Introduce some basic test cases for virFileIsSharedFS(). More
will be added later. In order to achieve desired result, mocks
for setmntent() and statfs() need to be invented because the
first thing that virFileIsSharedFS() does is calling the latter.
If it finds a FUSE mount it'll call the former.

The mock might look a bit complicated, but in fact it's quite
simple. The test sets LIBVIRT_MTAB env variable to hold the
absolute path to a file containing mount table. Then, statfs()
returns matching FS it finds, and setmntent() is there just to
replace /proc/mounts with the file the test wants to load.

Adding this test also exposed a bug we have - because we assume
the given path points to a file we cut off what we assume is a
file name to obtain directory path and only then we call
statfs(). This is buggy because the passed path could be already
a mount point.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
---
 tests/Makefile.am             |   7 +-
 tests/virfiledata/mounts3.txt |  33 ++++++++
 tests/virfilemock.c           | 154 ++++++++++++++++++++++++++++++++++
 tests/virfiletest.c           |  62 +++++++++++++-
 4 files changed, 254 insertions(+), 2 deletions(-)
 create mode 100644 tests/virfiledata/mounts3.txt
 create mode 100644 tests/virfilemock.c

diff --git a/tests/Makefile.am b/tests/Makefile.am
index 51be1509e1..d7ec7e3a6f 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -242,6 +242,7 @@ test_libraries += virusbmock.la \
 	virnetdevbandwidthmock.la \
 	virnumamock.la \
 	virtestmock.la \
+	virfilemock.la \
 	$(NULL)
 endif WITH_LINUX
 
@@ -1170,9 +1171,13 @@ virresctrltest_SOURCES = \
 	virresctrltest.c testutils.h testutils.c virfilewrapper.h virfilewrapper.c
 virresctrltest_LDADD = $(LDADDS)
 
+virfilemock_la_SOURCES = \
+	virfilemock.c
+virfilemock_la_LDFLAGS = $(MOCKLIBS_LDFLAGS)
+virfilemock_la_LIBADD = $(MOCKLIBS_LIBS)
 else ! WITH_LINUX
 EXTRA_DIST += vircaps2xmltest.c virnumamock.c virfilewrapper.c \
-			  virfilewrapper.h virresctrltest.c
+			  virfilewrapper.h virresctrltest.c virfilemock.c
 endif ! WITH_LINUX
 
