LCOV - code coverage report
Current view: top level - common - zb32.c (source / functions) Hit Total Coverage
Test: coverage.info Lines: 41 44 93.2 %
Date: 2016-09-12 12:29:17 Functions: 1 1 100.0 %

          Line data    Source code
       1             : /* zb32.c - z-base-32 functions
       2             :  * Copyright (C) 2014  Werner Koch
       3             :  *
       4             :  * This file is part of GnuPG.
       5             :  *
       6             :  * This file is free software; you can redistribute it and/or modify
       7             :  * it under the terms of either
       8             :  *
       9             :  *   - the GNU Lesser General Public License as published by the Free
      10             :  *     Software Foundation; either version 3 of the License, or (at
      11             :  *     your option) any later version.
      12             :  *
      13             :  * or
      14             :  *
      15             :  *   - the GNU General Public License as published by the Free
      16             :  *     Software Foundation; either version 2 of the License, or (at
      17             :  *     your option) any later version.
      18             :  *
      19             :  * or both in parallel, as here.
      20             :  *
      21             :  * This file is distributed in the hope that it will be useful,
      22             :  * but WITHOUT ANY WARRANTY; without even the implied warranty of
      23             :  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      24             :  * GNU General Public License for more details.
      25             :  *
      26             :  * You should have received a copy of the GNU General Public License
      27             :  * along with this program; if not, see <http://www.gnu.org/licenses/>.
      28             :  */
      29             : 
      30             : #include <config.h>
      31             : #include <stdio.h>
      32             : #include <stdlib.h>
      33             : #include <string.h>
      34             : #include <errno.h>
      35             : #include <assert.h>
      36             : 
      37             : #include "util.h"
      38             : #include "zb32.h"
      39             : 
      40             : /* Zooko's base32 variant. See RFC-6189 and
      41             :    http://philzimmermann.com/docs/human-oriented-base-32-encoding.txt
      42             :    Caller must xfree the returned string.  Returns NULL and sets ERRNO
      43             :    on error.  To avoid integer overflow DATALEN is limited to 2^16
      44             :    bytes.  Note, that DATABITS is measured in bits!.  */
      45             : char *
      46         766 : zb32_encode (const void *data, unsigned int databits)
      47             : {
      48             :   static char const zb32asc[32] = {'y','b','n','d','r','f','g','8',
      49             :                                    'e','j','k','m','c','p','q','x',
      50             :                                    'o','t','1','u','w','i','s','z',
      51             :                                    'a','3','4','5','h','7','6','9' };
      52             :   const unsigned char *s;
      53             :   char *output, *d;
      54             :   size_t datalen;
      55             : 
      56         766 :   datalen = (databits + 7) / 8;
      57         766 :   if (datalen > (1 << 16))
      58             :     {
      59           0 :       errno = EINVAL;
      60           0 :       return NULL;
      61             :     }
      62             : 
      63         766 :   d = output = xtrymalloc (8 * (datalen / 5)
      64             :                            + 2 * (datalen % 5)
      65             :                            - ((datalen%5)>2)
      66             :                            + 1);
      67         766 :   if (!output)
      68           0 :     return NULL;
      69             : 
      70             :   /* I use straightforward code.  The compiler should be able to do a
      71             :      better job on optimization than me and it is easier to read.  */
      72        3015 :   for (s = data; datalen >= 5; s += 5, datalen -= 5)
      73             :     {
      74        2249 :       *d++ = zb32asc[((s[0]      ) >> 3)               ];
      75        2249 :       *d++ = zb32asc[((s[0] &   7) << 2) | (s[1] >> 6) ];
      76        2249 :       *d++ = zb32asc[((s[1] &  63) >> 1)               ];
      77        2249 :       *d++ = zb32asc[((s[1] &   1) << 4) | (s[2] >> 4) ];
      78        2249 :       *d++ = zb32asc[((s[2] &  15) << 1) | (s[3] >> 7) ];
      79        2249 :       *d++ = zb32asc[((s[3] & 127) >> 2)               ];
      80        2249 :       *d++ = zb32asc[((s[3] &   3) << 3) | (s[4] >> 5) ];
      81        2249 :       *d++ = zb32asc[((s[4] &  31)     )               ];
      82             :     }
      83             : 
      84         766 :   switch (datalen)
      85             :     {
      86             :     case 4:
      87           1 :       *d++ = zb32asc[((s[0]      ) >> 3)               ];
      88           1 :       *d++ = zb32asc[((s[0] &   7) << 2) | (s[1] >> 6) ];
      89           1 :       *d++ = zb32asc[((s[1] &  63) >> 1)               ];
      90           1 :       *d++ = zb32asc[((s[1] &   1) << 4) | (s[2] >> 4) ];
      91           1 :       *d++ = zb32asc[((s[2] &  15) << 1) | (s[3] >> 7) ];
      92           1 :       *d++ = zb32asc[((s[3] & 127) >> 2)               ];
      93           1 :       *d++ = zb32asc[((s[3] &   3) << 3)               ];
      94           1 :       break;
      95             :     case 3:
      96           5 :       *d++ = zb32asc[((s[0]      ) >> 3)               ];
      97           5 :       *d++ = zb32asc[((s[0] &   7) << 2) | (s[1] >> 6) ];
      98           5 :       *d++ = zb32asc[((s[1] &  63) >> 1)               ];
      99           5 :       *d++ = zb32asc[((s[1] &   1) << 4) | (s[2] >> 4) ];
     100           5 :       *d++ = zb32asc[((s[2] &  15) << 1)               ];
     101           5 :       break;
     102             :     case 2:
     103           5 :       *d++ = zb32asc[((s[0]      ) >> 3)               ];
     104           5 :       *d++ = zb32asc[((s[0] &   7) << 2) | (s[1] >> 6) ];
     105           5 :       *d++ = zb32asc[((s[1] &  63) >> 1)               ];
     106           5 :       *d++ = zb32asc[((s[1] &   1) << 4)               ];
     107           5 :       break;
     108             :     case 1:
     109           4 :       *d++ = zb32asc[((s[0]      ) >> 3)               ];
     110           4 :       *d++ = zb32asc[((s[0] &   7) << 2)               ];
     111           4 :       break;
     112             :     default:
     113         751 :       break;
     114             :     }
     115         766 :   *d = 0;
     116             : 
     117             :   /* Need to strip some bytes if not a multiple of 40.  */
     118         766 :   output[(databits + 5 - 1) / 5] = 0;
     119         766 :   return output;
     120             : }

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