mirror of
https://github.com/qpdf/qpdf.git
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d71f05ca07
This makes all integer type conversions that have potential data loss explicit with calls that do range checks and raise an exception. After this commit, qpdf builds with no warnings when -Wsign-conversion -Wconversion is used with gcc or clang or when -W3 -Wd4800 is used with MSVC. This significantly reduces the likelihood of potential crashes from bogus integer values. There are some parts of the code that take int when they should take size_t or an offset. Such places would make qpdf not support files with more than 2^31 of something that usually wouldn't be so large. In the event that such a file shows up and is valid, at least qpdf would raise an error in the right spot so the issue could be legitimately addressed rather than failing in some weird way because of a silent overflow condition.
436 lines
12 KiB
C++
436 lines
12 KiB
C++
// This file implements a class for computation of MD5 checksums.
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// It is derived from the reference algorithm for MD5 as given in
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// RFC 1321. The original copyright notice is as follows:
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//
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/////////////////////////////////////////////////////////////////////////
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//
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// Copyright (C) 1991-2, RSA Data Security, Inc. Created 1991. All
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// rights reserved.
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//
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// License to copy and use this software is granted provided that it
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// is identified as the "RSA Data Security, Inc. MD5 Message-Digest
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// Algorithm" in all material mentioning or referencing this software
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// or this function.
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//
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// License is also granted to make and use derivative works provided
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// that such works are identified as "derived from the RSA Data
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// Security, Inc. MD5 Message-Digest Algorithm" in all material
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// mentioning or referencing the derived work.
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//
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// RSA Data Security, Inc. makes no representations concerning either
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// the merchantability of this software or the suitability of this
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// software for any particular purpose. It is provided "as is"
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// without express or implied warranty of any kind.
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//
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// These notices must be retained in any copies of any part of this
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// documentation and/or software.
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//
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/////////////////////////////////////////////////////////////////////////
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#include <qpdf/MD5.hh>
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#include <qpdf/QUtil.hh>
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#include <qpdf/QIntC.hh>
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#include <stdio.h>
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#include <memory.h>
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#include <stdlib.h>
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#include <string.h>
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#include <errno.h>
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int const S11 = 7;
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int const S12 = 12;
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int const S13 = 17;
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int const S14 = 22;
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int const S21 = 5;
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int const S22 = 9;
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int const S23 = 14;
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int const S24 = 20;
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int const S31 = 4;
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int const S32 = 11;
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int const S33 = 16;
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int const S34 = 23;
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int const S41 = 6;
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int const S42 = 10;
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int const S43 = 15;
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int const S44 = 21;
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static unsigned char PADDING[64] = {
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0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
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};
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// F, G, H and I are basic MD5 functions.
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#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
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#define G(x, y, z) (((x) & (z)) | ((y) & (~z)))
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#define H(x, y, z) ((x) ^ (y) ^ (z))
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#define I(x, y, z) ((y) ^ ((x) | (~z)))
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// ROTATE_LEFT rotates x left n bits.
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#define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))
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// FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4.
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// Rotation is separate from addition to prevent recomputation.
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#define FF(a, b, c, d, x, s, ac) { \
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(a) += F ((b), (c), (d)) + (x) + static_cast<UINT4>(ac); \
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(a) = ROTATE_LEFT ((a), (s)); \
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(a) += (b); \
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}
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#define GG(a, b, c, d, x, s, ac) { \
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(a) += G ((b), (c), (d)) + (x) + static_cast<UINT4>(ac); \
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(a) = ROTATE_LEFT ((a), (s)); \
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(a) += (b); \
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}
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#define HH(a, b, c, d, x, s, ac) { \
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(a) += H ((b), (c), (d)) + (x) + static_cast<UINT4>(ac); \
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(a) = ROTATE_LEFT ((a), (s)); \
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(a) += (b); \
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}
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#define II(a, b, c, d, x, s, ac) { \
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(a) += I ((b), (c), (d)) + (x) + static_cast<UINT4>(ac); \
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(a) = ROTATE_LEFT ((a), (s)); \
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(a) += (b); \
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}
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// MD5 initialization. Begins an MD5 operation, writing a new context.
