[libvirt] [PATCH] virfile: Take symlink into account in virFileIsSharedFixFUSE

[Michal Privoznik]

https://bugzilla.redhat.com/show_bug.cgi?id=1640465

Weirdly enough, there can be symlinks in the path we are trying
to fix. If it is the case our clever algorithm that finds matches
against mount table won't work. Canonicalize path at the
beginning then.

Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
---
 cfg.mk              |  2 +-
 src/util/virfile.c  | 17 ++++++++++++++---
 tests/virfilemock.c | 33 ++++++++++++++++++++++++++++++++-
 tests/virfiletest.c |  1 +
 4 files changed, 48 insertions(+), 5 deletions(-)

diff --git a/cfg.mk b/cfg.mk
index 4790d0b7e7..d0183c02ff 100644
--- a/cfg.mk
+++ b/cfg.mk
@@ -1229,7 +1229,7 @@ exclude_file_name_regexp--sc_prohibit_select = \
 	^cfg\.mk$$
 
 exclude_file_name_regexp--sc_prohibit_canonicalize_file_name = \
-  ^cfg\.mk$$
+  ^(cfg\.mk|tests/virfilemock\.c)$$
 
 exclude_file_name_regexp--sc_prohibit_raw_allocation = \
   ^(docs/hacking\.html\.in|src/util/viralloc\.[ch]|examples/.*|tests/(securityselinuxhelper|(vircgroup|nss)mock|commandhelper)\.c|tools/wireshark/src/packet-libvirt\.c)$$
diff --git a/src/util/virfile.c b/src/util/virfile.c
index e09992e41a..4747a26ad3 100644
--- a/src/util/virfile.c
+++ b/src/util/virfile.c
@@ -3473,9 +3473,19 @@ virFileIsSharedFixFUSE(const char *path,
     char mntbuf[1024];
     char *mntDir = NULL;
     char *mntType = NULL;
+    char *canonPath = NULL;
     size_t maxMatching = 0;
     int ret = -1;
 
+    if (!(canonPath = virFileCanonicalizePath(path))) {
+        virReportSystemError(errno,
+                             _("unable to canonicalize %s"),
+                             path);
+        return -1;
+    }
+
+    VIR_DEBUG("Path %s after canonicalization %s", path, canonPath);
+
     if (!(f = setmntent(PROC_MOUNTS, "r"))) {
         virReportSystemError(errno,
                              _("Unable to open %s"),
@@ -3487,7 +3497,7 @@ virFileIsSharedFixFUSE(const char *path,
         const char *p;
         size_t len = strlen(mb.mnt_dir);
 
-        if (!(p = STRSKIP(path, mb.mnt_dir)))
+        if (!(p = STRSKIP(canonPath, mb.mnt_dir)))
             continue;
 
         if (*(p - 1) != '/' && *p != '/' && *p != '\0')
@@ -3504,13 +3514,14 @@ virFileIsSharedFixFUSE(const char *path,
     }
 
     if (STREQ_NULLABLE(mntType, "fuse.glusterfs")) {
-        VIR_DEBUG("Found gluster FUSE mountpoint=%s for path=%s. "
-                  "Fixing shared FS type", mntDir, path);
+        VIR_DEBUG("Found gluster FUSE mountpoint=%s for canonPath=%s. "
+                  "Fixing shared FS type", mntDir, canonPath);
         *f_type = GFS2_MAGIC;
     }
 
     ret = 0;
  cleanup:
+    VIR_FREE(canonPath);
     VIR_FREE(mntType);
     VIR_FREE(mntDir);
     endmntent(f);
diff --git a/tests/virfilemock.c b/tests/virfilemock.c
index 822c757380..ae5c8d025a 100644
--- a/tests/virfilemock.c
+++ b/tests/virfilemock.c
@@ -28,11 +28,14 @@
 #endif
 
 #include "virmock.h"
+#include "virstring.h"
+#include "viralloc.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 char *(*real_canonicalize_file_name)(const char *path);
 
 
 static void
@@ -43,6 +46,7 @@ init_syms(void)
 
     VIR_MOCK_REAL_INIT(setmntent);
     VIR_MOCK_REAL_INIT(statfs);
+    VIR_MOCK_REAL_INIT(canonicalize_file_name);
 }
 
 
@@ -94,6 +98,7 @@ statfs_mock(const char *mtab,
     FILE *f;
     struct mntent mb;
     char mntbuf[1024];
+    char *canonPath = NULL;
     int ret = -1;
 
     if (!(f = real_setmntent(mtab, "r"))) {
@@ -101,10 +106,16 @@ statfs_mock(const char *mtab,
         return -1;
     }
 
+    /* We don't need to do this in callers because real statfs(2)
+     * does that for us. However, in mocked implementation we
+     * need to do this. */
+    if (!(canonPath = canonicalize_file_name(path)))
+        return -1;
+
     while (getmntent_r(f, &mb, mntbuf, sizeof(mntbuf))) {
         int ftype;
 
-        if (STRNEQ(mb.mnt_dir, path))
+        if (STRNEQ(mb.mnt_dir, canonPath))
             continue;
 
         if (STREQ(mb.mnt_type, "nfs") ||
@@ -136,6 +147,7 @@ statfs_mock(const char *mtab,
     }
 
     endmntent(f);
+    VIR_FREE(canonPath);
     return ret;
 }
 
@@ -152,3 +164,22 @@ statfs(const char *path, struct statfs *buf)
 
     return real_statfs(path, buf);
 }
+
+
+char *
+canonicalize_file_name(const char *path)
+{
+    if (getenv("LIBVIRT_MTAB")) {
+        const char *p;
+        char *ret;
+
+        if ((p = STRSKIP(path, "/some/symlink")))
+            ignore_value(virAsprintfQuiet(&ret, "/gluster%s", p));
+        else
+            ignore_value(VIR_STRDUP_QUIET(ret, path));
+
+        return ret;
+    }
+
+    return real_canonicalize_file_name(path);
+}
diff --git a/tests/virfiletest.c b/tests/virfiletest.c
index 1f2be74c8d..f7b263f2e9 100644
--- a/tests/virfiletest.c
+++ b/tests/virfiletest.c
@@ -456,6 +456,7 @@ mymain(void)
     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);
+    DO_TEST_FILE_IS_SHARED_FS_TYPE("mounts3.txt", "/some/symlink/file", true);
 
     return ret != 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 }
-- 
2.18.1