usr/src/sys/kern/kern_descrip.c

/*
 * Copyright (c) 1982 Regents of the University of California.
 * All rights reserved.  The Berkeley software License Agreement
 * specifies the terms and conditions for redistribution.
 *
 *      @(#)kern_descrip.c      6.13 (Berkeley) %G%
 */

#include "param.h"
#include "systm.h"
#include "dir.h"
#include "user.h"
#include "kernel.h"
#include "inode.h"
#include "proc.h"
#include "file.h"
#include "socket.h"
#include "socketvar.h"
#include "mount.h"
#include "stat.h"

#include "ioctl.h"

/*
 * Descriptor management.
 */

/*
 * TODO:
 *      eliminate u.u_error side effects
 */

/*
 * System calls on descriptors.
 */
getdtablesize()
{

        u.u_r.r_val1 = NOFILE;
}

getdopt()
{

}

setdopt()
{

}

dup()
{
        register struct a {
                int     i;
        } *uap = (struct a *) u.u_ap;
        struct file *fp;
        int j;

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

        GETF(fp, uap->i);
        j = ufalloc(0);
        if (j < 0)
                return;
        dupit(j, fp, u.u_pofile[uap->i] &~ UF_EXCLOSE);
}

dup2()
{
        register struct a {
                int     i, j;
        } *uap = (struct a *) u.u_ap;
        register struct file *fp;

        GETF(fp, uap->i);
        if (uap->j < 0 || uap->j >= NOFILE) {
                u.u_error = EBADF;
                return;
        }
        u.u_r.r_val1 = uap->j;
        if (uap->i == uap->j)
                return;
        if (u.u_ofile[uap->j]) {
                if (u.u_pofile[uap->j] & UF_MAPPED)
                        munmapfd(uap->j);
                closef(u.u_ofile[uap->j]);
                if (u.u_error)
                        return;
        }
        dupit(uap->j, fp, u.u_pofile[uap->i] &~ UF_EXCLOSE);
}

dupit(fd, fp, flags)
        int fd;
        register struct file *fp;
        register int flags;
{

        u.u_ofile[fd] = fp;
        u.u_pofile[fd] = flags;
        fp->f_count++;
        if (fd > u.u_lastfile)
                u.u_lastfile = fd;
}

/*
 * The file control system call.
 */
fcntl()
{
        register struct file *fp;
        register struct a {
                int     fdes;
                int     cmd;
                int     arg;
        } *uap;
        register i;
        register char *pop;

        uap = (struct a *)u.u_ap;
        GETF(fp, uap->fdes);
        pop = &u.u_pofile[uap->fdes];
        switch(uap->cmd) {
        case F_DUPFD:
                i = uap->arg;
                if (i < 0 || i >= NOFILE) {
                        u.u_error = EINVAL;
                        return;
                }
                if ((i = ufalloc(i)) < 0)
                        return;
                dupit(i, fp, *pop &~ UF_EXCLOSE);
                break;

        case F_GETFD:
                u.u_r.r_val1 = *pop & 1;
                break;

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

        case F_GETFL:
                u.u_r.r_val1 = fp->f_flag+FOPEN;
                break;

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

        case F_GETOWN:
                u.u_error = fgetown(fp, &u.u_r.r_val1);
                break;

        case F_SETOWN:
                u.u_error = fsetown(fp, uap->arg);
                break;

        default:
                u.u_error = EINVAL;
        }
}

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_pgrp;
                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_pgrp = value;
                return (0);
        }
        if (value > 0) {
                struct proc *p = pfind(value);
                if (p == 0)
                        return (ESRCH);
                value = p->p_pgrp;
        } 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()
{
        struct a {
                int     i;
        } *uap = (struct a *)u.u_ap;
        register int i = uap->i;
        register struct file *fp;
        register u_char *pf;

        GETF(fp, i);
        pf = (u_char *)&u.u_pofile[i];
        if (*pf & UF_MAPPED)
                munmapfd(i);
        u.u_ofile[i] = NULL;
        while (u.u_lastfile >= 0 && u.u_ofile[u.u_lastfile] == NULL)
                u.u_lastfile--;
        *pf = 0;
        closef(fp);
        /* WHAT IF u.u_error ? */
}

fstat()
{
        register struct file *fp;
        register struct a {
                int     fdes;
                struct  stat *sb;
        } *uap;
        struct stat ub;

        uap = (struct a *)u.u_ap;
        GETF(fp, uap->fdes);
        switch (fp->f_type) {

        case DTYPE_INODE:
                u.u_error = ino_stat((struct inode *)fp->f_data, &ub);
                break;

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

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

/*
 * Allocate a user file descriptor.
 */
ufalloc(i)
        register int i;
{

        for (; i < NOFILE; i++)
                if (u.u_ofile[i] == NULL) {
                        u.u_r.r_val1 = i;
                        u.u_pofile[i] = 0;
                        if (i > u.u_lastfile)
                                u.u_lastfile = i;
                        return (i);
                }
        u.u_error = EMFILE;
        return (-1);
}

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.
 */
struct file *
falloc()
{
        register struct file *fp;
        register i;

        i = ufalloc(0);
        if (i < 0)
                return (NULL);
        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");
        u.u_error = ENFILE;
        return (NULL);
slot:
        u.u_ofile[i] = fp;
        fp->f_count = 1;
        fp->f_data = 0;
        fp->f_offset = 0;
        lastf = fp + 1;
        return (fp);
}

/*
 * Convert a user supplied file descriptor into a pointer
 * to a file structure.  Only task is to check range of the descriptor.
 * Critical paths should use the GETF macro.
 */
struct file *
getf(f)
        register int f;
{
        register struct file *fp;

        if ((unsigned)f >= NOFILE || (fp = u.u_ofile[f]) == NULL) {
                u.u_error = EBADF;
                return (NULL);
        }
        return (fp);
}

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

        if (fp == NULL)
                return;
        if (fp->f_count > 1) {
                fp->f_count--;
                return;
        }
        (*fp->f_ops->fo_close)(fp);
        fp->f_count = 0;
}

/*
 * Apply an advisory lock on a file descriptor.
 */
flock()
{
        register struct a {
                int     fd;
                int     how;
        } *uap = (struct a *)u.u_ap;
        register struct file *fp;

        GETF(fp, uap->fd);
        if (fp->f_type != DTYPE_INODE) {
                u.u_error = EOPNOTSUPP;
                return;
        }
        if (uap->how & LOCK_UN) {
                ino_unlock(fp, FSHLOCK|FEXLOCK);
                return;
        }
        if ((uap->how & (LOCK_SH | LOCK_EX)) == 0)
                return;                                 /* 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;
        u.u_error = ino_lock(fp, uap->how);
}