1  /* sm3.c - Functions to compute SM3 message digest of files or memory blocks
       2     according to the specification GM/T 004-2012 Cryptographic Hash Algorithm
       3     SM3, published by State Encryption Management Bureau, China.
       4  
       5     SM3 cryptographic hash algorithm.
       6     <http://www.sca.gov.cn/sca/xwdt/2010-12/17/content_1002389.shtml>
       7  
       8     Copyright (C) 2017-2023 Free Software Foundation, Inc.
       9  
      10     This file is free software: you can redistribute it and/or modify
      11     it under the terms of the GNU Lesser General Public License as
      12     published by the Free Software Foundation; either version 2.1 of the
      13     License, or (at your option) any later version.
      14  
      15     This file is distributed in the hope that it will be useful,
      16     but WITHOUT ANY WARRANTY; without even the implied warranty of
      17     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      18     GNU Lesser General Public License for more details.
      19  
      20     You should have received a copy of the GNU Lesser General Public License
      21     along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
      22  
      23  /* Written by Jia Zhang <qianyue.zj@alibaba-inc.com>, 2017,
      24     considerably copypasting from David Madore's sha256.c */
      25  
      26  #include <config.h>
      27  
      28  /* Specification.  */
      29  #if HAVE_OPENSSL_SM3
      30  # define GL_OPENSSL_INLINE _GL_EXTERN_INLINE
      31  #endif
      32  #include "sm3.h"
      33  
      34  #include <stdlib.h>
      35  
      36  #if USE_UNLOCKED_IO
      37  # include "unlocked-io.h"
      38  #endif
      39  
      40  #define BLOCKSIZE 32768
      41  #if BLOCKSIZE % 64 != 0
      42  # error "invalid BLOCKSIZE"
      43  #endif
      44  
      45  /* Compute SM3 message digest for bytes read from STREAM.  The
      46     resulting message digest number will be written into the 32 bytes
      47     beginning at RESBLOCK.  */
      48  int
      49  sm3_stream (FILE *stream, void *resblock)
      50  {
      51    struct sm3_ctx ctx;
      52    size_t sum;
      53  
      54    char *buffer = malloc (BLOCKSIZE + 72);
      55    if (!buffer)
      56      return 1;
      57  
      58    /* Initialize the computation context.  */
      59    sm3_init_ctx (&ctx);
      60  
      61    /* Iterate over full file contents.  */
      62    while (1)
      63      {
      64        /* We read the file in blocks of BLOCKSIZE bytes.  One call of the
      65           computation function processes the whole buffer so that with the
      66           next round of the loop another block can be read.  */
      67        size_t n;
      68        sum = 0;
      69  
      70        /* Read block.  Take care for partial reads.  */
      71        while (1)
      72          {
      73            n = fread (buffer + sum, 1, BLOCKSIZE - sum, stream);
      74  
      75            sum += n;
      76  
      77            if (sum == BLOCKSIZE)
      78              break;
      79  
      80            if (n == 0)
      81              {
      82                /* Check for the error flag IFF N == 0, so that we don't
      83                   exit the loop after a partial read due to e.g., EAGAIN
      84                   or EWOULDBLOCK.  */
      85                if (ferror (stream))
      86                  {
      87                    free (buffer);
      88                    return 1;
      89                  }
      90                goto process_partial_block;
      91              }
      92  
      93            /* We've read at least one byte, so ignore errors.  But always
      94               check for EOF, since feof may be true even though N > 0.
      95               Otherwise, we could end up calling fread after EOF.  */
      96            if (feof (stream))
      97              goto process_partial_block;
      98          }
      99  
     100        /* Process buffer with BLOCKSIZE bytes.  Note that
     101                          BLOCKSIZE % 64 == 0
     102         */
     103        sm3_process_block (buffer, BLOCKSIZE, &ctx);
     104      }
     105  
     106   process_partial_block:;
     107  
     108    /* Process any remaining bytes.  */
     109    if (sum > 0)
     110      sm3_process_bytes (buffer, sum, &ctx);
     111  
     112    /* Construct result in desired memory.  */
     113    sm3_finish_ctx (&ctx, resblock);
     114    free (buffer);
     115    return 0;
     116  }
     117  
     118  /*
     119   * Hey Emacs!
     120   * Local Variables:
     121   * coding: utf-8
     122   * End:
     123   */