svn commit: trunk/busybox/archival/libunarchive

vda at busybox.net vda at busybox.net
Sat Jun 28 18:10:10 UTC 2008


Author: vda
Date: 2008-06-28 11:10:09 -0700 (Sat, 28 Jun 2008)
New Revision: 22550

Log:
bunzip2: make proper fix for the problem "fixed" in rev. 22521
 Thanks for Rob Landley <rob at landley.net>



Modified:
   trunk/busybox/archival/libunarchive/decompress_bunzip2.c


Changeset:
Modified: trunk/busybox/archival/libunarchive/decompress_bunzip2.c
===================================================================
--- trunk/busybox/archival/libunarchive/decompress_bunzip2.c	2008-06-28 06:37:30 UTC (rev 22549)
+++ trunk/busybox/archival/libunarchive/decompress_bunzip2.c	2008-06-28 18:10:09 UTC (rev 22550)
@@ -66,7 +66,6 @@
  *  | grep 'bd->' | sed 's/^.*bd->/bd->/' | sort | $PAGER
  * and moved it (inbufBitCount) to offset 0.
  */
-
 struct bunzip_data {
 	/* I/O tracking data (file handles, buffers, positions, etc.) */
 	unsigned inbufBitCount, inbufBits;
@@ -102,11 +101,9 @@
 
 	/* If we need to get more data from the byte buffer, do so.  (Loop getting
 	   one byte at a time to enforce endianness and avoid unaligned access.) */
-
 	while ((int)(bd->inbufBitCount) < bits_wanted) {
 
 		/* If we need to read more data from file into byte buffer, do so */
-
 		if (bd->inbufPos == bd->inbufCount) {
 			/* if "no input fd" case: in_fd == -1, read fails, we jump */
 			bd->inbufCount = read(bd->in_fd, bd->inbuf, IOBUF_SIZE);
@@ -116,7 +113,6 @@
 		}
 
 		/* Avoid 32-bit overflow (dump bit buffer to top of output) */
-
 		if (bd->inbufBitCount >= 24) {
 			bits = bd->inbufBits & ((1 << bd->inbufBitCount) - 1);
 			bits_wanted -= bd->inbufBitCount;
@@ -125,13 +121,11 @@
 		}
 
 		/* Grab next 8 bits of input from buffer. */
-
 		bd->inbufBits = (bd->inbufBits << 8) | bd->inbuf[bd->inbufPos++];
 		bd->inbufBitCount += 8;
 	}
 
 	/* Calculate result */
-
 	bd->inbufBitCount -= bits_wanted;
 	bits |= (bd->inbufBits >> bd->inbufBitCount) & ((1 << bits_wanted) - 1);
 
@@ -139,29 +133,24 @@
 }
 
 /* Unpacks the next block and sets up for the inverse burrows-wheeler step. */
-
 static int get_next_block(bunzip_data *bd)
 {
 	struct group_data *hufGroup;
-	int dbufCount, nextSym, dbufSize, groupCount, *base, selector,
+	int dbufCount, nextSym, dbufSize, groupCount, *base, *limit, selector,
 		i, j, k, t, runPos, symCount, symTotal, nSelectors, byteCount[256];
 	unsigned char uc, symToByte[256], mtfSymbol[256], *selectors;
-	/* limit was int* but was changed to unsigned* - grep for '[x]'
-	 * in comment to see where it is important. -- vda */
-	unsigned *dbuf, *limit, origPtr;
+	unsigned *dbuf, origPtr;
 
 	dbuf = bd->dbuf;
 	dbufSize = bd->dbufSize;
 	selectors = bd->selectors;
 
 	/* Reset longjmp I/O error handling */
-
 	i = setjmp(bd->jmpbuf);
 	if (i) return i;
 
