src/lib/compress/compress_none.c

   1 /* Copyright (c) 2004, Roger Dingledine.
   2  * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
   3  * Copyright (c) 2007-2021, The Tor Project, Inc. */
   4 /* See LICENSE for licensing information */
   5
   6 /**
   7  * \file compress_none.c
   8  * \brief Compression backend for identity compression.
   9  *
  10  * We actually define this backend so that we can treat the identity transform
  11  * as another case of compression.
  12  *
  13  * This module should never be invoked directly. Use the compress module
  14  * instead.
  15  **/
  16
  17 #include "orconfig.h"
  18
  19 #include "lib/log/log.h"
  20 #include "lib/compress/compress.h"
  21 #include "lib/compress/compress_none.h"
  22 #include "lib/intmath/cmp.h"
  23
  24 #include <string.h>
  25
  26 /** Transfer some bytes using the identity transformation.  Read up to
  27  * *<b>in_len</b> bytes from *<b>in</b>, and write up to *<b>out_len</b> bytes
  28  * to *<b>out</b>, adjusting the values as we go.  If <b>finish</b> is true,
  29  * we've reached the end of the input.
  30  *
  31  * Return TOR_COMPRESS_DONE if we've finished the entire
  32  * compression/decompression.
  33  * Return TOR_COMPRESS_OK if we're processed everything from the input.
  34  * Return TOR_COMPRESS_BUFFER_FULL if we're out of space on <b>out</b>.
  35  * Return TOR_COMPRESS_ERROR if the stream is corrupt.
  36  */
  37 tor_compress_output_t
  38 tor_cnone_compress_process(char **out, size_t *out_len,
  39                            const char **in, size_t *in_len,
  40                            int finish)
  41 {
  42   size_t n_to_copy = MIN(*in_len, *out_len);
  43
  44   memcpy(*out, *in, n_to_copy);
  45   *out += n_to_copy;
  46   *in += n_to_copy;
  47   *out_len -= n_to_copy;
  48   *in_len -= n_to_copy;
  49   if (*in_len == 0) {
  50     return finish ? TOR_COMPRESS_DONE : TOR_COMPRESS_OK;
  51   } else {
  52     return TOR_COMPRESS_BUFFER_FULL;
  53   }
  54 }