bunzip2: make proper fix for the problem "fixed" in rev. 22521

 Thanks for Rob Landley <rob@landley.net>

1 files changed, 13 insertions, 80 deletions

diff --git a/archival/libunarchive/decompress_bunzip2.c b/archival/libunarchive/decompress_bunzip2.c
index 106a08b54..654dc28a9 100644
--- a/archival/libunarchive/decompress_bunzip2.c
+++ b/archival/libunarchive/decompress_bunzip2.c
@@ -66,7 +66,6 @@ struct group_data {
  *  | 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 @@ static unsigned get_bits(bunzip_data *bd, int bits_wanted)
 
         /* 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 @@ static unsigned get_bits(bunzip_data *bd, int bits_wanted)
                 }
 
                 /* 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 @@ static unsigned get_bits(bunzip_data *bd, int bits_wanted)
                 }
 
                 /* 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 @@ static unsigned get_bits(bunzip_data *bd, int bits_wanted)
 }
 
 /* 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 @@ static int get_next_block(bunzip_data *bd)
         /* 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 @@ static int get_next_block(bunzip_data *bd)
            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 @@ static int get_next_block(bunzip_data *bd)
         }
 
         /* 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 @@ static int get_next_block(bunzip_data *bd)
            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 @@ static int get_next_block(bunzip_data *bd)
 
         /* 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 @@ static int get_next_block(bunzip_data *bd)
                    (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 @@ static int get_next_block(bunzip_data *bd)
                                 /* 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 @@ static int get_next_block(bunzip_data *bd)
                                 }
 
                                 /* 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 @@ static int get_next_block(bunzip_data *bd)
                  * 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 @@ static int get_next_block(bunzip_data *bd)
                 /* 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 @@ static int get_next_block(bunzip_data *bd)
                 }
 
                 /* 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 @@ static int get_next_block(bunzip_data *bd)
                            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 @@ static int get_next_block(bunzip_data *bd)
            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 @@ static int get_next_block(bunzip_data *bd)
         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 @@ static int get_next_block(bunzip_data *bd)
                    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 @@ static int get_next_block(bunzip_data *bd)
  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 @@ static int get_next_block(bunzip_data *bd)
                    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 @@ static int get_next_block(bunzip_data *bd)
                            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 @@ static int get_next_block(bunzip_data *bd)
                    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 @@ static int get_next_block(bunzip_data *bd)
                 }
 
                 /* Is this the terminating symbol? */
-
                 if (nextSym > symTotal) break;
 
                 /* At this point, nextSym indicates a new literal character.  Subtract
@@ -451,7 +415,6 @@ static int get_next_block(bunzip_data *bd)
                    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 @@ static int get_next_block(bunzip_data *bd)
                  * 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 @@ static int get_next_block(bunzip_data *bd)
                 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 @@ static int get_next_block(bunzip_data *bd)
          */
 
         /* 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 @@ static int get_next_block(bunzip_data *bd)
         }
 
         /* 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 @@ static int get_next_block(bunzip_data *bd)
         /* 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 @@ static int get_next_block(bunzip_data *bd)
    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 @@ int FAST_FUNC read_bunzip(bunzip_data *bd, char *outbuf, int len)
         /* 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 @@ int FAST_FUNC read_bunzip(bunzip_data *bd, char *outbuf, int len)
                         }
 
                         /* 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 @@ int FAST_FUNC read_bunzip(bunzip_data *bd, char *outbuf, int len)
                         /* 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 @@ int FAST_FUNC read_bunzip(bunzip_data *bd, char *outbuf, int len)
 
         /* 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 @@ int FAST_FUNC read_bunzip(bunzip_data *bd, char *outbuf, int len)
         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 @@ int FAST_FUNC read_bunzip(bunzip_data *bd, char *outbuf, int len)
 /* 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 @@ int FAST_FUNC start_bunzip(bunzip_data **bdp, int in_fd, const unsigned char *in
         };
 
         /* 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 @@ int FAST_FUNC start_bunzip(bunzip_data **bdp, int in_fd, const unsigned char *in
                 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 @@ void FAST_FUNC dealloc_bunzip(bunzip_data *bd)
 
 
 /* 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)
 {