[Libguestfs] [PATCH v3 4/5] appliance: Added filesystem_walk command
noxdafox
noxdafox at gmail.com
Tue Apr 5 18:39:02 UTC 2016
On 05/04/16 20:26, Pino Toscano wrote:
> "appliance: Added filesystem_walk command"
>
> -> "New API: filesystem_walk"
>
> On Tuesday 05 April 2016 18:47:31 Matteo Cafasso wrote:
>> The filesystem_walk command is the appliance's
>> counterpart of the daemon's internal_filesystem_walk command.
> It is not the counterpart in the appliance, but in the library.
> The appliance is the small VM used to do all the operations with the
> disk images, and the guestfsd daemon runs there.
>
> This non-daemon API exists only in the library, hence in userspace.
>
>> 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 at gmail.com>
>> ---
>> generator/actions.ml | 69 +++++++++++++++++++++++++++++
>> src/Makefile.am | 1 +
>> src/tsk.c | 123 +++++++++++++++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 193 insertions(+)
>> create mode 100644 src/tsk.c
>>
>> diff --git a/generator/actions.ml b/generator/actions.ml
>> index 8073370..afff402 100644
>> --- a/generator/actions.ml
>> +++ b/generator/actions.ml
>> @@ -3546,6 +3546,75 @@ 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, 18);
>> + 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.
>> +
>> +If the entry is not allocated (ex: it has been deleted),
>> +its inode, type or size might not be recovered correctly.
>> +In such case, the inode might be 0, the size might be -1 and the type
>> +might be unidentified 'u'.
> Use POD C<..> for the special values 0, -1, 'u'.
>
>> +This call returns as well basic file type information about each
>> +file. 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
>> diff --git a/src/Makefile.am b/src/Makefile.am
>> index 3b4cd10..9f8af4c 100644
>> --- a/src/Makefile.am
>> +++ b/src/Makefile.am
>> @@ -130,6 +130,7 @@ libguestfs_la_SOURCES = \
>> structs-copy.c \
>> structs-free.c \
>> tmpdirs.c \
>> + tsk.c \
>> whole-file.c \
>> libguestfs.syms
>>
>> diff --git a/src/tsk.c b/src/tsk.c
>> new file mode 100644
>> index 0000000..4d7fd7c
>> --- /dev/null
>> +++ b/src/tsk.c
>> @@ -0,0 +1,123 @@
>> +/* 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/types.h>
>> +#include <sys/stat.h>
>> +#include <string.h>
>> +#include <rpc/xdr.h>
>> +#include <rpc/types.h>
>> +
>> +#include "full-read.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 *, char *, size_t );
> Extra space at the end.
>
>> +int deserialise_dirent_list (guestfs_h *, char *, size_t , struct guestfs_tsk_dirent_list *);
> deserialise_dirent_list can be static.
>
>> +
>> +struct guestfs_tsk_dirent_list *
>> +guestfs_impl_filesystem_walk (guestfs_h *g, const char *mountable)
>> +{
>> + int ret = 0;
>> + size_t size = 0;
>> + CLEANUP_FREE char *buf = 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;
>> +
>> + ret = guestfs_int_read_whole_file (g, tmpfile, &buf, &size);
> I think there should be checks for the size of the downloaded file, to
> avoid reading too much.
>
>> + if (ret < 0)
>> + return NULL;
>> +
>> + return parse_filesystem_walk (g, buf, size); /* caller frees */
>> +}
>> +
>> +/* Parse buf 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, char *buf, size_t bufsize)
>> +{
>> + 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, buf, bufsize, dirents);
>> + if (ret < 0) {
>> + guestfs_free_tsk_dirent_list (dirents);
>> + return NULL;
>> + }
>> +
>> + return dirents;
>> +}
>> +
>> +/* Deserialise buf content and populate the dirent list.
>> + * Return the number of deserialised dirents, -1 on error.
>> + */
>> +int
>> +deserialise_dirent_list (guestfs_h *g, char *buf, size_t bufsize,
>> + struct guestfs_tsk_dirent_list *dirents)
>> +{
>> + XDR xdr;
>> + bool_t ret = 0;
>> + uint32_t index = 0;
>> +
>> + xdrmem_create (&xdr, buf, bufsize, XDR_DECODE);
>> +
>> + for (index = 0; xdr_getpos (&xdr) < bufsize; index++) {
>> + if (index == dirents->len) {
>> + dirents->len = 2 * dirents->len;
>> + dirents->val = safe_realloc (g, dirents->val,
>> + dirents->len *
>> + sizeof (*dirents->val));
>> + }
>> +
>> + memset(&dirents->val[index], 0, sizeof (*dirents->val));
> I think this should not be needed at all, the XDR decoding should set
> every field in the struct.
This is indeed needed as the initialized memory won't be zeroed thus
confusing the inner 'xdr_string' function (very bad API IMHO).
>
>> + ret = xdr_guestfs_int_tsk_dirent(&xdr, (guestfs_int_tsk_dirent *)
> Why is "(guestfs_int_tsk_dirent *)" needed? (Also, missing space.)
The struct is guestfs_tsk_dirent, the function parameter is of type
guestfs_int_tsk_dirent.
>
> Thanks,
>
>
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