ref: 88b386a4a15654bcc9d34a534812f1ec9c77e069
dir: /sys/src/cmd/aux/unbflz.c/
#include <u.h> #include <libc.h> #include <bio.h> void usage(void) { fprint(2, "usage: unbflz [file]\n"); exits("usage"); } int Bgetint(Biobuf *b) { uchar p[4]; if(Bread(b, p, 4) != 4) sysfatal("short read"); return (p[0]<<24)|(p[1]<<16)|(p[2]<<8)|p[3]; } /* * memmove but make sure overlap works properly. */ void copy(uchar *dst, uchar *src, int n) { while(n-- > 0) *dst++ = *src++; } void main(int argc, char **argv) { Biobuf *b, bin; char buf[5]; uchar *data; ulong *blk, l; int nblk, mblk; int sum; int i, j, length, m, n, o; ARGBEGIN{ default: usage(); }ARGEND switch(argc){ default: usage(); case 0: Binit(&bin, 0, OREAD); b = &bin; break; case 1: if((b = Bopen(argv[0], OREAD)) == nil) sysfatal("open %s: %r", argv[0]); break; } if(Bread(b, buf, 4) != 4) sysfatal("short read"); if(memcmp(buf, "BLZ\n", 4) != 0) sysfatal("bad header"); length = Bgetint(b); data = malloc(length); if(data == nil) sysfatal("out of memory"); sum = 0; nblk = 0; mblk = 0; blk = nil; while(sum < length){ if(nblk>=mblk){ mblk += 16384; blk = realloc(blk, (mblk+1)*sizeof(blk[0])); if(blk == nil) sysfatal("out of memory"); } l = Bgetint(b); blk[nblk++] = l; if(l&(1<<31)) l &= ~(1<<31); else blk[nblk++] = Bgetint(b); sum += l; } if(sum != length) sysfatal("bad compressed data %d %d", sum, length); i = 0; j = 0; while(i < length){ assert(j < nblk); n = blk[j++]; if(n&(1<<31)){ n &= ~(1<<31); if((m=Bread(b, data+i, n)) != n) sysfatal("short read %d %d", n, m); }else{ o = blk[j++]; copy(data+i, data+o, n); } i += n; } write(1, data, length); exits(nil); }