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Implement real upx_lzma_test_overlap().

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Also make Packer::findOverlapOverhead() more pessimistic in worst case.
This commit is contained in:
John Reiser 2007-04-25 16:11:33 -07:00
parent 6ce71e6694
commit 465307655b
2 changed files with 22 additions and 13 deletions
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33
src/compress_lzma.cpp
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@ -486,6 +486,15 @@ error:
// test_overlap
**************************************************************************/
// from <ucl/ucl.h>:
// test an overlapping in-place decompression within a buffer:
// - try a virtual decompression from &buf[src_off] -> &buf[0]
// - no data is actually written
// - only the bytes at buf[src_off..src_off+src_len-1] will get accessed
//
// 2007-04-25 However, I do not see any "virtual decompress" function in lzma
// that avoids writing the result. Therefore, do an actual decompress.
int upx_lzma_test_overlap ( const upx_bytep buf, unsigned src_off,
unsigned src_len, unsigned* dst_len,
int method,
@ -493,22 +502,22 @@ int upx_lzma_test_overlap ( const upx_bytep buf, unsigned src_off,
{
assert(M_IS_LZMA(method));
// FIXME - implement this
// Note that Packer::verifyOverlappingDecompression() will
// verify the final result in any case.
UNUSED(buf);
unsigned dlen = *dst_len;
unsigned const overlap_overhead = src_off + src_len - dlen;
// printf("upx_lzma_test_overlap: %d\n", overlap_overhead);
unsigned overlap_overhead = src_off + src_len - *dst_len;
//printf("upx_lzma_test_overlap: %d\n", overlap_overhead);
// 2007-04-25 lower bound 0x810 using --lzma on
// http://www.equi4.com/pub/tk/8.4.13/tclkit-linux-x86.gz
// So that file will fail until this function does a real
// decompress+verify.
if ((int)overlap_overhead >= 256)
upx_bytep const dst = (upx_bytep)malloc(overlap_overhead + dlen);
upx_bytep const src = (overlap_overhead + dlen + dst) - src_len;
// High end of src aligns with high end of dst (including overlap_overhead).
memcpy(src, &buf[src_off], src_len);
int const rv = upx_lzma_decompress(src, src_len, dst, &dlen,
method, cresult);
free(dst);
if (UPX_E_OK==rv) {
return UPX_E_OK;
UNUSED(cresult);
}
return UPX_E_ERROR;
}

2
src/packer.cpp
View File

@ -481,7 +481,7 @@ unsigned Packer::findOverlapOverhead(const upx_bytep buf,
// prepare to deal with very pessimistic values
unsigned low = 1;
unsigned high = UPX_MIN(ph.u_len / 4 + 512, upper_limit);
unsigned high = UPX_MIN(ph.u_len + 512, upper_limit);
// but be optimistic for first try (speedup)
unsigned m = UPX_MIN(16u, high);
//