Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.

===================================================================
RCS file: /ftp/cvs/cvsroot/src/lib/libc/gen/popen.c,v
rcsdiff: /ftp/cvs/cvsroot/src/lib/libc/gen/popen.c,v: warning: Unknown phrases like `commitid ...;' are present.
retrieving revision 1.11
retrieving revision 1.18
diff -u -p -r1.11 -r1.18
--- src/lib/libc/gen/popen.c	1995/06/16 07:05:33	1.11
+++ src/lib/libc/gen/popen.c	1998/02/03 01:16:03	1.18
@@ -1,4 +1,4 @@
-/*	$NetBSD: popen.c,v 1.11 1995/06/16 07:05:33 jtc Exp $	*/
+/*	$NetBSD: popen.c,v 1.18 1998/02/03 01:16:03 perry Exp $	*/
 
 /*
  * Copyright (c) 1988, 1993
@@ -36,16 +36,19 @@
  * SUCH DAMAGE.
  */
 
+#include <sys/cdefs.h>
 #if defined(LIBC_SCCS) && !defined(lint)
 #if 0
-static char sccsid[] = "@(#)popen.c	8.1 (Berkeley) 6/4/93";
+static char sccsid[] = "@(#)popen.c	8.3 (Berkeley) 5/3/95";
 #else
-static char rcsid[] = "$NetBSD: popen.c,v 1.11 1995/06/16 07:05:33 jtc Exp $";
+__RCSID("$NetBSD: popen.c,v 1.18 1998/02/03 01:16:03 perry Exp $");
 #endif
 #endif /* LIBC_SCCS and not lint */
 
+#include "namespace.h"
 #include <sys/param.h>
 #include <sys/wait.h>
+#include <sys/socket.h>
 
 #include <signal.h>
 #include <errno.h>
@@ -55,6 +58,11 @@ static char rcsid[] = "$NetBSD: popen.c,
 #include <string.h>
 #include <paths.h>
 
+#ifdef __weak_alias
+__weak_alias(popen,_popen);
+__weak_alias(pclose,_pclose);
+#endif
+
 static struct pid {
 	struct pid *next;
 	FILE *fp;
@@ -62,27 +70,35 @@ static struct pid {
 } *pidlist; 
 	
 FILE *
-popen(program, type)
-	const char *program;
-	const char *type;
+popen(command, type)
+	const char *command, *type;
 {
-	struct pid *cur;
+	struct pid *cur, *old;
 	FILE *iop;
-	int pdes[2], pid;
+	int pdes[2], pid, twoway;
 
-	if (*type != 'r' && *type != 'w' || type[1]) {
-		errno = EINVAL;
-		return (NULL);
+#ifdef __GNUC__
+	/* This outrageous construct just to shut up a GCC warning. */
+	(void) &cur; (void) &twoway; (void) &type;
+#endif
+
+	if (strchr(type, '+')) {
+		twoway = 1;
+		type = "r+";
+		if (socketpair(AF_UNIX, SOCK_STREAM, 0, pdes) < 0)
+			return (NULL);
+	} else  {
+		twoway = 0;
+		if ((*type != 'r' && *type != 'w') || type[1] ||
+		    (pipe(pdes) < 0)) {
+			errno = EINVAL;
+			return (NULL);
+		}
 	}
 
 	if ((cur = malloc(sizeof(struct pid))) == NULL)
 		return (NULL);
 
-	if (pipe(pdes) < 0) {
-		free(cur);
-		return (NULL);
-	}
-
 	switch (pid = vfork()) {
 	case -1:			/* Error. */
 		(void)close(pdes[0]);
@@ -95,8 +111,11 @@ popen(program, type)
 			if (pdes[1] != STDOUT_FILENO) {
 				(void)dup2(pdes[1], STDOUT_FILENO);
 				(void)close(pdes[1]);
+				pdes[1] = STDOUT_FILENO;
 			}
 			(void) close(pdes[0]);
+			if (twoway && (pdes[1] != STDIN_FILENO))
+				(void)dup2(pdes[1], STDIN_FILENO);
 		} else {
 			if (pdes[0] != STDIN_FILENO) {
 				(void)dup2(pdes[0], STDIN_FILENO);
@@ -104,7 +123,14 @@ popen(program, type)
 			}
 			(void)close(pdes[1]);
 		}
-		execl(_PATH_BSHELL, "sh", "-c", program, NULL);
+
+		/* POSIX.2 B.3.2.2 "popen() shall ensure that any streams
+		   from previous popen() calls that remain open in the 
+		   parent process are closed in the new child process. */
+		for (old = pidlist; old; old = old->next)
+			close(fileno(old->fp));
+		
+		execl(_PATH_BSHELL, "sh", "-c", command, NULL);
 		_exit(127);
 		/* NOTREACHED */
 	}
@@ -140,8 +166,6 @@ pclose(iop)
 	int pstat;
 	pid_t pid;
 
-	(void)fclose(iop);
-
 	/* Find the appropriate file pointer. */
 	for (last = NULL, cur = pidlist; cur; last = cur, cur = cur->next)
 		if (cur->fp == iop)
@@ -149,6 +173,8 @@ pclose(iop)
 	if (cur == NULL)
 		return (-1);
 
+	(void)fclose(iop);
+
 	do {
 		pid = waitpid(cur->pid, &pstat, 0);
 	} while (pid == -1 && errno == EINTR);