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   1 /*
   2 ** vfgets.c -- virtual fgets
   3 **
   4 ** This code is Copyright (c) 2002, 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 <sysexits.h>
  10 #include <h/mh.h>
  11 #include <h/utils.h>
  12
  13 #define QUOTE '\\'
  14
  15
  16 int
  17 vfgets(FILE *in, char **bp)
  18 {
  19         int toggle;
  20         char *cp, *dp, *ep, *fp;
  21         static int len = 0;
  22         static char *pp = NULL;
  23
  24         if (pp == NULL)
  25                 pp = mh_xcalloc(len = BUFSIZ, sizeof(char));
  26
  27         for (ep = (cp = pp) + len - 1;;) {
  28                 if (fgets(cp, ep - cp + 1, in) == NULL) {
  29                         if (cp != pp) {
  30                                 *bp = pp;
  31                                 return 0;
  32                         }
  33                         return (ferror(in) && !feof(in) ? -1 : 1);
  34                 }
  35
  36                 if ((dp = cp + strlen(cp) - 2) < cp || *dp != QUOTE) {
  37 wrong_guess:
  38                         if (cp > ++dp)
  39                                 adios(EX_SOFTWARE, NULL, "vfgets() botch -- you lose big");
  40                         if (*dp == '\n') {
  41                                 *bp = pp;
  42                                 return 0;
  43                         } else {
  44                                 cp = ++dp;
  45                         }
  46                 } else {
  47                         for (fp = dp - 1, toggle = 0; fp >= cp; fp--) {
  48                                 if (*fp != QUOTE)
  49                                         break;
  50                                 else
  51                                         toggle = !toggle;
  52                         }
  53                         if (toggle)
  54                                 goto wrong_guess;
  55
  56                         if (*++dp == '\n') {
  57                                 *--dp = 0;
  58                                 cp = dp;
  59                         } else {
  60                                 cp = ++dp;
  61                         }
  62                 }
  63
  64                 if (cp >= ep) {
  65                         int curlen = cp - pp;
  66
  67                         dp = mh_xrealloc(pp, len += BUFSIZ);
  68                         cp = dp + curlen;
  69                         ep = (pp = dp) + len - 1;
  70                 }
  71         }
  72 }