diff options
Diffstat (limited to 'fuse/mount_util.c')
| -rw-r--r-- | fuse/mount_util.c | 363 |
1 files changed, 363 insertions, 0 deletions
diff --git a/fuse/mount_util.c b/fuse/mount_util.c new file mode 100644 index 000000000..de1bd6714 --- /dev/null +++ b/fuse/mount_util.c @@ -0,0 +1,363 @@ +/* + FUSE: Filesystem in Userspace + Copyright (C) 2001-2007 Miklos Szeredi <miklos@szeredi.hu> + + This program can be distributed under the terms of the GNU LGPLv2. + See the file COPYING.LIB. +*/ + +#include "mount_util.h" +#include <stdio.h> +#include <unistd.h> +#include <stdlib.h> +#include <string.h> +#include <dirent.h> +#include <errno.h> +#include <fcntl.h> +#include <limits.h> +#include <mntent.h> +#include <sys/stat.h> +#include <sys/wait.h> +#include <sys/mount.h> +#include <sys/param.h> + +#include <paths.h> + +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 { + if (S_ISLNK(stbuf.st_mode)) + return 0; + + res = access(_PATH_MOUNTED, W_OK); + if (res == -1 && errno == EROFS) + return 0; + } + + return 1; +} + +static int add_mount_legacy(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 templ[] = "/tmp/fusermountXXXXXX"; + char *tmp; + + sigprocmask(SIG_SETMASK, &oldmask, NULL); + setuid(geteuid()); + + /* + * hide in a directory, where mount isn't able to resolve + * fsname as a valid path + */ + tmp = mkdtemp(templ); + if (!tmp) { + fprintf(stderr, + "%s: failed to create temporary directory\n", + progname); + exit(1); + } + if (chdir(tmp)) { + fprintf(stderr, "%s: failed to chdir to %s: %s\n", + progname, tmp, strerror(errno)); + exit(1); + } + rmdir(tmp); + execl("/bin/mount", "/bin/mount", "-i", "-f", "-t", type, + "-o", opts, fsname, mnt, NULL); + 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; +} + +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) { + /* + * Hide output, because old versions don't support + * --no-canonicalize + */ + int fd = open("/dev/null", O_RDONLY); + dup2(fd, 1); + dup2(fd, 2); + + sigprocmask(SIG_SETMASK, &oldmask, NULL); + setuid(geteuid()); + execl("/bin/mount", "/bin/mount", "--no-canonicalize", "-i", + "-f", "-t", type, "-o", opts, fsname, mnt, NULL); + 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) +{ + int res; + + if (!mtab_needs_update(mnt)) + return 0; + + res = add_mount(progname, fsname, mnt, type, opts); + if (res == -1) + res = add_mount_legacy(progname, fsname, mnt, type, opts); + + return res; +} + +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) { + sigprocmask(SIG_SETMASK, &oldmask, NULL); + setuid(geteuid()); + execl("/bin/umount", "/bin/umount", "-i", rel_mnt, + lazy ? "-l" : NULL, NULL); + 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); +} + +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_empty(const char *progname, const char *mnt, + mode_t rootmode, off64_t rootsize) +{ + int isempty = 1; + + if (S_ISDIR(rootmode)) { + struct dirent *ent; + DIR *dp = opendir(mnt); + if (dp == NULL) { + fprintf(stderr, + "%s: failed to open mountpoint for reading: %s\n", + progname, strerror(errno)); + return -1; + } + while ((ent = readdir(dp)) != NULL) { + if (strcmp(ent->d_name, ".") != 0 && + strcmp(ent->d_name, "..") != 0) { + isempty = 0; + break; + } + } + closedir(dp); + } else if (rootsize) + isempty = 0; + + if (!isempty) { + fprintf(stderr, "%s: mountpoint is not empty\n", progname); + fprintf(stderr, "%s: if you are sure this is safe, use the 'nonempty' mount option\n", progname); + return -1; + } + return 0; +} + +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; +} |