc;
}
// Parse options, if necessary parse fstab/mtab, and call singlemount for
// each directory to be mounted.
int mount_main(int argc, char **argv)
{
char *cmdopts = bb_xstrdup(""), *fstabname, *fstype=0, *storage_path=0;
FILE *fstab;
int i, opt, all = FALSE, rc = 0;
struct mntent mtpair[2], *mtcur = mtpair;
/* parse long options, like --bind and --move. Note that -o option
* and --option are synonymous. Yes, this means --remount,rw works. */
for (i = opt = 0; i < argc; i++) {
if (argv[i][0] == '-' && argv[i][1] == '-') {
append_mount_options(&cmdopts,argv[i]+2);
} else argv[opt++] = argv[i];
}
argc = opt;
// Parse remaining options
while ((opt = getopt(argc, argv, "o:t:rwavnf")) > 0) {
switch (opt) {
case 'o':
append_mount_options(&cmdopts, optarg);
break;
case 't':
fstype = optarg;
break;
case 'r':
append_mount_options(&cmdopts, "ro");
break;
case 'w':
append_mount_options(&cmdopts, "rw");
break;
case 'a':
all = TRUE;
break;
case 'n':
USE_FEATURE_MTAB_SUPPORT(useMtab = FALSE;)
break;
case 'f':
USE_FEATURE_MTAB_SUPPORT(fakeIt = FALSE;)
break;
case 'v':
break; // ignore -v
default:
bb_show_usage();
}
}
// Three or more non-option arguments? Die with a usage message.
if (optind-argc>2) bb_show_usage();
// If we have no arguments, show currently mounted filesystems
if (optind == argc) {
if (!all) {
FILE *mountTable = setmntent(bb_path_mtab_file, "r");
if(!mountTable) bb_error_msg_and_die("No %s",bb_path_mtab_file);
while (getmntent_r(mountTable,mtpair,bb_common_bufsiz1,
sizeof(bb_common_bufsiz1)))
{
// Don't show rootfs.
if (!strcmp(mtpair->mnt_fsname, "rootfs")) continue;
if (!fstype || !strcmp(mtpair->mnt_type, fstype))
printf("%s on %s type %s (%s)\n", mtpair->mnt_fsname,
mtpair->mnt_dir, mtpair->mnt_type,
mtpair->mnt_opts);
}
if (ENABLE_FEATURE_CLEAN_UP) endmntent(mountTable);
return EXIT_SUCCESS;
}
}
// When we have two arguments, the second is the directory and we can
// skip looking at fstab entirely. We can always abspath() the directory
// argument when we get it.
if (optind+2 == argc) {
mtpair->mnt_fsname = argv[optind];
mtpair->mnt_dir = argv[optind+1];
mtpair->mnt_type = fstype;
mtpair->mnt_opts = cmdopts;
rc = singlemount(mtpair, 0);
goto clean_up;
}
// If we have at least one argument, it's the storage location
if (optind < argc) storage_path = bb_simplify_path(argv[optind]);
// Open either fstab or mtab
if (parse_mount_options(cmdopts,0) & MS_REMOUNT)
fstabname = (char *)bb_path_mtab_file; // Again with the evil const.
else fstabname="/etc/fstab";
if (!(fstab=setmntent(fstabname,"r")))
bb_perror_msg_and_die("Cannot read %s",fstabname);
// Loop through entries until we find what we're looking for.
memset(mtpair,0,sizeof(mtpair));
for (;;) {
struct mntent *mtnext = mtpair + (mtcur==mtpair ? 1 : 0);
// Get next fstab entry
if (!getmntent_r(fstab, mtcur, bb_common_bufsiz1
+ (mtcur==mtpair ? sizeof(bb_common_bufsiz1)/2 : 0),
sizeof(bb_common_bufsiz1)/2))
{
// Were we looking for something specific?
if (optind != argc) {
// If we didn't find anything, complain.
if (!mtnext->mnt_fsname)
bb_error_msg_and_die("Can't find %s in %s",
argv[optind], fstabname);
// Mount the last thing we found.
mtcur = mtnext;
mtcur->mnt_opts=bb_xstrdup(mtcur->mnt_opts);
append_mount_options(&(mtcur->mnt_opts),cmdopts);
rc = singlemount(mtcur, 0);
free(mtcur->mnt_opts);
}
goto clean_up;
}
/* If we're trying to mount something specific and this isn't it,
* skip it. Note we must match both the exact text in fstab (ala
* "proc") or a full path from root */
if (optind != argc) {
// Is this what we're looking for?
if(strcmp(argv[optind],mtcur->mnt_fsname) &&
strcmp(storage_path,mtcur->mnt_fsname) &&
strcmp(argv[optind],mtcur->mnt_dir) &&
strcmp(storage_path,mtcur->mnt_dir)) continue;
// Remember this entry. Something later may have overmounted
// it, and we want the _last_ match.
mtcur = mtnext;
// If we're mounting all.
} else {
// Do we need to match a filesystem type?
if (fstype && strcmp(mtcur->mnt_type,fstype)) continue;
// Skip noauto and swap anyway.
if (parse_mount_options(mtcur->mnt_opts,0)
& (MOUNT_NOAUTO | MOUNT_SWAP)) continue;
// Mount this thing.
if (singlemount(mtcur, 1)) {
/* Count number of failed mounts */
rc++;
}
}
}
if (ENABLE_FEATURE_CLEAN_UP) endmntent(fstab);
clean_up:
if (ENABLE_FEATURE_CLEAN_UP) {
free(storage_path);
free(cmdopts);
}
return rc;
}