mount.c

Util-linux 软件包包含许多工具。其中比较重要的是加载、卸载、格式化、分区和管理硬盘驱动器

	return (stat(s, &statbuf) == 0);
}

/*
 * Return 0 for success (either mounted sth or -a and NOAUTO was given)
 */
static int
mount_one (const char *spec, const char *node, const char *types,
	   const char *opts, char *cmdlineopts, int freq, int pass) {
	int status, status2;
	const char *nspec;

	/* Substitute values in opts, if required */
	opts = usersubst(opts);

	/* Merge the fstab and command line options.  */
	if (opts == NULL)
		opts = cmdlineopts;
	else if (cmdlineopts != NULL)
		opts = xstrconcat3(opts, ",", cmdlineopts);

	/* Handle possible LABEL= and UUID= forms of spec */
	nspec = mount_get_devname_for_mounting(spec);
	if (nspec)
		spec = nspec;

	if (types == NULL && !mounttype && !is_existing_file(spec)) {
		if (strchr (spec, ':') != NULL) {
			types = "nfs";
			if (verbose)
				printf(_("mount: no type was given - "
					 "I'll assume nfs because of "
					 "the colon\n"));
		} else if(!strncmp(spec, "//", 2)) {
			types = "smbfs";
			if (verbose)
				printf(_("mount: no type was given - "
					 "I'll assume smbfs because of "
					 "the // prefix\n"));
		}
	}

	/*
	 * Try to mount the file system. When the exit status is EX_BG,
	 * we will retry in the background. Otherwise, we're done.
	 */
	status = try_mount_one (spec, node, types, opts, freq, pass, 0, 0);
	if (status != EX_BG)
		return status;

	/*
	 * Retry in the background.
	 */
	printf (_("mount: backgrounding \"%s\"\n"), spec);
	fflush( stdout );		/* prevent duplicate output */
	if (fork() > 0)
		return 0;			/* parent returns "success" */
	spec = xstrdup(spec);		/* arguments will be destroyed */
	node = xstrdup(node);		/* by set_proc_name()          */
	types = xstrdup(types);
	opts = xstrdup(opts);
	set_proc_name (spec);		/* make a nice "ps" listing */
	status2 = try_mount_one (spec, node, types, opts, freq, pass, 1, 0);
	if (verbose && status2)
		printf (_("mount: giving up \"%s\"\n"), spec);
	exit (0);			/* child stops here */
}

/* Check if an fsname/dir pair was already in the old mtab.  */
static int
mounted (const char *spec0, const char *node0) {
	struct mntentchn *mc, *mc0;
	char *spec, *node;
	int ret = 0;

	/* Handle possible UUID= and LABEL= in spec */
	spec0 = mount_get_devname(spec0);
	if (!spec0)
		return ret;

	spec = canonicalize(spec0);
	node = canonicalize(node0);

	mc0 = mtab_head();
	for (mc = mc0->nxt; mc && mc != mc0; mc = mc->nxt)
		if (streq (spec, mc->m.mnt_fsname) &&
		    streq (node, mc->m.mnt_dir)) {
			ret = 1;
			break;
		}

	my_free(spec);
	my_free(node);

	return ret;
}

/* avoid using stat() on things we are not going to mount anyway.. */
static int
has_noauto (const char *opts) {
	char *s;

	if (!opts)
		return 0;
	s = strstr(opts, "noauto");
	if (!s)
		return 0;
	return (s == opts || s[-1] == ',') && (s[6] == 0 || s[6] == ',');
}

/* Mount all filesystems of the specified types except swap and root.  */
/* With the --fork option: fork and let different incarnations of
   mount handle different filesystems.  However, try to avoid several
   simultaneous mounts on the same physical disk, since that is very slow. */
#define DISKMAJOR(m)	(((int) m) & ~0xf)

static int
do_mount_all (char *types, char *options, char *test_opts) {
	struct mntentchn *mc, *mc0, *mtmp;
	int status = 0;
	struct stat statbuf;
	struct child {
		pid_t pid;
		char *group;
		struct mntentchn *mec;
		struct mntentchn *meclast;
		struct child *nxt;
	} childhead, *childtail, *cp;
	char major[22];
	char *g, *colon;