 	/* Read in header signature and CRC, then validate signature.
 	   (last block signature means CRC is for whole file, return now) */
-
 	i = get_bits(bd, 24);
 	j = get_bits(bd, 24);
 	bd->headerCRC = get_bits(bd, 32);
@@ -171,7 +160,6 @@
 	/* We can add support for blockRandomised if anybody complains.  There was
 	   some code for this in busybox 1.0.0-pre3, but nobody ever noticed that
 	   it didn't actually work. */
-
 	if (get_bits(bd, 1)) return RETVAL_OBSOLETE_INPUT;
 	origPtr = get_bits(bd, 24);
 	if ((int)origPtr > dbufSize) return RETVAL_DATA_ERROR;
@@ -181,7 +169,6 @@
 	   symbols to deal with, and writes a sparse bitfield indicating which
 	   values were present.  We make a translation table to convert the symbols
 	   back to the corresponding bytes. */
-
 	t = get_bits(bd, 16);
 	symTotal = 0;
 	for (i = 0; i < 16; i++) {
@@ -194,7 +181,6 @@
 	}
 
 	/* How many different Huffman coding groups does this block use? */
-
 	groupCount = get_bits(bd, 3);
 	if (groupCount < 2 || groupCount > MAX_GROUPS)
 		return RETVAL_DATA_ERROR;
@@ -203,19 +189,16 @@
 	   group.  Read in the group selector list, which is stored as MTF encoded
 	   bit runs.  (MTF=Move To Front, as each value is used it's moved to the
 	   start of the list.) */
-
 	nSelectors = get_bits(bd, 15);
 	if (!nSelectors) return RETVAL_DATA_ERROR;
 	for (i = 0; i < groupCount; i++) mtfSymbol[i] = i;
 	for (i = 0; i < nSelectors; i++) {
 
 		/* Get next value */
-
 		for (j = 0; get_bits(bd, 1); j++)
 			if (j >= groupCount) return RETVAL_DATA_ERROR;
 
 		/* Decode MTF to get the next selector */
-
 		uc = mtfSymbol[j];
 		for (;j;j--) mtfSymbol[j] = mtfSymbol[j-1];
 		mtfSymbol[0] = selectors[i] = uc;
@@ -223,10 +206,11 @@
 
 	/* Read the Huffman coding tables for each group, which code for symTotal
 	   literal symbols, plus two run symbols (RUNA, RUNB) */
-
 	symCount = symTotal + 2;
 	for (j = 0; j < groupCount; j++) {
-		unsigned char length[MAX_SYMBOLS], temp[MAX_HUFCODE_BITS+1];
+		unsigned char length[MAX_SYMBOLS];
+		/* 8 bits is ALMOST enough for temp[], see below */
+		unsigned temp[MAX_HUFCODE_BITS+1];
 		int minLen, maxLen, pp;
 
 		/* Read Huffman code lengths for each symbol.  They're stored in
@@ -235,7 +219,6 @@
 		   (Subtracting 1 before the loop and then adding it back at the end is
 		   an optimization that makes the test inside the loop simpler: symbol
 		   length 0 becomes negative, so an unsigned inequality catches it.) */
-
 		t = get_bits(bd, 5) - 1;
 		for (i = 0; i < symCount; i++) {
 			for (;;) {
@@ -245,7 +228,6 @@
 				/* If first bit is 0, stop.  Else second bit indicates whether
 				   to increment or decrement the value.  Optimization: grab 2
 				   bits and unget the second if the first was 0. */
-
 				k = get_bits(bd, 2);
 				if (k < 2) {
 					bd->inbufBitCount++;
@@ -253,17 +235,14 @@
 				}
 
 				/* Add one if second bit 1, else subtract 1.  Avoids if/else */
-
 				t += (((k+1) & 2) - 1);
 			}
 
 			/* Correct for the initial -1, to get the final symbol length */
-
 			length[i] = t + 1;
 		}
 
 		/* Find largest and smallest lengths in this group */
-
 		minLen = maxLen = length[0];
 		for (i = 1; i < symCount; i++) {
 			if (length[i] > maxLen) maxLen = length[i];
@@ -280,7 +259,6 @@
 		 * number of bits can have.  This is how the Huffman codes can vary in
 		 * length: each code with a value>limit[length] needs another bit.
 		 */
-
 		hufGroup = bd->groups + j;
 		hufGroup->minLen = minLen;
 		hufGroup->maxLen = maxLen;
@@ -288,12 +266,10 @@
 		/* Note that minLen can't be smaller than 1, so we adjust the base
 		   and limit array pointers so we're not always wasting the first
 		   entry.  We do this again when using them (during symbol decoding).*/
-
 		base = hufGroup->base - 1;
-		limit = (unsigned*)hufGroup->limit - 1;
+		limit = hufGroup->limit - 1;
 
