lib/mount_util.c - platform/external/libfuse - Gitiles

 /*
   FUSE: Filesystem in Userspace
   Copyright (C) 2001-2007  Miklos Szeredi <miklos@szeredi.hu>

   Architecture-independent mounting code.

   This program can be distributed under the terms of the GNU LGPLv2.
   See the file COPYING.LIB.
 */

 #include "config.h"
 #include "mount_util.h"
 #include <stdio.h>
 #include <unistd.h>
 #include <stdlib.h>
 #include <string.h>
 #include <signal.h>
 #include <dirent.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <limits.h>
 #include <paths.h>
 #ifndef __NetBSD__
 #include <mntent.h>
 #endif
 #include <sys/stat.h>
 #include <sys/wait.h>
 #include <sys/mount.h>
 #include <sys/param.h>

 #ifdef __NetBSD__
 #define umount2(mnt, flags) unmount(mnt, (flags == 2) ? MNT_FORCE : 0)
 #endif

 #ifdef IGNORE_MTAB
 #define mtab_needs_update(mnt) 0
 #else
 static int mtab_needs_update(const char *mnt)
 {
 	int res;
 	struct stat stbuf;

 	/* If mtab is within new mount, don't touch it */
 	if (strncmp(mnt, _PATH_MOUNTED, strlen(mnt)) == 0 &&
 	    _PATH_MOUNTED[strlen(mnt)] == '/')
 		return 0;

 	/*
 	 * Skip mtab update if /etc/mtab:
 	 *
 	 *  - doesn't exist,
 	 *  - is a symlink,
 	 *  - is on a read-only filesystem.
 	 */
 	res = lstat(_PATH_MOUNTED, &stbuf);
 	if (res == -1) {
 		if (errno == ENOENT)
 			return 0;
 	} else {
 		uid_t ruid;
 		int err;

 		if (S_ISLNK(stbuf.st_mode))
 			return 0;

 		ruid = getuid();
 		if (ruid != 0)
 			setreuid(0, -1);

 		res = access(_PATH_MOUNTED, W_OK);
 		err = (res == -1) ? errno : 0;
 		if (ruid != 0)
 			setreuid(ruid, -1);

 		if (err == EROFS)
 			return 0;
 	}

 	return 1;
 }
 #endif /* IGNORE_MTAB */

 static int add_mount(const char *progname, const char *fsname,
 		       const char *mnt, const char *type, const char *opts)
 {
 	int res;
 	int status;
 	sigset_t blockmask;
 	sigset_t oldmask;

 	sigemptyset(&blockmask);
 	sigaddset(&blockmask, SIGCHLD);
 	res = sigprocmask(SIG_BLOCK, &blockmask, &oldmask);
 	if (res == -1) {
 		fprintf(stderr, "%s: sigprocmask: %s\n", progname, strerror(errno));
 		return -1;
 	}

 	res = fork();
 	if (res == -1) {
 		fprintf(stderr, "%s: fork: %s\n", progname, strerror(errno));
 		goto out_restore;
 	}
 	if (res == 0) {
 		char *env = NULL;

 		sigprocmask(SIG_SETMASK, &oldmask, NULL);

 		if(setuid(geteuid()) == -1) {
 			fprintf(stderr, "%s: setuid: %s\n", progname, strerror(errno));
 			res = -1;
 			goto out_restore;
 		}

 		execle("/bin/mount", "/bin/mount", "--no-canonicalize", "-i",
 		       "-f", "-t", type, "-o", opts, fsname, mnt, NULL, &env);
 		fprintf(stderr, "%s: failed to execute /bin/mount: %s\n",
 			progname, strerror(errno));
 		exit(1);
 	}
 	res = waitpid(res, &status, 0);
 	if (res == -1)
 		fprintf(stderr, "%s: waitpid: %s\n", progname, strerror(errno));

 	if (status != 0)
 		res = -1;

  out_restore:
 	sigprocmask(SIG_SETMASK, &oldmask, NULL);

 	return res;
 }

 int fuse_mnt_add_mount(const char *progname, const char *fsname,
 		       const char *mnt, const char *type, const char *opts)
 {
 	if (!mtab_needs_update(mnt))
 		return 0;

