mdw@git.distorted.org.uk Git - ezmlm/blob - encodeB.c

   1 /* $Id: encodeB.c,v 1.3 1998/03/21 18:30:27 lindberg Exp $*/
   2 /* $Name: ezmlm-idx-040 $*/
   3
   4 #include "stralloc.h"
   5 #include "uint32.h"
   6 #include "mime.h"
   7 #include "strerr.h"
   8 #include "errtxt.h"
   9
  10 static void die_nomem(fatal)
  11   char *fatal;
  12 {
  13   strerr_die2x(111,fatal,ERR_NOMEM);
  14 }
  15
  16 static unsigned char base64char[] =
  17    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  18
  19 static unsigned int pos = 0;
  20 static unsigned int i = 0;
  21 static uint32 hold32;
  22 static unsigned char *cpout;
  23
  24 static void addone(ch)
  25 unsigned char ch;
  26 {
  27  if (!(pos++))
  28     hold32 = (uint32) ch;
  29   else
  30     hold32 = (hold32 << 8) | ch;
  31   if (pos == 3) {
  32     *cpout++ = base64char[(hold32 >> 18) & 0x3f];
  33     *cpout++ = base64char[(hold32 >> 12) & 0x3f];
  34     *cpout++ = base64char[(hold32 >>  6) & 0x3f];
  35     *cpout++ = base64char[hold32 & 0x3f];
  36     if (++i == 18) {
  37       *cpout++ = '\n';
  38       i = 0;
  39     }
  40     pos = 0;
  41   }
  42 }
  43
  44 static void dorest()
  45 {
  46   switch (pos) {
  47     case 2:
  48       hold32 = hold32 << 2;
  49       *cpout++ = base64char[(hold32 >> 12) & 0x3f];
  50       *cpout++ = base64char[(hold32 >> 06) & 0x3f];
  51       *cpout++ = base64char[hold32 & 0x3f];
  52       *cpout++ = '=';
  53       break;
  54     case 1:
  55       hold32 = hold32 << 4;
  56       *cpout++ = base64char[(hold32 >> 06) & 0x3f];
  57       *cpout++ = base64char[hold32 & 0x3f];
  58       *cpout++ = '=';
  59       *cpout++ = '=';
  60       break;
  61     default:
  62       break;
  63   }
  64   *cpout++ = '\n';
  65 }
  66
  67 void encodeB(indata,n,outdata,control,fatal)
  68 unsigned char *indata;
  69 unsigned int n;
  70 stralloc *outdata;
  71 int control;    /* 1 = init, 2 = flush */
  72 char *fatal;
  73         /* converts any character with the high order bit set to */
  74         /* base64. In: n chars of indata, out: stralloc outdata  */
  75         /* as '=' is not allowed within the block, we cannot flush after */
  76         /* each line, so we carry over data from call to call. The last  */
  77         /* call to encodeB should have control = 2 to do the flushing.   */
  78         /* control = 0 resets, and the routine starts out reset. */
  79 {
  80   register unsigned char ch;
  81
  82   if (control == 1) {
  83     pos = 0;
  84     i = 0;
  85   }
  86   if (!stralloc_copys(outdata,"")) die_nomem(fatal);
  87   if (!stralloc_ready(outdata,n*8/3 + n/72 + 5)) die_nomem(fatal);
  88   cpout = (unsigned char *) outdata->s;
  89   while (n--) {
  90     ch = *indata++;
  91     if (ch == '\n')
  92       addone('\r');
  93     addone(ch);
  94   }
  95   if (control == 2)
  96     dorest();
  97   outdata->len = (unsigned int) (cpout - (unsigned char *) outdata->s);
  98 }
  99