vnc-encoding-zlib.c

   1 /*
   2  * QEMU VNC display driver: zlib encoding
   3  *
   4  * Copyright (C) 2006 Anthony Liguori <anthony@codemonkey.ws>
   5  * Copyright (C) 2006 Fabrice Bellard
   6  * Copyright (C) 2009 Red Hat, Inc
   7  *
   8  * Permission is hereby granted, free of charge, to any person obtaining a copy
   9  * of this software and associated documentation files (the "Software"), to deal
  10  * in the Software without restriction, including without limitation the rights
  11  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  12  * copies of the Software, and to permit persons to whom the Software is
  13  * furnished to do so, subject to the following conditions:
  14  *
  15  * The above copyright notice and this permission notice shall be included in
  16  * all copies or substantial portions of the Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  19  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  21  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  22  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  23  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  24  * THE SOFTWARE.
  25  */
  26
  27 #include "vnc.h"
  28
  29 #define ZALLOC_ALIGNMENT 16
  30
  31 void *vnc_zlib_zalloc(void *x, unsigned items, unsigned size)
  32 {
  33     void *p;
  34
  35     size *= items;
  36     size = (size + ZALLOC_ALIGNMENT - 1) & ~(ZALLOC_ALIGNMENT - 1);
  37
  38     p = qemu_mallocz(size);
  39
  40     return (p);
  41 }
  42
  43 void vnc_zlib_zfree(void *x, void *addr)
  44 {
  45     qemu_free(addr);
  46 }
  47
  48 static void vnc_zlib_start(VncState *vs)
  49 {
  50     buffer_reset(&vs->zlib);
  51
  52     // make the output buffer be the zlib buffer, so we can compress it later
  53     vs->zlib_tmp = vs->output;
  54     vs->output = vs->zlib;
  55 }
  56
  57 static int vnc_zlib_stop(VncState *vs)
  58 {
  59     z_streamp zstream = &vs->zlib_stream;
  60     int previous_out;
  61
  62     // switch back to normal output/zlib buffers
  63     vs->zlib = vs->output;
  64     vs->output = vs->zlib_tmp;
  65
  66     // compress the zlib buffer
  67
  68     // initialize the stream
  69     // XXX need one stream per session
  70     if (zstream->opaque != vs) {
  71         int err;
  72
  73         VNC_DEBUG("VNC: initializing zlib stream\n");
  74         VNC_DEBUG("VNC: opaque = %p | vs = %p\n", zstream->opaque, vs);
  75         zstream->zalloc = vnc_zlib_zalloc;
  76         zstream->zfree = vnc_zlib_zfree;
  77
  78         err = deflateInit2(zstream, vs->tight_compression, Z_DEFLATED, MAX_WBITS,
  79                            MAX_MEM_LEVEL, Z_DEFAULT_STRATEGY);
  80
  81         if (err != Z_OK) {
  82             fprintf(stderr, "VNC: error initializing zlib\n");
  83             return -1;
  84         }
  85
  86         vs->zlib_level = vs->tight_compression;
  87         zstream->opaque = vs;
  88     }
  89
  90     if (vs->tight_compression != vs->zlib_level) {
  91         if (deflateParams(zstream, vs->tight_compression,
  92                           Z_DEFAULT_STRATEGY) != Z_OK) {
  93             return -1;
  94         }
  95         vs->zlib_level = vs->tight_compression;
  96     }
  97
  98     // reserve memory in output buffer
  99     buffer_reserve(&vs->output, vs->zlib.offset + 64);
 100
 101     // set pointers
 102     zstream->next_in = vs->zlib.buffer;
 103     zstream->avail_in = vs->zlib.offset;
 104     zstream->next_out = vs->output.buffer + vs->output.offset;
 105     zstream->avail_out = vs->output.capacity - vs->output.offset;
 106     zstream->data_type = Z_BINARY;
 107     previous_out = zstream->total_out;
 108
 109     // start encoding
 110     if (deflate(zstream, Z_SYNC_FLUSH) != Z_OK) {
 111         fprintf(stderr, "VNC: error during zlib compression\n");
 112         return -1;
 113     }
 114
 115     vs->output.offset = vs->output.capacity - zstream->avail_out;
 116     return zstream->total_out - previous_out;
 117 }
 118
 119 int vnc_zlib_send_framebuffer_update(VncState *vs, int x, int y, int w, int h)
 120 {
 121     int old_offset, new_offset, bytes_written;
 122
 123     vnc_framebuffer_update(vs, x, y, w, h, VNC_ENCODING_ZLIB);
 124
 125     // remember where we put in the follow-up size
 126     old_offset = vs->output.offset;
 127     vnc_write_s32(vs, 0);
 128
 129     // compress the stream
 130     vnc_zlib_start(vs);
 131     vnc_raw_send_framebuffer_update(vs, x, y, w, h);
 132     bytes_written = vnc_zlib_stop(vs);
 133
 134     if (bytes_written == -1)
 135         return 0;
 136
 137     // hack in the size
 138     new_offset = vs->output.offset;
 139     vs->output.offset = old_offset;
 140     vnc_write_u32(vs, bytes_written);
 141     vs->output.offset = new_offset;
 142
 143     return 1;
 144 }
 145
 146 void vnc_zlib_clear(VncState *vs)
 147 {
 148     if (vs->zlib_stream.opaque) {
 149         deflateEnd(&vs->zlib_stream);
 150     }
 151     buffer_free(&vs->zlib);
 152 }