mount: (new) add --source and --target

In some cases (for example if only one mount argument is given) may be
mount request ambivalent:

	# mount /foo

and fstab:

	/dev/sda5	/foo	rw	0	0
	/foo		/bar	bind	0	0

the new options allows to be more explicit

        # mount --target /foo		(mounts /dev/sda5)

	# mount --source /foo		(binds /foo to /bar)

It's possible to use the options together

	# mount --source /dev/sda2 --target /home

Signed-off-by: Karel Zak <kzak@redhat.com>

1 files changed, 73 insertions, 25 deletions

diff --git a/sys-utils/mount.c b/sys-utils/mount.c
index 9116e8081..461569f2b 100644
--- a/sys-utils/mount.c
+++ b/sys-utils/mount.c
@@ -355,8 +355,19 @@ try_readonly:
 			warnx(_("%s is already mounted"), src);
 			return MOUNT_EX_USAGE;
 		case -MNT_ERR_NOFSTAB:
-			warnx(_("can't find %s in %s"), src ? src : tgt,
+			if (mnt_context_is_swapmatch(cxt)) {
+				warnx(_("can't find %s in %s"),
+						src ? src : tgt,
 						mnt_get_fstab_path());
+				return MOUNT_EX_USAGE;
+			}
+			/* source/target explicitly defined */
+			if (tgt)
+				warnx(_("can't find mountpoint %s in %s"),
+						tgt, mnt_get_fstab_path());
+			else
+				warnx(_("can't find mount source %s in %s"),
+						src, mnt_get_fstab_path());
 			return MOUNT_EX_USAGE;
 		case -MNT_ERR_NOFSTYPE:
 			if (restricted)
@@ -595,7 +606,7 @@ static void __attribute__((__noreturn__)) usage(FILE *out)
 	fprintf(out, _(
 		" %1$s [-lhV]\n"
 		" %1$s -a [options]\n"
-		" %1$s [options] <source> | <directory>\n"
+		" %1$s [options] [--source] <source> | [--target] <directory>\n"
 		" %1$s [options] <source> <directory>\n"
 		" %1$s <operation> <mountpoint> [<target>]\n"),
 		program_invocation_short_name);
@@ -619,6 +630,9 @@ static void __attribute__((__noreturn__)) usage(FILE *out)
 	" -r, --read-only         mount the filesystem read-only (same as -o ro)\n"
 	" -t, --types <list>      limit the set of filesystem types\n"));
 	fprintf(out, _(
+	"     --source <src>      explicitly specifies source (path, label, uuid)\n"
+	"     --target <target>   explicitly specifies mountpoint\n"));
+	fprintf(out, _(
 	" -v, --verbose           say what is being done\n"
 	" -V, --version           display version information and exit\n"
 	" -w, --read-write        mount the filesystem read-write (default)\n"));
@@ -667,7 +681,7 @@ int main(int argc, char **argv)
 	int c, rc = MOUNT_EX_SUCCESS, all = 0, show_labels = 0;
 	struct libmnt_context *cxt;
 	struct libmnt_table *fstab = NULL;
-	char *source = NULL, *srcbuf = NULL;
+	char *srcbuf = NULL;
 	char *types = NULL;
 	unsigned long oper = 0;
 
@@ -679,7 +693,9 @@ int main(int argc, char **argv)
 		MOUNT_OPT_RSHARED,
 		MOUNT_OPT_RSLAVE,
 		MOUNT_OPT_RPRIVATE,
-		MOUNT_OPT_RUNBINDABLE
+		MOUNT_OPT_RUNBINDABLE,
+		MOUNT_OPT_TARGET,
+		MOUNT_OPT_SOURCE
 	};
 
 	enum {
@@ -692,9 +708,12 @@ int main(int argc, char **argv)
 	        EXCL_MAKE_RSHARED,
 	        EXCL_MAKE_RSLAVE,
 	        EXCL_MAKE_RPRIVATE,
-	        EXCL_MAKE_RUNBINDABLE
+	        EXCL_MAKE_RUNBINDABLE,
+		EXCL_SOURCE,
+		EXCL_UUID,
+		EXCL_LABEL
 	};
-	int excl_any = EXCL_NONE;
+	int excl_any = EXCL_NONE, excl_src = EXCL_NONE;
 
 	static const struct option longopts[] = {
 		{ "all", 0, 0, 'a' },
@@ -729,6 +748,8 @@ int main(int argc, char **argv)
 		{ "no-canonicalize", 0, 0, 'c' },
 		{ "internal-only", 0, 0, 'i' },
 		{ "show-labels", 0, 0, 'l' },
+		{ "target", 1, 0, MOUNT_OPT_TARGET },
+		{ "source", 1, 0, MOUNT_OPT_SOURCE },
 		{ NULL, 0, 0, 0 }
 	};
 
@@ -749,7 +770,10 @@ int main(int argc, char **argv)
 					longopts, NULL)) != -1) {
 
