151 lines
3.1 KiB
C
151 lines
3.1 KiB
C
/* adler32.c - adler32 check. */
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/*
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* GRUB -- GRand Unified Bootloader
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* Copyright (C) 2011 Free Software Foundation, Inc.
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*
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* GRUB is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* GRUB 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
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with GRUB. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <grub/types.h>
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#include <grub/dl.h>
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#include <grub/crypto.h>
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/* Based on adler32() from adler32.c of zlib-1.2.5 library. */
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#define BASE 65521UL
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#define NMAX 5552
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#define DO1(buf,i) {adler += (buf)[i]; sum2 += adler;}
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#define DO2(buf,i) DO1(buf,i); DO1(buf,i+1);
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#define DO4(buf,i) DO2(buf,i); DO2(buf,i+2);
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#define DO8(buf,i) DO4(buf,i); DO4(buf,i+4);
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#define DO16(buf) DO8(buf,0); DO8(buf,8);
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static grub_uint32_t
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update_adler32 (grub_uint32_t adler, const grub_uint8_t *buf, grub_size_t len)
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{
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unsigned long sum2;
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unsigned int n;
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sum2 = (adler >> 16) & 0xffff;
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adler &= 0xffff;
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if (len == 1)
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{
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adler += buf[0];
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if (adler >= BASE)
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adler -= BASE;
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sum2 += adler;
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if (sum2 >= BASE)
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sum2 -= BASE;
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return adler | (sum2 << 16);
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}
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if (len < 16)
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{
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while (len--)
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{
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adler += *buf++;
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sum2 += adler;
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}
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if (adler >= BASE)
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adler -= BASE;
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sum2 %= BASE;
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return adler | (sum2 << 16);
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}
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while (len >= NMAX)
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{
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len -= NMAX;
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n = NMAX / 16;
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do
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{
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DO16 (buf);
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buf += 16;
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}
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while (--n);
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adler %= BASE;
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sum2 %= BASE;
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}
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if (len)
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{
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while (len >= 16)
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{
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len -= 16;
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DO16 (buf);
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buf += 16;
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}
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while (len--)
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{
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adler += *buf++;
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sum2 += adler;
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}
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adler %= BASE;
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sum2 %= BASE;
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}
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return adler | (sum2 << 16);
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}
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typedef struct
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{
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grub_uint32_t adler;
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}
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adler32_context;
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static void
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adler32_init (void *context)
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{
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adler32_context *ctx = (adler32_context *) context;
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ctx->adler = 1;
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}
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static void
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adler32_write (void *context, const void *inbuf, grub_size_t inlen)
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{
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adler32_context *ctx = (adler32_context *) context;
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if (!inbuf)
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return;
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ctx->adler = update_adler32 (ctx->adler, inbuf, inlen);
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}
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static grub_uint8_t *
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adler32_read (void *context)
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{
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adler32_context *ctx = (adler32_context *) context;
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return (grub_uint8_t *) &ctx->adler;
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}
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static void
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adler32_final (void *context __attribute__ ((unused)))
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{
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}
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gcry_md_spec_t _gcry_digest_spec_adler32 = {
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"ADLER32",0 , 0, 0 , 4,
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adler32_init, adler32_write, adler32_final, adler32_read,
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sizeof (adler32_context),
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.blocksize = 64
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};
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GRUB_MOD_INIT(adler32)
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{
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grub_md_register (&_gcry_digest_spec_adler32);
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}
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GRUB_MOD_FINI(adler32)
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{
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grub_md_unregister (&_gcry_digest_spec_adler32);
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}
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