 	return add_mount(progname, fsname, mnt, type, opts);
 }

 static int exec_umount(const char *progname, const char *rel_mnt, int lazy)
 {
 	int res;
 	int status;
 	sigset_t blockmask;
 	sigset_t oldmask;

 	sigemptyset(&blockmask);
 	sigaddset(&blockmask, SIGCHLD);
 	res = sigprocmask(SIG_BLOCK, &blockmask, &oldmask);
 	if (res == -1) {
 		fprintf(stderr, "%s: sigprocmask: %s\n", progname, strerror(errno));
 		return -1;
 	}

 	res = fork();
 	if (res == -1) {
 		fprintf(stderr, "%s: fork: %s\n", progname, strerror(errno));
 		goto out_restore;
 	}
 	if (res == 0) {
 		char *env = NULL;

 		sigprocmask(SIG_SETMASK, &oldmask, NULL);

 		if(setuid(geteuid()) == -1) {
 			fprintf(stderr, "%s: setuid: %s\n", progname, strerror(errno));
 			res = -1;
 			goto out_restore;
 		}

 		if (lazy) {
 			execle("/bin/umount", "/bin/umount", "-i", rel_mnt,
 			       "-l", NULL, &env);
 		} else {
 			execle("/bin/umount", "/bin/umount", "-i", rel_mnt,
 			       NULL, &env);
 		}
 		fprintf(stderr, "%s: failed to execute /bin/umount: %s\n",
 			progname, strerror(errno));
 		exit(1);
 	}
 	res = waitpid(res, &status, 0);
 	if (res == -1)
 		fprintf(stderr, "%s: waitpid: %s\n", progname, strerror(errno));

 	if (status != 0) {
 		res = -1;
 	}

  out_restore:
 	sigprocmask(SIG_SETMASK, &oldmask, NULL);
 	return res;

 }

 int fuse_mnt_umount(const char *progname, const char *abs_mnt,
 		    const char *rel_mnt, int lazy)
 {
 	int res;

 	if (!mtab_needs_update(abs_mnt)) {
 		res = umount2(rel_mnt, lazy ? 2 : 0);
 		if (res == -1)
 			fprintf(stderr, "%s: failed to unmount %s: %s\n",
 				progname, abs_mnt, strerror(errno));
 		return res;
 	}

 	return exec_umount(progname, rel_mnt, lazy);
 }

 static int remove_mount(const char *progname, const char *mnt)
 {
 	int res;
 	int status;
 	sigset_t blockmask;
 	sigset_t oldmask;

 	sigemptyset(&blockmask);
 	sigaddset(&blockmask, SIGCHLD);
 	res = sigprocmask(SIG_BLOCK, &blockmask, &oldmask);
 	if (res == -1) {
 		fprintf(stderr, "%s: sigprocmask: %s\n", progname, strerror(errno));
 		return -1;
 	}

 	res = fork();
 	if (res == -1) {
 		fprintf(stderr, "%s: fork: %s\n", progname, strerror(errno));
 		goto out_restore;
 	}
 	if (res == 0) {
 		char *env = NULL;

 		sigprocmask(SIG_SETMASK, &oldmask, NULL);

 		if(setuid(geteuid()) == -1) {
 			fprintf(stderr, "%s: setuid: %s\n", progname, strerror(errno));
 			res = -1;
 			goto out_restore;
 		}

 		execle("/bin/umount", "/bin/umount", "--no-canonicalize", "-i",
 		       "--fake", mnt, NULL, &env);
 		fprintf(stderr, "%s: failed to execute /bin/umount: %s\n",
 			progname, strerror(errno));
 		exit(1);
 	}
 	res = waitpid(res, &status, 0);
 	if (res == -1)
 		fprintf(stderr, "%s: waitpid: %s\n", progname, strerror(errno));

 	if (status != 0)
 		res = -1;

  out_restore:
 	sigprocmask(SIG_SETMASK, &oldmask, NULL);
 	return res;
 }

 int fuse_mnt_remove_mount(const char *progname, const char *mnt)
 {
 	if (!mtab_needs_update(mnt))
 		return 0;

 	return remove_mount(progname, mnt);
 }

 char *fuse_mnt_resolve_path(const char *progname, const char *orig)
 {
 	char buf[PATH_MAX];
 	char *copy;
 	char *dst;
 	char *end;
 	char *lastcomp;
 	const char *toresolv;

