BSD 4_3_Reno release

[unix-history] / usr / src / sys / kern / kern_descrip.c

/*
* Copyright (c) 1982, 1986, 1989 Regents of the University of California.
* All rights reserved.
*
* Redistribution is only permitted until one year after the first shipment
* of 4.4BSD by the Regents.  Otherwise, redistribution and use in source and
* binary forms are permitted provided that: (1) source distributions retain
* this entire copyright notice and comment, and (2) distributions including
* binaries display the following acknowledgement:  This product includes
* software developed by the University of California, Berkeley and its
* contributors'' in the documentation or other materials provided with the
* distribution and in all advertising materials mentioning features or use
* of this software.  Neither the name of the University nor the names of
* its contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
* THIS SOFTWARE IS PROVIDED AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*
*      @(#)kern_descrip.c      7.16 (Berkeley) 6/28/90
*/

#include "param.h"
#include "systm.h"
#include "user.h"
#include "kernel.h"
#include "vnode.h"
#include "proc.h"
#include "file.h"
#include "socket.h"
#include "socketvar.h"
#include "stat.h"
#include "ioctl.h"

/*
* Descriptor management.
*/

/*
* System calls on descriptors.
*/
/* ARGSUSED */
getdtablesize(p, uap, retval)
       struct proc *p;
       struct args *uap;
       int *retval;
{

       *retval = NOFILE;
       return (0);
}

/*
* Duplicate a file descriptor.
*/
/* ARGSUSED */
dup(p, uap, retval)
       struct proc *p;
       struct args {
               int     i;
       } *uap;
       int *retval;
{
       struct file *fp;
       int fd, error;

       /*
        * XXX Compatibility
        */
       if (uap->i &~ 077) { uap->i &= 077; return (dup2(p, uap, retval)); }

       if ((unsigned)uap->i >= NOFILE || (fp = u.u_ofile[uap->i]) == NULL)
               return (EBADF);
       if (error = ufalloc(0, &fd))
               return (error);
       u.u_ofile[fd] = fp;
       u.u_pofile[fd] = u.u_pofile[uap->i] &~ UF_EXCLOSE;
       fp->f_count++;
       if (fd > u.u_lastfile)
               u.u_lastfile = fd;
       *retval = fd;
       return (0);
}

/*
* Duplicate a file descriptor to a particular value.
*/
/* ARGSUSED */
dup2(p, uap, retval)
       struct proc *p;
       register struct args {
               int     i;
               int     j;
       } *uap;
       int *retval;
{
       register struct file *fp;
       int error;

       if ((unsigned)uap->i >= NOFILE || (fp = u.u_ofile[uap->i]) == NULL)
               return (EBADF);
       if (uap->j < 0 || uap->j >= NOFILE)
               return (EBADF);
       *retval = uap->j;
       if (uap->i == uap->j)
               return (0);
       if (u.u_ofile[uap->j]) {
               if (u.u_pofile[uap->j] & UF_MAPPED)
                       munmapfd(uap->j);
               error = closef(u.u_ofile[uap->j]);
       }
       u.u_ofile[uap->j] = fp;
       u.u_pofile[uap->j] = u.u_pofile[uap->i] &~ UF_EXCLOSE;
       fp->f_count++;
       if (uap->j > u.u_lastfile)
               u.u_lastfile = uap->j;
       /*
        * dup2() must suceed even though the close had an error.
        */
       error = 0;              /* XXX */
       return (error);
}

/*
* The file control system call.
*/
/* ARGSUSED */
fcntl(p, uap, retval)
       struct proc *p;
       register struct args {
               int     fdes;
               int     cmd;
               int     arg;
       } *uap;
       int *retval;
{
       register struct file *fp;
       register char *pop;
       int i, error;

       if ((unsigned)uap->fdes >= NOFILE ||
           (fp = u.u_ofile[uap->fdes]) == NULL)
               return (EBADF);
       pop = &u.u_pofile[uap->fdes];
       switch(uap->cmd) {
       case F_DUPFD:
               if (uap->arg < 0 || uap->arg >= NOFILE)
                       return (EINVAL);
               if (error = ufalloc(uap->arg, &i))
                       return (error);
               u.u_ofile[i] = fp;
               u.u_pofile[i] = *pop &~ UF_EXCLOSE;
               fp->f_count++;
               if (i > u.u_lastfile)
                       u.u_lastfile = i;
               *retval = i;
               return (0);

       case F_GETFD:
               *retval = *pop & 1;
               return (0);

       case F_SETFD:
               *pop = (*pop &~ 1) | (uap->arg & 1);
               return (0);