 		/* Calculate permute[].  Concurently, initialize temp[] and limit[]. */
-
 		pp = 0;
 		for (i = minLen; i <= maxLen; i++) {
 			temp[i] = limit[i] = 0;
@@ -303,14 +279,14 @@
 		}
 
 		/* Count symbols coded for at each bit length */
-
+		/* NB: in pathological cases, temp[8] can end ip being 256.
+		 * That's why uint8_t is too small for temp[]. */
 		for (i = 0; i < symCount; i++) temp[length[i]]++;
 
 		/* Calculate limit[] (the largest symbol-coding value at each bit
 		 * length, which is (previous limit<<1)+symbols at this level), and
 		 * base[] (number of symbols to ignore at each bit length, which is
 		 * limit minus the cumulative count of symbols coded for already). */
-
 		pp = t = 0;
 		for (i = minLen; i < maxLen; i++) {
 			pp += temp[i];
@@ -321,14 +297,12 @@
 			   each level we're really only interested in the first few bits,
 			   so here we set all the trailing to-be-ignored bits to 1 so they
 			   don't affect the value>limit[length] comparison. */
-
 			limit[i] = (pp << (maxLen - i)) - 1;
 			pp <<= 1;
 			t += temp[i];
 			base[i+1] = pp - t;
 		}
 		limit[maxLen+1] = INT_MAX; /* Sentinel value for reading next sym. */
-		/* [x] was observed to occasionally have -1 here: -- vda */
 		limit[maxLen] = pp + temp[maxLen] - 1;
 		base[minLen] = 0;
 	}
@@ -338,7 +312,6 @@
 	   and run length encoding, saving the result into dbuf[dbufCount++] = uc */
 
 	/* Initialize symbol occurrence counters and symbol Move To Front table */
-
 	memset(byteCount, 0, sizeof(byteCount)); /* smaller, maybe slower? */
 	for (i = 0; i < 256; i++) {
 		//byteCount[i] = 0;
@@ -350,13 +323,12 @@
 	runPos = dbufCount = selector = 0;
 	for (;;) {
 
-		/* fetch next Huffman coding group from list. */
-
+		/* Fetch next Huffman coding group from list. */
 		symCount = GROUP_SIZE - 1;
 		if (selector >= nSelectors) return RETVAL_DATA_ERROR;
 		hufGroup = bd->groups + selectors[selector++];
 		base = hufGroup->base - 1;
-		limit = (unsigned*)hufGroup->limit - 1;
+		limit = hufGroup->limit - 1;
  continue_this_group:
 
 		/* Read next Huffman-coded symbol. */
@@ -370,7 +342,6 @@
 		   dry).  The following (up to got_huff_bits:) is equivalent to
 		   j = get_bits(bd, hufGroup->maxLen);
 		 */
-
 		while ((int)(bd->inbufBitCount) < hufGroup->maxLen) {
 			if (bd->inbufPos == bd->inbufCount) {
 				j = get_bits(bd, hufGroup->maxLen);
@@ -385,13 +356,11 @@
  got_huff_bits:
 
 		/* Figure how how many bits are in next symbol and unget extras */
-
 		i = hufGroup->minLen;
-		while ((unsigned)j > limit[i]) ++i;
+		while (j > limit[i]) ++i;
 		bd->inbufBitCount += (hufGroup->maxLen - i);
 
 		/* Huffman decode value to get nextSym (with bounds checking) */
-
 		if (i > hufGroup->maxLen)
 			return RETVAL_DATA_ERROR;
 		j = (j >> (hufGroup->maxLen - i)) - base[i];
@@ -403,11 +372,9 @@
 		   byte, or a repeated run of the most recent literal byte.  First,
 		   check if nextSym indicates a repeated run, and if so loop collecting
 		   how many times to repeat the last literal. */
-
 		if ((unsigned)nextSym <= SYMBOL_RUNB) { /* RUNA or RUNB */
 