 	if (!orig[0]) {
 		fprintf(stderr, "%s: invalid mountpoint '%s'\n", progname,
 			orig);
 		return NULL;
 	}

 	copy = strdup(orig);
 	if (copy == NULL) {
 		fprintf(stderr, "%s: failed to allocate memory\n", progname);
 		return NULL;
 	}

 	toresolv = copy;
 	lastcomp = NULL;
 	for (end = copy + strlen(copy) - 1; end > copy && *end == '/'; end --);
 	if (end[0] != '/') {
 		char *tmp;
 		end[1] = '\0';
 		tmp = strrchr(copy, '/');
 		if (tmp == NULL) {
 			lastcomp = copy;
 			toresolv = ".";
 		} else {
 			lastcomp = tmp + 1;
 			if (tmp == copy)
 				toresolv = "/";
 		}
 		if (strcmp(lastcomp, ".") == 0 || strcmp(lastcomp, "..") == 0) {
 			lastcomp = NULL;
 			toresolv = copy;
 		}
 		else if (tmp)
 			tmp[0] = '\0';
 	}
 	if (realpath(toresolv, buf) == NULL) {
 		fprintf(stderr, "%s: bad mount point %s: %s\n", progname, orig,
 			strerror(errno));
 		free(copy);
 		return NULL;
 	}
 	if (lastcomp == NULL)
 		dst = strdup(buf);
 	else {
 		dst = (char *) malloc(strlen(buf) + 1 + strlen(lastcomp) + 1);
 		if (dst) {
 			unsigned buflen = strlen(buf);
 			if (buflen && buf[buflen-1] == '/')
 				sprintf(dst, "%s%s", buf, lastcomp);
 			else
 				sprintf(dst, "%s/%s", buf, lastcomp);
 		}
 	}
 	free(copy);
 	if (dst == NULL)
 		fprintf(stderr, "%s: failed to allocate memory\n", progname);
 	return dst;
 }

 int fuse_mnt_check_fuseblk(void)
 {
 	char buf[256];
 	FILE *f = fopen("/proc/filesystems", "r");
 	if (!f)
 		return 1;

 	while (fgets(buf, sizeof(buf), f))
 		if (strstr(buf, "fuseblk\n")) {
 			fclose(f);
 			return 1;
 		}

 	fclose(f);
 	return 0;
 }
	/*
	FUSE: Filesystem in Userspace
	Copyright (C) 2001-2007 Miklos Szeredi <miklos@szeredi.hu>

	Architecture-independent mounting code.

	This program can be distributed under the terms of the GNU LGPLv2.
	See the file COPYING.LIB.
	*/

	#include "config.h"
	#include "mount_util.h"
	#include <stdio.h>
	#include <unistd.h>
	#include <stdlib.h>
	#include <string.h>
	#include <signal.h>
	#include <dirent.h>
	#include <errno.h>
	#include <fcntl.h>
	#include <limits.h>
	#include <paths.h>
	#ifndef __NetBSD__
	#include <mntent.h>
	#endif
	#include <sys/stat.h>
	#include <sys/wait.h>
	#include <sys/mount.h>
	#include <sys/param.h>

	#ifdef __NetBSD__
	#define umount2(mnt, flags) unmount(mnt, (flags == 2) ? MNT_FORCE : 0)
	#endif

	#ifdef IGNORE_MTAB
	#define mtab_needs_update(mnt) 0
	#else
	static int mtab_needs_update(const char *mnt)
	{
	int res;
	struct stat stbuf;

	/* If mtab is within new mount, don't touch it */
	if (strncmp(mnt, _PATH_MOUNTED, strlen(mnt)) == 0 &&
	_PATH_MOUNTED[strlen(mnt)] == '/')
	return 0;

