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 static void *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 static void 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, int stream_id)
  58 {
  59     z_streamp zstream = &vs->zlib_stream[stream_id];
  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 %d\n", stream_id);
  74         VNC_DEBUG("VNC: opaque = %p | vs = %p\n", zstream->opaque, vs);
  75         zstream->zalloc = zalloc;
  76         zstream->zfree = 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         zstream->opaque = vs;
  87     }
  88
  89     // XXX what to do if tight_compression changed in between?
  90
  91     // reserve memory in output buffer
  92     buffer_reserve(&vs->output, vs->zlib.offset + 64);
  93
  94     // set pointers
  95     zstream->next_in = vs->zlib.buffer;
  96     zstream->avail_in = vs->zlib.offset;
  97     zstream->next_out = vs->output.buffer + vs->output.offset;
  98     zstream->avail_out = vs->output.capacity - vs->output.offset;
  99     zstream->data_type = Z_BINARY;
 100     previous_out = zstream->total_out;
 101
 102     // start encoding
 103     if (deflate(zstream, Z_SYNC_FLUSH) != Z_OK) {
 104         fprintf(stderr, "VNC: error during zlib compression\n");
 105         return -1;
 106     }
 107
 108     vs->output.offset = vs->output.capacity - zstream->avail_out;
 109     return zstream->total_out - previous_out;
 110 }
 111
 112 void vnc_zlib_send_framebuffer_update(VncState *vs, int x, int y, int w, int h)
 113 {
 114     int old_offset, new_offset, bytes_written;
 115
 116     vnc_framebuffer_update(vs, x, y, w, h, VNC_ENCODING_ZLIB);
 117
 118     // remember where we put in the follow-up size
 119     old_offset = vs->output.offset;
 120     vnc_write_s32(vs, 0);
 121
 122     // compress the stream
 123     vnc_zlib_start(vs);
 124     vnc_raw_send_framebuffer_update(vs, x, y, w, h);
 125     bytes_written = vnc_zlib_stop(vs, 0);
 126
 127     if (bytes_written == -1)
 128         return;
 129
 130     // hack in the size
 131     new_offset = vs->output.offset;
 132     vs->output.offset = old_offset;
 133     vnc_write_u32(vs, bytes_written);
 134     vs->output.offset = new_offset;
 135 }
 136
 137 void vnc_zlib_init(VncState *vs)
 138 {
 139     int i;
 140     for (i=0; i<(sizeof(vs->zlib_stream) / sizeof(z_stream)); i++)
 141         vs->zlib_stream[i].opaque = NULL;
 142 }