source/texk/web2c/lib/eofeoln.c

   1 /* eofeoln.c: implement Pascal's ideas for end-of-file and end-of-line
   2    testing.  Public domain. */
   3
   4 #include <w2c/config.h>
   5 #include "lib.h"
   6
   7 /* Return true if we're at the end of FILE, else false.  This implements
   8    Pascal's `eof' builtin.  */
   9
  10 boolean
  11 eof (FILE *file)
  12 {
  13   register int c;
  14
  15   /* If FILE doesn't exist, return true. This happens, for example,
  16      when a user does `mft foo.mf' -- there's no change file,
  17      so we never open it, so we end up calling this with a null pointer. */
  18   if (!file)
  19     return true;
  20
  21   /* Maybe we're already at the end?  */
  22   if (feof (file))
  23     return true;
  24
  25   if ((c = getc (file)) == EOF)
  26     return true;
  27
  28   /* We weren't at the end.  Back up.  */
  29   (void) ungetc (c, file);
  30
  31   return false;
  32 }
  33
  34
  35 /* Return true on end-of-line in FILE or at the end of FILE, else false.  */
  36 /* Accept both CR and LF as end-of-line. */
  37
  38 boolean
  39 eoln (FILE *file)
  40 {
  41   register int c;
  42
  43   if (feof (file))
  44     return true;
  45
  46   c = getc (file);
  47
  48   if (c != EOF)
  49     (void) ungetc (c, file);
  50
  51   return c == '\n' || c == '\r' || c == EOF;
  52 }
  53
  54 /* Consume input up and including the first eol encountered. */
  55 /* Handle CRLF as a single end-of-line. */
  56
  57 void
  58 readln (FILE *f)
  59 {
  60     int c;
  61     while ((c = getc (f)) != '\n' && c != '\r' && c != EOF)
  62         ;
  63     if (c == '\r' && (c = getc (f)) != '\n' && c != EOF)
  64         ungetc (c, f);
  65 }