diplodocus.org Git - nmh/blob - sbr/base64.c

   1 /*
   2  * base64.c -- routines for converting to base64
   3  *
   4  * This code is Copyright (c) 2012, by the authors of nmh.  See the
   5  * COPYRIGHT file in the root directory of the nmh distribution for
   6  * complete copyright information.
   7  */
   8
   9 #include <h/mh.h>
  10 #include <h/mime.h>
  11
  12 static char nib2b64[0x40+1] =
  13         "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  14
  15 int
  16 writeBase64aux (FILE *in, FILE *out)
  17 {
  18     unsigned int cc, n;
  19     char inbuf[3];
  20
  21     n = BPERLIN;
  22     while ((cc = fread (inbuf, sizeof(*inbuf), sizeof(inbuf), in)) > 0) {
  23         unsigned long bits;
  24         char *bp;
  25         char outbuf[4];
  26
  27         if (cc < sizeof(inbuf)) {
  28             inbuf[2] = 0;
  29             if (cc < sizeof(inbuf) - 1)
  30                 inbuf[1] = 0;
  31         }
  32         bits = (inbuf[0] & 0xff) << 16;
  33         bits |= (inbuf[1] & 0xff) << 8;
  34         bits |= inbuf[2] & 0xff;
  35
  36         for (bp = outbuf + sizeof(outbuf); bp > outbuf; bits >>= 6)
  37             *--bp = nib2b64[bits & 0x3f];
  38         if (cc < sizeof(inbuf)) {
  39             outbuf[3] = '=';
  40             if (cc < sizeof inbuf - 1)
  41                 outbuf[2] = '=';
  42         }
  43
  44         fwrite (outbuf, sizeof(*outbuf), sizeof(outbuf), out);
  45
  46         if (cc < sizeof(inbuf)) {
  47             putc ('\n', out);
  48             return OK;
  49         }
  50
  51         if (--n <= 0) {
  52             n = BPERLIN;
  53             putc ('\n', out);
  54         }
  55     }
  56     if (n != BPERLIN)
  57         putc ('\n', out);
  58
  59     return OK;
  60 }
  61
  62
  63 /* Caller is responsible for ensuring that the out array is long
  64    enough.  Given length is that of in, out should be have at
  65    least this capacity:
  66      4 * [length/3]  +  length/57  +  2
  67    But double the length will certainly be sufficient. */
  68 int
  69 writeBase64 (unsigned char *in, size_t length, unsigned char *out)
  70 {
  71     unsigned int n = BPERLIN;
  72
  73     while (1) {
  74         unsigned long bits;
  75         unsigned char *bp;
  76         unsigned int cc;
  77         for (cc = 0, bp = in; length > 0 && cc < 3; ++cc, ++bp, --length)
  78           /* empty */ ;
  79
  80         if (cc == 0) {
  81             break;
  82         } else {
  83             bits = (in[0] & 0xff) << 16;
  84             if (cc > 1) {
  85                 bits |= (in[1] & 0xff) << 8;
  86                 if (cc > 2) {
  87                     bits |= in[2] & 0xff;
  88                 }
  89             }
  90         }
  91
  92         for (bp = out + 4; bp > out; bits >>= 6)
  93             *--bp = nib2b64[bits & 0x3f];
  94         if (cc < 3) {
  95             out[3] = '=';
  96             if (cc < 2)
  97                 out[2] = '=';
  98             out += 4;
  99             n = 0;
 100             break;
 101         }
 102
 103         in += 3;
 104         out += 4;
 105         if (--n <= 0) {
 106             n = BPERLIN;
 107             *out++ = '\n';
 108         }
 109     }
 110     if (n != BPERLIN)
 111         *out++ = '\n';
 112
 113     *out = '\0';
 114
 115     return OK;
 116 }