/*
* Note: This routine is single threaded
* Protected by FIFOOPEN flag (i.e. flk_lock is not held)
* Upon successful completion, the original fifo is unlocked
* and FIFOOPEN is cleared for the original vpp.
* The new fifo returned has FIFOOPEN set.
*/
static int
fifo_connld(struct vnode **vpp, int flag, cred_t *crp)
{
struct vnode *vp1;
struct vnode *vp2;
struct fifonode *oldfnp;
struct fifonode *fn_dest;
int error;
struct file *filep;
struct fifolock *fn_lock;
cred_t *c;
/*
* Get two vnodes that will represent the pipe ends for the new pipe.
*/
makepipe(&vp1, &vp2);
/*
* Allocate a file descriptor and file pointer for one of the pipe
* ends. The file descriptor will be used to send that pipe end to
* the process on the other end of this stream. Note that we get
* the file structure only, there is no file list entry allocated.
*/
if (error = falloc(vp1, FWRITE|FREAD, &filep, NULL)) {
VN_RELE(vp1);
VN_RELE(vp2);
return (error);
}
mutex_exit(&filep->f_tlock);
oldfnp = VTOF(*vpp);
fn_lock = oldfnp->fn_lock;
fn_dest = oldfnp->fn_dest;
/*
* Create two new stream heads and attach them to the two vnodes for
* the new pipe.
*/
if ((error = fifo_stropen(&vp1, FREAD|FWRITE, filep->f_cred, 0, 0)) !=
0 ||
(error = fifo_stropen(&vp2, flag, filep->f_cred, 0, 0)) != 0) {
#if DEBUG
cmn_err(CE_NOTE, "fifo stropen failed error 0x%x", error);
#endif
/*
* this will call fifo_close and VN_RELE on vp1
*/
(void) closef(filep);
VN_RELE(vp2);
return (error);
}
/*
* twist the ends of the pipe together
*/
strmate(vp1, vp2);
/*
* Set our end to busy in open
* Note: Don't need lock around this because we're the only
* one who knows about it
*/
VTOF(vp2)->fn_flag |= FIFOOPEN;
mutex_enter(&fn_lock->flk_lock);
fn_dest->fn_flag |= FIFOSEND;
/*
* check to make sure neither end of pipe has gone away
*/
if (!(fn_dest->fn_flag & FIFOISOPEN)) {
error = ENXIO;
fn_dest->fn_flag &= ~FIFOSEND;
mutex_exit(&fn_lock->flk_lock);
/*
* this will call fifo_close and VN_RELE on vp1
*/
goto out;
}
mutex_exit(&fn_lock->flk_lock);
/*
* Tag the sender's credential on the pipe descriptor.
*/
crhold(VTOF(vp1)->fn_pcredp = crp);
VTOF(vp1)->fn_cpid = curproc->p_pid;
/*
* send the file descriptor to other end of pipe
*/
if (error = do_sendfp((*vpp)->v_stream, filep, crp)) {
mutex_enter(&fn_lock->flk_lock);
fn_dest->fn_flag &= ~FIFOSEND;
mutex_exit(&fn_lock->flk_lock);
/*
* this will call fifo_close and VN_RELE on vp1
*/
goto out;
}
mutex_enter(&fn_lock->flk_lock);
/*
* Wait for other end to receive file descriptor
* FIFOCLOSE indicates that one or both sides of the pipe
* have gone away.
*/
while ((fn_dest->fn_flag & (FIFOCLOSE | FIFOSEND)) == FIFOSEND) {
if (!cv_wait_sig(&oldfnp->fn_wait_cv, &fn_lock->flk_lock)) {
error = EINTR;
fn_dest->fn_flag &= ~FIFOSEND;
mutex_exit(&fn_lock->flk_lock);
goto out;
}
}
/*
* If either end of pipe has gone away and the other end did not
* receive pipe, reject the connld open
*/
if ((fn_dest->fn_flag & FIFOSEND)) {
error = ENXIO;
fn_dest->fn_flag &= ~FIFOSEND;
mutex_exit(&fn_lock->flk_lock);
goto out;
}
oldfnp->fn_flag &= ~FIFOOPEN;
cv_broadcast(&oldfnp->fn_wait_cv);
mutex_exit(&fn_lock->flk_lock);
VN_RELE(*vpp);
*vpp = vp2;
(void) closef(filep);
return (0);
out:
c = filep->f_cred;
crhold(c);
(void) closef(filep);
VTOF(vp2)->fn_flag &= ~FIFOOPEN;
(void) fifo_close(vp2, flag, 1, (offset_t)0, c, NULL);
crfree(c);
VN_RELE(vp2);
return (error);
}
/*
* pipe(2) system call.