 			/* If this is the start of a new run, zero out counter */
-
 			if (!runPos) {
 				runPos = 1;
 				t = 0;
@@ -420,7 +387,6 @@
 			   the basic or 0/1 method (except all bits 0, which would use no
 			   symbols, but a run of length 0 doesn't mean anything in this
 			   context).  Thus space is saved. */
-
 			t += (runPos << nextSym); /* +runPos if RUNA; +2*runPos if RUNB */
 			if (runPos < dbufSize) runPos <<= 1;
 			goto end_of_huffman_loop;
@@ -430,7 +396,6 @@
 		   how many times to repeat the last literal, so append that many
 		   copies to our buffer of decoded symbols (dbuf) now.  (The last
 		   literal used is the one at the head of the mtfSymbol array.) */
-
 		if (runPos) {
 			runPos = 0;
 			if (dbufCount + t >= dbufSize) return RETVAL_DATA_ERROR;
@@ -441,7 +406,6 @@
 		}
 
 		/* Is this the terminating symbol? */
-
 		if (nextSym > symTotal) break;
 
 		/* At this point, nextSym indicates a new literal character.  Subtract
@@ -451,7 +415,6 @@
 		   first symbol in the mtf array, position 0, would have been handled
 		   as part of a run above.  Therefore 1 unused mtf position minus
 		   2 non-literal nextSym values equals -1.) */
-
 		if (dbufCount >= dbufSize) return RETVAL_DATA_ERROR;
 		i = nextSym - 1;
 		uc = mtfSymbol[i];
@@ -460,7 +423,6 @@
 		 * small number of symbols, and are bound by 256 in any case, using
 		 * memmove here would typically be bigger and slower due to function
 		 * call overhead and other assorted setup costs. */
-
 		do {
 			mtfSymbol[i] = mtfSymbol[i-1];
 		} while (--i);
@@ -468,13 +430,11 @@
 		uc = symToByte[uc];
 
 		/* We have our literal byte.  Save it into dbuf. */
-
 		byteCount[uc]++;
 		dbuf[dbufCount++] = (unsigned)uc;
 
 		/* Skip group initialization if we're not done with this group.  Done
 		 * this way to avoid compiler warning. */
-
  end_of_huffman_loop:
 		if (symCount--) goto continue_this_group;
 	}
@@ -487,7 +447,6 @@
 	 */
 
 	/* Turn byteCount into cumulative occurrence counts of 0 to n-1. */
-
 	j = 0;
 	for (i = 0; i < 256; i++) {
 		k = j + byteCount[i];
@@ -496,7 +455,6 @@
 	}
 
 	/* Figure out what order dbuf would be in if we sorted it. */
-
 	for (i = 0; i < dbufCount; i++) {
 		uc = (unsigned char)(dbuf[i] & 0xff);
 		dbuf[byteCount[uc]] |= (i << 8);
@@ -506,7 +464,6 @@
 	/* Decode first byte by hand to initialize "previous" byte.  Note that it
 	   doesn't get output, and if the first three characters are identical
 	   it doesn't qualify as a run (hence writeRunCountdown=5). */
-
 	if (dbufCount) {
 		if ((int)origPtr >= dbufCount) return RETVAL_DATA_ERROR;
 		bd->writePos = dbuf[origPtr];
@@ -525,7 +482,6 @@
    error (all errors are negative numbers).  If out_fd!=-1, outbuf and len
    are ignored, data is written to out_fd and return is RETVAL_OK or error.
 */
-
 int FAST_FUNC read_bunzip(bunzip_data *bd, char *outbuf, int len)
 {
 	const unsigned *dbuf;
@@ -542,19 +498,15 @@
 	/* We will always have pending decoded data to write into the output
 	   buffer unless this is the very first call (in which case we haven't
 	   Huffman-decoded a block into the intermediate buffer yet). */
-
 	if (bd->writeCopies) {
 
 		/* Inside the loop, writeCopies means extra copies (beyond 1) */
-
 		--bd->writeCopies;
 
 		/* Loop outputting bytes */
-
 		for (;;) {
 
 			/* If the output buffer is full, snapshot state and return */
-
 			if (gotcount >= len) {
 				bd->writePos = pos;
 				bd->writeCurrent = current;
@@ -563,13 +515,11 @@
 			}
 
 			/* Write next byte into output buffer, updating CRC */
-
 			outbuf[gotcount++] = current;
 			bd->writeCRC = (bd->writeCRC << 8)
-						  ^ bd->crc32Table[(bd->writeCRC >> 24) ^ current];
+				^ bd->crc32Table[(bd->writeCRC >> 24) ^ current];
 
