libhandle: always use a good path for by-handle ioctls

[thirdparty/xfsprogs-dev.git] / libhandle / handle.c

diff --git a/libhandle/handle.c b/libhandle/handle.c
index 6276797485ec12360f53af2ea772b4fb8b9e7ead..c3a61299c1739a9ba26167086ef975a51d5541cc 100644 (file)
--- a/libhandle/handle.c
+++ b/libhandle/handle.c
@@ -16,6 +16,7 @@
  * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  */
 
+#include <libgen.h>
 #include <xfs/xfs.h>
 #include <xfs/handle.h>
 #include <xfs/parent.h>
@@ -40,6 +41,7 @@ typedef union {
 
 static int obj_to_handle(char *, int, unsigned int, comarg_t, void**, size_t*);
 static int handle_to_fsfd(void *, char **);
+static char *path_to_fspath(char *path);
 
 
 /*
@@ -70,13 +72,18 @@ path_to_fshandle(
        comarg_t        obj;
        struct fdhash   *fdhp;
        char            *tmppath;
+       char            *fspath;
 
-       fd = open(path, O_RDONLY);
+       fspath = path_to_fspath(path);
+       if (fspath == NULL)
+               return -1;
+
+       fd = open(fspath, O_RDONLY);
        if (fd < 0)
                return -1;
 
        obj.path = path;
-       result = obj_to_handle(path, fd, XFS_IOC_PATH_TO_FSHANDLE,
+       result = obj_to_handle(fspath, fd, XFS_IOC_PATH_TO_FSHANDLE,
                                obj, fshanp, fshlen);
        if (result < 0) {
                close(fd);
@@ -95,7 +102,7 @@ path_to_fshandle(
                }
 
                fdhp->fsfd = fd;
-               strncpy(fdhp->fspath, path, sizeof(fdhp->fspath));
+               strncpy(fdhp->fspath, fspath, sizeof(fdhp->fspath));
                memcpy(fdhp->fsh, *fshanp, FSIDSIZE);
 
                fdhp->fnxt = fdhash_head;
@@ -114,18 +121,46 @@ path_to_handle(
        int             fd;
        int             result;
        comarg_t        obj;
+       char            *fspath;
 
-       fd = open(path, O_RDONLY);
+       fspath = path_to_fspath(path);
+       if (fspath == NULL)
+               return -1;
+
+       fd = open(fspath, O_RDONLY);
        if (fd < 0)
                return -1;
 
        obj.path = path;
-       result = obj_to_handle(path, fd, XFS_IOC_PATH_TO_HANDLE,
+       result = obj_to_handle(fspath, fd, XFS_IOC_PATH_TO_HANDLE,
                                obj, hanp, hlen);
        close(fd);
        return result;
 }
 
+/* Given a path, return a suitable "fspath" for use in obtaining
+ * an fd for xfsctl calls. For regular files and directories the
+ * input path is sufficient. For other types the parent directory
+ * is used to avoid issues with opening dangling symlinks and
+ * potentially blocking in an open on a named pipe. Also
+ * symlinks to files on other filesystems would be a problem,
+ * since an fd would be obtained for the wrong fs.
+ */
+static char *
+path_to_fspath(char *path)
+{
+       static char dirpath[MAXPATHLEN];
+       struct stat statbuf;
+
+       if (lstat(path, &statbuf) != 0)
+               return NULL;
+
+       if (S_ISREG(statbuf.st_mode) || S_ISDIR(statbuf.st_mode))
+               return path;
+
+       strcpy(dirpath, path);
+       return dirname(dirpath);
+}
 
 int
 fd_to_handle (