       case F_GETFL:
               *retval = fp->f_flag + FOPEN;
               return (0);

       case F_SETFL:
               fp->f_flag &= FCNTLCANT;
               fp->f_flag |= (uap->arg-FOPEN) &~ FCNTLCANT;
               if (error = fset(fp, FNDELAY, fp->f_flag & FNDELAY))
                       return (error);
               if (error = fset(fp, FASYNC, fp->f_flag & FASYNC))
                       (void) fset(fp, FNDELAY, 0);
               return (error);

       case F_GETOWN:
               return (fgetown(fp, retval));

       case F_SETOWN:
               return (fsetown(fp, uap->arg));

       default:
               return (EINVAL);
       }
       /* NOTREACHED */
}

fset(fp, bit, value)
       struct file *fp;
       int bit, value;
{

       if (value)
               fp->f_flag |= bit;
       else
               fp->f_flag &= ~bit;
       return (fioctl(fp, (int)(bit == FNDELAY ? FIONBIO : FIOASYNC),
           (caddr_t)&value));
}

fgetown(fp, valuep)
       struct file *fp;
       int *valuep;
{
       int error;

       switch (fp->f_type) {

       case DTYPE_SOCKET:
               *valuep = ((struct socket *)fp->f_data)->so_pgid;
               return (0);

       default:
               error = fioctl(fp, (int)TIOCGPGRP, (caddr_t)valuep);
               *valuep = -*valuep;
               return (error);
       }
}

fsetown(fp, value)
       struct file *fp;
       int value;
{

       if (fp->f_type == DTYPE_SOCKET) {
               ((struct socket *)fp->f_data)->so_pgid = value;
               return (0);
       }
       if (value > 0) {
               struct proc *p = pfind(value);
               if (p == 0)
                       return (ESRCH);
               value = p->p_pgrp->pg_id;
       } else
               value = -value;
       return (fioctl(fp, (int)TIOCSPGRP, (caddr_t)&value));
}

fioctl(fp, cmd, value)
       struct file *fp;
       int cmd;
       caddr_t value;
{

       return ((*fp->f_ops->fo_ioctl)(fp, cmd, value));
}

/*
* Close a file descriptor.
*/
/* ARGSUSED */
close(p, uap, retval)
       struct proc *p;
       struct args {
               int     fdes;
       } *uap;
       int *retval;
{
       register struct file *fp;
       register u_char *pf;

       if ((unsigned)uap->fdes >= NOFILE ||
           (fp = u.u_ofile[uap->fdes]) == NULL)
               return (EBADF);
       pf = (u_char *)&u.u_pofile[uap->fdes];
       if (*pf & UF_MAPPED)
               munmapfd(uap->fdes);
       u.u_ofile[uap->fdes] = NULL;
       while (u.u_lastfile >= 0 && u.u_ofile[u.u_lastfile] == NULL)
               u.u_lastfile--;
       *pf = 0;
       return (closef(fp));
}

/*
* Return status information about a file descriptor.
*/
/* ARGSUSED */
fstat(p, uap, retval)
       struct proc *p;
       register struct args {
               int     fdes;
               struct  stat *sb;
       } *uap;
       int *retval;
{
       register struct file *fp;
       struct stat ub;
       int error;

       if ((unsigned)uap->fdes >= NOFILE ||
           (fp = u.u_ofile[uap->fdes]) == NULL)
               return (EBADF);
       switch (fp->f_type) {

       case DTYPE_VNODE:
               error = vn_stat((struct vnode *)fp->f_data, &ub);
               break;

       case DTYPE_SOCKET:
               error = soo_stat((struct socket *)fp->f_data, &ub);
               break;

       default:
               panic("fstat");
               /*NOTREACHED*/
       }
       if (error == 0)
               error = copyout((caddr_t)&ub, (caddr_t)uap->sb, sizeof (ub));
       return (error);
}

/*
* Allocate a user file descriptor.
*/
ufalloc(want, result)
       register int want;
       int *result;
{

       for (; want < NOFILE; want++) {
               if (u.u_ofile[want] == NULL) {
                       u.u_pofile[want] = 0;
                       if (want > u.u_lastfile)
                               u.u_lastfile = want;
                       *result = want;
                       return (0);
               }
       }
       return (EMFILE);
}