	/*
	* Skip mtab update if /etc/mtab:
	*
	* - doesn't exist,
	* - is a symlink,
	* - is on a read-only filesystem.
	*/
	res = lstat(_PATH_MOUNTED, &stbuf);
	if (res == -1) {
	if (errno == ENOENT)
	return 0;
	} else {
	uid_t ruid;
	int err;

	if (S_ISLNK(stbuf.st_mode))
	return 0;

	ruid = getuid();
	if (ruid != 0)
	setreuid(0, -1);

	res = access(_PATH_MOUNTED, W_OK);
	err = (res == -1) ? errno : 0;
	if (ruid != 0)
	setreuid(ruid, -1);

	if (err == EROFS)
	return 0;
	}

	return 1;
	}
	#endif /* IGNORE_MTAB */

	static int add_mount(const char progname, const char fsname,
	const char mnt, const char type, const char *opts)
	{
	int res;
	int status;
	sigset_t blockmask;
	sigset_t oldmask;

	sigemptyset(&blockmask);
	sigaddset(&blockmask, SIGCHLD);
	res = sigprocmask(SIG_BLOCK, &blockmask, &oldmask);
	if (res == -1) {
	fprintf(stderr, "%s: sigprocmask: %s\n", progname, strerror(errno));
	return -1;
	}

	res = fork();
	if (res == -1) {
	fprintf(stderr, "%s: fork: %s\n", progname, strerror(errno));
	goto out_restore;
	}
	if (res == 0) {
	char *env = NULL;

	sigprocmask(SIG_SETMASK, &oldmask, NULL);

	if(setuid(geteuid()) == -1) {
	fprintf(stderr, "%s: setuid: %s\n", progname, strerror(errno));
	res = -1;
	goto out_restore;
	}

	execle("/bin/mount", "/bin/mount", "--no-canonicalize", "-i",
	"-f", "-t", type, "-o", opts, fsname, mnt, NULL, &env);
	fprintf(stderr, "%s: failed to execute /bin/mount: %s\n",
	progname, strerror(errno));
	exit(1);
	}
	res = waitpid(res, &status, 0);
	if (res == -1)
	fprintf(stderr, "%s: waitpid: %s\n", progname, strerror(errno));

	if (status != 0)
	res = -1;

	out_restore:
	sigprocmask(SIG_SETMASK, &oldmask, NULL);

	return res;
	}

	int fuse_mnt_add_mount(const char progname, const char fsname,
	const char mnt, const char type, const char *opts)
	{
	if (!mtab_needs_update(mnt))
	return 0;

	return add_mount(progname, fsname, mnt, type, opts);
	}

	static int exec_umount(const char progname, const char rel_mnt, int lazy)
	{
	int res;
	int status;
	sigset_t blockmask;
	sigset_t oldmask;

	sigemptyset(&blockmask);
	sigaddset(&blockmask, SIGCHLD);
	res = sigprocmask(SIG_BLOCK, &blockmask, &oldmask);
	if (res == -1) {
	fprintf(stderr, "%s: sigprocmask: %s\n", progname, strerror(errno));
	return -1;
	}

	res = fork();
	if (res == -1) {
	fprintf(stderr, "%s: fork: %s\n", progname, strerror(errno));
	goto out_restore;
	}
	if (res == 0) {
	char *env = NULL;

	sigprocmask(SIG_SETMASK, &oldmask, NULL);

	if(setuid(geteuid()) == -1) {
	fprintf(stderr, "%s: setuid: %s\n", progname, strerror(errno));
	res = -1;
	goto out_restore;
	}

	if (lazy) {
	execle("/bin/umount", "/bin/umount", "-i", rel_mnt,
	"-l", NULL, &env);
	} else {
	execle("/bin/umount", "/bin/umount", "-i", rel_mnt,
	NULL, &env);
	}
	fprintf(stderr, "%s: failed to execute /bin/umount: %s\n",
	progname, strerror(errno));
	exit(1);
	}
	res = waitpid(res, &status, 0);
	if (res == -1)
	fprintf(stderr, "%s: waitpid: %s\n", progname, strerror(errno));

	if (status != 0) {
	res = -1;
	}

	out_restore:
	sigprocmask(SIG_SETMASK, &oldmask, NULL);
	return res;

