From 84bf8cdeeafb80b7ea8e42f5a98934b90f9bd447 Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Mon, 14 Aug 2000 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 2000-08-14

---
 port/sysfile.c | 61 +++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 48 insertions(+), 13 deletions(-)

diff --git a/port/sysfile.c b/port/sysfile.c
index f08348b7c0468ae82dbcedb67d5c09154434998d..4984dd32c31bea032fe908ef2d2ba289c7422916 100644
--- a/port/sysfile.c
+++ b/port/sysfile.c
@@ -42,6 +42,22 @@ growfd(Fgrp *f, int fd)	/* fd is always >= 0 */
 	return 1;
 }
 
+/*
+ *  this assumes that the fgrp is locked
+ */
+int
+findfreefd(Fgrp *f, int start)
+{
+	int fd;
+
+	for(fd=start; fd<f->nfd; fd++)
+		if(f->fd[fd] == 0)
+			break;
+	if(fd >= f->nfd && growfd(f, fd) < 0)
+		return -1;
+	return fd;
+}
+
 int
 newfd(Chan *c)
 {
@@ -50,10 +66,8 @@ newfd(Chan *c)
 
 	f = up->fgrp;
 	lock(f);
-	for(fd=0; fd<f->nfd; fd++)
-		if(f->fd[fd] == 0)
-			break;
-	if(fd >= f->nfd && growfd(f, fd) < 0){
+	fd = findfreefd(f, 0);
+	if(fd < 0){
 		unlock(f);
 		return -1;
 	}
@@ -64,6 +78,32 @@ newfd(Chan *c)
 	return fd;
 }
 
+int
+newfd2(int fd[2], Chan *c[2])
+{
+	Fgrp *f;
+
+	f = up->fgrp;
+	lock(f);
+	fd[0] = findfreefd(f, 0);
+	if(fd[0] < 0){
+		unlock(f);
+		return -1;
+	}
+	fd[1] = findfreefd(f, fd[0]+1);
+	if(fd[1] < 0){
+		unlock(f);
+		return -1;
+	}
+	if(fd[1] > f->maxfd)
+		f->maxfd = fd[1];
+	f->fd[fd[0]] = c[0];
+	f->fd[fd[1]] = c[1];
+	unlock(f);
+
+	return 0;
+}
+
 Chan*
 fdtochan(int fd, int mode, int chkmnt, int iref)
 {
@@ -140,7 +180,6 @@ syspipe(ulong *arg)
 	int fd[2];
 	Chan *c[2];
 	Dev *d;
-	Fgrp *f = up->fgrp;
 
 	validaddr(arg[0], 2*BY2WD, 1);
 	evenaddr(arg[0]);
@@ -149,14 +188,11 @@ syspipe(ulong *arg)
 	c[1] = 0;
 	fd[0] = -1;
 	fd[1] = -1;
+
 	if(waserror()){
 		cclose(c[0]);
 		if(c[1])
 			cclose(c[1]);
-		if(fd[0] >= 0)
-			f->fd[fd[0]]=0;
-		if(fd[1] >= 0)
-			f->fd[fd[1]]=0;
 		nexterror();
 	}
 	c[1] = cclone(c[0], 0);
@@ -166,13 +202,12 @@ syspipe(ulong *arg)
 		error(Egreg);
 	c[0] = d->open(c[0], ORDWR);
 	c[1] = d->open(c[1], ORDWR);
-	fd[0] = newfd(c[0]);
-	fd[1] = newfd(c[1]);
-	if(fd[0] < 0 || fd[1] < 0)
+	if(newfd2(fd, c) < 0)
 		error(Enofd);
+	poperror();
+
 	((long*)arg[0])[0] = fd[0];
 	((long*)arg[0])[1] = fd[1];
-	poperror();
 	return 0;
 }