tsk3.h

/* SleuthKit functions.
 *
 * Copyright 2010, Michael Cohen <sucdette@gmail.com>.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/* Note on thread-safety:
 *
 * pytsk3 declares Py_MOD_GIL_NOT_USED on free-threaded Python builds
 * and is built against libtsk with TSK_MULTITHREAD_LIB enabled. The
 * intended contract for callers is:
 *
 *   - Any pytsk3 object may be shared across threads. Methods on
 *     Img_Info, FS_Info, File, Directory, Volume_Info, and Attribute
 *     can be called concurrently from multiple threads on the same
 *     instance without external locking.
 *
 *   - Per-instance state (iterator cursors, open/close transitions)
 *     is protected by a per-instance tsk_lock_t inside the C class
 *     struct. Iterators advance atomically, so two threads sharing a
 *     Directory or Volume_Info will each consume distinct entries
 *     without skipping or duplicating.
 *
 *   - libtsk's image cache (cache_lock) and per-thread error TLS
 *     (tsk_error_get) provide the underlying primitives. Both depend
 *     on TSK_MULTITHREAD_LIB; see setup.py.
 *
 *   - Python subclasses that override read() (e.g. an Img_Info that
 *     wraps a file-like object) must provide their own locking around
 *     any stateful resource they touch -- pytsk3 will dispatch into
 *     the override from any thread. tests/test_lib.py shows the
 *     pattern.
 *
 *   - User code that mixes raw libtsk handles obtained from a pytsk3
 *     wrapper (e.g. via .info on a borrowed struct) with concurrent
 *     parent destruction is unsafe; the parent-keepalive on yielded
 *     children prevents this for normal Python reference flow.
 */

#if !defined( TSK3_H_ )
#define TSK3_H_

#include <tsk/libtsk.h>

#include "aff4_errors.h"
#include "class.h"

typedef struct {
  TSK_IMG_INFO base;
  struct Img_Info_t *container;
} Extended_TSK_IMG_INFO;

BIND_STRUCT(Extended_TSK_IMG_INFO);

/** Bind the following structs */
BIND_STRUCT(TSK_FS_INFO);
BIND_STRUCT(TSK_FS_NAME);
BIND_STRUCT(TSK_FS_META);
BIND_STRUCT(TSK_FS_DIR);
BIND_STRUCT(TSK_FS_FILE);
BIND_STRUCT(TSK_FS_BLOCK);
BIND_STRUCT(TSK_FS_ATTR);
BIND_STRUCT(TSK_FS_ATTR_RUN);
BIND_STRUCT(TSK_VS_PART_INFO);
BIND_STRUCT(TSK_VS_INFO);

/** This is a normal IMG_INFO which takes a filename and passes it
    to TSK. It just uses the standard TSK image handling code to
    support EWF, AFF etc.

    This is usually the first object you would instantiate in order to
    use the TSK library:

    img = Img_Info(filename)

    you would then pass it to an FS_Info object:

    fs = FS_Info(img)

    Then open an inode or path

    f = fs.open_dir(inode = 2)

    Thread-safety: methods on Img_Info are safe to call concurrently
    from multiple threads. Img_Info_close serializes against in-flight
    Img_Info_read via state_lock so a reader never observes a torn
    img_is_open transition.
*/
CCLASS(Img_Info, Object)
     PRIVATE Extended_TSK_IMG_INFO *img;

     /* Value to indicate if img is managed internally
      */
     PRIVATE int img_is_internal;

     /* Value to indicate if img is open. Read/written under state_lock
      * so concurrent close() and read() see a consistent value.
      */
     PRIVATE int img_is_open;

     /* Per-instance mutex protecting open/close transitions. Init in
      * Con, deinit in dest. Held while Img_Info_read consults
      * img_is_open and dispatches to libtsk so a parallel close()
      * cannot tear down state mid-read. Not exposed to Python.
      */
     PRIVATE tsk_lock_t state_lock;
     PRIVATE int state_lock_initialized;

     /* Open an image using the Sleuthkit.
      *
      * DEFAULT(type) = TSK_IMG_TYPE_DETECT;
      * DEFAULT(url) = "";
      */
     Img_Info METHOD(Img_Info, Con, ZString url, TSK_IMG_TYPE_ENUM type);

     /* Read a random buffer from the image */
     uint64_t METHOD(Img_Info, read, TSK_OFF_T off, OUT char *buf, size_t len);

     /* Retrieve the size of the image */
     uint64_t METHOD(Img_Info, get_size);

     /* Closes the image */
     void METHOD(Img_Info, close);
END_CCLASS

/** This object handles volumes.

    Thread-safety: the iterator cursor (current) is mutated under
    iter_lock during __iter__ and iternext, so two threads can share
    a Volume_Info and iterate concurrently without skipping or
    duplicating partitions or scribbling on the cursor.
 */
CCLASS(Volume_Info, Object)
  FOREIGN TSK_VS_INFO *info;
  int current;

  /* Per-instance mutex serializing iterator cursor updates. */
  PRIVATE tsk_lock_t iter_lock;
  PRIVATE int iter_lock_initialized;

  /** Open a volume using the Sleuthkit.

