don't do 1 byte writes, buffer and flush unbuffered I/O (stderr).

[unix-history] / usr / src / lib / libc / stdio / fopen.c

/* @(#)fopen.c  4.3 (Berkeley) %G% */
#include        <stdio.h>
#include        <errno.h>

FILE *
fopen(file, mode)
char *file;
register char *mode;
{
       extern int errno;
       register f, rw;
       register FILE *iop;
       extern FILE *_lastbuf;

       for (iop = _iob; iop->_flag&(_IOREAD|_IOWRT|_IORW); )
               if (++iop >= _lastbuf)
                       return(NULL);

       rw = mode[1] == '+';

       if (*mode=='w') {
               f = creat(file, 0666);
               if (rw && f>=0) {
                       close(f);
                       f = open(file, 2);
               }
       } else if (*mode=='a') {
               if ((f = open(file, rw? 2: 1)) < 0) {
                       if (errno == ENOENT) {
                               f = creat(file, 0666);
                               if (rw && f>=0) {
                                       close(f);
                                       f = open(file, 2);
                               }
                       }
               }
               if (f >= 0)
                       lseek(f, 0L, 2);
       } else
               f = open(file, rw? 2: 0);
       if (f < 0)
               return(NULL);
       iop->_cnt = 0;
       iop->_file = f;
       if (rw)
               iop->_flag |= _IORW;
       else if (*mode != 'r')
               iop->_flag |= _IOWRT;
       else
               iop->_flag |= _IOREAD;
       return(iop);
}