From adf87ab01c2e33bc55526faa821e32eda43bbc2a Mon Sep 17 00:00:00 2001
From: Mateusz Guzik <mjg@FreeBSD.org>
Date: Sun, 22 Jun 2014 01:31:55 +0000
Subject: [PATCH] fd: replace fd_nfiles with fd_lastfile where appropriate

fd_lastfile is guaranteed to be the biggest open fd, so when the intent
is to iterate over active fds or lookup one, there is no point in looking
beyond that limit.

Few places are left unpatched for now.

MFC after:	1 week
---
 sys/kern/kern_descrip.c | 12 ++++++------
 sys/kern/sys_generic.c  |  2 +-
 sys/kern/vfs_syscalls.c |  2 +-
 sys/sys/filedesc.h      |  2 +-
 4 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/sys/kern/kern_descrip.c b/sys/kern/kern_descrip.c
index 9c0d7c0e61a..267b3170624 100644
--- a/sys/kern/kern_descrip.c
+++ b/sys/kern/kern_descrip.c
@@ -1234,7 +1234,7 @@ sys_closefrom(struct thread *td, struct closefrom_args *uap)
 	if (uap->lowfd < 0)
 		uap->lowfd = 0;
 	FILEDESC_SLOCK(fdp);
-	for (fd = uap->lowfd; fd < fdp->fd_nfiles; fd++) {
+	for (fd = uap->lowfd; fd <= fdp->fd_lastfile; fd++) {
 		if (fdp->fd_ofiles[fd].fde_file != NULL) {
 			FILEDESC_SUNLOCK(fdp);
 			(void)kern_close(td, fd);
@@ -2916,7 +2916,7 @@ sysctl_kern_file(SYSCTL_HANDLER_ARGS)
 		if (fdp == NULL)
 			continue;
 		FILEDESC_SLOCK(fdp);
-		for (n = 0; fdp->fd_refcnt > 0 && n < fdp->fd_nfiles; ++n) {
+		for (n = 0; fdp->fd_refcnt > 0 && n <= fdp->fd_lastfile; ++n) {
 			if ((fp = fdp->fd_ofiles[n].fde_file) == NULL)
 				continue;
 			xf.xf_fd = n;
@@ -3026,7 +3026,7 @@ sysctl_kern_proc_ofiledesc(SYSCTL_HANDLER_ARGS)
 	if (fdp->fd_jdir != NULL)
 		export_vnode_for_osysctl(fdp->fd_jdir, KF_FD_TYPE_JAIL, kif,
 				fdp, req);
-	for (i = 0; fdp->fd_refcnt > 0 && i < fdp->fd_nfiles; i++) {
+	for (i = 0; fdp->fd_refcnt > 0 && i <= fdp->fd_lastfile; i++) {
 		if ((fp = fdp->fd_ofiles[i].fde_file) == NULL)
 			continue;
 		bzero(kif, sizeof(*kif));
@@ -3395,7 +3395,7 @@ kern_proc_filedesc_out(struct proc *p,  struct sbuf *sb, ssize_t maxlen)
 		export_fd_to_sb(data, KF_TYPE_VNODE, KF_FD_TYPE_JAIL,
 		    FREAD, -1, -1, NULL, efbuf);
 	}
-	for (i = 0; fdp->fd_refcnt > 0 && i < fdp->fd_nfiles; i++) {
+	for (i = 0; fdp->fd_refcnt > 0 && i <= fdp->fd_lastfile; i++) {
 		if ((fp = fdp->fd_ofiles[i].fde_file) == NULL)
 			continue;
 		data = NULL;
@@ -3766,7 +3766,7 @@ file_to_first_proc(struct file *fp)
 		fdp = p->p_fd;
 		if (fdp == NULL)
 			continue;
-		for (n = 0; n < fdp->fd_nfiles; n++) {
+		for (n = 0; n <= fdp->fd_lastfile; n++) {
 			if (fp == fdp->fd_ofiles[n].fde_file)
 				return (p);
 		}
@@ -3816,7 +3816,7 @@ DB_SHOW_COMMAND(files, db_show_files)
 			continue;
 		if ((fdp = p->p_fd) == NULL)
 			continue;
-		for (n = 0; n < fdp->fd_nfiles; ++n) {
+		for (n = 0; n <= fdp->fd_lastfile; ++n) {
 			if ((fp = fdp->fd_ofiles[n].fde_file) == NULL)
 				continue;
 			db_print_file(fp, header);
diff --git a/sys/kern/sys_generic.c b/sys/kern/sys_generic.c
index 6cc4f13fe1a..50bc91dea01 100644
--- a/sys/kern/sys_generic.c
+++ b/sys/kern/sys_generic.c
@@ -1458,7 +1458,7 @@ pollscan(td, fds, nfd)
 
 	FILEDESC_SLOCK(fdp);
 	for (i = 0; i < nfd; i++, fds++) {
-		if (fds->fd >= fdp->fd_nfiles) {
+		if (fds->fd > fdp->fd_lastfile) {
 			fds->revents = POLLNVAL;
 			n++;
 		} else if (fds->fd < 0) {
diff --git a/sys/kern/vfs_syscalls.c b/sys/kern/vfs_syscalls.c
index 8481fb48f13..7aa457e6071 100644
--- a/sys/kern/vfs_syscalls.c
+++ b/sys/kern/vfs_syscalls.c
@@ -828,7 +828,7 @@ chroot_refuse_vdir_fds(fdp)
 
 	FILEDESC_LOCK_ASSERT(fdp);
 
-	for (fd = 0; fd < fdp->fd_nfiles ; fd++) {
+	for (fd = 0; fd <= fdp->fd_lastfile; fd++) {
 		fp = fget_locked(fdp, fd);
 		if (fp == NULL)
 			continue;
diff --git a/sys/sys/filedesc.h b/sys/sys/filedesc.h
index 516ef1b6192..972cfc92475 100644
--- a/sys/sys/filedesc.h
+++ b/sys/sys/filedesc.h
@@ -175,7 +175,7 @@ fget_locked(struct filedesc *fdp, int fd)
 
 	FILEDESC_LOCK_ASSERT(fdp);
 
-	if (fd < 0 || fd >= fdp->fd_nfiles)
+	if (fd < 0 || fd > fdp->fd_lastfile)
 		return (NULL);
 
 	return (fdp->fd_ofiles[fd].fde_file);