sys/src/cmd/aux/unbflz.c

   1 #include <u.h>
   2 #include <libc.h>
   3 #include <bio.h>
   4
   5 void
   6 usage(void)
   7 {
   8         fprint(2, "usage: unbflz [file]\n");
   9         exits("usage");
  10 }
  11
  12 int
  13 Bgetint(Biobuf *b)
  14 {
  15         uchar p[4];
  16
  17         if(Bread(b, p, 4) != 4)
  18                 sysfatal("short read");
  19         return (p[0]<<24)|(p[1]<<16)|(p[2]<<8)|p[3];
  20 }
  21
  22 /*
  23  * memmove but make sure overlap works properly.
  24  */
  25 void
  26 copy(uchar *dst, uchar *src, int n)
  27 {
  28         while(n-- > 0)
  29                 *dst++ = *src++;
  30 }
  31
  32 void
  33 main(int argc, char **argv)
  34 {
  35         Biobuf *b, bin;
  36         char buf[5];
  37         uchar *data;
  38         ulong *blk, l;
  39         int nblk, mblk;
  40         int sum;
  41         int i, j, length, m, n, o;
  42
  43         ARGBEGIN{
  44         default:
  45                 usage();
  46         }ARGEND
  47
  48         switch(argc){
  49         default:
  50                 usage();
  51         case 0:
  52                 Binit(&bin, 0, OREAD);
  53                 b = &bin;
  54                 break;
  55         case 1:
  56                 if((b = Bopen(argv[0], OREAD)) == nil)
  57                         sysfatal("open %s: %r", argv[0]);
  58                 break;
  59         }
  60
  61         if(Bread(b, buf, 4) != 4)
  62                 sysfatal("short read");
  63
  64         if(memcmp(buf, "BLZ\n", 4) != 0)
  65                 sysfatal("bad header");
  66
  67         length = Bgetint(b);
  68         data = malloc(length);
  69         if(data == nil)
  70                 sysfatal("out of memory");
  71         sum = 0;
  72         nblk = 0;
  73         mblk = 0;
  74         blk = nil;
  75         while(sum < length){
  76                 if(nblk>=mblk){
  77                         mblk += 16384;
  78                         blk = realloc(blk, (mblk+1)*sizeof(blk[0]));
  79                         if(blk == nil)
  80                                 sysfatal("out of memory");
  81                 }
  82                 l = Bgetint(b);
  83                 blk[nblk++] = l;
  84                 if(l&(1<<31))
  85                         l &= ~(1<<31);
  86                 else
  87                         blk[nblk++] = Bgetint(b);
  88                 sum += l;
  89         }
  90         if(sum != length)
  91                 sysfatal("bad compressed data %d %d", sum, length);
  92         i = 0;
  93         j = 0;
  94         while(i < length){
  95                 assert(j < nblk);
  96                 n = blk[j++];
  97                 if(n&(1<<31)){
  98                         n &= ~(1<<31);
  99                         if((m=Bread(b, data+i, n)) != n)
 100                                 sysfatal("short read %d %d", n, m);
 101                 }else{
 102                         o = blk[j++];
 103                         copy(data+i, data+o, n);
 104                 }
 105                 i += n;
 106         }
 107         write(1, data, length);
 108         exits(nil);
 109 }