diff options
Diffstat (limited to 'appl/lib/inflate.b')
| -rw-r--r-- | appl/lib/inflate.b | 103 |
1 files changed, 89 insertions, 14 deletions
diff --git a/appl/lib/inflate.b b/appl/lib/inflate.b index 0f4d6ba7..3ee2503a 100644 --- a/appl/lib/inflate.b +++ b/appl/lib/inflate.b @@ -135,6 +135,7 @@ offdec: ref DeHuff; revtab: array of byte; # bit reversal for endian swap of huffman codes mask: array of int; # for masking low-order n bits of an int +Hnone, Hgzip, Hzlib: con iota; # State.headers State: adt { ibuf, obuf: array of byte; c: chan of ref Rq; @@ -145,7 +146,8 @@ State: adt { hist: array of byte; # history buffer for lempel-ziv backward references usehist: int; # == 1 if 'hist' is valid crctab: array of int; - crc, tot: int; + crc, tot: int; # for gzip trailer + sum: big; # for zlib trailer reg: int; # 24-bit shift register nbits: int; # number of valid bits in reg @@ -226,9 +228,16 @@ start(params: string): chan of ref Rq s.nbits = 0; s.crc = 0; s.tot = 0; + s.sum = big 1; s.hist = array[Blocksize] of byte; - s.headers = (params != nil && params[0] == 'h'); - if (s.headers) + s.headers = Hnone; + if(params != nil) { + if(params[0] == 'h') + s.headers = Hgzip; + if(params[0] == 'z') + s.headers = Hzlib; + } + if (s.headers == Hgzip) s.crctab = mkcrctab(GZCRCPOLY); spawn inflate(s); return s.c; @@ -237,8 +246,7 @@ start(params: string): chan of ref Rq inflate(s: ref State) { s.c <-= ref Rq.Start(sys->pctl(0, nil)); - if (s.headers) - header(s); + header(s); for(;;) { bfinal := getn(s, 1, 0); @@ -268,23 +276,21 @@ inflate(s: ref State) } if(bfinal) { if(s.out) { - if (s.headers) - outblock(s); + outblock(s); s.c <- = ref Rq.Result(s.obuf[0:s.out], s.rc); flag := <- s.rc; if (flag == -1) exit; } flushbits(s); - if (s.headers) - footer(s); + footer(s); s.c <-= ref Rq.Finished(s.ibuf[s.in - s.nbits/8:s.ein]); exit; } } } -header(s: ref State) +headergzip(s: ref State) { if(byte getb(s) != GZMAGIC1 || byte getb(s) != GZMAGIC2) fatal(s, "not a gzip file"); @@ -335,7 +341,33 @@ header(s: ref State) } } -footer(s: ref State) +headerzlib(s: ref State) +{ + Fdict: con 1<<5; + CMshift: con 8; + CMmask: con (1<<4)-1; + CMdeflate: con 8; + + h := 0; + h |= getb(s)<<8; + h |= getb(s); + if(h % 31 != 0) + fatal(s, "invalid zlib header"); + if(h&Fdict) + fatal(s, "preset dictionary not supported"); + if(((h>>CMshift)&CMmask) != CMdeflate) + fatal(s, "zlib compression method not deflate"); +} + +header(s: ref State) +{ + case s.headers { + Hgzip => headergzip(s); + Hzlib => headerzlib(s); + } +} + +footergzip(s: ref State) { fcrc := getword(s); if(s.crc != fcrc) @@ -345,6 +377,25 @@ footer(s: ref State) fatal(s, sys->sprint("byte count mismatch: computed %d, expected %d", s.tot, ftot)); } +footerzlib(s: ref State) +{ + sum := big 0; + sum = (sum<<8)|big getb(s); + sum = (sum<<8)|big getb(s); + sum = (sum<<8)|big getb(s); + sum = (sum<<8)|big getb(s); + if(sum != s.sum) + fatal(s, sys->sprint("adler32 mismatch: computed %bux, expected %bux", s.sum, sum)); +} + +footer(s: ref State) +{ + case s.headers { + Hgzip => footergzip(s); + Hzlib => footerzlib(s); + } +} + getword(s: ref State): int { n := 0; @@ -694,8 +745,7 @@ flushbits(s: ref State) # flushout(s: ref State) { - if (s.headers) - outblock(s); + outblock(s); s.c <-= ref Rq.Result(s.obuf[0:s.out], s.rc); flag := <- s.rc; if (flag == -1) @@ -723,7 +773,7 @@ mkcrctab(poly: int): array of int return crctab; } -outblock(s: ref State) +outblockgzip(s: ref State) { buf := s.obuf; n := s.out; @@ -735,6 +785,31 @@ outblock(s: ref State) s.tot += n; } +outblockzlib(s: ref State) +{ + ZLADLERBASE: con big 65521; + + buf := s.obuf; + n := s.out; + + s1 := s.sum & big 16rffff; + s2 := (s.sum>>16) & big 16rffff; + + for(i := 0; i < n; i++) { + s1 = (s1 + big buf[i]) % ZLADLERBASE; + s2 = (s2 + s1) % ZLADLERBASE; + } + s.sum = (s2<<16) + s1; +} + +outblock(s: ref State) +{ + case s.headers { + Hgzip => outblockgzip(s); + Hzlib => outblockzlib(s); + } +} + # # irrecoverable error; invariably denotes data corruption # |