[LTP] [PATCH v3 1/1] safe_macros.c: Fix missing ro flag for FUSE mounts

[Jan Polensky]

The test incorrectly assumes that FUSE mounts are read-only, but the mount
command does not explicitly set the read-only flag. As a result, the test fails
when checking `sb_flags` against `MS_RDONLY`.

Old behavior:

    sudo LTP_SINGLE_FS_TYPE=ntfs strace -e trace=mount,statmount -o log.log -s 128 -f ./statmount02
    ...
    statmount02.c:47: TFAIL: st_mount->sb_flags (0) != MS_RDONLY (1)
    ...

Relevant log excerpt:

    3890601 mount("/dev/zero", "/tmp/mountBDSEqk", "ntfs", 0, NULL) = -1 ENOTBLK (Block device required)
    3890608 mount("/dev/loop0", "/tmp/LTP_staTPRruR/mntpoint", "fuseblk", 0, "allow_other,blksize=4096,fd=4,rootmode=40000,user_id=0,group_id=0") = 0
    3890607 statmount({size=24, mnt_id=0x80010957, param=STATMOUNT_SB_BASIC}, {size=512, mask=STATMOUNT_SB_BASIC, sb_dev_major=7, sb_dev_minor=0, sb_magic=FUSE_SUPER_MAGIC, sb_flags=0}, 512, 0) = 0

Reviewed-by: Avinesh Kumar <akumar@suse.de>
Reviewed-by: Petr Vorel <pvorel@suse.cz>
Signed-off-by: Jan Polensky <japo@linux.ibm.com>
---
Change since v1 (Thanks Cyril & thanks for the ping):
* Removed restriction for NTFS.
Change since v2 (Thanks Avinesh):
* Changed commit title from: "Fix missing ro flag for FUSE NTFS mounts"

 lib/safe_macros.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/lib/safe_macros.c b/lib/safe_macros.c
index d52b55ab70fe..25fad4b7cae0 100644
--- a/lib/safe_macros.c
+++ b/lib/safe_macros.c
@@ -945,10 +945,15 @@ int safe_mount(const char *file, const int lineno, void (*cleanup_fn)(void),
 	tst_resm_(file, lineno, TINFO, "tst_is_fuse: %d", tst_is_fuse(source));
 	if (possibly_fuse(filesystemtype)) {
 		char buf[1024];
+		const char* mount_fmt;

 		tst_resm_(file, lineno, TINFO, "Trying FUSE...");
-		snprintf(buf, sizeof(buf), "mount.%s '%s' '%s'",
-			filesystemtype, source, target);
+		if (mountflags == MS_RDONLY)
+			mount_fmt = "mount.%s -o ro '%s' '%s'";
+		else
+			mount_fmt = "mount.%s '%s' '%s'";
+		snprintf(buf, sizeof(buf), mount_fmt, filesystemtype,
+				source, target);

 		rval = tst_system(buf);
 	tst_resm_(file, lineno, TINFO, "tst_is_fuse: %d", tst_is_fuse(source));
--
2.50.1