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void MD5::init()
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{
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count[0] = count[1] = 0;
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// Load magic initialization constants.
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state[0] = 0x67452301;
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state[1] = 0xefcdab89;
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state[2] = 0x98badcfe;
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state[3] = 0x10325476;
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finalized = false;
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memset(digest_val, 0, sizeof(digest_val));
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}
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// MD5 block update operation. Continues an MD5 message-digest
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// operation, processing another message block, and updating the
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// context.
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void MD5::update(unsigned char *input,
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size_t inputLen)
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{
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unsigned int i, index, partLen;
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// Compute number of bytes mod 64
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index = static_cast<unsigned int>((count[0] >> 3) & 0x3f);
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// Update number of bits
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if ((count[0] += (static_cast<UINT4>(inputLen) << 3)) <
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(static_cast<UINT4>(inputLen) << 3))
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count[1]++;
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count[1] += (static_cast<UINT4>(inputLen) >> 29);
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partLen = 64 - index;
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// Transform as many times as possible.
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if (inputLen >= partLen) {
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memcpy(&buffer[index], input, partLen);
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transform(state, buffer);
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for (i = partLen; i + 63 < inputLen; i += 64)
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transform(state, &input[i]);
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index = 0;
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}
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else
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i = 0;
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// Buffer remaining input
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memcpy(&buffer[index], &input[i], inputLen-i);
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}
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// MD5 finalization. Ends an MD5 message-digest operation, writing the
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// the message digest and zeroizing the context.
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void MD5::final()
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{
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if (finalized)
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{
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return;
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}
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unsigned char bits[8];
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unsigned int index, padLen;
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// Save number of bits
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encode(bits, count, 8);
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// Pad out to 56 mod 64.
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index = static_cast<unsigned int>((count[0] >> 3) & 0x3f);
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padLen = (index < 56) ? (56 - index) : (120 - index);
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update(PADDING, padLen);
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// Append length (before padding)
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update(bits, 8);
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// Store state in digest_val
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encode(digest_val, state, 16);
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// Zeroize sensitive information.
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memset(state, 0, sizeof(state));
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memset(count, 0, sizeof(count));
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memset(buffer, 0, sizeof(buffer));
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finalized = true;
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}
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// MD5 basic transformation. Transforms state based on block.
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void MD5::transform(UINT4 state[4], unsigned char block[64])
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{
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UINT4 a = state[0], b = state[1], c = state[2], d = state[3], x[16];
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decode(x, block, 64);
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// Round 1
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FF (a, b, c, d, x[ 0], S11, 0xd76aa478); // 1
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FF (d, a, b, c, x[ 1], S12, 0xe8c7b756); // 2
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FF (c, d, a, b, x[ 2], S13, 0x242070db); // 3
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FF (b, c, d, a, x[ 3], S14, 0xc1bdceee); // 4
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FF (a, b, c, d, x[ 4], S11, 0xf57c0faf); // 5
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FF (d, a, b, c, x[ 5], S12, 0x4787c62a); // 6
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FF (c, d, a, b, x[ 6], S13, 0xa8304613); // 7
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FF (b, c, d, a, x[ 7], S14, 0xfd469501); // 8