	}

	int fuse_mnt_umount(const char progname, const char abs_mnt,
	const char *rel_mnt, int lazy)
	{
	int res;

	if (!mtab_needs_update(abs_mnt)) {
	res = umount2(rel_mnt, lazy ? 2 : 0);
	if (res == -1)
	fprintf(stderr, "%s: failed to unmount %s: %s\n",
	progname, abs_mnt, strerror(errno));
	return res;
	}

	return exec_umount(progname, rel_mnt, lazy);
	}

	static int remove_mount(const char progname, const char mnt)
	{
	int res;
	int status;
	sigset_t blockmask;
	sigset_t oldmask;

	sigemptyset(&blockmask);
	sigaddset(&blockmask, SIGCHLD);
	res = sigprocmask(SIG_BLOCK, &blockmask, &oldmask);
	if (res == -1) {
	fprintf(stderr, "%s: sigprocmask: %s\n", progname, strerror(errno));
	return -1;
	}

	res = fork();
	if (res == -1) {
	fprintf(stderr, "%s: fork: %s\n", progname, strerror(errno));
	goto out_restore;
	}
	if (res == 0) {
	char *env = NULL;

	sigprocmask(SIG_SETMASK, &oldmask, NULL);

	if(setuid(geteuid()) == -1) {
	fprintf(stderr, "%s: setuid: %s\n", progname, strerror(errno));
	res = -1;
	goto out_restore;
	}

	execle("/bin/umount", "/bin/umount", "--no-canonicalize", "-i",
	"--fake", mnt, NULL, &env);
	fprintf(stderr, "%s: failed to execute /bin/umount: %s\n",
	progname, strerror(errno));
	exit(1);
	}
	res = waitpid(res, &status, 0);
	if (res == -1)
	fprintf(stderr, "%s: waitpid: %s\n", progname, strerror(errno));

	if (status != 0)
	res = -1;

	out_restore:
	sigprocmask(SIG_SETMASK, &oldmask, NULL);
	return res;
	}

	int fuse_mnt_remove_mount(const char progname, const char mnt)
	{
	if (!mtab_needs_update(mnt))
	return 0;

	return remove_mount(progname, mnt);
	}

	char fuse_mnt_resolve_path(const char progname, const char *orig)
	{
	char buf[PATH_MAX];
	char *copy;
	char *dst;
	char *end;
	char *lastcomp;
	const char *toresolv;

	if (!orig[0]) {
	fprintf(stderr, "%s: invalid mountpoint '%s'\n", progname,
	orig);
	return NULL;
	}

	copy = strdup(orig);
	if (copy == NULL) {
	fprintf(stderr, "%s: failed to allocate memory\n", progname);
	return NULL;
	}

	toresolv = copy;
	lastcomp = NULL;
	for (end = copy + strlen(copy) - 1; end > copy && *end == '/'; end --);
	if (end[0] != '/') {
	char *tmp;
	end[1] = '\0';
	tmp = strrchr(copy, '/');
	if (tmp == NULL) {
	lastcomp = copy;
	toresolv = ".";
	} else {
	lastcomp = tmp + 1;
	if (tmp == copy)
	toresolv = "/";
	}
	if (strcmp(lastcomp, ".") == 0 \|\| strcmp(lastcomp, "..") == 0) {
	lastcomp = NULL;
	toresolv = copy;
	}
	else if (tmp)
	tmp[0] = '\0';
	}
	if (realpath(toresolv, buf) == NULL) {
	fprintf(stderr, "%s: bad mount point %s: %s\n", progname, orig,
	strerror(errno));
	free(copy);
	return NULL;
	}
	if (lastcomp == NULL)
	dst = strdup(buf);
	else {
	dst = (char *) malloc(strlen(buf) + 1 + strlen(lastcomp) + 1);
	if (dst) {
	unsigned buflen = strlen(buf);
	if (buflen && buf[buflen-1] == '/')
	sprintf(dst, "%s%s", buf, lastcomp);
	else
	sprintf(dst, "%s/%s", buf, lastcomp);
	}
	}
	free(copy);
	if (dst == NULL)
	fprintf(stderr, "%s: failed to allocate memory\n", progname);
	return dst;
	}

	int fuse_mnt_check_fuseblk(void)
	{
	char buf[256];
	FILE *f = fopen("/proc/filesystems", "r");
	if (!f)
	return 1;

	while (fgets(buf, sizeof(buf), f))
	if (strstr(buf, "fuseblk\n")) {
	fclose(f);
	return 1;
	}

	fclose(f);
	return 0;
	}