diff options
author | Robert Griebl <griebl@gmx.de> | 2002-05-19 23:00:14 +0400 |
---|---|---|
committer | Robert Griebl <griebl@gmx.de> | 2002-05-19 23:00:14 +0400 |
commit | 94a6a956f0ec733e1c80ff97645692d041292088 (patch) | |
tree | 8ea7c7a9112731a1888da57665d43da58c4e67a5 /libbb | |
parent | c6def44cfc0de0f5eb3cafb2909908097d6d9e4b (diff) |
Support old-style compress (.Z) files via libbb / unzip( ) calls
(configurable) - When enabled an applet "uncompress" is also made
available (oddname to gunzip)
[the cvs add for this file got lost somehow...]
Diffstat (limited to 'libbb')
-rw-r--r-- | libbb/uncompress.c | 313 |
1 files changed, 313 insertions, 0 deletions
diff --git a/libbb/uncompress.c b/libbb/uncompress.c new file mode 100644 index 000000000..903e6aa6d --- /dev/null +++ b/libbb/uncompress.c @@ -0,0 +1,313 @@ +#include "config.h" +#include "libbb.h" + +#ifdef CONFIG_FEATURE_UNCOMPRESS + +/* uncompress for busybox -- (c) 2002 Robert Griebl + * + * based on the original compress42.c source + * (see disclaimer below) + */ + + +/* (N)compress42.c - File compression ala IEEE Computer, Mar 1992. + * + * Authors: + * Spencer W. Thomas (decvax!harpo!utah-cs!utah-gr!thomas) + * Jim McKie (decvax!mcvax!jim) + * Steve Davies (decvax!vax135!petsd!peora!srd) + * Ken Turkowski (decvax!decwrl!turtlevax!ken) + * James A. Woods (decvax!ihnp4!ames!jaw) + * Joe Orost (decvax!vax135!petsd!joe) + * Dave Mack (csu@alembic.acs.com) + * Peter Jannesen, Network Communication Systems + * (peter@ncs.nl) + * + * marc@suse.de : a small security fix for a buffer overflow + * + * [... History snipped ...] + * + */ +#include <stdio.h> + + +#define IBUFSIZ 2048 /* Defailt input buffer size */ +#define OBUFSIZ 2048 /* Default output buffer size */ + + /* Defines for third byte of header */ +#define MAGIC_1 (char_type)'\037'/* First byte of compressed file */ +#define MAGIC_2 (char_type)'\235'/* Second byte of compressed file */ +#define BIT_MASK 0x1f /* Mask for 'number of compresssion bits' */ + /* Masks 0x20 and 0x40 are free. */ + /* I think 0x20 should mean that there is */ + /* a fourth header byte (for expansion). */ +#define BLOCK_MODE 0x80 /* Block compresssion if table is full and */ + /* compression rate is dropping flush tables */ + + /* the next two codes should not be changed lightly, as they must not */ + /* lie within the contiguous general code space. */ +#define FIRST 257 /* first free entry */ +#define CLEAR 256 /* table clear output code */ + +#define INIT_BITS 9 /* initial number of bits/code */ + + +/* + * machine variants which require cc -Dmachine: pdp11, z8000, DOS + */ +#define FAST + +#define HBITS 17 /* 50% occupancy */ +#define HSIZE (1<<HBITS) +#define HMASK (HSIZE-1) +#define HPRIME 9941 +#define BITS 16 +#undef MAXSEG_64K + +typedef long int code_int; + +typedef long int count_int; +typedef long int cmp_code_int; + +typedef unsigned char char_type; + +#define MAXCODE(n) (1L << (n)) + + + +int block_mode = BLOCK_MODE;/* Block compress mode -C compatible with 2.0*/ +int maxbits = BITS; /* user settable max # bits/code */ +int exit_code = -1; /* Exitcode of compress (-1 no file compressed) */ + +char_type inbuf[IBUFSIZ+64]; /* Input buffer */ +char_type outbuf[OBUFSIZ+2048];/* Output buffer */ + + +count_int htab[HSIZE]; +unsigned short codetab[HSIZE]; + +#define htabof(i) htab[i] +#define codetabof(i) codetab[i] +#define tab_prefixof(i) codetabof(i) +#define tab_suffixof(i) ((char_type *)(htab))[i] +#define de_stack ((char_type *)&(htab[HSIZE-1])) +#define clear_htab() memset(htab, -1, sizeof(htab)) +#define clear_tab_prefixof() memset(codetab, 0, 256); + + +extern int uncompress ( FILE *, FILE * ); + + +/* + * Decompress stdin to stdout. This routine adapts to the codes in the + * file building the "string" table on-the-fly; requiring no table to + * be stored in the compressed file. The tables used herein are