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FF (a, b, c, d, x[ 8], S11, 0x698098d8); // 9
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FF (d, a, b, c, x[ 9], S12, 0x8b44f7af); // 10
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FF (c, d, a, b, x[10], S13, 0xffff5bb1); // 11
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FF (b, c, d, a, x[11], S14, 0x895cd7be); // 12
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FF (a, b, c, d, x[12], S11, 0x6b901122); // 13
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FF (d, a, b, c, x[13], S12, 0xfd987193); // 14
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FF (c, d, a, b, x[14], S13, 0xa679438e); // 15
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FF (b, c, d, a, x[15], S14, 0x49b40821); // 16
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// Round 2
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GG (a, b, c, d, x[ 1], S21, 0xf61e2562); // 17
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GG (d, a, b, c, x[ 6], S22, 0xc040b340); // 18
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GG (c, d, a, b, x[11], S23, 0x265e5a51); // 19
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GG (b, c, d, a, x[ 0], S24, 0xe9b6c7aa); // 20
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GG (a, b, c, d, x[ 5], S21, 0xd62f105d); // 21
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GG (d, a, b, c, x[10], S22, 0x2441453); // 22
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GG (c, d, a, b, x[15], S23, 0xd8a1e681); // 23
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GG (b, c, d, a, x[ 4], S24, 0xe7d3fbc8); // 24
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GG (a, b, c, d, x[ 9], S21, 0x21e1cde6); // 25
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GG (d, a, b, c, x[14], S22, 0xc33707d6); // 26
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GG (c, d, a, b, x[ 3], S23, 0xf4d50d87); // 27
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GG (b, c, d, a, x[ 8], S24, 0x455a14ed); // 28
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GG (a, b, c, d, x[13], S21, 0xa9e3e905); // 29
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GG (d, a, b, c, x[ 2], S22, 0xfcefa3f8); // 30
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GG (c, d, a, b, x[ 7], S23, 0x676f02d9); // 31
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GG (b, c, d, a, x[12], S24, 0x8d2a4c8a); // 32
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// Round 3
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HH (a, b, c, d, x[ 5], S31, 0xfffa3942); // 33
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HH (d, a, b, c, x[ 8], S32, 0x8771f681); // 34
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HH (c, d, a, b, x[11], S33, 0x6d9d6122); // 35
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HH (b, c, d, a, x[14], S34, 0xfde5380c); // 36
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HH (a, b, c, d, x[ 1], S31, 0xa4beea44); // 37
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HH (d, a, b, c, x[ 4], S32, 0x4bdecfa9); // 38
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HH (c, d, a, b, x[ 7], S33, 0xf6bb4b60); // 39
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HH (b, c, d, a, x[10], S34, 0xbebfbc70); // 40
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HH (a, b, c, d, x[13], S31, 0x289b7ec6); // 41
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HH (d, a, b, c, x[ 0], S32, 0xeaa127fa); // 42
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HH (c, d, a, b, x[ 3], S33, 0xd4ef3085); // 43
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HH (b, c, d, a, x[ 6], S34, 0x4881d05); // 44
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HH (a, b, c, d, x[ 9], S31, 0xd9d4d039); // 45
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HH (d, a, b, c, x[12], S32, 0xe6db99e5); // 46
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HH (c, d, a, b, x[15], S33, 0x1fa27cf8); // 47
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HH (b, c, d, a, x[ 2], S34, 0xc4ac5665); // 48
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// Round 4
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II (a, b, c, d, x[ 0], S41, 0xf4292244); // 49
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II (d, a, b, c, x[ 7], S42, 0x432aff97); // 50
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II (c, d, a, b, x[14], S43, 0xab9423a7); // 51
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II (b, c, d, a, x[ 5], S44, 0xfc93a039); // 52
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II (a, b, c, d, x[12], S41, 0x655b59c3); // 53
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II (d, a, b, c, x[ 3], S42, 0x8f0ccc92); // 54
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II (c, d, a, b, x[10], S43, 0xffeff47d); // 55
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II (b, c, d, a, x[ 1], S44, 0x85845dd1); // 56
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II (a, b, c, d, x[ 8], S41, 0x6fa87e4f); // 57
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II (d, a, b, c, x[15], S42, 0xfe2ce6e0); // 58
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II (c, d, a, b, x[ 6], S43, 0xa3014314); // 59
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II (b, c, d, a, x[13], S44, 0x4e0811a1); // 60
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II (a, b, c, d, x[ 4], S41, 0xf7537e82); // 61
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II (d, a, b, c, x[11], S42, 0xbd3af235); // 62
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II (c, d, a, b, x[ 2], S43, 0x2ad7d2bb); // 63
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II (b, c, d, a, x[ 9], S44, 0xeb86d391); // 64
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state[0] += a;
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state[1] += b;
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state[2] += c;
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state[3] += d;
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// Zeroize sensitive information.
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memset (x, 0, sizeof (x));
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}
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// Encodes input (UINT4) into output (unsigned char). Assumes len is a
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// multiple of 4.