	/* build a chain of what we have to do, or maybe
	   several chains, one for each major or NFS host */
	childhead.nxt = 0;
	childtail = &childhead;
	mc0 = fstab_head();
	for (mc = mc0->nxt; mc && mc != mc0; mc = mc->nxt) {
		if (has_noauto (mc->m.mnt_opts))
			continue;
		if (matching_type (mc->m.mnt_type, types)
		    && matching_opts (mc->m.mnt_opts, test_opts)
		    && !streq (mc->m.mnt_dir, "/")
		    && !streq (mc->m.mnt_dir, "root")) {

			if (mounted (mc->m.mnt_fsname, mc->m.mnt_dir)) {
				if (verbose)
					printf(_("mount: %s already mounted "
						 "on %s\n"),
					       mc->m.mnt_fsname,
					       mc->m.mnt_dir);
				continue;
			}

			mtmp = (struct mntentchn *) xmalloc(sizeof(*mtmp));
			*mtmp = *mc;
			mtmp->nxt = 0;
			g = NULL;
			if (optfork) {
				if (stat(mc->m.mnt_fsname, &statbuf) == 0 &&
				    S_ISBLK(statbuf.st_mode)) {
					sprintf(major, "#%x",
						DISKMAJOR(statbuf.st_rdev));
					g = major;
				}
#ifdef HAVE_NFS
				if (strcmp(mc->m.mnt_type, "nfs") == 0) {
					g = xstrdup(mc->m.mnt_fsname);
					colon = strchr(g, ':');
					if (colon)
						*colon = '\0';
				}
#endif
			}
			if (g) {
				for (cp = childhead.nxt; cp; cp = cp->nxt)
					if (cp->group &&
					    strcmp(cp->group, g) == 0) {
						cp->meclast->nxt = mtmp;
						cp->meclast = mtmp;
						goto fnd;
					}
			}
			cp = (struct child *) xmalloc(sizeof *cp);
			cp->nxt = 0;
			cp->mec = cp->meclast = mtmp;
			cp->group = xstrdup(g);
			cp->pid = 0;
			childtail->nxt = cp;
			childtail = cp;
		fnd:;

		}
	}
			      
	/* now do everything */
	for (cp = childhead.nxt; cp; cp = cp->nxt) {
		pid_t p = -1;
		if (optfork) {
			p = fork();
			if (p == -1) {
				int errsv = errno;
				error(_("mount: cannot fork: %s"),
				      strerror (errsv));
			}
			else if (p != 0)
				cp->pid = p;
		}

		/* if child, or not forked, do the mounting */
		if (p == 0 || p == -1) {
			for (mc = cp->mec; mc; mc = mc->nxt) {
				status |= mount_one (mc->m.mnt_fsname,
						     mc->m.mnt_dir,
						     mc->m.mnt_type,
						     mc->m.mnt_opts,
						     options, 0, 0);
			}
			if (mountcount)
				status |= EX_SOMEOK;
			if (p == 0)
				exit(status);
		}
	}

	/* wait for children, if any */
	while ((cp = childhead.nxt) != NULL) {
		childhead.nxt = cp->nxt;
		if (cp->pid) {
			int ret;
		keep_waiting:
			if(waitpid(cp->pid, &ret, 0) == -1) {
				if (errno == EINTR)
					goto keep_waiting;
				perror("waitpid");
			} else if (WIFEXITED(ret))
				status |= WEXITSTATUS(ret);
			else
				status |= EX_SYSERR;
		}
	}
	if (mountcount)
		status |= EX_SOMEOK;
	return status;
}

extern char version[];
static struct option longopts[] = {
	{ "all", 0, 0, 'a' },
	{ "fake", 0, 0, 'f' },
	{ "fork", 0, 0, 'F' },
	{ "help", 0, 0, 'h' },
	{ "no-mtab", 0, 0, 'n' },
	{ "read-only", 0, 0, 'r' },
	{ "ro", 0, 0, 'r' },
	{ "verbose", 0, 0, 'v' },
	{ "version", 0, 0, 'V' },
	{ "read-write", 0, 0, 'w' },
	{ "rw", 0, 0, 'w' },
	{ "options", 1, 0, 'o' },
	{ "test-opts", 1, 0, 'O' },
	{ "pass-fd", 1, 0, 'p' },
	{ "types", 1, 0, 't' },
	{ "bind", 0, 0, 128 },
	{ "replace", 0, 0, 129 },
	{ "after", 0, 0, 130 },
	{ "before", 0, 0, 131 },
	{ "over", 0, 0, 132 },
	{ "move", 0, 0, 133 },
	{ "guess-fstype", 1, 0, 134 },
	{ "rbind", 0, 0, 135 },
	{ "internal-only", 0, 0, 'i' },
	{ NULL, 0, 0, 0 }
};

