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