sys/src/cmd/upas/unesc/unesc.c

   1 /*
   2  *      upas/unesc - interpret =?foo?bar?=char?= escapes
   3  */
   4 #include <u.h>
   5 #include <libc.h>
   6 #include <bio.h>
   7
   8 int
   9 hex(int c)
  10 {
  11         if('0' <= c && c <= '9')
  12                 return c - '0';
  13         if('a' <= c && c <= 'f')
  14                 return c - 'a' + 10;
  15         if('A' <= c && c <= 'F')
  16                 return c - 'A' + 10;
  17         return 0;
  18 }
  19
  20 void
  21 main(void)
  22 {
  23         int c;
  24         Biobuf bin, bout;
  25
  26         Binit(&bin,  0, OREAD);
  27         Binit(&bout, 1, OWRITE);
  28         while((c = Bgetc(&bin)) != Beof)
  29                 if(c != '=')
  30                         Bputc(&bout, c);
  31                 else if((c = Bgetc(&bin)) != '?'){
  32                         Bputc(&bout, '=');
  33                         Bputc(&bout, c);
  34                 } else {
  35                         while((c = Bgetc(&bin)) != Beof && c != '?')
  36                                 continue;               /* consume foo */
  37                         while((c = Bgetc(&bin)) != Beof && c != '?')
  38                                 continue;               /* consume bar */
  39                         while((c = Bgetc(&bin)) != Beof && c != '?'){
  40                                 if(c == '='){
  41                                         c  = hex(Bgetc(&bin)) << 4;
  42                                         c |= hex(Bgetc(&bin));
  43                                 }
  44                                 Bputc(&bout, c);
  45                         }
  46                         c = Bgetc(&bin);                /* consume '=' */
  47                         if (c != '=')
  48                                 Bungetc(&bin);
  49                 }
  50         Bterm(&bout);
  51         exits(0);
  52 }