| /* vi: set sw=4 ts=4: */ |
| /* 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 "libbb.h" |
| #include "bb_archive.h" |
| |
| |
| /* Default input buffer size */ |
| #define IBUFSIZ 2048 |
| |
| /* Default output buffer size */ |
| #define OBUFSIZ 2048 |
| |
| /* Defines for third byte of header */ |
| #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 compression 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 HBITS 17 /* 50% occupancy */ |
| #define HSIZE (1<<HBITS) |
| #define HMASK (HSIZE-1) /* unused */ |
| #define HPRIME 9941 /* unused */ |
| #define BITS 16 |
| #define BITS_STR "16" |
| #undef MAXSEG_64K /* unused */ |
| #define MAXCODE(n) (1L << (n)) |
| |
| #define htabof(i) htab[i] |
| #define codetabof(i) codetab[i] |
| #define tab_prefixof(i) codetabof(i) |
| #define tab_suffixof(i) ((unsigned char *)(htab))[i] |
| #define de_stack ((unsigned char *)&(htab[HSIZE-1])) |
| #define clear_tab_prefixof() memset(codetab, 0, 256) |
| |
| /* |
| * 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. |
| */ |
| |
| IF_DESKTOP(long long) int FAST_FUNC |
| unpack_Z_stream(transformer_state_t *xstate) |
| { |
| IF_DESKTOP(long long total_written = 0;) |
| IF_DESKTOP(long long) int retval = -1; |
| unsigned char *stackp; |
| int finchar; |
| long oldcode; |
| long incode; |
| int inbits; |
| int posbits; |
| int outpos; |
| int insize; |
| int bitmask; |
| long free_ent; |
| long maxcode; |
| long maxmaxcode; |
| int n_bits; |
| int rsize = 0; |
| unsigned char *inbuf; /* were eating insane amounts of stack - */ |
| unsigned char *outbuf; /* bad for some embedded targets */ |
| unsigned char *htab; |
| unsigned short *codetab; |
| |
| /* Hmm, these were statics - why?! */ |
| /* user settable max # bits/code */ |
| int maxbits; /* = BITS; */ |
| /* block compress mode -C compatible with 2.0 */ |
| int block_mode; /* = BLOCK_MODE; */ |
| |
| if (check_signature16(xstate, COMPRESS_MAGIC)) |
| return -1; |
| |
| inbuf = xzalloc(IBUFSIZ + 64); |
| outbuf = xzalloc(OBUFSIZ + 2048); |
| htab = xzalloc(HSIZE); /* wasn't zeroed out before, maybe can xmalloc? */ |
| codetab = xzalloc(HSIZE * sizeof(codetab[0])); |
| |
| insize = 0; |
| |
| /* xread isn't good here, we have to return - caller may want |
| * to do some cleanup (e.g. delete incomplete unpacked file etc) */ |
| if (full_read(xstate->src_fd, inbuf, 1) != 1) { |
| bb_error_msg("short read"); |
| goto err; |
| } |
| |
| maxbits = inbuf[0] & BIT_MASK; |
| block_mode = inbuf[0] & BLOCK_MODE; |
| maxmaxcode = MAXCODE(maxbits); |
| |
| if (maxbits > BITS) { |
| bb_error_msg("compressed with %d bits, can only handle " |
| BITS_STR" bits", maxbits); |
| goto err; |
| } |
| |
| n_bits = INIT_BITS; |
| maxcode = MAXCODE(INIT_BITS) - 1; |
| bitmask = (1 << INIT_BITS) - 1; |
| oldcode = -1; |
| finchar = 0; |
| outpos = 0; |
| posbits = 0 << 3; |
| |
| free_ent = ((block_mode) ? FIRST : 256); |
| |
| /* As above, initialize the first 256 entries in the table. */ |
| /*clear_tab_prefixof(); - done by xzalloc */ |
| |
| { |
| int i; |
| for (i = 255; i >= 0; --i) |
| tab_suffixof(i) = (unsigned char) i; |
| } |
| |
| do { |
| resetbuf: |
| { |
