src/stdio/setvbuf.c

   1 #include "stdio_impl.h"
   2
   3 /* The behavior of this function is undefined except when it is the first
   4  * operation on the stream, so the presence or absence of locking is not
   5  * observable in a program whose behavior is defined. Thus no locking is
   6  * performed here. No allocation of buffers is performed, but a buffer
   7  * provided by the caller is used as long as it is suitably sized. */
   8
   9 int setvbuf(FILE *restrict f, char *restrict buf, int type, size_t size)
  10 {
  11         f->lbf = EOF;
  12
  13         if (type == _IONBF) {
  14                 f->buf_size = 0;
  15         } else if (type == _IOLBF || type == _IOFBF) {
  16                 if (buf && size >= UNGET) {
  17                         f->buf = (void *)(buf + UNGET);
  18                         f->buf_size = size - UNGET;
  19                 }
  20                 if (type == _IOLBF && f->buf_size)
  21                         f->lbf = '\n';
  22         } else {
  23                 return -1;
  24         }
  25
  26         f->flags |= F_SVB;
  27
  28         return 0;
  29 }