274 lines
7.4 KiB
C
274 lines
7.4 KiB
C
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/* Functions to compute MD5 message digest of files or memory blocks.
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according to the definition of MD5 in RFC 1321 from April 1992.
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Copyright (C) 1995-2022 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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/* Written by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1995. */
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#ifdef HAVE_CONFIG_H
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# include <config.h>
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#endif
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#include <sys/types.h>
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#if STDC_HEADERS || defined _LIBC
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# include <stdlib.h>
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# include <string.h>
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#else
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# ifndef HAVE_MEMCPY
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# define memcpy(d, s, n) (bcopy ((s), (d), (n)), (d))
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# endif
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#endif
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#include "md5.h"
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#ifdef _LIBC
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# include <endian.h>
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# if __BYTE_ORDER == __BIG_ENDIAN
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# define WORDS_BIGENDIAN 1
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# endif
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/* We need to keep the namespace clean so define the MD5 function
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protected using leading __ . */
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# define md5_init_ctx __md5_init_ctx
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# define md5_process_bytes __md5_process_bytes
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# define md5_finish_ctx __md5_finish_ctx
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# define md5_read_ctx __md5_read_ctx
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# define md5_stream __md5_stream
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# define md5_buffer __md5_buffer
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#endif
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#ifdef WORDS_BIGENDIAN
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# define SWAP(n) \
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(((n) << 24) | (((n) & 0xff00) << 8) | (((n) >> 8) & 0xff00) | ((n) >> 24))
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#else
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# define SWAP(n) (n)
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#endif
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/* This array contains the bytes used to pad the buffer to the next
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64-byte boundary. (RFC 1321, 3.1: Step 1) */
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static const unsigned char fillbuf[64] = { 0x80, 0 /* , 0, 0, ... */ };
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/* Initialize structure containing state of computation.
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(RFC 1321, 3.3: Step 3) */
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void
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md5_init_ctx (struct md5_ctx *ctx)
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{
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ctx->A = 0x67452301;
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ctx->B = 0xefcdab89;
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ctx->C = 0x98badcfe;
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ctx->D = 0x10325476;
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ctx->total[0] = ctx->total[1] = 0;
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ctx->buflen = 0;
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}
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/* Put result from CTX in first 16 bytes following RESBUF. The result
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must be in little endian byte order.
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IMPORTANT: On some systems it is required that RESBUF is correctly
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aligned for a 32 bits value. */
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void *
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md5_read_ctx (const struct md5_ctx *ctx, void *resbuf)
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{
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((md5_uint32 *) resbuf)[0] = SWAP (ctx->A);
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((md5_uint32 *) resbuf)[1] = SWAP (ctx->B);
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((md5_uint32 *) resbuf)[2] = SWAP (ctx->C);
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((md5_uint32 *) resbuf)[3] = SWAP (ctx->D);
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return resbuf;
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}
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/* Process the remaining bytes in the internal buffer and the usual
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prolog according to the standard and write the result to RESBUF.
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IMPORTANT: On some systems it is required that RESBUF is correctly
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aligned for a 32 bits value. */
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void *
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md5_finish_ctx (struct md5_ctx *ctx, void *resbuf)
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{
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/* Take yet unprocessed bytes into account. */
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md5_uint32 bytes = ctx->buflen;
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size_t pad;
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/* Now count remaining bytes. */
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ctx->total[0] += bytes;
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if (ctx->total[0] < bytes)
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++ctx->total[1];
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pad = bytes >= 56 ? 64 + 56 - bytes : 56 - bytes;
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memcpy (&ctx->buffer[bytes], fillbuf, pad);
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/* Put the 64-bit file length in *bits* at the end of the buffer. */
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ctx->buffer32[(bytes + pad) / 4] = SWAP (ctx->total[0] << 3);
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ctx->buffer32[(bytes + pad + 4) / 4] = SWAP ((ctx->total[1] << 3)
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| (ctx->total[0] >> 29));
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/* Process last bytes. */
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__md5_process_block (ctx->buffer, bytes + pad + 8, ctx);
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return md5_read_ctx (ctx, resbuf);
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}
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/* Compute MD5 message digest for bytes read from STREAM. The
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resulting message digest number will be written into the 16 bytes
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beginning at RESBLOCK. */
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int
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md5_stream (FILE *stream, void *resblock)
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{
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/* Important: BLOCKSIZE must be a multiple of 64. */
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#define BLOCKSIZE 4096
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struct md5_ctx ctx;
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char buffer[BLOCKSIZE + 72];
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size_t sum;
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/* Initialize the computation context. */
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md5_init_ctx (&ctx);
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/* Iterate over full file contents. */
