From 9cbc6bfeb9853a5d535b5a629a83101103332063 Mon Sep 17 00:00:00 2001
From: Alexander Rosenberg <zanderpkg@pm.me>
Date: Thu, 4 May 2023 00:50:10 -0700
Subject: [PATCH] Save client tags and monitors only on restart

---
 dwm.c | 49 ++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 42 insertions(+), 7 deletions(-)

diff --git a/dwm.c b/dwm.c
index a54bdc0..1566830 100644
--- a/dwm.c
+++ b/dwm.c
@@ -77,7 +77,7 @@ enum { SchemeNorm, SchemeSel, SchemeStatus, SchemeTagsSel, SchemeTagsNorm, Schem
 enum { NetSupported, NetWMName, NetWMState, NetWMCheck,
        NetSystemTray, NetSystemTrayOP, NetSystemTrayOrientation, NetSystemTrayOrientationHorz,
        NetWMFullscreen, NetActiveWindow, NetWMWindowType,
-       NetWMWindowTypeDialog, NetClientList, NetLast }; /* EWMH atoms */
+       NetWMWindowTypeDialog, NetClientList, NetClientInfo, NetLast }; /* EWMH atoms */
 enum { Manager, Xembed, XembedInfo, XLast }; /* Xembed atoms */
 enum { WMProtocols, WMDelete, WMState, WMTakeFocus, WMLast }; /* default atoms */
 enum { ClkTagBar, ClkLtSymbol, ClkStatusText, ClkWinTitle,
@@ -220,6 +220,7 @@ static void resizeclient(Client *c, int x, int y, int w, int h);
 static void resizemouse(const Arg *arg);
 static void resizerequest(XEvent *e);
 static void restack(Monitor *m);
+static void restart(const Arg *arg);
 static void run(void);
 static void scan(void);
 static int sendevent(Window w, Atom proto, int m, long d0, long d1, long d2, long d3, long d4);
@@ -268,7 +269,6 @@ static int xerror(Display *dpy, XErrorEvent *ee);
 static int xerrordummy(Display *dpy, XErrorEvent *ee);
 static int xerrorstart(Display *dpy, XErrorEvent *ee);
 static void zoom(const Arg *arg);
-static void restart(const Arg *arg);
 
 /* variables */
 static const char *exec_name;
@@ -1188,6 +1188,26 @@ manage(Window w, XWindowAttributes *wa)
 	updatewindowtype(c);
 	updatesizehints(c);
 	updatewmhints(c);
+	{
+		int format;
+		unsigned long *data, n, extra;
+		Monitor *m;
+		Atom atom;
+		if (XGetWindowProperty(dpy, c->win, netatom[NetClientInfo], 0L, 2L, False, XA_CARDINAL,
+				&atom, &format, &n, &extra, (unsigned char **)&data) == Success && n == 2) {
+			c->tags = *data;
+			for (m = mons; m; m = m->next) {
+				if (m->num == *(data+1)) {
+					c->mon = m;
+					break;
+				}
+			}
+			/* remove the property */
+			XDeleteProperty(dpy, c->win, netatom[NetClientInfo]);
+		}
+		if (n > 0)
+			XFree(data);
+	}
 	XSelectInput(dpy, w, EnterWindowMask|FocusChangeMask|PropertyChangeMask|StructureNotifyMask);
 	grabbuttons(c, 0);
 	if (!c->isfloating)
@@ -1562,6 +1582,25 @@ restack(Monitor *m)
 	while (XCheckMaskEvent(dpy, EnterWindowMask, &ev));
 }
 
+void
+restart(const Arg *arg)
+{
+	Monitor *m;
+	Client *c;
+
+	/* tag each client so we can restart with it on the correct tag*/
+	for (m = mons; m; m = m->next) {
+ 		for (c = m->clients; c; c = c->next) {
+			long data[] = { (long) c->tags, (long) c->mon->num };
+			XChangeProperty(dpy, c->win, netatom[NetClientInfo], XA_CARDINAL, 32,
+				PropModeReplace, (unsigned char *) data, 2);
+		}
+	}
+	XFlush(dpy);
+
+	execlp(exec_name, exec_name, NULL);
+}
+
 void
 run(void)
 {
@@ -1787,6 +1826,7 @@ setup(void)
 	netatom[NetWMWindowType] = XInternAtom(dpy, "_NET_WM_WINDOW_TYPE", False);
 	netatom[NetWMWindowTypeDialog] = XInternAtom(dpy, "_NET_WM_WINDOW_TYPE_DIALOG", False);
 	netatom[NetClientList] = XInternAtom(dpy, "_NET_CLIENT_LIST", False);
+	netatom[NetClientInfo] = XInternAtom(dpy, "_NET_CLIENT_INFO", False);
 	xatom[Manager] = XInternAtom(dpy, "MANAGER", False);
 	xatom[Xembed] = XInternAtom(dpy, "_XEMBED", False);
 	xatom[XembedInfo] = XInternAtom(dpy, "_XEMBED_INFO", False);
@@ -2553,11 +2593,6 @@ zoom(const Arg *arg)
 	pop(c);
 }
 
-void
-restart(const Arg *arg) {
-	execlp(exec_name, exec_name, NULL);
-}
-
 int
 main(int argc, char *argv[])
 {