src/lib/compress/compress_buf.c

   1 /* Copyright (c) 2003, 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_buf.c
   8  *
   9  * \brief Working with compressed data in buffers.
  10  **/
  11
  12 #define BUFFERS_PRIVATE
  13 #include "lib/cc/compat_compiler.h"
  14 #include "lib/buf/buffers.h"
  15 #include "lib/compress/compress.h"
  16 #include "lib/log/util_bug.h"
  17
  18 #ifdef PARANOIA
  19 /** Helper: If PARANOIA is defined, assert that the buffer in local variable
  20  * <b>buf</b> is well-formed. */
  21 #define check() STMT_BEGIN buf_assert_ok(buf); STMT_END
  22 #else
  23 #define check() STMT_NIL
  24 #endif /* defined(PARANOIA) */
  25
  26 /** Compress or uncompress the <b>data_len</b> bytes in <b>data</b> using the
  27  * compression state <b>state</b>, appending the result to <b>buf</b>.  If
  28  * <b>done</b> is true, flush the data in the state and finish the
  29  * compression/uncompression.  Return -1 on failure, 0 on success. */
  30 int
  31 buf_add_compress(buf_t *buf, tor_compress_state_t *state,
  32                  const char *data, size_t data_len,
  33                  const int done)
  34 {
  35   char *next;
  36   size_t old_avail, avail;
  37   int over = 0;
  38
  39   do {
  40     int need_new_chunk = 0;
  41     if (!buf->tail || ! CHUNK_REMAINING_CAPACITY(buf->tail)) {
  42       size_t cap = data_len / 4;
  43       buf_add_chunk_with_capacity(buf, cap, 1);
  44     }
  45     next = CHUNK_WRITE_PTR(buf->tail);
  46     avail = old_avail = CHUNK_REMAINING_CAPACITY(buf->tail);
  47     switch (tor_compress_process(state, &next, &avail,
  48                                  &data, &data_len, done)) {
  49       case TOR_COMPRESS_DONE:
  50         over = 1;
  51         break;
  52       case TOR_COMPRESS_ERROR:
  53         return -1;
  54       case TOR_COMPRESS_OK:
  55         if (data_len == 0) {
  56           tor_assert_nonfatal(!done);
  57           over = 1;
  58         }
  59         break;
  60       case TOR_COMPRESS_BUFFER_FULL:
  61         if (avail) {
  62           /* The compression module says we need more room
  63            * (TOR_COMPRESS_BUFFER_FULL).  Start a new chunk automatically,
  64            * whether were going to or not. */
  65           need_new_chunk = 1;
  66         }
  67         if (data_len == 0 && !done) {
  68           /* We've consumed all the input data, though, so there's no
  69            * point in forging ahead right now. */
  70           over = 1;
  71         }
  72         break;
  73     }
  74     buf->datalen += old_avail - avail;
  75     buf->tail->datalen += old_avail - avail;
  76     if (need_new_chunk) {
  77       buf_add_chunk_with_capacity(buf, data_len/4, 1);
  78     }
  79
  80   } while (!over);
  81   check();
  82   return 0;
  83 }