From d2df5d6cbd345e101732fe7d22bb5b3baa5fb61a Mon Sep 17 00:00:00 2001
From: Russ Cox <rsc@swtch.com>
Date: Mon, 13 Jan 2020 18:15:57 -0500
Subject: acme: fix crash in X |cat with multiple windows

Fixes #9.
Fixes #219.
Fixes #222.
Fixes #330.
---
 src/cmd/acme/ecmd.c | 29 ++++++++++++++++++++++++-----
 1 file changed, 24 insertions(+), 5 deletions(-)

diff --git a/src/cmd/acme/ecmd.c b/src/cmd/acme/ecmd.c
index 75cf710f..f7613172 100644
--- a/src/cmd/acme/ecmd.c
+++ b/src/cmd/acme/ecmd.c
@@ -28,7 +28,7 @@ int	append(File*, Cmd*, long);
 int	pdisplay(File*);
 void	pfilename(File*);
 void	looper(File*, Cmd*, int);
-void	filelooper(Cmd*, int);
+void	filelooper(Text*, Cmd*, int);
 void	linelooper(File*, Cmd*);
 Address	lineaddr(long, Address, int);
 int	filematch(File*, String*);
@@ -584,7 +584,7 @@ X_cmd(Text *t, Cmd *cp)
 {
 	USED(t);
 
-	filelooper(cp, cp->cmdc=='X');
+	filelooper(t, cp, cp->cmdc=='X');
 	return TRUE;
 }
 
@@ -978,9 +978,10 @@ alllocker(Window *w, void *v)
 }
 
 void
-filelooper(Cmd *cp, int XY)
+filelooper(Text *t, Cmd *cp, int XY)
 {
 	int i;
+	Text *targ;
 
 	if(Glooping++)
 		editerror("can't nest %c command", "YX"[XY]);
@@ -1001,8 +1002,26 @@ filelooper(Cmd *cp, int XY)
 	 */
 	allwindows(alllocker, (void*)1);
 	globalincref = 1;
-	for(i=0; i<loopstruct.nw; i++)
-		cmdexec(&loopstruct.w[i]->body, cp->u.cmd);
+	
+	/*
+	 * Unlock the window running the X command.
+	 * We'll need to lock and unlock each target window in turn.
+	 */
+	if(t && t->w)
+		winunlock(t->w);
+	
+	for(i=0; i<loopstruct.nw; i++) {
+		targ = &loopstruct.w[i]->body;
+		if(targ && targ->w)
+			winlock(targ->w, cp->cmdc);
+		cmdexec(targ, cp->u.cmd);
+		if(targ && targ->w)
+			winunlock(targ->w);
+	}
+
+	if(t && t->w)
+		winlock(t->w, cp->cmdc);
+
 	allwindows(alllocker, (void*)0);
 	globalincref = 0;
 	free(loopstruct.w);
-- 
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