From 1dbf6222dd5e1fedcbe335fc0852ef66e7a92901 Mon Sep 17 00:00:00 2001
From: Michal Privoznik <mprivozn@redhat.com>
Date: Tue, 9 Oct 2018 13:08:07 +0200
Subject: [PATCH] virfile: Rework virFileIsSharedFixFUSE

There are couple of things wrong with the current implementation.
The first one is that in the first loop the code tries to build a
list of fuse.glusterfs mount points. Well, since the strings are
allocated in a temporary buffer and are not duplicated this
results in wrong decision made later in the code.

The second problem is that the code does not take into account
subtree mounts. For instance, if there's a fuse.gluster mounted
at /some/path and another FS mounted at /some/path/subdir the
code would not recognize this subdir mount.

Reported-by: Han Han <hhan@redhat.com>
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Jiri Denemark <jdenemar@redhat.com>
---
 src/util/virfile.c            | 59 ++++++++++++++---------------------
 tests/virfiledata/mounts3.txt |  2 ++
 tests/virfiletest.c           |  2 ++
 3 files changed, 28 insertions(+), 35 deletions(-)

diff --git a/src/util/virfile.c b/src/util/virfile.c
index a49bc30eb2..e09992e41a 100644
--- a/src/util/virfile.c
+++ b/src/util/virfile.c
@@ -3468,18 +3468,14 @@ static int
 virFileIsSharedFixFUSE(const char *path,
                        long long *f_type)
 {
-    char *dirpath = NULL;
-    const char **mounts = NULL;
-    size_t nmounts = 0;
-    char *p;
     FILE *f = NULL;
     struct mntent mb;
     char mntbuf[1024];
+    char *mntDir = NULL;
+    char *mntType = NULL;
+    size_t maxMatching = 0;
     int ret = -1;
 
-    if (VIR_STRDUP(dirpath, path) < 0)
-        return -1;
-
     if (!(f = setmntent(PROC_MOUNTS, "r"))) {
         virReportSystemError(errno,
                              _("Unable to open %s"),
@@ -3488,43 +3484,36 @@ virFileIsSharedFixFUSE(const char *path,
     }
 
     while (getmntent_r(f, &mb, mntbuf, sizeof(mntbuf))) {
-        if (STRNEQ("fuse.glusterfs", mb.mnt_type))
-            continue;
+        const char *p;
+        size_t len = strlen(mb.mnt_dir);
 
-        if (VIR_APPEND_ELEMENT_COPY(mounts, nmounts, mb.mnt_dir) < 0)
-            goto cleanup;
-    }
+        if (!(p = STRSKIP(path, mb.mnt_dir)))
+            continue;
 
-    /* Add NULL sentinel so that this is a virStringList */
-    if (VIR_REALLOC_N(mounts, nmounts + 1) < 0)
-        goto cleanup;
-    mounts[nmounts] = NULL;
+        if (*(p - 1) != '/' && *p != '/' && *p != '\0')
+            continue;
 
-    do {
-        if ((p = strrchr(dirpath, '/')) == NULL) {
-            virReportSystemError(EINVAL,
-                                 _("Invalid relative path '%s'"), path);
-            goto cleanup;
+        if (len > maxMatching) {
+            maxMatching = len;
+            VIR_FREE(mntType);
+            VIR_FREE(mntDir);
+            if (VIR_STRDUP(mntDir, mb.mnt_dir) < 0 ||
+                VIR_STRDUP(mntType, mb.mnt_type) < 0)
+                goto cleanup;
         }
+    }
 
-        if (p == dirpath)
-            *(p+1) = '\0';
-        else
-            *p = '\0';
-
-        if (virStringListHasString(mounts, dirpath)) {
-            VIR_DEBUG("Found gluster FUSE mountpoint=%s for path=%s. "
-                      "Fixing shared FS type", dirpath, path);
-            *f_type = GFS2_MAGIC;
-            break;
-        }
-    } while (p != dirpath);
+    if (STREQ_NULLABLE(mntType, "fuse.glusterfs")) {
+        VIR_DEBUG("Found gluster FUSE mountpoint=%s for path=%s. "
+                  "Fixing shared FS type", mntDir, path);
+        *f_type = GFS2_MAGIC;
+    }
 
     ret = 0;
  cleanup:
+    VIR_FREE(mntType);
+    VIR_FREE(mntDir);
     endmntent(f);
-    VIR_FREE(mounts);
-    VIR_FREE(dirpath);
     return ret;
 }
 
diff --git a/tests/virfiledata/mounts3.txt b/tests/virfiledata/mounts3.txt
index 226f67dc00..134c6e8f81 100644
--- a/tests/virfiledata/mounts3.txt
+++ b/tests/virfiledata/mounts3.txt
@@ -31,3 +31,5 @@ hugetlbfs /hugepages2M hugetlbfs rw,relatime,mode=1777,pagesize=2M 0 0
 none /run/user/1000 tmpfs rw,relatime,mode=700,uid=1000 0 0
 host:/nfs /nfs nfs4 rw,relatime,vers=4.1,rsize=1048576,wsize=1048576,namlen=255,hard,proto=tcp6,timeo=600,retrans=2,sec=sys,clientaddr=::,local_lock=none,addr=:: 0 0
 dev /nfs/blah devtmpfs rw,nosuid,relatime,size=10240k,nr_inodes=4093060,mode=755 0 0
+host:/gv0 /gluster fuse.glusterfs rw 0 0
+root@host:/tmp/mkdir /gluster/sshfs fuse.sshfs rw 0 0
diff --git a/tests/virfiletest.c b/tests/virfiletest.c
index 42d918aecc..d5102b1cc4 100644
--- a/tests/virfiletest.c
+++ b/tests/virfiletest.c
@@ -454,6 +454,8 @@ mymain(void)
     DO_TEST_FILE_IS_SHARED_FS_TYPE("mounts2.txt", "/run/user/501/gvfs/some/file", false);
     DO_TEST_FILE_IS_SHARED_FS_TYPE("mounts3.txt", "/nfs/file", true);
     DO_TEST_FILE_IS_SHARED_FS_TYPE("mounts3.txt", "/nfs/blah", false);
+    DO_TEST_FILE_IS_SHARED_FS_TYPE("mounts3.txt", "/gluster/file", true);
+    DO_TEST_FILE_IS_SHARED_FS_TYPE("mounts3.txt", "/gluster/sshfs/file", false);
 
     return ret != 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 }
-- 
2.39.5