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while (1)
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{
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/* We read the file in blocks of BLOCKSIZE bytes. One call of the
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computation function processes the whole buffer so that with the
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next round of the loop another block can be read. */
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size_t n;
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sum = 0;
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/* Read block. Take care for partial reads. */
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do
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{
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n = fread (buffer + sum, 1, BLOCKSIZE - sum, stream);
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sum += n;
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}
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while (sum < BLOCKSIZE && n != 0);
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if (n == 0 && ferror (stream))
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return 1;
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/* If end of file is reached, end the loop. */
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if (n == 0)
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break;
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/* Process buffer with BLOCKSIZE bytes. Note that
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BLOCKSIZE % 64 == 0
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*/
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__md5_process_block (buffer, BLOCKSIZE, &ctx);
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}
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/* Add the last bytes if necessary. */
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if (sum > 0)
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md5_process_bytes (buffer, sum, &ctx);
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/* Construct result in desired memory. */
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md5_finish_ctx (&ctx, resblock);
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return 0;
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}
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/* Compute MD5 message digest for LEN bytes beginning at BUFFER. The
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result is always in little endian byte order, so that a byte-wise
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output yields to the wanted ASCII representation of the message
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digest. */
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void *
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md5_buffer (const char *buffer, size_t len, void *resblock)
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{
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struct md5_ctx ctx;
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/* Initialize the computation context. */
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md5_init_ctx (&ctx);
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/* Process whole buffer but last len % 64 bytes. */
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md5_process_bytes (buffer, len, &ctx);
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/* Put result in desired memory area. */
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return md5_finish_ctx (&ctx, resblock);
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}
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void
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md5_process_bytes (const void *buffer, size_t len, struct md5_ctx *ctx)
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{
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/* When we already have some bits in our internal buffer concatenate
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both inputs first. */
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if (ctx->buflen != 0)
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{
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size_t left_over = ctx->buflen;
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size_t add = 128 - left_over > len ? len : 128 - left_over;
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memcpy (&ctx->buffer[left_over], buffer, add);
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ctx->buflen += add;
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if (ctx->buflen > 64)
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{
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__md5_process_block (ctx->buffer, ctx->buflen & ~63, ctx);
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ctx->buflen &= 63;
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/* The regions in the following copy operation cannot overlap. */
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memcpy (ctx->buffer, &ctx->buffer[(left_over + add) & ~63],
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ctx->buflen);
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}
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buffer = (const char *) buffer + add;
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len -= add;
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}
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/* Process available complete blocks. */
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if (len >= 64)
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{
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#if !_STRING_ARCH_unaligned
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/* To check alignment gcc has an appropriate operator. Other
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compilers don't. */
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# if __GNUC__ >= 2
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# define UNALIGNED_P(p) (((md5_uintptr) p) % __alignof__ (md5_uint32) != 0)
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# else
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# define UNALIGNED_P(p) (((md5_uintptr) p) % sizeof (md5_uint32) != 0)
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# endif
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if (UNALIGNED_P (buffer))
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while (len > 64)
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{
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__md5_process_block (memcpy (ctx->buffer, buffer, 64), 64, ctx);
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buffer = (const char *) buffer + 64;
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len -= 64;
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}
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else
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#endif
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{
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__md5_process_block (buffer, len & ~63, ctx);
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buffer = (const char *) buffer + (len & ~63);
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len &= 63;
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}
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}
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/* Move remaining bytes in internal buffer. */
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if (len > 0)
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{
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size_t left_over = ctx->buflen;
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memcpy (&ctx->buffer[left_over], buffer, len);
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left_over += len;
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if (left_over >= 64)
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{
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__md5_process_block (ctx->buffer, 64, ctx);
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left_over -= 64;
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memcpy (ctx->buffer, &ctx->buffer[64], left_over);
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}
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ctx->buflen = left_over;
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}
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}
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#include <md5-block.c>
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