common/sfio/sfsetfd.c

	sfsetfd.c revision 7c2fbfb345896881c631598ee3852ce9ce33fb07
/***********************************************************************
*                                                                      *
*               This software is part of the ast package               *
*          Copyright (c) 1985-2008 AT&T Intellectual Property          *
*                      and is licensed under the                       *
*                  Common Public License, Version 1.0                  *
*                    by AT&T Intellectual Property                     *
*                                                                      *
*                A copy of the License is available at                 *
*            http://www.opensource.org/licenses/cpl1.0.txt             *
*         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
*                                                                      *
*              Information and Software Systems Research               *
*                            AT&T Research                             *
*                           Florham Park NJ                            *
*                                                                      *
*                 Glenn Fowler <gsf@research.att.com>                  *
*                  David Korn <dgk@research.att.com>                   *
*                   Phong Vo <kpv@research.att.com>                    *
*                                                                      *
***********************************************************************/
#include    "sfhdr.h"

/*  Change the file descriptor
**
**  Written by Kiem-Phong Vo.
*/

#if __STD_C
static int _sfdup(int fd, int newfd)
#else
static int _sfdup(fd,newfd)
int fd;
int newfd;
#endif
{
    reg int dupfd;

#ifdef F_DUPFD  /* the simple case */
    while((dupfd = sysfcntlf(fd,F_DUPFD,newfd)) < 0 && errno == EINTR)
        errno = 0;
    return dupfd;

#else   /* do it the hard way */
    if((dupfd = sysdupf(fd)) < 0 || dupfd >= newfd)
        return dupfd;

    /* dup() succeeded but didn't get the right number, recurse */
    newfd = _sfdup(fd,newfd);

    /* close the one that didn't match */
    CLOSE(dupfd);

    return newfd;
#endif
}

#if __STD_C
int sfsetfd(Sfio_t* f, int newfd)
#else
int sfsetfd(f,newfd)
Sfio_t  *f;
int newfd;
#endif
{
    reg int     oldfd;
    SFMTXDECL(f);

    SFMTXENTER(f, -1);

    if(f->flags&SF_STRING)
        SFMTXRETURN(f, -1);

    if((f->mode&SF_INIT) && f->file < 0)
    {   /* restoring file descriptor after a previous freeze */
        if(newfd < 0)
            SFMTXRETURN(f, -1);
    }
    else
    {   /* change file descriptor */
        if((f->mode&SF_RDWR) != f->mode && _sfmode(f,0,0) < 0)
            SFMTXRETURN(f, -1);
        SFLOCK(f,0);

        oldfd = f->file;
        if(oldfd >= 0)
        {   if(newfd >= 0)
            {   if((newfd = _sfdup(oldfd,newfd)) < 0)
                {   SFOPEN(f,0);
                    SFMTXRETURN(f, -1);
                }
                CLOSE(oldfd);
            }
            else
            {   /* sync stream if necessary */
                if(((f->mode&SF_WRITE) && f->next > f->data) ||
                   (f->mode&SF_READ) || f->disc == _Sfudisc)
                {   if(SFSYNC(f) < 0)
                    {   SFOPEN(f,0);
                        SFMTXRETURN(f, -1);
                    }
                }

                if(((f->mode&SF_WRITE) && f->next > f->data) ||
                   ((f->mode&SF_READ) && f->extent < 0 &&
                    f->next < f->endb) )
                {   SFOPEN(f,0);
                    SFMTXRETURN(f, -1);
                }

#ifdef MAP_TYPE
                if((f->bits&SF_MMAP) && f->data)
                {   SFMUNMAP(f,f->data,f->endb-f->data);
                    f->data = NIL(uchar*);
                }
#endif

                /* make stream appears uninitialized */
                f->endb = f->endr = f->endw = f->data;
                f->extent = f->here = 0;
                f->mode = (f->mode&SF_RDWR)|SF_INIT;
                f->bits &= ~SF_NULL;    /* off /dev/null handling */
            }
        }

        SFOPEN(f,0);
    }

    /* notify changes */
    if(_Sfnotify)
        (*_Sfnotify)(f, SF_SETFD, (void*)((long)newfd));

    f->file = newfd;

    SFMTXRETURN(f,newfd);
}