* Create a pipe by connecting two streams together. Associate
* each end of the pipe with a vnode, a file descriptor and
* one of the streams.
*/
longlong_t
pipe()
{
vnode_t *vp1, *vp2;
struct file *fp1, *fp2;
int error = 0;
int fd1, fd2;
rval_t r;
/*
* Allocate and initialize two vnodes.
*/
makepipe(&vp1, &vp2);
/*
* Allocate and initialize two file table entries and two
* file pointers. Each file pointer is open for read and
* write.
*/
if (error = falloc(vp1, FWRITE|FREAD, &fp1, &fd1)) {
VN_RELE(vp1);
VN_RELE(vp2);
return ((longlong_t)set_errno(error));
}
if (error = falloc(vp2, FWRITE|FREAD, &fp2, &fd2))
goto out2;
/*
* Create two stream heads and attach to each vnode.
*/
if (error = fifo_stropen(&vp1, FWRITE|FREAD, fp1->f_cred, 0, 0))
goto out;
if (error = fifo_stropen(&vp2, FWRITE|FREAD, fp2->f_cred, 0, 0)) {
(void) VOP_CLOSE(vp1, FWRITE|FREAD, 1, (offset_t)0,
fp1->f_cred);
goto out;
}
strmate(vp1, vp2);
VTOF(vp1)->fn_ino = VTOF(vp2)->fn_ino = fifogetid();
/*
* Now fill in the entries that falloc reserved
*/
mutex_exit(&fp1->f_tlock);
mutex_exit(&fp2->f_tlock);
setf(fd1, fp1);
setf(fd2, fp2);
/*
* Return the file descriptors to the user. They now
* point to two different vnodes which have different
* stream heads.
*/
r.r_val1 = fd1;
r.r_val2 = fd2;
return (r.r_vals);
out:
unfalloc(fp2);
setf(fd2, NULL);
out2:
unfalloc(fp1);
setf(fd1, NULL);
VN_RELE(vp1);
VN_RELE(vp2);
return ((longlong_t)set_errno(error));
}
/*
* Stream a pipe/FIFO.
* The FIFOCONNLD flag is used when CONNLD has been pushed on the stream.
* If the flag is set, a new vnode is created by calling fifo_connld().
* Connld logic was moved to fifo_connld() to speed up the open
* operation, simplify the connld/fifo interaction, and remove inherent
* race conditions between the connld module and fifos.
* This routine is single threaded for two reasons.
* 1) connld requests are synchronous; that is, they must block
* until the server does an I_RECVFD (oh, well). Single threading is
* the simplest way to accomplish this.
* 2) fifo_close() must not send M_HANGUP or M_ERROR while we are
* in stropen. Stropen() has a tendency to reset things and
* we would like streams to remember that a hangup occurred.
*/
int
fifo_stropen(vnode_t **vpp, int flag, cred_t *crp, int dotwist, int lockheld)
{
int error = 0;
vnode_t *oldvp = *vpp;
fifonode_t *fnp = VTOF(*vpp);
dev_t pdev = 0;
int firstopen = 0;
fifolock_t *fn_lock;
fn_lock = fnp->fn_lock;
if (!lockheld)
mutex_enter(&fn_lock->flk_lock);
ASSERT(MUTEX_HELD(&fnp->fn_lock->flk_lock));
/*
* FIFO is in the process of opening. Wait for it
* to complete before starting another open on it
* This prevents races associated with connld open
*/
while (fnp->fn_flag & FIFOOPEN) {
if (!cv_wait_sig(&fnp->fn_wait_cv, &fn_lock->flk_lock)) {
fifo_cleanup(oldvp, flag);
if (!lockheld)
mutex_exit(&fn_lock->flk_lock);
return (EINTR);
}
}
/*
* The other end of the pipe is almost closed so
* reject any other open on this end of the pipe
* This only happens with a pipe mounted under namefs
*/
if ((fnp->fn_flag & (FIFOCLOSE|ISPIPE)) == (FIFOCLOSE|ISPIPE)) {
fifo_cleanup(oldvp, flag);
cv_broadcast(&fnp->fn_wait_cv);
if (!lockheld)
mutex_exit(&fn_lock->flk_lock);
return (ENXIO);
}
fnp->fn_flag |= FIFOOPEN;
/*
* can't allow close to happen while we are
* in the middle of stropen().