 if WITH_NSS
diff --git a/tests/virfiledata/mounts3.txt b/tests/virfiledata/mounts3.txt
new file mode 100644
index 0000000000..226f67dc00
--- /dev/null
+++ b/tests/virfiledata/mounts3.txt
@@ -0,0 +1,33 @@
+/dev/root / xfs rw,noatime,attr2,inode64,noquota 0 0
+proc /proc proc rw,nosuid,nodev,noexec,relatime 0 0
+tmpfs /run tmpfs rw,nodev,relatime,size=3281436k,mode=755 0 0
+sysfs /sys sysfs rw,nosuid,nodev,noexec,relatime 0 0
+dev /dev devtmpfs rw,nosuid,relatime,size=10240k,nr_inodes=4093060,mode=755 0 0
+securityfs /sys/kernel/security securityfs rw,nosuid,nodev,noexec,relatime 0 0
+debugfs /sys/kernel/debug debugfs rw,nosuid,nodev,noexec,relatime 0 0
+mqueue /dev/mqueue mqueue rw,nosuid,nodev,noexec,relatime 0 0
+configfs /sys/kernel/config configfs rw,nosuid,nodev,noexec,relatime 0 0
+devpts /dev/pts devpts rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0
+fusectl /sys/fs/fuse/connections fusectl rw,nosuid,nodev,noexec,relatime 0 0
+shm /dev/shm tmpfs rw,nosuid,nodev,noexec,relatime 0 0
+cgroup_root /sys/fs/cgroup tmpfs rw,nosuid,nodev,noexec,relatime,size=10240k,mode=755 0 0
+openrc /sys/fs/cgroup/openrc cgroup rw,nosuid,nodev,noexec,relatime,release_agent=/lib/rc/sh/cgroup-release-agent.sh,name=openrc 0 0
+none /sys/fs/cgroup/unified cgroup2 rw,nosuid,nodev,noexec,relatime,nsdelegate 0 0
+cpuset /sys/fs/cgroup/cpuset cgroup rw,nosuid,nodev,noexec,relatime,cpuset 0 0
+cpu /sys/fs/cgroup/cpu cgroup rw,nosuid,nodev,noexec,relatime,cpu 0 0
+cpuacct /sys/fs/cgroup/cpuacct cgroup rw,nosuid,nodev,noexec,relatime,cpuacct 0 0
+blkio /sys/fs/cgroup/blkio cgroup rw,nosuid,nodev,noexec,relatime,blkio 0 0
+memory /sys/fs/cgroup/memory cgroup rw,nosuid,nodev,noexec,relatime,memory 0 0
+devices /sys/fs/cgroup/devices cgroup rw,nosuid,nodev,noexec,relatime,devices 0 0
+freezer /sys/fs/cgroup/freezer cgroup rw,nosuid,nodev,noexec,relatime,freezer 0 0
+net_cls /sys/fs/cgroup/net_cls cgroup rw,nosuid,nodev,noexec,relatime,net_cls 0 0
+perf_event /sys/fs/cgroup/perf_event cgroup rw,nosuid,nodev,noexec,relatime,perf_event 0 0
+net_prio /sys/fs/cgroup/net_prio cgroup rw,nosuid,nodev,noexec,relatime,net_prio 0 0
+hugetlb /sys/fs/cgroup/hugetlb cgroup rw,nosuid,nodev,noexec,relatime,hugetlb 0 0
+pids /sys/fs/cgroup/pids cgroup rw,nosuid,nodev,noexec,relatime,pids 0 0
+rdma /sys/fs/cgroup/rdma cgroup rw,nosuid,nodev,noexec,relatime,rdma 0 0
+binfmt_misc /proc/sys/fs/binfmt_misc binfmt_misc rw,nosuid,nodev,noexec,relatime 0 0
+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
diff --git a/tests/virfilemock.c b/tests/virfilemock.c
new file mode 100644
index 0000000000..d458616899
--- /dev/null
+++ b/tests/virfilemock.c
@@ -0,0 +1,154 @@
+/*
+ * Copyright (C) 2018 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * Author: Michal Privoznik <mprivozn@redhat.com>
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <mntent.h>
+#include <sys/vfs.h>
+#if HAVE_LINUX_MAGIC_H
+# include <linux/magic.h>
+#endif
+
+#include "virmock.h"
+
+#define VIR_FROM_THIS VIR_FROM_NONE
+
