From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org
X-Spam-Level: 
X-Spam-Status: No, score=0.2 required=5.0 tests=DKIM_INVALID,DKIM_SIGNED
	autolearn=no autolearn_force=no version=3.4.4
Received: (qmail 5066 invoked from network); 31 Dec 2021 01:27:53 -0000
Received: from 4ess.inri.net (216.126.196.42)
  by inbox.vuxu.org with ESMTPUTF8; 31 Dec 2021 01:27:53 -0000
Received: from wopr.sciops.net ([216.126.196.60]) by 4ess; Thu Dec 30 20:20:44 -0500 2021
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sciops.net; s=20210706;
	t=1640913639;
	h=from:from:reply-to:subject:subject:date:date:message-id:message-id:
	 to:to:cc:mime-version:mime-version:content-type:content-type:
	 content-transfer-encoding:content-transfer-encoding:  in-reply-to:in-reply-to;
	bh=5y+kiDr5IG0XoTsTUgLDPTm4em7YcZqM8y0M2AaHe8M=;
	b=JHijMkOw7ADxeYaioPWz+uVdN3O1hJ32mS+y/ncidDoFHkTGN4pHEod2JGkdvlhRaPgU+Y
	fFxQNVK8h8LzX3BSVa89DKtqJMtJnrJe4fDHyBpP2HmfIhx/7Xi1TCyB4PGyw4PCzknmMt
	91/5ABFXce5XmA2JuzWQZ0Exa+sGSkk=
Received: 
	by wopr.sciops.net (OpenSMTPD) with ESMTPSA id a8002841 (TLSv1.2:ECDHE-RSA-CHACHA20-POLY1305:256:NO)
	for <9front@9front.org>;
	Thu, 30 Dec 2021 17:20:38 -0800 (PST)
Message-ID: <5628D0A34F0089B1D3753D6886A1ECFF@wopr.sciops.net>
Date: Fri, 31 Dec 2021 03:22:28 +0200
From: qwx@sciops.net
To: 9front@9front.org
In-Reply-To: <B898A3370CCC5475FB2E3F4057570468@prosimetrum.com>
MIME-Version: 1.0
Content-Type: text/plain; charset="US-ASCII"
Content-Transfer-Encoding: 7bit
List-ID: <9front.9front.org>
List-Help: <http://lists.9front.org>
X-Glyph: ➈
X-Bullshit: progressive pipelining CMS pipelining framework 
Subject: Re: [9front] delete in page(1)
Reply-To: 9front@9front.org
Precedence: bulk

diff 855cf4326f5a07d7142c2d8918f5fa856d912b85 uncommitted
--- a//sys/src/cmd/page.c
+++ b//sys/src/cmd/page.c
@@ -74,6 +74,7 @@
 	Czerox,
 	Cwrite,
 	Cext,
+	Cdel,
 	Cdummy2,
 	Cquit,
 };
@@ -98,6 +99,7 @@
 	[Czerox]	"zerox",	'z', 0, 0,
 	[Cwrite]	"write",	'w', 0, 0,
 	[Cext]		"ext",		'x', 0, 0,
+	[Cdel]		"del",		'd', 0, 0,
 	[Cdummy2]	"",		0, 0, 0,
 	[Cquit]		"quit",		'q', Kdel, Keof,
 };
@@ -134,6 +136,7 @@
 void showpage(Page *);
 void drawpage(Page *);
 Point pagesize(Page *);
+void drawlock(int);
 
 Page*
 addpage(Page *up, char *name, int (*popen)(Page *), void *pdata, int fd)
@@ -986,6 +989,54 @@
 	}
 }
 
+/* page entries are never freed, there's no point
+ * and would break everything */
+Page*
+delpage(Page *p)
+{
+	Page *t, *q;
+
+	if(p == nil)
+		return nil;
+	/* to remove(2) subpages in documents makes no sense, and just
+	 * removing a subentry doesn't seem like a feature worth the bother */
+	if(p->up != root)
+		return p;
+	if(p->fd >= 0)
+		close(p->fd);
+	p->fd = -1;
+	if(remove(p->name) < 0){
+		fprint(2, "remove %s: %r", p->name);
+		return p;
+	}
+	qlock(&pagelock);
+	for(t = p->down; t != nil && t->up != root; t = q){
+		qlock(t);
+		drawlock(0);
+		unloadpage(t);
+		drawlock(1);
+		free(t->name);
+		free(t->data);
+		t->name = t->data = nil;
+		q = nextpage(t);
+		qunlock(t);
+	}
+	drawlock(0);
+	unloadpage(p);
+	drawlock(1);
+	free(p->name);
+	free(p->data);
+	p->name = p->data = nil;
+	if(root->down != p){
+		t = prevpage(p);
+		t->next = p->next;
+	}else
+		root->down = p->next;
+	qunlock(&pagelock);
+	qunlock(p);
+	return p->next != nil ? p->next : t;
+}
+
 /*
  * A draw operation that touches only the area contained in bot but not in top.
  * mp and sp get aligned with bot.min.
@@ -1461,6 +1512,7 @@
 	char buf[NPATH], *s;
 	Point o;
 	int fd;
+	Page *p;
 
 	switch(i){
 	case Corigsize:
@@ -1545,6 +1597,19 @@
 		break;
 	case Csnarf:
 		writeaddr(current, "/dev/snarf");
+		break;
+	case Cdel:
+		if(current == nil || !canqlock(current))
+			break;
+		if((p = delpage(current)) == current){
+			qunlock(current);
+			break;
+		}
+		current = p;
+		if(current == nil)
+			break;
+		forward = 1;
+		showpage(current);
 		break;
 	case Cnext:
 		forward = 1;