/*
* Check to see if any user file descriptors are available.
*/
ufavail()
{
       register int i, avail = 0;

       for (i = 0; i < NOFILE; i++)
               if (u.u_ofile[i] == NULL)
                       avail++;
       return (avail);
}

struct  file *lastf;
/*
* Allocate a user file descriptor
* and a file structure.
* Initialize the descriptor
* to point at the file structure.
*/
falloc(resultfp, resultfd)
       struct file **resultfp;
       int *resultfd;
{
       register struct file *fp;
       int error, i;

       if (error = ufalloc(0, &i))
               return (error);
       if (lastf == 0)
               lastf = file;
       for (fp = lastf; fp < fileNFILE; fp++)
               if (fp->f_count == 0)
                       goto slot;
       for (fp = file; fp < lastf; fp++)
               if (fp->f_count == 0)
                       goto slot;
       tablefull("file");
       return (ENFILE);
slot:
       u.u_ofile[i] = fp;
       fp->f_count = 1;
       fp->f_data = 0;
       fp->f_offset = 0;
       fp->f_cred = u.u_cred;
       crhold(fp->f_cred);
       lastf = fp + 1;
       if (resultfp)
               *resultfp = fp;
       if (resultfd)
               *resultfd = i;
       return (0);
}

/*
* Internal form of close.
* Decrement reference count on file structure.
*/
closef(fp)
       register struct file *fp;
{
       int error;

       if (fp == NULL)
               return (0);
       if (fp->f_count > 1) {
               fp->f_count--;
               return (0);
       }
       if (fp->f_count < 1)
               panic("closef: count < 1");
       error = (*fp->f_ops->fo_close)(fp);
       crfree(fp->f_cred);
       fp->f_count = 0;
       return (error);
}

/*
* Apply an advisory lock on a file descriptor.
*/
/* ARGSUSED */
flock(p, uap, retval)
       struct proc *p;
       register struct args {
               int     fdes;
               int     how;
       } *uap;
       int *retval;
{
       register struct file *fp;

       if ((unsigned)uap->fdes >= NOFILE ||
           (fp = u.u_ofile[uap->fdes]) == NULL)
               return (EBADF);
       if (fp->f_type != DTYPE_VNODE)
               return (EOPNOTSUPP);
       if (uap->how & LOCK_UN) {
               vn_unlock(fp, FSHLOCK|FEXLOCK);
               return (0);
       }
       if ((uap->how & (LOCK_SH | LOCK_EX)) == 0)
               return (0);                             /* error? */
       if (uap->how & LOCK_EX)
               uap->how &= ~LOCK_SH;
       /* avoid work... */
       if ((fp->f_flag & FEXLOCK) && (uap->how & LOCK_EX) ||
           (fp->f_flag & FSHLOCK) && (uap->how & LOCK_SH))
               return (0);
       return (vn_lock(fp, uap->how));
}

/*
* File Descriptor pseudo-device driver (/dev/fd/).
*
* Opening minor device N dup()s the file (if any) connected to file
* descriptor N belonging to the calling process.  Note that this driver
* consists of only the ``open()'' routine, because all subsequent
* references to this file will be direct to the other driver.
*/
/* ARGSUSED */
fdopen(dev, mode, type)
       dev_t dev;
       int mode, type;
{
       struct proc *p = u.u_procp;             /* XXX */

       /*
        * XXX Kludge: set p->p_dupfd to contain the value of the
        * the file descriptor being sought for duplication. The error 
        * return ensures that the vnode for this device will be released
        * by vn_open. Open will detect this special error and take the
        * actions in dupfdopen below. Other callers of vn_open or VOP_OPEN
        * will simply report the error.
        */
       p->p_dupfd = minor(dev);
       return (ENODEV);
}

/*
* Duplicate the specified descriptor to a free descriptor.
*/
dupfdopen(indx, dfd, mode)
       register int indx, dfd;
       int mode;
{
       register struct file *wfp;
       struct file *fp;
       
       /*
        * If the to-be-dup'd fd number is greater than the allowed number
        * of file descriptors, or the fd to be dup'd has already been
        * closed, reject.  Note, check for new == old is necessary as
        * falloc could allocate an already closed to-be-dup'd descriptor
        * as the new descriptor.
        */
       fp = u.u_ofile[indx];
       if ((u_int)dfd >= NOFILE || (wfp = u.u_ofile[dfd]) == NULL ||
           fp == wfp)
               return (EBADF);

       /*
        * Check that the mode the file is being opened for is a subset 
        * of the mode of the existing descriptor.
        */
       if (((mode & (FREAD|FWRITE)) | wfp->f_flag) != wfp->f_flag)
               return (EACCES);
       u.u_ofile[indx] = wfp;
       u.u_pofile[indx] = u.u_pofile[dfd];
       wfp->f_count++;
       if (indx > u.u_lastfile)
               u.u_lastfile = indx;
       return (0);
}