      DEFAULT(offset) = 0;
      DEFAULT(type) = TSK_VS_TYPE_DETECT;
  */
  Volume_Info METHOD(Volume_Info, Con, Img_Info img,
                     TSK_VS_TYPE_ENUM type, TSK_OFF_T offset);
  void METHOD(Volume_Info, __iter__);
  TSK_VS_PART_INFO *METHOD(Volume_Info, iternext);
END_CCLASS

// Forward declerations
struct FS_Info_t;
struct Directory_t;

/** An attribute is associated with a file. In some filesystem
    (e.g. NTFS) a file may contain many attributes.

    Attributes can be iterated over to obtain the attribute runs
    (e.g. to recover block allocation information).

*/
CCLASS(Attribute, Object)
   FOREIGN TSK_FS_ATTR *info;
   FOREIGN TSK_FS_ATTR_RUN *current;

   /* Per-instance mutex serializing iterator cursor updates. See
    * Volume_Info above for rationale.
    */
   PRIVATE tsk_lock_t iter_lock;
   PRIVATE int iter_lock_initialized;

   Attribute METHOD(Attribute, Con, TSK_FS_ATTR *info);

   void METHOD(Attribute, __iter__);
   TSK_FS_ATTR_RUN *METHOD(Attribute, iternext);
END_CCLASS


/** This represents a file object. A file has both metadata and
    data streams.

    Its usually not useful to instantiate this C class by itself -
    you need to call FS_Info.open() or iterate over a Directory()
    object.

    This object may be used to read the content of the file using
    read_random().

    Iterating over this object will return all the attributes for
    this file.
*/
CCLASS(File, Object)
     FOREIGN TSK_FS_FILE *info;

     /* Value to indicate if info is managed internally
      */
     PRIVATE int info_is_internal;

     PRIVATE struct FS_Info_t *fs;

     int max_attr;
     int current_attr;

     /* Per-instance mutex serializing iterator cursor updates so two
      * threads can share a File and iterate its attributes safely.
      */
     PRIVATE tsk_lock_t iter_lock;
     PRIVATE int iter_lock_initialized;

     File METHOD(File, Con, struct FS_Info_t *fs, TSK_FS_FILE *info);

     /** Read a buffer from a random location in the file.

         DEFAULT(flags) = 0;
         DEFAULT(type) = TSK_FS_ATTR_TYPE_DEFAULT;
         DEFAULT(id) = -1;
     */
     uint64_t METHOD(File, read_random, TSK_OFF_T offset,
                    OUT char *buff, int len,
                    TSK_FS_ATTR_TYPE_ENUM type, int id,
                    TSK_FS_FILE_READ_FLAG_ENUM flags);

     /* Obtain a directory object that represents this inode. This may
        be useful if the file is actually a directory and we want to
        iterate over its contents.
      */
     struct Directory_t *METHOD(File, as_directory);

     void METHOD(File, __iter__);
     Attribute METHOD(File, iternext);
END_CCLASS

/** This represents a Directory within the filesystem. You can
    iterate over this object to obtain all the File objects
    contained within this directory:

    for f in d:
        print f.info.name.name
*/
CCLASS(Directory, Object)
     TSK_FS_DIR *info;
     PRIVATE struct FS_Info_t *fs;

     /* Total number of files in this directory */
     size_t size;

     /* Current file returned in the next iteration. Mutated under
      * iter_lock so two threads can share a Directory and iterate
      * concurrently without missed or duplicated entries.
      */
     int current;

     PRIVATE tsk_lock_t iter_lock;
     PRIVATE int iter_lock_initialized;

     /* We can open the directory using a path, its inode number.

        DEFAULT(path) = NULL;
        DEFAULT(inode) = 0;
      */
     Directory METHOD(Directory, Con, struct FS_Info_t *fs, \
                      ZString path, TSK_INUM_T inode);

     /** An iterator of all files in the present directory. */
     void METHOD(Directory, __iter__);
     File METHOD(Directory, iternext);
END_CCLASS

/** This is used to obtain a filesystem object from an Img_Info object.

    From this FS_Info we can open files or directories by inode, or
    path.
 */
CCLASS(FS_Info, Object)
     FOREIGN TSK_FS_INFO *info;

     PRIVATE Extended_TSK_IMG_INFO *extended_img_info;

     /** Open the filesystem stored on image.

       DEFAULT(type) = TSK_FS_TYPE_DETECT;
       DEFAULT(offset) = 0;
     */
     FS_Info METHOD(FS_Info, Con, Img_Info img, TSK_OFF_T offset,
                    TSK_FS_TYPE_ENUM type);

     /** A convenience function to open a directory in this image.

         DEFAULT(path) = NULL;
         DEFAULT(inode) = 2;
     */
     Directory METHOD(FS_Info, open_dir, ZString path, TSK_INUM_T inode);

     /** A convenience function to open a file in this image. */
     File METHOD(FS_Info, open, ZString path);

     // Open a file by inode number
     File METHOD(FS_Info, open_meta, TSK_INUM_T inode);

     void METHOD(FS_Info, exit);

END_CCLASS

     int *tsk_get_current_error(char **buff);

void tsk_init(void);

#endif /* !TSK3_H_ */