102 lines
2.1 KiB
C
102 lines
2.1 KiB
C
/*
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* GRUB -- GRand Unified Bootloader
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* Copyright (C) 2012 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/dl.h>
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#include <grub/crypto.h>
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GRUB_MOD_LICENSE ("GPLv3+");
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struct adler32_context
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{
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grub_uint16_t a, b;
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grub_uint32_t c;
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};
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static void
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adler32_init (void *context)
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{
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struct adler32_context *ctx = context;
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ctx->a = 1;
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ctx->b = 0;
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}
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#define MOD 65521
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static grub_uint16_t
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mod_add (grub_uint16_t a, grub_uint16_t b)
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{
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if ((grub_uint32_t) a + (grub_uint32_t) b >= MOD)
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return a + b - MOD;
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return a + b;
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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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struct adler32_context *ctx = context;
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const grub_uint8_t *ptr = inbuf;
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while (inlen)
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{
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ctx->a = mod_add (ctx->a, *ptr);
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ctx->b = mod_add (ctx->a, ctx->b);
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inlen--;
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ptr++;
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}
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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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static grub_uint8_t *
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adler32_read (void *context)
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{
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struct adler32_context *ctx = context;
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if (ctx->a > MOD)
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ctx->a -= MOD;
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if (ctx->b > MOD)
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ctx->b -= MOD;
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ctx->c = grub_cpu_to_be32 (ctx->a | (ctx->b << 16));
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return (grub_uint8_t *) &ctx->c;
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}
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static gcry_md_spec_t spec_adler32 =
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{
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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 (struct adler32_context),
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#ifdef GRUB_UTIL
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.modname = "adler32",
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#endif
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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 (&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 (&spec_adler32);
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}
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