| int i; |
| int e; |
| int o; |
| |
| o = posbits >> 3; |
| e = insize - o; |
| |
| for (i = 0; i < e; ++i) |
| inbuf[i] = inbuf[i + o]; |
| |
| insize = e; |
| posbits = 0; |
| } |
| |
| if (insize < (int) (IBUFSIZ + 64) - IBUFSIZ) { |
| rsize = safe_read(xstate->src_fd, inbuf + insize, IBUFSIZ); |
| if (rsize < 0) |
| bb_error_msg_and_die(bb_msg_read_error); |
| insize += rsize; |
| } |
| |
| inbits = ((rsize > 0) ? (insize - insize % n_bits) << 3 : |
| (insize << 3) - (n_bits - 1)); |
| |
| while (inbits > posbits) { |
| long code; |
| |
| 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; |
| } |
| { |
| unsigned char *p = &inbuf[posbits >> 3]; |
| code = ((p[0] |
| | ((long) (p[1]) << 8) |
| | ((long) (p[2]) << 16)) >> (posbits & 0x7)) & bitmask; |
| } |
| posbits += n_bits; |
| |
| if (oldcode == -1) { |
| if (code >= 256) |
| bb_error_msg_and_die("corrupted data"); /* %ld", code); */ |
| oldcode = code; |
| finchar = (int) oldcode; |
| outbuf[outpos++] = (unsigned char) finchar; |
| 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))); |
| n_bits = INIT_BITS; |
| maxcode = MAXCODE(INIT_BITS) - 1; |
| bitmask = (1 << INIT_BITS) - 1; |
| goto resetbuf; |
| } |
| |
| incode = code; |
| stackp = de_stack; |
| |
| /* Special case for KwKwK string. */ |
| if (code >= free_ent) { |
| if (code > free_ent) { |
| /* |
| unsigned char *p; |
| |
| posbits -= n_bits; |
| p = &inbuf[posbits >> 3]; |
| bb_error_msg |
| ("insize:%d posbits:%d inbuf:%02X %02X %02X %02X %02X (%d)", |
| insize, posbits, p[-1], p[0], p[1], p[2], p[3], |
| (posbits & 07)); |
| */ |
| bb_error_msg("corrupted data"); |
| goto err; |
| } |
| |
| *--stackp = (unsigned char) finchar; |
| code = oldcode; |
| } |
| |
| /* Generate output characters in reverse order */ |
| while (code >= 256) { |
| if (stackp <= &htabof(0)) |
| bb_error_msg_and_die("corrupted data"); |
| *--stackp = tab_suffixof(code); |
| code = tab_prefixof(code); |
| } |
| |
| finchar = tab_suffixof(code); |
| *--stackp = (unsigned char) finchar; |
| |
| /* And put them out in forward order */ |
| { |
| int i; |
| |
| i = de_stack - stackp; |
| if (outpos + i >= OBUFSIZ) { |
| do { |
| if (i > OBUFSIZ - outpos) { |
| i = OBUFSIZ - outpos; |
| } |
| |
| if (i > 0) { |
| memcpy(outbuf + outpos, stackp, i); |
| outpos += i; |
| } |
| |
| if (outpos >= OBUFSIZ) { |
| xtransformer_write(xstate, outbuf, outpos); |
| IF_DESKTOP(total_written += outpos;) |
| outpos = 0; |
| } |
| stackp += i; |
| i = de_stack - stackp; |
| } while (i > 0); |
| } else { |
| memcpy(outbuf + outpos, stackp, i); |
| outpos += i; |
| } |
| } |
| |
| /* Generate the new entry. */ |
| if (free_ent < maxmaxcode) { |
| tab_prefixof(free_ent) = (unsigned short) oldcode; |
| tab_suffixof(free_ent) = (unsigned char) finchar; |
| free_ent++; |
| } |
| |
| /* Remember previous code. */ |
| oldcode = incode; |
| } |
| } while (rsize > 0); |
| |
| if (outpos > 0) { |
| xtransformer_write(xstate, outbuf, outpos); |
| IF_DESKTOP(total_written += outpos;) |
| } |
| |
| retval = IF_DESKTOP(total_written) + 0; |
| err: |
| free(inbuf); |
| free(outbuf); |
| free(htab); |
| free(codetab); |
| return retval; |
| } |