 			/* Loop now if we're outputting multiple copies of this byte */
-
 			if (bd->writeCopies) {
 				--bd->writeCopies;
 				continue;
@@ -585,35 +535,29 @@
 			/* After 3 consecutive copies of the same byte, the 4th
 			 * is a repeat count.  We count down from 4 instead
 			 * of counting up because testing for non-zero is faster */
-
 			if (--bd->writeRunCountdown) {
 				if (current != previous)
 					bd->writeRunCountdown = 4;
 			} else {
 
 				/* We have a repeated run, this byte indicates the count */
-
 				bd->writeCopies = current;
 				current = previous;
 				bd->writeRunCountdown = 5;
 
 				/* Sometimes there are just 3 bytes (run length 0) */
-
 				if (!bd->writeCopies) goto decode_next_byte;
 
 				/* Subtract the 1 copy we'd output anyway to get extras */
-
 				--bd->writeCopies;
 			}
 		}
 
 		/* Decompression of this block completed successfully */
-
 		bd->writeCRC = ~bd->writeCRC;
 		bd->totalCRC = ((bd->totalCRC << 1) | (bd->totalCRC >> 31)) ^ bd->writeCRC;
 
 		/* If this block had a CRC error, force file level CRC error. */
-
 		if (bd->writeCRC != bd->headerCRC) {
 			bd->totalCRC = bd->headerCRC + 1;
 			return RETVAL_LAST_BLOCK;
@@ -622,7 +566,6 @@
 
 	/* Refill the intermediate buffer by Huffman-decoding next block of input */
 	/* (previous is just a convenient unused temp variable here) */
-
 	previous = get_next_block(bd);
 	if (previous) {
 		bd->writeCount = previous;
@@ -634,7 +577,6 @@
 	goto decode_next_byte;
 }
 
-
 /* Allocate the structure, read file header.  If in_fd==-1, inbuf must contain
    a complete bunzip file (len bytes long).  If in_fd!=-1, inbuf and len are
    ignored, and data is read from file handle into temporary buffer. */
@@ -642,7 +584,6 @@
 /* Because bunzip2 is used for help text unpacking, and because bb_show_usage()
    should work for NOFORK applets too, we must be extremely careful to not leak
    any allocations! */
-
 int FAST_FUNC start_bunzip(bunzip_data **bdp, int in_fd, const unsigned char *inbuf,
 						int len)
 {
@@ -653,16 +594,13 @@
 	};
 
 	/* Figure out how much data to allocate */
-
 	i = sizeof(bunzip_data);
 	if (in_fd != -1) i += IOBUF_SIZE;
 
 	/* Allocate bunzip_data.  Most fields initialize to zero. */
-
 	bd = *bdp = xzalloc(i);
 
 	/* Setup input buffer */
-
 	bd->in_fd = in_fd;
 	if (-1 == in_fd) {
 		/* in this case, bd->inbuf is read-only */
@@ -672,22 +610,18 @@
 		bd->inbuf = (unsigned char *)(bd + 1);
 
 	/* Init the CRC32 table (big endian) */
-
 	crc32_filltable(bd->crc32Table, 1);
 
 	/* Setup for I/O error handling via longjmp */
-
 	i = setjmp(bd->jmpbuf);
 	if (i) return i;
 
 	/* Ensure that file starts with "BZh['1'-'9']." */
-
 	i = get_bits(bd, 32);
 	if ((unsigned)(i - BZh0 - 1) >= 9) return RETVAL_NOT_BZIP_DATA;
 
-	/* Fourth byte (ascii '1'-'9'), indicates block size in units of 100k of
+	/* Fourth byte (ascii '1'-'9') indicates block size in units of 100k of
 	   uncompressed data.  Allocate intermediate buffer for block. */
-
 	bd->dbufSize = 100000 * (i - BZh0);
 
 	/* Cannot use xmalloc - may leak bd in NOFORK case! */
@@ -707,7 +641,6 @@
 
 
 /* Decompress src_fd to dst_fd.  Stops at end of bzip data, not end of file. */
-
 USE_DESKTOP(long long) int FAST_FUNC
 unpack_bz2_stream(int src_fd, int dst_fd)
 {




More information about the busybox-cvs mailing list