virfile: Take symlink into account in virFileIsSharedFixFUSE

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@redhat.com>
Reviewed-by: Erik Skultety <eskultet@redhat.com>

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)$$

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 canonicalization: %s->%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')
@@ -3505,12 +3515,13 @@ 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);
+                  "Fixing shared FS type", mntDir, canonPath);
         *f_type = GFS2_MAGIC;
     }
 
     ret = 0;
  cleanup:
+    VIR_FREE(canonPath);
     VIR_FREE(mntType);
     VIR_FREE(mntDir);
     endmntent(f);

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);
+}

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;
 }