From fc1edd3e2ce7bb33d93dddaf7e4d837d535e3ab2 Mon Sep 17 00:00:00 2001
From: Bill Joy <wnj@ucbvax.Berkeley.EDU>
Date: Thu, 27 Sep 1979 04:23:43 -0800
Subject: [PATCH] BSD 3 development Work on file usr/src/libc/stdio/popen.c

Synthesized-from: 3bsd
---
 usr/src/libc/stdio/popen.c | 54 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)
 create mode 100644 usr/src/libc/stdio/popen.c

diff --git a/usr/src/libc/stdio/popen.c b/usr/src/libc/stdio/popen.c
new file mode 100644
index 0000000000..09b725e901
--- /dev/null
+++ b/usr/src/libc/stdio/popen.c
@@ -0,0 +1,54 @@
+#include <stdio.h>
+#include <signal.h>
+#define	tst(a,b)	(*mode == 'r'? (b) : (a))
+#define	RDR	0
+#define	WTR	1
+static	int	popen_pid[20];
+
+FILE *
+popen(cmd,mode)
+char	*cmd;
+char	*mode;
+{
+	int p[2];
+	register myside, hisside, pid;
+
+	if(pipe(p) < 0)
+		return NULL;
+	myside = tst(p[WTR], p[RDR]);
+	hisside = tst(p[RDR], p[WTR]);
+	if((pid = vfork()) == 0) {
+		/* myside and hisside reverse roles in child */
+		close(myside);
+		dup2(hisside, tst(0, 1));
+		close(hisside);
+		execl("/bin/sh", "sh", "-c", cmd, 0);
+		_exit(1);
+	}
+	if(pid == -1)
+		return NULL;
+	popen_pid[myside] = pid;
+	close(hisside);
+	return(fdopen(myside, mode));
+}
+
+pclose(ptr)
+FILE *ptr;
+{
+	register f, r, (*hstat)(), (*istat)(), (*qstat)();
+	int status;
+
+	f = fileno(ptr);
+	fclose(ptr);
+	istat = signal(SIGINT, SIG_IGN);
+	qstat = signal(SIGQUIT, SIG_IGN);
+	hstat = signal(SIGHUP, SIG_IGN);
+	while((r = wait(&status)) != popen_pid[f] && r != -1)
+		;
+	if(r == -1)
+		status = -1;
+	signal(SIGINT, istat);
+	signal(SIGQUIT, qstat);
+	signal(SIGHUP, hstat);
+	return(status);
+}
-- 
2.20.1