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void MD5::encode(unsigned char *output, UINT4 *input, size_t len)
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{
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unsigned int i, j;
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for (i = 0, j = 0; j < len; i++, j += 4) {
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output[j] = static_cast<unsigned char>(input[i] & 0xff);
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output[j+1] = static_cast<unsigned char>((input[i] >> 8) & 0xff);
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output[j+2] = static_cast<unsigned char>((input[i] >> 16) & 0xff);
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output[j+3] = static_cast<unsigned char>((input[i] >> 24) & 0xff);
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}
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}
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// Decodes input (unsigned char) into output (UINT4). Assumes len is a
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// multiple of 4.
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void MD5::decode(UINT4 *output, unsigned char *input, size_t len)
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{
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unsigned int i, j;
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for (i = 0, j = 0; j < len; i++, j += 4)
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output[i] =
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static_cast<UINT4>(input[j]) |
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(static_cast<UINT4>(input[j+1]) << 8) |
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(static_cast<UINT4>(input[j+2]) << 16) |
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(static_cast<UINT4>(input[j+3]) << 24);
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}
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// Public functions
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MD5::MD5()
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{
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init();
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}
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void MD5::reset()
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{
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init();
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}
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void MD5::encodeString(char const* str)
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{
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size_t len = strlen(str);
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update(QUtil::unsigned_char_pointer(str), len);
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final();
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}
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void MD5::appendString(char const* input_string)
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{
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update(QUtil::unsigned_char_pointer(input_string), strlen(input_string));
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}
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void MD5::encodeDataIncrementally(char const* data, size_t len)
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{
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update(QUtil::unsigned_char_pointer(data), len);
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}
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void MD5::encodeFile(char const *filename, qpdf_offset_t up_to_offset)
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{
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unsigned char buffer[1024];
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FILE *file = QUtil::safe_fopen(filename, "rb");
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size_t len;
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size_t so_far = 0;
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size_t to_try = 1024;
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size_t up_to_size = 0;
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if (up_to_offset >= 0)
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{
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up_to_size = QIntC::to_size(up_to_offset);
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}
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do
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{
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if ((up_to_offset >= 0) && ((so_far + to_try) > up_to_size))
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{
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to_try = up_to_size - so_far;
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}
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len = fread(buffer, 1, to_try, file);
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if (len > 0)
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{
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update(buffer, len);
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so_far += len;
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if ((up_to_offset >= 0) && (so_far >= up_to_size))
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{
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break;
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}
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}
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} while (len > 0);
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if (ferror(file))
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{
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// Assume, perhaps incorrectly, that errno was set by the
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// underlying call to read....
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(void) fclose(file);
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QUtil::throw_system_error(
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std::string("MD5: read error on ") + filename);
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}
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(void) fclose(file);
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final();
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}
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void MD5::digest(Digest result)
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{
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final();
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memcpy(result, digest_val, sizeof(digest_val));
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}
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void MD5::print()
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{
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final();
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unsigned int i;
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for (i = 0; i < 16; ++i)
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{
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printf("%02x", digest_val[i]);
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}
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printf("\n");
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}
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std::string MD5::unparse()
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{
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final();
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return QUtil::hex_encode(
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std::string(reinterpret_cast<char*>(digest_val), 16));
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}
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std::string
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MD5::getDataChecksum(char const* buf, size_t len)
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{
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MD5 m;
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m.encodeDataIncrementally(buf, len);
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return m.unparse();
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}
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std::string
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MD5::getFileChecksum(char const* filename, qpdf_offset_t up_to_offset)
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{
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MD5 m;
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m.encodeFile(filename, up_to_offset);
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return m.unparse();
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}
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bool
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MD5::checkDataChecksum(char const* const checksum,
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char const* buf, size_t len)
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{
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std::string actual_checksum = getDataChecksum(buf, len);
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return (checksum == actual_checksum);
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}
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bool
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MD5::checkFileChecksum(char const* const checksum,
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char const* filename, qpdf_offset_t up_to_offset)
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{
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bool result = false;
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try
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{
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std::string actual_checksum = getFileChecksum(filename, up_to_offset);
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result = (checksum == actual_checksum);
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}
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catch (std::runtime_error const&)
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{
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// Ignore -- return false
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}
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return result;
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}
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