/* Keep the usage message at max 22 lines, each at most 70 chars long.
   The user should not need a pager to read it. */
static void
usage (FILE *fp, int n) {
	fprintf(fp, _(
	  "Usage: mount -V                 : print version\n"
	  "       mount -h                 : print this help\n"
	  "       mount                    : list mounted filesystems\n"
	  "       mount -l                 : idem, including volume labels\n"
	  "So far the informational part. Next the mounting.\n"
	  "The command is `mount [-t fstype] something somewhere'.\n"
	  "Details found in /etc/fstab may be omitted.\n"
	  "       mount -a [-t|-O] ...     : mount all stuff from /etc/fstab\n"
	  "       mount device             : mount device at the known place\n"
	  "       mount directory          : mount known device here\n"
	  "       mount -t type dev dir    : ordinary mount command\n"
	  "Note that one does not really mount a device, one mounts\n"
	  "a filesystem (of the given type) found on the device.\n"
	  "One can also mount an already visible directory tree elsewhere:\n"
	  "       mount --bind olddir newdir\n"
	  "or move a subtree:\n"
	  "       mount --move olddir newdir\n"
	  "A device can be given by name, say /dev/hda1 or /dev/cdrom,\n"
	  "or by label, using  -L label  or by uuid, using  -U uuid .\n"
	  "Other options: [-nfFrsvw] [-o options] [-p passwdfd].\n"
	  "For many more details, say  man 8 mount .\n"
	));
/*
	  "Union or stack mounts are specified using one of\n"
	  "       --replace, --after, --before, --over\n"
*/
	unlock_mtab();
	exit (n);
}

char *progname;

int
main(int argc, char *argv[]) {
	int c, result = 0, specseen;
	char *options = NULL, *test_opts = NULL, *node;
	const char *spec;
	char *volumelabel = NULL;
	char *uuid = NULL;
	char *types = NULL;
	char *p;
	struct mntentchn *mc;
	int fd;

	sanitize_env();
	setlocale(LC_ALL, "");
	bindtextdomain(PACKAGE, LOCALEDIR);
	textdomain(PACKAGE);

	progname = argv[0];
	if ((p = strrchr(progname, '/')) != NULL)
		progname = p+1;

	umask(033);

	/* People report that a mount called from init without console
	   writes error messages to /etc/mtab
	   Let us try to avoid getting fd's 0,1,2 */
	while((fd = open("/dev/null", O_RDWR)) == 0 || fd == 1 || fd == 2) ;
	if (fd > 2)
		close(fd);

	mount_blkid_get_cache();

#ifdef DO_PS_FIDDLING
	initproctitle(argc, argv);
#endif

	while ((c = getopt_long (argc, argv, "afFhilL:no:O:p:rsU:vVwt:",
				 longopts, NULL)) != -1) {
		switch (c) {
		case 'a':	       /* mount everything in fstab */
			++mount_all;
			break;
		case 'f':	       /* fake: don't actually call mount(2) */
			++fake;
			break;
		case 'F':
			++optfork;
			break;
		case 'h':		/* help */
			usage (stdout, 0);
			break;
		case 'i':
			external_allowed = 0;
			break;
		case 'l':
			list_with_volumelabel = 1;
			break;
		case 'L':
			volumelabel = optarg;
			break;
		case 'n':		/* do not write /etc/mtab */
			++nomtab;
			break;
		case 'o':		/* specify mount options */
			if (options)
				options = xstrconcat3(options, ",", optarg);
			else
				options = xstrdup(optarg);
			break;
		case 'O':		/* with -t: mount only if (not) opt */
			if (test_opts)
				test_opts = xstrconcat3(test_opts, ",", optarg);
			else
				test_opts = xstrdup(optarg);
			break;
		case 'p':		/* fd on which to read passwd */
			set_pfd(optarg);
			break;
		case 'r':		/* mount readonly */
			readonly = 1;
			readwrite = 0;
			break;
		case 's':		/* allow sloppy mount options */
			sloppy = 1;
			break;
		case 't':		/* specify file system types */
			types = optarg;
			break;
		case 'U':
			uuid = optarg;
			break;
		case 'v':		/* be chatty - more so if repeated */
			++verbose;
			break;
		case 'V':		/* version */
			printf ("mount: %s\n", version);
			exit (0);
		case 'w':		/* mount read/write */
			readwrite = 1;
			readonly = 0;
			break;
		case 0:
			break;

