diplodocus.org Git - nmh/blob - docs/historical/mh-6.8.5/sbr/cpydgst.c

   1 /* cpydgst.c - copy from one fd to another in encapsulating mode */
   2 #ifndef lint
   3 static char ident[] = "@(#)$Id: cpydgst.c,v 1.4 1992/12/15 00:20:22 jromine Exp $";
   4 #endif  /* lint */
   5
   6 #include "../h/mh.h"
   7 #include <stdio.h>
   8
   9
  10 /* All we want to do is to perform the substitution
  11
  12         \n(-.*)\n       -->     \n- \1\n
  13
  14     we could use
  15
  16         sed -e 's%^-%- -%' < ifile > ofile
  17
  18     to do this, but the routine below is faster than the pipe, fork, and
  19     exec.
  20  */
  21
  22 #define S1      0
  23 #define S2      1
  24
  25 #define output(c)   if (bp >= dp) {flush(); *bp++ = c;} else *bp++ = c
  26 #define flush()     if ((j = bp - outbuf) && write (out, outbuf, j) != j) \
  27                         adios (ofile, "error writing"); \
  28                     else \
  29                         bp = outbuf
  30
  31 /* \f */
  32
  33 void cpydgst (in, out, ifile, ofile)
  34 register int    in,
  35                 out;
  36 register char  *ifile,
  37                *ofile;
  38 {
  39     register int    i,
  40                     state;
  41     register char  *cp,
  42                    *ep;
  43     char    buffer[BUFSIZ];
  44     register int    j;
  45     register char  *bp,
  46                    *dp;
  47     char    outbuf[BUFSIZ];
  48
  49     dp = (bp = outbuf) + sizeof outbuf;
  50     for (state = S1; (i = read (in, buffer, sizeof buffer)) > 0;)
  51         for (ep = (cp = buffer) + i; cp < ep; cp++) {
  52             if (*cp == '\0')
  53                 continue;
  54             switch (state) {
  55                 case S1:
  56                     if (*cp == '-') {
  57                         output ('-');
  58                         output (' ');
  59                     }
  60                     state = S2; /* fall */
  61
  62                 case S2:
  63                     output (*cp);
  64                     if (*cp == '\n')
  65                         state = S1;
  66                     break;
  67             }
  68         }
  69
  70     if (i == NOTOK)
  71         adios (ifile, "error reading");
  72     flush ();
  73 }