X-Git-Url: https://git.gag.com/?a=blobdiff_plain;f=unpack.c;h=56cc98c5ad5c36d004a98fc9fdbbaf373bb4003f;hb=92249085071a973e2c0621b0415b93d2e48bb00d;hp=b1f3ef3836ce72eae0a2ada17a3302990080d8e9;hpb=8ba3484138b5d1e72fd4ef49d27159263cb6bea6;p=debian%2Fgzip diff --git a/unpack.c b/unpack.c index b1f3ef3..56cc98c 100644 --- a/unpack.c +++ b/unpack.c @@ -1,17 +1,25 @@ /* unpack.c -- decompress files in pack format. - * Copyright (C) 1992-1993 Jean-loup Gailly - * This is free software; you can redistribute it and/or modify it under the - * terms of the GNU General Public License, see the file COPYING. - */ -#ifdef RCSID -static char rcsid[] = "$Id: unpack.c,v 1.4 1993/06/11 19:25:36 jloup Exp $"; -#endif + Copyright (C) 1997, 1999, 2006, 2009-2018 Free Software Foundation, Inc. + Copyright (C) 1992-1993 Jean-loup Gailly + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3, or (at your option) + any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software Foundation, + Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ #include #include "tailor.h" #include "gzip.h" -#include "crypt.h" #define MIN(a,b) ((a) <= (b) ? (a) : (b)) /* The arguments must not have side effects. */ @@ -68,6 +76,16 @@ local ulg bitbuf; local int valid; /* number of valid bits in bitbuf */ /* all bits above the last valid bit are always zero */ +/* Read an input byte, reporting an error at EOF. */ +static unsigned char +read_byte (void) +{ + int b = get_byte (); + if (b < 0) + gzip_error ("invalid compressed data -- unexpected end of file"); + return b; +} + /* Set code to the next 'bits' input bits without skipping them. code * must be the name of a simple variable and bits must not have side effects. * IN assertions: bits <= 25 (so that we still have room for an extra byte @@ -75,7 +93,7 @@ local int valid; /* number of valid bits in bitbuf */ */ #define look_bits(code,bits,mask) \ { \ - while (valid < (bits)) bitbuf = (bitbuf<<8) | (ulg)get_byte(), valid += 8; \ + while (valid < (bits)) bitbuf = (bitbuf<<8) | read_byte(), valid += 8; \ code = (bitbuf >> (valid-(bits))) & (mask); \ } @@ -86,8 +104,8 @@ local int valid; /* number of valid bits in bitbuf */ /* Local functions */ -local void read_tree OF((void)); -local void build_tree OF((void)); +local void read_tree (void); +local void build_tree (void); /* =========================================================================== * Read the Huffman tree. @@ -97,32 +115,33 @@ local void read_tree() int len; /* bit length */ int base; /* base offset for a sequence of leaves */ int n; - int max_leaves; + int max_leaves = 1; /* Read the original input size, MSB first */ orig_len = 0; - for (n = 1; n <= 4; n++) orig_len = (orig_len << 8) | (ulg)get_byte(); + for (n = 1; n <= 4; n++) + orig_len = (orig_len << 8) | read_byte (); - max_len = (int)get_byte(); /* maximum bit length of Huffman codes */ - if (max_len > MAX_BITLEN) { - error("invalid compressed data -- Huffman code > 32 bits"); - } + /* Read the maximum bit length of Huffman codes. */ + max_len = read_byte (); + if (! (0 < max_len && max_len <= MAX_BITLEN)) + gzip_error ("invalid compressed data -- " + "Huffman code bit length out of range"); /* Get the number of leaves at each bit length */ n = 0; - max_leaves = 1; for (len = 1; len <= max_len; len++) { - leaves[len] = (int)get_byte(); - if (leaves[len] > max_leaves - (len == max_len)) - error("too many leaves in Huffman tree"); - max_leaves = (max_leaves - leaves[len] + 1) * 2 - 1; - n += leaves[len]; + leaves[len] = read_byte (); + if (max_leaves - (len == max_len) < leaves[len]) + gzip_error ("too many leaves in Huffman tree"); + max_leaves = (max_leaves - leaves[len] + 1) * 2 - 1; + n += leaves[len]; } - if (n >= LITERALS) { - error("too many leaves in Huffman tree"); + if (LITERALS <= n) { + gzip_error ("too many leaves in Huffman tree"); } Trace((stderr, "orig_len %lu, max_len %d, leaves %d\n", - orig_len, max_len, n)); + orig_len, max_len, n)); /* There are at least 2 and at most 256 leaves of length max_len. * (Pack arbitrarily rejects empty files and files consisting of * a single byte even repeated.) To fit the last leaf count in a @@ -135,12 +154,12 @@ local void read_tree() /* Now read the leaves themselves */ base = 0; for (len = 1; len <= max_len; len++) { - /* Remember where the literals of this length start in literal[] : */ - lit_base[len] = base; - /* And read the literals: */ - for (n = leaves[len]; n > 0; n--) { - literal[base++] = (uch)get_byte(); - } + /* Remember where the literals of this length start in literal[] : */ + lit_base[len] = base; + /* And read the literals: */ + for (n = leaves[len]; n > 0; n--) { + literal[base++] = read_byte (); + } } leaves[max_len]++; /* Now include the EOB code in the Huffman tree */ } @@ -155,26 +174,29 @@ local void build_tree() uch *prefixp; /* pointer in prefix_len */ for (len = max_len; len >= 1; len--) { - /* The number of parent nodes at this level is half the total - * number of nodes at parent level: - */ - nodes >>= 1; - parents[len] = nodes; - /* Update lit_base by the appropriate bias to skip the parent nodes - * (which are not represented in the literal array): - */ - lit_base[len] -= nodes; - /* Restore nodes to be parents+leaves: */ - nodes += leaves[len]; + /* The number of parent nodes at this level is half the total + * number of nodes at parent level: + */ + nodes >>= 1; + parents[len] = nodes; + /* Update lit_base by the appropriate bias to skip the parent nodes + * (which are not represented in the literal array): + */ + lit_base[len] -= nodes; + /* Restore nodes to be parents+leaves: */ + nodes += leaves[len]; } + if ((nodes >> 1) != 1) + gzip_error ("too few leaves in Huffman tree"); + /* Construct the prefix table, from shortest leaves to longest ones. * The shortest code is all ones, so we start at the end of the table. */ peek_bits = MIN(max_len, MAX_PEEK); prefixp = &prefix_len[1< prefix_len) *--prefixp = 0; @@ -210,35 +232,38 @@ int unpack(in, out) /* Decode the input data: */ for (;;) { - /* Since eob is the longest code and not shorter than max_len, + /* Since eob is the longest code and not shorter than max_len, * we can peek at max_len bits without having the risk of reading * beyond the end of file. - */ - look_bits(peek, peek_bits, peek_mask); - len = prefix_len[peek]; - if (len > 0) { - peek >>= peek_bits - len; /* discard the extra bits */ - } else { - /* Code of more than peek_bits bits, we must traverse the tree */ - ulg mask = peek_mask; - len = peek_bits; - do { + */ + look_bits(peek, peek_bits, peek_mask); + len = prefix_len[peek]; + if (len > 0) { + peek >>= peek_bits - len; /* discard the extra bits */ + } else { + /* Code of more than peek_bits bits, we must traverse the tree */ + ulg mask = peek_mask; + len = peek_bits; + + /* Loop as long as peek is a parent node. */ + while (peek < parents[len]) + { len++, mask = (mask<<1)+1; - look_bits(peek, len, mask); - } while (peek < (unsigned)parents[len]); - /* loop as long as peek is a parent node */ - } - /* At this point, peek is the next complete code, of len bits */ - if (peek == eob && len == max_len) break; /* end of file? */ - put_ubyte(literal[peek+lit_base[len]]); - Tracev((stderr,"%02d %04x %c\n", len, peek, - literal[peek+lit_base[len]])); - skip_bits(len); + look_bits(peek, len, mask); + } + } + /* At this point, peek is the next complete code, of len bits */ + if (peek == eob && len == max_len) + break; /* End of file. */ + put_ubyte(literal[peek+lit_base[len]]); + Tracev((stderr,"%02d %04x %c\n", len, peek, + literal[peek+lit_base[len]])); + skip_bits(len); } /* for (;;) */ flush_window(); if (orig_len != (ulg)(bytes_out & 0xffffffff)) { - error("invalid compressed data--length error"); + gzip_error ("invalid compressed data--length error"); } return OK; }