lib/libc/stdio/fillbuf.c

   1 /*
   2  * fillbuf.c - fill a buffer
   3  */
   4 /* $Header$ */
   5
   6 #if     defined(_POSIX_SOURCE)
   7 #include        <sys/types.h>
   8 #endif
   9 #include        <stdio.h>
  10 #include        <stdlib.h>
  11 #include        "loc_incl.h"
  12
  13 ssize_t _read(ssize_t d, char *buf, size_t nbytes);
  14
  15 int
  16 __fillbuf(register FILE *stream)
  17 {
  18         static unsigned char ch[FOPEN_MAX];
  19         register int i;
  20
  21         stream->_count = 0;
  22         if (fileno(stream) < 0) return EOF;
  23         if (io_testflag(stream, (_IOEOF | _IOERR ))) return EOF;
  24         if (!io_testflag(stream, _IOREAD))
  25              { stream->_flags |= _IOERR; return EOF; }
  26         if (io_testflag(stream, _IOWRITING))
  27              { stream->_flags |= _IOERR; return EOF; }
  28
  29         if (!io_testflag(stream, _IOREADING))
  30                 stream->_flags |= _IOREADING;
  31
  32         if (!io_testflag(stream, _IONBF) && !stream->_buf) {
  33                 stream->_buf = (unsigned char *) malloc(BUFSIZ);
  34                 if (!stream->_buf) {
  35                         stream->_flags |= _IONBF;
  36                 }
  37                 else {
  38                         stream->_flags |= _IOMYBUF;
  39                         stream->_bufsiz = BUFSIZ;
  40                 }
  41         }
  42
  43         /* flush line-buffered output when filling an input buffer */
  44         for (i = 0; i < FOPEN_MAX; i++) {
  45                 if (__iotab[i] && io_testflag(__iotab[i], _IOLBF))
  46                         if (io_testflag(__iotab[i], _IOWRITING))
  47                                 (void) fflush(__iotab[i]);
  48         }
  49
  50         if (!stream->_buf) {
  51                 stream->_buf = &ch[fileno(stream)];
  52                 stream->_bufsiz = 1;
  53         }
  54         stream->_ptr = stream->_buf;
  55         stream->_count = _read(stream->_fd, (char *)stream->_buf, stream->_bufsiz);
  56
  57         if (stream->_count <= 0){
  58                 if (stream->_count == 0) {
  59                         stream->_flags |= _IOEOF;
  60                 }
  61                 else
  62                         stream->_flags |= _IOERR;
  63
  64                 return EOF;
  65         }
  66         stream->_count--;
  67
  68         return *stream->_ptr++;
  69 }