 		/* only few options are allowed for non-root users */
-		if (mnt_context_is_restricted(cxt) && !strchr("hlLUVvpris", c))
+		if (mnt_context_is_restricted(cxt) &&
+		    !strchr("hlLUVvpris", c) &&
+		    c != MOUNT_OPT_TARGET &&
+		    c != MOUNT_OPT_SOURCE)
 			exit_non_root(option_to_longopt(c, longopts));
 
 		switch(c) {
@@ -803,13 +827,18 @@ int main(int argc, char **argv)
 					_("invalid passphrase file descriptor"));
 			break;
 		case 'L':
+			exclusive_option(&excl_src, EXCL_LABEL, _("-L, -U and --source"));
+			xasprintf(&srcbuf, "LABEL=\"%s\"", optarg);
+			mnt_context_disable_swapmatch(cxt, 1);
+			mnt_context_set_source(cxt, srcbuf);
+			free(srcbuf);
+			break;
 		case 'U':
-			if (source)
-				errx(MOUNT_EX_USAGE, _("only one <source> may be specified"));
-			if (xasprintf(&srcbuf, "%s=\"%s\"",
-				     c == 'L' ? "LABEL" : "UUID", optarg) <= 0)
-				err(MOUNT_EX_SYSERR, _("failed to allocate source buffer"));
-			source = srcbuf;
+			exclusive_option(&excl_src, EXCL_UUID, _("-L, -U and --source"));
+			xasprintf(&srcbuf, "UUID=\"%s\"", optarg);
+			mnt_context_disable_swapmatch(cxt, 1);
+			mnt_context_set_source(cxt, srcbuf);
+			free(srcbuf);
 			break;
 		case 'l':
 			show_labels = 1;
@@ -865,6 +894,15 @@ int main(int argc, char **argv)
 			exclusive_option(&excl_any, EXCL_MAKE_RUNBINDABLE, EXCL_ERROR);
 			oper |= (MS_UNBINDABLE | MS_REC);
 			break;
+		case MOUNT_OPT_TARGET:
+			mnt_context_disable_swapmatch(cxt, 1);
+			mnt_context_set_target(cxt, optarg);
+			break;
+		case MOUNT_OPT_SOURCE:
+			exclusive_option(&excl_src, EXCL_SOURCE, _("-L, -U and --source"));
+			mnt_context_disable_swapmatch(cxt, 1);
+			mnt_context_set_source(cxt, optarg);
+			break;
 		default:
 			usage(stderr);
 			break;
@@ -874,14 +912,17 @@ int main(int argc, char **argv)
 	argc -= optind;
 	argv += optind;
 
-	if (!source && !argc && !all) {
+	if (!mnt_context_get_source(cxt) &&
+	    !mnt_context_get_target(cxt) &&
+	    !argc &&
+	    !all) {
 		if (oper)
 			usage(stderr);
 		print_all(cxt, types, show_labels);
 		goto done;
 	}
 
-	if (oper && (types || all || source))
+	if (oper && (types || all || mnt_context_get_source(cxt)))
 		usage(stderr);
 
 	if (types && (all || strchr(types, ',') ||
@@ -899,25 +940,31 @@ int main(int argc, char **argv)
 		rc = mount_all(cxt);
 		goto done;
 
-	} else if (argc == 0 && source) {
+	} else if (argc == 0 && (mnt_context_get_source(cxt) ||
+				 mnt_context_get_target(cxt))) {
 		/*
-		 * B) mount -L|-U
+		 * B) mount -L|-U|--source|--target
 		 */
-		mnt_context_set_source(cxt, source);
+		if (mnt_context_is_restricted(cxt) &&
+		    mnt_context_get_source(cxt) &&
+		    mnt_context_get_target(cxt))
+			exit_non_root(NULL);
 
 	} else if (argc == 1) {
 		/*
-		 * C) mount [-L|-U] <target>
+		 * C) mount [-L|-U|--source] <target>
 		 *    mount <source|target>
+		 *
+		 * non-root may specify source *or* target, but not both
 		 */
-		if (source) {
-			if (mnt_context_is_restricted(cxt))
-				exit_non_root(NULL);
-			 mnt_context_set_source(cxt, source);
-		}
+		if (mnt_context_is_restricted(cxt) &&
+		    mnt_context_get_source(cxt))
+			exit_non_root(NULL);
+
 		mnt_context_set_target(cxt, argv[0]);
 
-	} else if (argc == 2 && !source) {
+	} else if (argc == 2 && !mnt_context_get_source(cxt)
+			     && !mnt_context_get_target(cxt)) {
 		/*
 		 * D) mount <source> <target>
 		 */
@@ -925,6 +972,7 @@ int main(int argc, char **argv)
 			exit_non_root(NULL);
 		mnt_context_set_source(cxt, argv[0]);
 		mnt_context_set_target(cxt, argv[1]);
+
 	} else
 		usage(stderr);