Split out a number of mostly VFS and signal related syscalls into

a kernel-internal kern_*() version and a wrapper that is called via
the syscall vector table. For paths and structure pointers, the
internal version either takes a uio_seg parameter or requires the
caller to copyin() the data to kernel memory as appropiate. This
will permit emulation layers to use these syscalls without having
to copy out translated arguments to the stack gap.

Discussed on:		-arch
Review/suggestions:	bde, jhb, peter, marcel

1 files changed, 38 insertions, 21 deletions

diff --git a/sys/kern/sys_generic.c b/sys/kern/sys_generic.c
index 54214e8..ec9958d 100644
--- a/sys/kern/sys_generic.c
+++ b/sys/kern/sys_generic.c
@@ -57,6 +57,7 @@
 #include <sys/poll.h>
 #include <sys/resourcevar.h>
 #include <sys/selinfo.h>
+#include <sys/syscallsubr.h>
 #include <sys/sysctl.h>
 #include <sys/sysent.h>
 #include <sys/bio.h>
@@ -713,6 +714,24 @@ select(td, uap)
 	register struct thread *td;
 	register struct select_args *uap;
 {
+	struct timeval tv, *tvp;
+	int error;
+
+	if (uap->tv != NULL) {
+		error = copyin(uap->tv, &tv, sizeof(tv));
+		if (error)
+			return (error);
+		tvp = &tv;
+	} else
+		tvp = NULL;
+
+	return (kern_select(td, uap->nd, uap->in, uap->ou, uap->ex, tvp));
+}
+
+int
+kern_select(struct thread *td, int nd, fd_set *fd_in, fd_set *fd_ou,
+    fd_set *fd_ex, struct timeval *tvp)
+{
 	struct filedesc *fdp;
 	/*
 	 * The magic 2048 here is chosen to be just enough for FD_SETSIZE
@@ -726,28 +745,28 @@ select(td, uap)
 	int error, timo;
 	u_int ncoll, nbufbytes, ncpbytes, nfdbits;
 
-	if (uap->nd < 0)
+	if (nd < 0)
 		return (EINVAL);
 	fdp = td->td_proc->p_fd;
 	mtx_lock(&Giant);
 	FILEDESC_LOCK(fdp);
 
-	if (uap->nd > td->td_proc->p_fd->fd_nfiles)
-		uap->nd = td->td_proc->p_fd->fd_nfiles;   /* forgiving; slightly wrong */
+	if (nd > td->td_proc->p_fd->fd_nfiles)
+		nd = td->td_proc->p_fd->fd_nfiles;   /* forgiving; slightly wrong */
 	FILEDESC_UNLOCK(fdp);
 
 	/*
 	 * Allocate just enough bits for the non-null fd_sets.  Use the
 	 * preallocated auto buffer if possible.
 	 */
-	nfdbits = roundup(uap->nd, NFDBITS);
+	nfdbits = roundup(nd, NFDBITS);
 	ncpbytes = nfdbits / NBBY;
 	nbufbytes = 0;
-	if (uap->in != NULL)
+	if (fd_in != NULL)
 		nbufbytes += 2 * ncpbytes;
-	if (uap->ou != NULL)
+	if (fd_ou != NULL)
 		nbufbytes += 2 * ncpbytes;
-	if (uap->ex != NULL)
+	if (fd_ex != NULL)
 		nbufbytes += 2 * ncpbytes;
 	if (nbufbytes <= sizeof s_selbits)
 		selbits = &s_selbits[0];
@@ -762,28 +781,26 @@ select(td, uap)
 	sbp = selbits;
 #define	getbits(name, x) \
 	do {								\
-		if (uap->name == NULL)					\
+		if (name == NULL)					\
 			ibits[x] = NULL;				\
 		else {							\
 			ibits[x] = sbp + nbufbytes / 2 / sizeof *sbp;	\
 			obits[x] = sbp;					\
 			sbp += ncpbytes / sizeof *sbp;			\
-			error = copyin(uap->name, ibits[x], ncpbytes);	\
+			error = copyin(name, ibits[x], ncpbytes);	\
 			if (error != 0)					\
 				goto done_nosellock;			\
 		}							\
 	} while (0)
-	getbits(in, 0);
-	getbits(ou, 1);
-	getbits(ex, 2);
+	getbits(fd_in, 0);
+	getbits(fd_ou, 1);
+	getbits(fd_ex, 2);
 #undef	getbits
 	if (nbufbytes != 0)
 		bzero(selbits, nbufbytes / 2);
 
-	if (uap->tv) {
-		error = copyin(uap->tv, &atv, sizeof (atv));
-		if (error)
-			goto done_nosellock;
+	if (tvp != NULL) {
+		atv = *tvp;
 		if (itimerfix(&atv)) {
 			error = EINVAL;
 			goto done_nosellock;
@@ -804,7 +821,7 @@ retry:
 	mtx_unlock_spin(&sched_lock);
 	mtx_unlock(&sellock);
 
-	error = selscan(td, ibits, obits, uap->nd);
+	error = selscan(td, ibits, obits, nd);
 	mtx_lock(&sellock);
 	if (error || td->td_retval[0])
 		goto done;
@@ -853,14 +870,14 @@ done_nosellock:
 	if (error == EWOULDBLOCK)
 		error = 0;
 #define	putbits(name, x) \
-	if (uap->name && (error2 = copyout(obits[x], uap->name, ncpbytes))) \
+	if (name && (error2 = copyout(obits[x], name, ncpbytes))) \
 		error = error2;
 	if (error == 0) {
 		int error2;
 
-		putbits(in, 0);
-		putbits(ou, 1);
-		putbits(ex, 2);
+		putbits(fd_in, 0);
+		putbits(fd_ou, 1);
+		putbits(fd_ex, 2);
 #undef putbits
 	}
 	if (selbits != &s_selbits[0])