BSD 4_3 release

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

/*
* Copyright (c) 1980 Regents of the University of California.
* All rights reserved.  The Berkeley software License Agreement
* specifies the terms and conditions for redistribution.
*/

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)fopen.c     5.2 (Berkeley) 3/9/86";
#endif LIBC_SCCS and not lint

#include <sys/types.h>
#include <sys/file.h>
#include <stdio.h>

FILE *
fopen(file, mode)
       char *file;
       register char *mode;
{
       register FILE *iop;
       register f, rw, oflags;
       extern FILE *_findiop();

       iop = _findiop();
       if (iop == NULL)
               return (NULL);

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

       switch (*mode) {
       case 'a':
               oflags = O_CREAT | (rw ? O_RDWR : O_WRONLY);
               break;
       case 'r':
               oflags = rw ? O_RDWR : O_RDONLY;
               break;
       case 'w':
               oflags = O_TRUNC | O_CREAT | (rw ? O_RDWR : O_WRONLY);
               break;
       default:
               return (NULL);
       }

       f = open(file, oflags, 0666);
       if (f < 0)
               return (NULL);

       if (*mode == 'a')
               lseek(f, (off_t)0, L_XTND);

       iop->_cnt = 0;
       iop->_file = f;
       iop->_bufsiz = 0;
       if (rw)
               iop->_flag = _IORW;
       else if (*mode == 'r')
               iop->_flag = _IOREAD;
       else
               iop->_flag = _IOWRT;
       iop->_base = iop->_ptr = NULL;
       return (iop);
}