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-rw-r--r--libbb/uncompress.c313
1 files changed, 313 insertions, 0 deletions
diff --git a/libbb/uncompress.c b/libbb/uncompress.c
new file mode 100644
index 0000000..903e6aa
--- /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
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