sys/src/libString/s_getline.c

   1 #include <u.h>
   2 #include <libc.h>
   3 #include <bio.h>
   4 #include "String.h"
   5
   6 /* Append an input line to a String.
   7  *
   8  * Returns a pointer to the character string (or 0).
   9  * Leading whitespace and newlines are removed.
  10  *
  11  * Empty lines and lines starting with '#' are ignored.
  12  */
  13 extern char *
  14 s_getline(Biobuf *fp, String *to)
  15 {
  16         int c;
  17         int len=0;
  18
  19         s_terminate(to);
  20
  21         /* end of input */
  22         if ((c = Bgetc(fp)) < 0)
  23                 return 0;
  24
  25         /* take care of inconsequentials */
  26         for(;;) {
  27                 /* eat leading white */
  28                 while(c==' ' || c=='\t' || c=='\n' || c=='\r')
  29                         c = Bgetc(fp);
  30
  31                 if(c < 0)
  32                         return 0;
  33
  34                 /* take care of comments */
  35                 if(c == '#'){
  36                         do {
  37                                 c = Bgetc(fp);
  38                                 if(c < 0)
  39                                         return 0;
  40                         } while(c != '\n');
  41                         continue;
  42                 }
  43
  44                 /* if we got here, we've gotten something useful */
  45                 break;
  46         }
  47
  48         /* gather up a line */
  49         for(;;) {
  50                 len++;
  51                 switch(c) {
  52                 case -1:
  53                         s_terminate(to);
  54                         return len ? to->ptr-len : 0;
  55                 case '\\':
  56                         c = Bgetc(fp);
  57                         if (c != '\n') {
  58                                 s_putc(to, '\\');
  59                                 s_putc(to, c);
  60                         }
  61                         break;
  62                 case '\n':
  63                         s_terminate(to);
  64                         return len ? to->ptr-len : 0;
  65                 default:
  66                         s_putc(to, c);
  67                         break;
  68                 }
  69                 c = Bgetc(fp);
  70         }
  71 }