		case 128: /* bind */
			mounttype = MS_BIND;
			break;
		case 129: /* replace */
			mounttype = MS_REPLACE;
			break;
		case 130: /* after */
			mounttype = MS_AFTER;
			break;
		case 131: /* before */
			mounttype = MS_BEFORE;
			break;
		case 132: /* over */
			mounttype = MS_OVER;
			break;
		case 133: /* move */
			mounttype = MS_MOVE;
			break;
		case 134:
			/* undocumented, may go away again:
			   call: mount --guess-fstype device
			   use only for testing purposes -
			   the guessing is not reliable at all */
		    {
			char *fstype;
			fstype = do_guess_fstype(optarg);
			printf("%s\n", fstype ? fstype : "unknown");
			exit(fstype ? 0 : EX_FAIL);
		    }
		case 135:
			mounttype = (MS_BIND | MS_REC);
			break;
		case '?':
		default:
			usage (stderr, EX_USAGE);
		}
	}

	argc -= optind;
	argv += optind;

	specseen = (uuid || volumelabel) ? 1 : 0; 	/* yes, .. i know */

	if (argc+specseen == 0 && !mount_all) {
		if (options || mounttype)
			usage (stderr, EX_USAGE);
		return print_all (types);
	}

	if (getuid () != geteuid ()) {
		suid = 1;
		if (types || options || readwrite || nomtab || mount_all ||
		    fake || mounttype || (argc + specseen) != 1)
			die (EX_USAGE, _("mount: only root can do that"));
	}

	if (!nomtab && mtab_does_not_exist()) {
		if (verbose > 1)
			printf(_("mount: no %s found - creating it..\n"),
			       MOUNTED);
		create_mtab ();
	}

	if (specseen) {
		if (uuid)
			spec = mount_get_devname_by_uuid(uuid);
		else
			spec = mount_get_devname_by_label(volumelabel);

		if (!spec)
			die (EX_USAGE, _("mount: no such partition found"));
		if (verbose)
			printf(_("mount: mounting %s\n"), spec);
	} else
		spec = NULL;		/* just for gcc */

	switch (argc+specseen) {
	case 0:
		/* mount -a */
		result = do_mount_all (types, options, test_opts);
		if (result == 0 && verbose)
			error(_("nothing was mounted"));
		break;

	case 1:
		/* mount [-nfrvw] [-o options] special | node */
		if (types != NULL)
			usage (stderr, EX_USAGE);
		if (specseen) {
			/* We know the device. Where shall we mount it? */
			mc = (uuid ? getfsuuidspec (uuid)
			           : getfsvolspec (volumelabel));
			if (mc == NULL)
				mc = getfsspec (spec);
			if (mc == NULL)
				die (EX_USAGE,
				     _("mount: cannot find %s in %s"),
				     spec, _PATH_FSTAB);
			mc->m.mnt_fsname = spec;
		} else {
			/* Try to find the other pathname in fstab.  */
			spec = canonicalize (*argv);
			if ((mc = getfsspec (spec)) == NULL &&
			    (mc = getfsfile (spec)) == NULL &&
			    /* Try noncanonical name in fstab
			       perhaps /dev/cdrom or /dos is a symlink */
			    (mc = getfsspec (*argv)) == NULL &&
			    (mc = getfsfile (*argv)) == NULL &&
			    /* Try mtab - maybe this was a remount */
			    (mc = getmntfile (spec)) == NULL)
				die (EX_USAGE,
				     _("mount: can't find %s in %s or %s"),
				     spec, _PATH_FSTAB, MOUNTED);
			/* Earlier mtab was tried first, but this would
			   sometimes try the wrong mount in case mtab had
			   the root device entry wrong. */

			my_free(spec);
		}

		result = mount_one (xstrdup (mc->m.mnt_fsname),
				    xstrdup (mc->m.mnt_dir),
				    xstrdup (mc->m.mnt_type),
				    mc->m.mnt_opts, options, 0, 0);
		break;

	case 2:
		/* mount [-nfrvw] [-t vfstype] [-o options] special node */
		if (specseen) {
			/* we have spec already */
			node = argv[0];
		} else {
			spec = argv[0];
			node = argv[1];
		}
		result = mount_one (spec, node, types, NULL, options, 0, 0);
		break;
      
	default:
		usage (stderr, EX_USAGE);
	}

	if (result == EX_SOMEOK)
		result = 0;

	mount_blkid_put_cache();

	exit (result);
}