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 1.4
retrieving revision 1.21
diff -u -p -r1.4 -r1.21
--- src/lib/libc/gen/popen.c	1993/08/23 21:56:31	1.4
+++ src/lib/libc/gen/popen.c	1998/03/19 18:21:25	1.21
@@ -1,6 +1,8 @@
+/*	$NetBSD: popen.c,v 1.21 1998/03/19 18:21:25 tv Exp $	*/
+
 /*
- * Copyright (c) 1988 The Regents of the University of California.
- * All rights reserved.
+ * Copyright (c) 1988, 1993
+ *	The Regents of the University of California.  All rights reserved.
  *
  * This code is derived from software written by Ken Arnold and
  * published in UNIX Review, Vol. 6, No. 8.
@@ -34,100 +36,157 @@
  * SUCH DAMAGE.
  */
 
+#include <sys/cdefs.h>
 #if defined(LIBC_SCCS) && !defined(lint)
-/*static char sccsid[] = "from: @(#)popen.c	5.15 (Berkeley) 2/23/91";*/
-static char rcsid[] = "$Id: popen.c,v 1.4 1993/08/23 21:56:31 jtc Exp $";
+#if 0
+static char sccsid[] = "@(#)popen.c	8.3 (Berkeley) 5/3/95";
+#else
+__RCSID("$NetBSD: popen.c,v 1.21 1998/03/19 18:21:25 tv 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>
+#include <unistd.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <unistd.h>
 #include <paths.h>
 
-static pid_t *pids;
-
+#ifdef __weak_alias
+__weak_alias(popen,_popen);
+__weak_alias(pclose,_pclose);
+#endif
+
+static struct pid {
+	struct pid *next;
+	FILE *fp;
+	pid_t pid;
+} *pidlist; 
+	
 FILE *
 popen(command, type)
-	const char *command;
-	const char *type;
+	const char *command, *type;
 {
+	struct pid *cur, *old;
 	FILE *iop;
-	int pdes[2], fds, pid;
+	int pdes[2], pid, twoway;
 
-	if (*type != 'r' && *type != 'w' || type[1]) {
-		errno = EINVAL;
-		return (NULL);
-	}
-
-	if (pids == NULL) {
-		if ((fds = getdtablesize()) <= 0)
+#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);
-		if ((pids = (pid_t *)malloc((u_int)(fds * sizeof(int)))) == NULL)
+	} else  {
+		twoway = 0;
+		if ((*type != 'r' && *type != 'w') || type[1] ||
+		    (pipe(pdes) < 0)) {
+			errno = EINVAL;
 			return (NULL);
-		bzero((char *)pids, fds * sizeof(pid_t));
+		}
 	}
-	if (pipe(pdes) < 0)
+
+	if ((cur = malloc(sizeof(struct pid))) == NULL) {
+		(void)close(pdes[0]);
+		(void)close(pdes[1]);
 		return (NULL);
+	}
+
 	switch (pid = vfork()) {
-	case -1:			/* error */
-		(void) close(pdes[0]);
-		(void) close(pdes[1]);
+	case -1:			/* Error. */
+		free(cur);
+		(void)close(pdes[0]);
+		(void)close(pdes[1]);
 		return (NULL);
 		/* NOTREACHED */
-	case 0:				/* child */
+	case 0:				/* Child. */
+		/* 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)); /* don't allow a flush */
+
 		if (*type == 'r') {
+			(void)close(pdes[0]);
 			if (pdes[1] != STDOUT_FILENO) {
-				(void) dup2(pdes[1], STDOUT_FILENO);
-				(void) close(pdes[1]);
+				(void)dup2(pdes[1], STDOUT_FILENO);
+				(void)close(pdes[1]);
 			}
-			(void) close(pdes[0]);
+			if (twoway)
+				(void)dup2(STDOUT_FILENO, STDIN_FILENO);
 		} else {
+			(void)close(pdes[1]);
 			if (pdes[0] != STDIN_FILENO) {
-				(void) dup2(pdes[0], STDIN_FILENO);
-				(void) close(pdes[0]);
+				(void)dup2(pdes[0], STDIN_FILENO);
+				(void)close(pdes[0]);
 			}
-			(void) close(pdes[1]);
 		}
-		execl(_PATH_BSHELL, "sh", "-c", command, (char *) 0);
+
+		execl(_PATH_BSHELL, "sh", "-c", command, NULL);
 		_exit(127);
 		/* NOTREACHED */
 	}
-	/* parent; assume fdopen can't fail...  */
+
+	/* Parent; assume fdopen can't fail. */
 	if (*type == 'r') {
 		iop = fdopen(pdes[0], type);
-		(void) close(pdes[1]);
+		(void)close(pdes[1]);
 	} else {
 		iop = fdopen(pdes[1], type);
-		(void) close(pdes[0]);
+		(void)close(pdes[0]);
 	}
-	pids[fileno(iop)] = pid;
+
+	/* Link into list of file descriptors. */
+	cur->fp = iop;
+	cur->pid =  pid;
+	cur->next = pidlist;
+	pidlist = cur;
+
 	return (iop);
 }
 
+/*
+ * pclose --
+ *	Pclose returns -1 if stream is not associated with a `popened' command,
+ *	if already `pclosed', or waitpid returns an error.
+ */
 int
 pclose(iop)
 	FILE *iop;
 {
-	register int fdes;
-	int omask;
+	struct pid *cur, *last;
 	int pstat;
 	pid_t pid;
 
-	/*
-	 * pclose returns -1 if stream is not associated with a
-	 * `popened' command, if already `pclosed', or waitpid
-	 * returns an error.
-	 */
-	if (pids == NULL || pids[fdes = fileno(iop)] == 0)
+	/* Find the appropriate file pointer. */
+	for (last = NULL, cur = pidlist; cur; last = cur, cur = cur->next)
+		if (cur->fp == iop)
+			break;
+	if (cur == NULL)
 		return (-1);
-	(void) fclose(iop);
+
+	(void)fclose(iop);
+
 	do {
-		pid = waitpid(pids[fdes], &pstat, 0);
+		pid = waitpid(cur->pid, &pstat, 0);
 	} while (pid == -1 && errno == EINTR);
-	pids[fdes] = 0;
+
+	/* Remove the entry from the linked list. */
+	if (last == NULL)
+		pidlist = cur->next;
+	else
+		last->next = cur->next;
+	free(cur);
+		
 	return (pid == -1 ? -1 : pstat);
 }