New API: filesystem_walk

Library's counterpart of the daemon's internal_filesystem_walk command.

It writes the daemon's command output on a temporary file and parses it,
deserialising the XDR formatted tsk_dirent structs.

It returns to the caller the list of tsk_dirent structs generated by the
internal_filesystem_walk command.

Signed-off-by: Matteo Cafasso <noxdafox@gmail.com>

generator/actions.ml

@@ -3551,6 +3551,120 @@ The environment variable C<XDG_RUNTIME_DIR> controls the default
 value: If C<XDG_RUNTIME_DIR> is set, then that is the default.
 Else F</tmp> is the default." };
 
+  { defaults with
+    name = "filesystem_walk"; added = (1, 33, 37);
+    style = RStructList ("dirents", "tsk_dirent"), [Mountable "device";], [];
+    optional = Some "libtsk";
+    progress = true; cancellable = true;
+    shortdesc = "walk through the filesystem content";
+    longdesc = "\
+Walk through the internal structures of a disk partition
+(eg. F</dev/sda1>) in order to return a list of all the files
+and directories stored within.
+
+It is not necessary to mount the disk partition to run this command.
+
+All entries in the filesystem are returned, excluding C<.> and
+C<..>. This function can list deleted or unaccessible files.
+The entries are I<not> sorted.
+
+The C<tsk_dirent> structure contains the following fields.
+
+=over 4
+
+=item 'tsk_inode'
+
+Filesystem reference number of the node. It migh be C<0>
+if the node has been deleted.
+
+=item 'tsk_type'
+
+Basic file type information.
+See below for a detailed list of values.
+
+=item 'tsk_size'
+
+File size in bytes. It migh be C<-1>
+if the node has been deleted.
+
+=item 'tsk_name'
+
+The file path relative to its directory.
+
+=item 'tsk_flags'
+
+Bitfield containing extra information regarding the entry.
+It contains the logical OR of the following values:
+
+=over 4
+
+=item 0x0001
+
+If set to C<1>, the file is allocated and visible within the filesystem.
+Otherwise, the file has been deleted.
+Under certain circumstances, the function C<download_inode>
+can be used to recover deleted files.
+
+=item 0x0002
+
+Filesystem such as NTFS and Ext2 or greater, separate the file name
+from the metadata structure.
+The bit is set to C<1> when the file name is in an unallocated state
+and the metadata structure is in an allocated one.
+This generally implies the metadata has been reallocated to a new file.
+Therefore, information such as file type and file size
+might not correspond with the ones of the original deleted entry.
+
+=back
+
+=back
+
+The C<tsk_type> field will contain one of the following characters:
+
+=over 4
+
+=item 'b'
+
+Block special
+
+=item 'c'
+
+Char special
+
+=item 'd'
+
+Directory
+
+=item 'f'
+
+FIFO (named pipe)
+
+=item 'l'
+
+Symbolic link
+
+=item 'r'
+
+Regular file
+
+=item 's'
+
+Socket
+
+=item 'h'
+
+Shadow inode (Solaris)
+
+=item 'w'
+
+Whiteout inode (BSD)
+
+=item 'u'
+
+Unknown file type
+
+=back" };
+
 ]
 
 (* daemon_functions are any functions which cause some action

src/Makefile.am

@@ -131,6 +131,7 @@ libguestfs_la_SOURCES = \
 	structs-copy.c \
 	structs-free.c \
 	tmpdirs.c \
+	tsk.c \
 	umask.c \
 	wait.c \
 	whole-file.c \

src/tsk.c

@@ -0,0 +1,128 @@
+/* libguestfs
+ * Copyright (C) 2016 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 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <string.h>
+#include <rpc/xdr.h>
+#include <rpc/types.h>
+
+#include "guestfs.h"
+#include "guestfs_protocol.h"
+#include "guestfs-internal.h"
+#include "guestfs-internal-all.h"
+#include "guestfs-internal-actions.h"
+
+static struct guestfs_tsk_dirent_list *parse_filesystem_walk (guestfs_h *, FILE *);
+static int deserialise_dirent_list (guestfs_h *, FILE *, struct guestfs_tsk_dirent_list *);
+
+struct guestfs_tsk_dirent_list *
+guestfs_impl_filesystem_walk (guestfs_h *g, const char *mountable)
+{
+  int ret = 0;
+  CLEANUP_FCLOSE FILE *fp = NULL;
+  CLEANUP_UNLINK_FREE char *tmpfile = NULL;
+
+  ret = guestfs_int_lazy_make_tmpdir (g);
+  if (ret < 0)
+    return NULL;
+
+  tmpfile = safe_asprintf (g, "%s/filesystem_walk%d", g->tmpdir, ++g->unique);
+
+  ret = guestfs_internal_filesystem_walk (g, mountable, tmpfile);
+  if (ret < 0)
+    return NULL;
+
+  fp = fopen (tmpfile, "r");
+  if (fp == NULL) {
+    perrorf (g, "fopen: %s", tmpfile);
+    return NULL;
+  }
+
+  return parse_filesystem_walk (g, fp);  /* caller frees */
+}
+
+/* Parse the file content and return dirents list.
+ * Return a list of tsk_dirent on success, NULL on error.
+ */
+static struct guestfs_tsk_dirent_list *
+parse_filesystem_walk (guestfs_h *g, FILE *fp)
+{
+  int ret = 0;
+  struct guestfs_tsk_dirent_list *dirents = NULL;
+
+  /* Initialise results array. */
+  dirents = safe_malloc (g, sizeof (*dirents));
+  dirents->len = 8;
+  dirents->val = safe_malloc (g, dirents->len * sizeof (*dirents->val));
+
+  /* Deserialise buffer into dirent list. */
+  ret = deserialise_dirent_list (g, fp, dirents);
+  if (ret < 0) {
+    guestfs_free_tsk_dirent_list (dirents);
+    return NULL;
+  }
+
+  return dirents;
+}
+
+/* Deserialise the file content and populate the dirent list.
+ * Return the number of deserialised dirents, -1 on error.
+ */
+static int
+deserialise_dirent_list (guestfs_h *g, FILE *fp,
+                         struct guestfs_tsk_dirent_list *dirents)
+{
+  XDR xdr;
+  int ret = 0;
+  uint32_t index = 0;
+  struct stat statbuf;
+
+  ret = fstat (fileno(fp), &statbuf);
+  if (ret == -1)
+    return -1;
+
+  xdrstdio_create (&xdr, fp, XDR_DECODE);
+
+  for (index = 0; xdr_getpos (&xdr) < statbuf.st_size; index++) {
+    if (index == dirents->len) {
+      dirents->len = 2 * dirents->len;
+      dirents->val = safe_realloc (g, dirents->val,
+                                   dirents->len *
+                                   sizeof (*dirents->val));
+    }
+
+    /* Clear the entry so xdr logic will allocate necessary memory. */
+    memset (&dirents->val[index], 0, sizeof (*dirents->val));
+    ret = xdr_guestfs_int_tsk_dirent (&xdr, (guestfs_int_tsk_dirent *)
+                                      &dirents->val[index]);
+    if (ret == 0)
+      break;
+  }
+
+  xdr_destroy (&xdr);
+  dirents->len = index;
+
+  return ret ? 0 : -1;
+}