* M_HANGUP and M_ERROR could leave the stream in a strange state
*/
while (fn_lock->flk_ocsync)
cv_wait(&fn_lock->flk_wait_cv, &fn_lock->flk_lock);
fn_lock->flk_ocsync = 1;
if (fnp->fn_flag & FIFOCONNLD) {
/*
* This is a reopen, so we should release the fifo lock
* just in case some strange module pushed on connld
* has some odd side effect.
* Note: this stropen is on the oldvp. It will
* have no impact on the connld vp returned and
* strclose() will only be called when we release
* flk_ocsync
*/
mutex_exit(&fn_lock->flk_lock);
if ((error = stropen(oldvp, &pdev, flag, crp)) != 0) {
mutex_enter(&fn_lock->flk_lock);
fifo_cleanup(oldvp, flag);
fn_lock->flk_ocsync = 0;
cv_broadcast(&fn_lock->flk_wait_cv);
goto out;
}
/*
* streams open done, allow close on other end if
* required. Do this now.. it could
* be a very long time before fifo_connld returns.
*/
mutex_enter(&fn_lock->flk_lock);
/*
* we need to fake an open here so that if this
* end of the pipe closes, we don't loose the
* stream head (kind of like single threading
* open and close for this end of the pipe)
* We'll need to call fifo_close() to do clean
* up in case this end of the pipe was closed
* down while we were in fifo_connld()
*/
ASSERT(fnp->fn_open > 0);
fnp->fn_open++;
fn_lock->flk_ocsync = 0;
cv_broadcast(&fn_lock->flk_wait_cv);
mutex_exit(&fn_lock->flk_lock);
/*
* Connld has been pushed onto the pipe
* Create new pipe on behalf of connld
*/
if (error = fifo_connld(vpp, flag, crp)) {
(void) fifo_close(oldvp, flag, 1, 0, crp, NULL);
mutex_enter(&fn_lock->flk_lock);
goto out;
}
/*
* undo fake open. We need to call fifo_close
* because some other thread could have done
* a close and detach of the named pipe while
* we were in fifo_connld(), so
* we want to make sure the close completes (yuk)
*/
(void) fifo_close(oldvp, flag, 1, 0, crp, NULL);
/*
* fifo_connld has changed the vp, so we
* need to re-initialize locals
*/
fnp = VTOF(*vpp);
fn_lock = fnp->fn_lock;
mutex_enter(&fn_lock->flk_lock);
} else {
/*
* release lock in case there are modules pushed that
* could have some strange side effect
*/
mutex_exit(&fn_lock->flk_lock);
/*
* If this is the first open of a fifo (dotwist
* will be non-zero) we will need to twist the queues.
*/
if (oldvp->v_stream == NULL)
firstopen = 1;
/*
* normal open of pipe/fifo
*/
if ((error = stropen(oldvp, &pdev, flag, crp)) != 0) {
mutex_enter(&fn_lock->flk_lock);
fifo_cleanup(oldvp, flag);
ASSERT(fnp->fn_open != 0 || oldvp->v_stream == NULL);
fn_lock->flk_ocsync = 0;
cv_broadcast(&fn_lock->flk_wait_cv);
goto out;
}
mutex_enter(&fn_lock->flk_lock);
/*
* twist the ends of the fifo together
*/
if (dotwist && firstopen)
strmate(*vpp, *vpp);
/*
* Show that this open has succeeded
* and allow closes or other opens to proceed
*/
fnp->fn_open++;
fn_lock->flk_ocsync = 0;
cv_broadcast(&fn_lock->flk_wait_cv);
}
out:
fnp->fn_flag &= ~FIFOOPEN;
if (error == 0) {
fnp->fn_flag |= FIFOISOPEN;
/*
* If this is a FIFO and has the close flag set
* and there are now writers, clear the close flag
* Note: close flag only gets set when last writer
* on a FIFO goes away.
*/
if (((fnp->fn_flag & (ISPIPE|FIFOCLOSE)) == FIFOCLOSE) &&
fnp->fn_wcnt > 0)
fnp->fn_flag &= ~FIFOCLOSE;
}
cv_broadcast(&fnp->fn_wait_cv);
if (!lockheld)
mutex_exit(&fn_lock->flk_lock);
return (error);
}
