test-libmount: let's see how libmount parses stuff

With libmount-2.33.1-3.fc30.x86_64 I get:
/* test_libmount_unescaping_one escaped space + utf8 */
from '729 38 0:59 / /tmp/\342\200\236zupa\\040z\304\231bowa\342\200\235 rw,relatime shared:395 - tmpfs die\\040Br\303\274he rw,seclabel'
source: 'die Brühe'
source: 'die Br\303\274he'
source: 'die Brühe'
expected: 'die Brühe'
target: '/tmp/„zupa zębowa”'
target: '/tmp/\342\200\236zupa z\304\231bowa\342\200\235'
target: '/tmp/„zupa zębowa”'
expected: '/tmp/„zupa zębowa”'
/* test_libmount_unescaping_one escaped newline */
from '729 38 0:59 / /tmp/x\\012y rw,relatime shared:395 - tmpfs newline rw,seclabel'
source: 'newline'
source: 'newline'
source: 'newline'
expected: 'newline'
target: '/tmp/x
y'
target: '/tmp/x\ny'
target: '/tmp/x
y'
expected: '/tmp/x
y'
/* test_libmount_unescaping_one empty source */
from '760 38 0:60 / /tmp/emptysource rw,relatime shared:410 - tmpfs  rw,seclabel'
source: ''
source: ''
source: ''
expected: ''
target: '/tmp/emptysource'
target: '/tmp/emptysource'
target: '/tmp/emptysource'
expected: '/tmp/emptysource'
/* test_libmount_unescaping_one foo\rbar */
from '790 38 0:61 / /tmp/foo\rbar rw,relatime shared:425 - tmpfs tmpfs rw,seclabel'
source: 'tmpfs'
source: 'tmpfs'
source: 'tmpfs'
expected: 'tmpfs'
target: '/tmp/foo'
target: '/tmp/foo'
target: '/tmp/foo'
expected: 'n/a'

With https://github.com/karelzak/util-linux/issues/780 fixed, we get

/* test_libmount_unescaping_one foo\rbar */
from '790 38 0:61 / /tmp/foo\rbar rw,relatime shared:425 - tmpfs tmpfs rw,seclabel'
source: 'tmpfs'
source: 'tmpfs'
source: 'tmpfs'
expected: 'tmpfs'
target: '/tmp/foo
bar'
target: '/tmp/foo\rbar'
target: '/tmp/foo
bar'
expected: '/tmp/foo
bar'

1 files changed, 118 insertions, 0 deletions

diff --git a/src/test/test-libmount.c b/src/test/test-libmount.c
new file mode 100644
index 0000000000..fc28f27d53
--- /dev/null
+++ b/src/test/test-libmount.c
@@ -0,0 +1,118 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include "alloc-util.h"
+#include "fd-util.h"
+#include "escape.h"
+#include "libmount-util.h"
+#include "tests.h"
+
+static void test_libmount_unescaping_one(
+                const char *title,
+                const char *string,
+                bool may_fail,
+                const char *expected_source,
+                const char *expected_target) {
+        /* A test for libmount really */
+        int r;
+
+        log_info("/* %s %s */", __func__, title);
+
+        _cleanup_(mnt_free_tablep) struct libmnt_table *table = NULL;
+        _cleanup_(mnt_free_iterp) struct libmnt_iter *iter = NULL;
+        _cleanup_fclose_ FILE *f = NULL;
+
+        assert_se(table = mnt_new_table());
+        assert_se(iter = mnt_new_iter(MNT_ITER_FORWARD));
+
+        f = fmemopen((char*) string, strlen(string), "re");
+        assert_se(f);
+
+        assert_se(mnt_table_parse_stream(table, f, title) >= 0);
+
+        struct libmnt_fs *fs;
+        const char *source, *target;
+        _cleanup_free_ char *x = NULL, *cs = NULL, *s = NULL, *ct = NULL, *t = NULL;
+
+        /* We allow this call and the checks below to fail in some cases. See the case definitions below. */
+
+        r = mnt_table_next_fs(table, iter, &fs);
+        if (r != 0 && may_fail) {
+                log_error_errno(r, "mnt_table_next_fs failed: %m");
+                return;
+        }
+        assert_se(r == 0);
+
+        assert_se(x = cescape(string));
+
+        assert_se(source = mnt_fs_get_source(fs));
+        assert_se(target = mnt_fs_get_target(fs));
+
+        assert_se(cs = cescape(source));
+        assert_se(ct = cescape(target));
+
+        assert_se(cunescape(source, UNESCAPE_RELAX, &s) >= 0);
+        assert_se(cunescape(target, UNESCAPE_RELAX, &t) >= 0);
+
+        log_info("from '%s'", x);
+        log_info("source: '%s'", source);
+        log_info("source: '%s'", cs);
+        log_info("source: '%s'", s);
+        log_info("expected: '%s'", strna(expected_source));
+        log_info("target: '%s'", target);
+        log_info("target: '%s'", ct);
+        log_info("target: '%s'", t);
+        log_info("expected: '%s'", strna(expected_target));
+
+        assert_se(may_fail || streq(source, expected_source));
+        assert_se(may_fail || streq(target, expected_target));
+
+        assert_se(mnt_table_next_fs(table, iter, &fs) == 1);
+}
+
+static void test_libmount_unescaping(void) {
+        test_libmount_unescaping_one(
+                        "escaped space + utf8",
+                        "729 38 0:59 / /tmp/„zupa\\040zębowa” rw,relatime shared:395 - tmpfs die\\040Brühe rw,seclabel",
+                        false,
+                        "die Brühe",
+                        "/tmp/„zupa zębowa”"
+        );
+
+        test_libmount_unescaping_one(
+                        "escaped newline",
+                        "729 38 0:59 / /tmp/x\\012y rw,relatime shared:395 - tmpfs newline rw,seclabel",
+                        false,
+                        "newline",
+                        "/tmp/x\ny"
+        );
+
+        /* The result of "mount -t tmpfs '' /tmp/emptysource".
+         * This will fail with libmount <= v2.33.
+         * See https://github.com/karelzak/util-linux/commit/18a52a5094.
+         */
+        test_libmount_unescaping_one(
+                        "empty source",
+                        "760 38 0:60 / /tmp/emptysource rw,relatime shared:410 - tmpfs  rw,seclabel",
+                        true,
+                        "",
+                        "/tmp/emptysource"
+        );
+
+        /* The kernel leaves \r as is.
+         * Also see https://github.com/karelzak/util-linux/issues/780.
+         */
+        test_libmount_unescaping_one(
+                        "foo\\rbar",
+                        "790 38 0:61 / /tmp/foo\rbar rw,relatime shared:425 - tmpfs tmpfs rw,seclabel",
+                        true,
+                        "tmpfs",
+                        "/tmp/foo\rbar"
+        );
+}
+
+int main(int argc, char *argv[]) {
+        test_setup_logging(LOG_DEBUG);
+
+        test_libmount_unescaping();
+        return 0;
+}