git.marmaro.de Git - mmh/blob - sbr/cpydgst.c

   1 /*
   2 ** cpydgst.c -- copy from one fd to another in encapsulating mode
   3 **           -- (do dashstuffing of input data).
   4 **
   5 ** This code is Copyright (c) 2002, by the authors of nmh.  See the
   6 ** COPYRIGHT file in the root directory of the nmh distribution for
   7 ** complete copyright information.
   8 */
   9
  10 #include <h/mh.h>
  11
  12 /*
  13 ** We want to perform the substitution
  14 **
  15 **     \n(-.*)\n    -->    \n- \1\n
  16 **
  17 ** This is equivalent to the sed substitution
  18 **
  19 **     sed -e 's%^-%- -%' < ifile > ofile
  20 **
  21 **  but the routine below is faster than the pipe, fork, and exec.
  22 */
  23
  24 #define S1 0
  25 #define S2 1
  26
  27 #define output(c)  if (bp >= dp) {flush(); *bp++ = c;} else *bp++ = c
  28 #define flush()  if ((j = bp - outbuf) && write(out, outbuf, j) != j) \
  29                 adios(ofile, "error writing"); \
  30         else \
  31                 bp = outbuf
  32
  33
  34 void
  35 cpydgst(int in, int out, char *ifile, char *ofile)
  36 {
  37         register int i, j, state;
  38         register char *cp, *ep;
  39         register char *bp, *dp;
  40         char buffer[BUFSIZ], outbuf[BUFSIZ];
  41
  42         dp = (bp = outbuf) + sizeof outbuf;
  43         for (state = S1; (i = read(in, buffer, sizeof buffer)) > 0;)
  44                 for (ep = (cp = buffer) + i; cp < ep; cp++) {
  45                         if (*cp == '\0')
  46                                 continue;
  47                         switch (state) {
  48                                 case S1:
  49                                         if (*cp == '-') {
  50                                                 output('-');
  51                                                 output(' ');
  52                                         }
  53                                         state = S2;  /* fall */
  54
  55                                 case S2:
  56                                         output(*cp);
  57                                         if (*cp == '\n')
  58                                                 state = S1;
  59                                         break;
  60                         }
  61                 }
  62
  63         if (i == -1)
  64                 adios(ifile, "error reading");
  65         flush();
  66 }