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

/* @(#)fdopen.c 4.5 (Berkeley) %G% */
/*
* Unix routine to do an "fopen" on file descriptor
* The mode has to be repeated because you can't query its
* status
*/

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

FILE *
fdopen(fd, mode)
       register char *mode;
{
       extern FILE *_findiop();
       static int nofile = -1;
       register FILE *iop;

       if (nofile < 0)
               nofile = getdtablesize();

       if (fd < 0 || fd >= nofile)
               return (NULL);

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

       iop->_cnt = 0;
       iop->_file = fd;
       iop->_bufsiz = 0;
       iop->_base = iop->_ptr = NULL;

       switch (*mode) {
       case 'r':
               iop->_flag = _IOREAD;
               break;
       case 'a':
               lseek(fd, (off_t)0, L_XTND);
               /* fall into ... */
       case 'w':
               iop->_flag = _IOWRT;
               break;
       default:
               return (NULL);
       }

       if (mode[1] == '+')
               iop->_flag = _IORW;

       return (iop);
}