+static FILE *(*real_setmntent)(const char *filename, const char *type);
+static int (*real_statfs)(const char *path, struct statfs *buf);
+
+
+static void
+init_syms(void)
+{
+    if (real_setmntent)
+        return;
+
+    VIR_MOCK_REAL_INIT(setmntent);
+    VIR_MOCK_REAL_INIT(statfs);
+}
+
+
+FILE *
+setmntent(const char *filename, const char *type)
+{
+    const char *mtab;
+
+    init_syms();
+
+    if ((mtab = getenv("LIBVIRT_MTAB")))
+        filename = mtab;
+
+    return real_setmntent(filename, type);
+}
+
+
+#ifndef NFS_SUPER_MAGIC
+# define NFS_SUPER_MAGIC 0x6969
+#endif
+#ifndef OCFS2_SUPER_MAGIC
+# define OCFS2_SUPER_MAGIC 0x7461636f
+#endif
+#ifndef GFS2_MAGIC
+# define GFS2_MAGIC 0x01161970
+#endif
+#ifndef AFS_FS_MAGIC
+# define AFS_FS_MAGIC 0x6B414653
+#endif
+#ifndef SMB_SUPER_MAGIC
+# define SMB_SUPER_MAGIC 0x517B
+#endif
+#ifndef CIFS_SUPER_MAGIC
+# define CIFS_SUPER_MAGIC 0xFF534D42
+#endif
+#ifndef HUGETLBFS_MAGIC
+# define HUGETLBFS_MAGIC 0x958458f6
+#endif
+#ifndef FUSE_SUPER_MAGIC
+# define FUSE_SUPER_MAGIC 0x65735546
+#endif
+
+
+static int
+statfs_mock(const char *mtab,
+            const char *path,
+            struct statfs *buf)
+{
+    FILE *f;
+    struct mntent mb;
+    char mntbuf[1024];
+    int ret = -1;
+
+    if (!(f = real_setmntent(mtab, "r"))) {
+        fprintf(stderr, "Unable to open %s", mtab);
+        abort();
+    }
+
+    while (getmntent_r(f, &mb, mntbuf, sizeof(mntbuf))) {
+        int ftype;
+
+        if (STRNEQ(mb.mnt_dir, path))
+            continue;
+
+        if (STREQ(mb.mnt_type, "nfs") ||
+            STREQ(mb.mnt_type, "nfs4")) {
+            ftype = NFS_SUPER_MAGIC;
+        } else if (STREQ(mb.mnt_type, "gfs2")||
+                   STREQ(mb.mnt_type, "gfs2meta")) {
+            ftype = GFS2_MAGIC;
+        } else if (STREQ(mb.mnt_type, "ocfs2")) {
+            ftype = OCFS2_SUPER_MAGIC;
+        } else if (STREQ(mb.mnt_type, "afs")) {
+            ftype = AFS_FS_MAGIC;
+        } else if (STREQ(mb.mnt_type, "smb3")) {
+            ftype = SMB_SUPER_MAGIC;
+        } else if (STREQ(mb.mnt_type, "cifs")) {
+            ftype = CIFS_SUPER_MAGIC;
+        } else if (STRPREFIX(mb.mnt_type, "fuse")) {
+            ftype = FUSE_SUPER_MAGIC;
+        } else {
+            /* Everything else is EXT4. We don't care really for other paths. */
+            ftype = EXT4_SUPER_MAGIC;
+        }
+
+        memset(buf, 0, sizeof(*buf));
+        /* We only care about f_type so far. */
+        buf->f_type = ftype;
+        ret = 0;
+        break;
+    }
+
+    endmntent(f);
+    return ret;
+}
+
+
+int
+statfs(const char *path, struct statfs *buf)
+{
+    const char *mtab;
+
+    init_syms();
+
+    if ((mtab = getenv("LIBVIRT_MTAB")))
+        return statfs_mock(mtab, path, buf);
+
+    return real_statfs(path, buf);
+}
diff --git a/tests/virfiletest.c b/tests/virfiletest.c
index 19dd06e49e..22c163f0a0 100644
--- a/tests/virfiletest.c
+++ b/tests/virfiletest.c
@@ -30,6 +30,7 @@
 # include <linux/falloc.h>
 #endif
 