shared + * with those of the compress() routine. See the definitions above. + */ + +int uncompress ( FILE * fdin, FILE * fdout ) +{ + char_type *stackp; + code_int code; + int finchar; + code_int oldcode; + code_int incode; + int inbits; + int posbits; + int outpos; + int insize; + int bitmask; + code_int free_ent; + code_int maxcode; + code_int maxmaxcode; + int n_bits; + int rsize = 0; + + insize = 0; + + inbuf [0] = fgetc(fdin); + + maxbits = inbuf[0] & BIT_MASK; + block_mode = inbuf[0] & BLOCK_MODE; + maxmaxcode = MAXCODE(maxbits); + + if (maxbits > BITS) + { + fprintf(stderr, "compressed with %d bits, can only handle %d bits\n", maxbits, BITS); + return -1; + } + + //fprintf(stderr, "Bits: %d, block_mode: %d\n", maxbits, block_mode ); + + maxcode = MAXCODE(n_bits = INIT_BITS)-1; + bitmask = (1<<n_bits)-1; + oldcode = -1; + finchar = 0; + outpos = 0; + posbits = 0<<3; + + free_ent = ((block_mode) ? FIRST : 256); + + clear_tab_prefixof(); /* As above, initialize the first + 256 entries in the table. */ + + for (code = 255 ; code >= 0 ; --code) + tab_suffixof(code) = (char_type)code; + + do + { +resetbuf: ; + { + int i; + int e; + int o; + + e = insize-(o = (posbits>>3)); + + for (i = 0 ; i < e ; ++i) + inbuf[i] = inbuf[i+o]; + + insize = e; + posbits = 0; + } + + if (insize < (int) sizeof(inbuf)-IBUFSIZ) + { + rsize = fread(inbuf+insize, 1,IBUFSIZ,fdin); + + if ( !rsize && ferror(fdin)) + return -1; + + insize += rsize; + } + + inbits = ((rsize > 0) ? (insize - insize%n_bits)<<3 : + (insize<<3)-(n_bits-1)); + + while (inbits > posbits) + { + if (free_ent > maxcode) + { + posbits = ((posbits-1) + ((n_bits<<3) - + (posbits-1+(n_bits<<3))%(n_bits<<3))); + + ++n_bits; + if (n_bits == maxbits) + maxcode = maxmaxcode; + else + maxcode = MAXCODE(n_bits)-1; + + bitmask = (1<<n_bits)-1; + goto resetbuf; + } + + + { + char_type *p = &inbuf[posbits>>3]; + code = ((((long)(p[0]))|((long)(p[1])<<8)|((long)(p[2])<<16))>>(posbits&0x7))&bitmask; + } + posbits += n_bits; + + + if (oldcode == -1) + { + outbuf[outpos++] = (char_type)(finchar = (int)(oldcode = code)); + continue; + } + + if (code == CLEAR && block_mode) + { + clear_tab_prefixof(); + free_ent = FIRST - 1; + posbits = ((posbits-1) + ((n_bits<<3) - + (posbits-1+(n_bits<<3))%(n_bits<<3))); + maxcode = MAXCODE(n_bits = INIT_BITS)-1; + bitmask = (1<<n_bits)-1; + goto resetbuf; + } + + incode = code; + stackp = de_stack; + + if (code >= free_ent) /* Special case for KwKwK string. */ + { + if (code > free_ent) + { + char_type *p; + + posbits -= n_bits; + p = &inbuf[posbits>>3]; + + fprintf(stderr, "insize:%d posbits:%d inbuf:%02X %02X %02X %02X %02X (%d)\n", insize, posbits, + p[-1],p[0],p[1],p[2],p[3], (posbits&07)); + fprintf(stderr, "uncompress: corrupt input\n"); + return -1; + } + + *--stackp = (char_type)finchar; + code = oldcode; + } + + while ((cmp_code_int)code >= (cmp_code_int)256) + { /* Generate output characters in reverse order */ + *--stackp = tab_suffixof(code); + code = tab_prefixof(code); + } + + *--stackp = (char_type)(finchar = tab_suffixof(code)); + + /* And put them out in forward order */ + + { + int i; + + if (outpos+(i = (de_stack-stackp)) >= OBUFSIZ) + { + do + { + if (i > OBUFSIZ-outpos) i = OBUFSIZ-outpos; + + if (i > 0) + { + memcpy(outbuf+outpos, stackp, i); + outpos += i; + } + + if (outpos >= OBUFSIZ) + { + fwrite(outbuf, 1,outpos,fdout); + + outpos = 0; + } + stackp+= i; + } + while ((i = (de_stack-stackp)) > 0); + } + else + { + memcpy(outbuf+outpos, stackp, i); + outpos += i; + } + } + + if ((code = free_ent) < maxmaxcode) /* Generate the new entry. */ + { + tab_prefixof(code) = (unsigned short)oldcode; + tab_suffixof(code) = (char_type)finchar; + free_ent = code+1; + } + + oldcode = incode; /* Remember previous code. */ + } + + } + while (rsize > 0); + + if (outpos > 0) + fwrite(outbuf, outpos,1, fdout); + + return 0; +} + + +#endif |