+#define VIR_FROM_THIS VIR_FROM_NONE
 
 #if defined HAVE_MNTENT_H && defined HAVE_GETMNTENT_R
 static int testFileCheckMounts(const char *prefix,
@@ -309,6 +310,48 @@ testFileInData(const void *opaque)
 }
 
 
+struct testFileIsSharedFSType {
+    const char *mtabFile;
+    const char *filename;
+    const bool expected;
+};
+
+static int
+testFileIsSharedFSType(const void *opaque ATTRIBUTE_UNUSED)
+{
+#ifndef __linux__
+    return EXIT_AM_SKIP;
+#else
+    const struct testFileIsSharedFSType *data = opaque;
+    char *mtabFile = NULL;
+    bool actual;
+    int ret = -1;
+
+    if (virAsprintf(&mtabFile, abs_srcdir "/virfiledata/%s", data->mtabFile) < 0)
+        return -1;
+
+    if (setenv("LIBVIRT_MTAB", mtabFile, 1) < 0) {
+        fprintf(stderr, "Unable to set env variable\n");
+        goto cleanup;
+    }
+
+    actual = virFileIsSharedFS(data->filename);
+
+    if (actual != data->expected) {
+        fprintf(stderr, "Unexpected FS type. Expected %d got %d\n",
+                data->expected, actual);
+        goto cleanup;
+    }
+
+    ret = 0;
+ cleanup:
+    VIR_FREE(mtabFile);
+    unsetenv("LIBVIRT_MTAB");
+    return ret;
+#endif
+}
+
+
 static int
 mymain(void)
 {
@@ -396,7 +439,24 @@ mymain(void)
         DO_TEST_IN_DATA(true, 8, 16, 32, 64, 128, 256, 512);
         DO_TEST_IN_DATA(false, 8, 16, 32, 64, 128, 256, 512);
     }
+
+#define DO_TEST_FILE_IS_SHARED_FS_TYPE(mtab, file, exp) \
+    do { \
+        struct testFileIsSharedFSType data = { \
+            .mtabFile = mtab, .filename = file, .expected = exp \
+        }; \
+        if (virTestRun(virTestCounterNext(), testFileIsSharedFSType, &data) < 0) \
+            ret = -1; \
+    } while (0)
+
+    virTestCounterReset("testFileIsSharedFSType ");
+    DO_TEST_FILE_IS_SHARED_FS_TYPE("mounts1.txt", "/boot/vmlinuz", false);
+    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);
+    /* TODO Detect bind mounts */
+    DO_TEST_FILE_IS_SHARED_FS_TYPE("mounts3.txt", "/nfs/blah", true);
+
     return ret != 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 }
 
-VIR_TEST_MAIN(mymain)
+VIR_TEST_MAIN_PRELOAD(mymain, abs_builddir "/.libs/virfilemock.so")
-- 
2.18.0

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On Tue, Oct 09, 2018 at 15:48:45 +0200, Michal Privoznik wrote:
> Introduce some basic test cases for virFileIsSharedFS(). More
> will be added later. In order to achieve desired result, mocks
> for setmntent() and statfs() need to be invented because the
> first thing that virFileIsSharedFS() does is calling the latter.
> If it finds a FUSE mount it'll call the former.
> 
> The mock might look a bit complicated, but in fact it's quite
> simple. The test sets LIBVIRT_MTAB env variable to hold the
> absolute path to a file containing mount table. Then, statfs()
> returns matching FS it finds, and setmntent() is there just to
> replace /proc/mounts with the file the test wants to load.
> 
> Adding this test also exposed a bug we have - because we assume
> the given path points to a file we cut off what we assume is a
> file name to obtain directory path and only then we call
> statfs(). This is buggy because the passed path could be already
> a mount point.
> 
> Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
> ---
>  tests/Makefile.am             |   7 +-
>  tests/virfiledata/mounts3.txt |  33 ++++++++
>  tests/virfilemock.c           | 154 ++++++++++++++++++++++++++++++++++
>  tests/virfiletest.c           |  62 +++++++++++++-
>  4 files changed, 254 insertions(+), 2 deletions(-)
>  create mode 100644 tests/virfiledata/mounts3.txt
>  create mode 100644 tests/virfilemock.c
...
> diff --git a/tests/virfilemock.c b/tests/virfilemock.c
> new file mode 100644
> index 0000000000..d458616899
> --- /dev/null
> +++ b/tests/virfilemock.c
...
> +static int
> +statfs_mock(const char *mtab,
> +            const char *path,
> +            struct statfs *buf)
> +{
> +    FILE *f;
> +    struct mntent mb;
> +    char mntbuf[1024];
> +    int ret = -1;
> +
> +    if (!(f = real_setmntent(mtab, "r"))) {
> +        fprintf(stderr, "Unable to open %s", mtab);
> +        abort();

I think just returning -1 would be better. The caller will take care of
reporting the error.

> +    }
> +
> +    while (getmntent_r(f, &mb, mntbuf, sizeof(mntbuf))) {
> +        int ftype;
> +
> +        if (STRNEQ(mb.mnt_dir, path))
> +            continue;

I was wondering how this can work as we call statfs on an arbitrary path
rather than on the exact mount point. But it works because
virFileIsSharedFSType calls statfs in a loop checking smaller part of
the path in each iteration. That said, the mocked function is not
generic, but it's good enough for our use case.

...

With the change suggested above
Reviewed-by: Jiri Denemark <jdenemar@redhat.com>

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