Add dwm patches

Add the preserveonrestart patch from
https://dwm.suckless.org/patches/preserveonrestart and a custom patch
based on https://dwm.suckless.org/patches/restartsig which failed to
apply cleanly.

nix/modules/nixos/desktop/dwm.nix

@@ -2,6 +2,7 @@
   config,
   lib,
   pkgs,
+  self,
   ...
 }:
 
@@ -113,6 +114,7 @@ with lib;
                 TAGKEYS(XK_8, 7)
                 TAGKEYS(XK_9, 8)
                 { MODKEY|ShiftMask, XK_q, quit, {0} },
+                { MODKEY|ControlMask|ShiftMask, XK_q, quit, {1} },
                 { MODKEY|ShiftMask, XK_b, spawn, SHCMD("${lib.getExe pkgs.brave}") },
                 { MODKEY|ShiftMask, XK_f, spawn, SHCMD("${pkgs.xfce.thunar}/bin/thunar") },
                 { MODKEY|ShiftMask, XK_i, spawn, SHCMD("${pkgs.xdotool}/bin/xdotool type $(cat ~/snippets.txt | grep -v '^#' | grep -v '^$' | sort | dmenu -i -l 50 | cut -d' ' -f1)") },
@@ -137,6 +139,13 @@ with lib;
             '';
 
             patches = with pkgs; [
+              "${self}/patches/dwm/restartsig.patch"
+
+              (fetchpatch {
+                url = "https://dwm.suckless.org/patches/preserveonrestart/dwm-preserveonrestart-6.3.diff";
+                sha256 = "zgwTCgD3YE+2K4BF6Em+qkM1Gax5vOZfeuWa6zXx8cE=";
+              })
+
               (fetchpatch {
                 url = "https://dwm.suckless.org/patches/hide_vacant_tags/dwm-hide_vacant_tags-6.4.diff";
                 sha256 = "GIbRW0Inwbp99rsKLfIDGvPwZ3pqihROMBp5vFlHx5Q=";

patches/dwm/restartsig.patch

@@ -0,0 +1,108 @@
+diff --git a/config.def.h b/config.def.h
+index 9efa774..3e9f854 100644
+--- a/config.def.h
++++ b/config.def.h
+@@ -95,6 +95,7 @@ static const Key keys[] = {
+ 	TAGKEYS(                        XK_8,                      7)
+ 	TAGKEYS(                        XK_9,                      8)
+ 	{ MODKEY|ShiftMask,             XK_q,      quit,           {0} },
++	{ MODKEY|ControlMask|ShiftMask, XK_q,      quit,           {1} },
+ };
+ 
+ /* button definitions */
+diff --git a/dwm.1 b/dwm.1
+index ddc8321..7b6cadb 100644
+--- a/dwm.1
++++ b/dwm.1
+@@ -142,6 +142,9 @@ Add/remove all windows with nth tag to/from the view.
+ .TP
+ .B Mod1\-Shift\-q
+ Quit dwm.
++.TP
++.B Mod1\-Control\-Shift\-q
++Restart dwm.
+ .SS Mouse commands
+ .TP
+ .B Mod1\-Button1
+@@ -155,6 +158,13 @@ Resize focused window while dragging. Tiled windows will be toggled to the float
+ .SH CUSTOMIZATION
+ dwm is customized by creating a custom config.h and (re)compiling the source
+ code. This keeps it fast, secure and simple.
++.SH SIGNALS
++.TP
++.B SIGHUP - 1
++Restart the dwm process.
++.TP
++.B SIGTERM - 15
++Cleanly terminate the dwm process.
+ .SH SEE ALSO
+ .BR dmenu (1),
+ .BR st (1)
+diff --git a/dwm.c b/dwm.c
+index 1443802..d183e80 100644
+--- a/dwm.c
++++ b/dwm.c
+@@ -204,6 +204,8 @@ static void setmfact(const Arg *arg);
+ static void setup(void);
+ static void seturgent(Client *c, int urg);
+ static void showhide(Client *c);
++static void sighup(int unused);
++static void sigterm(int unused);
+ static void spawn(const Arg *arg);
+ static void tag(const Arg *arg);
+ static void tagmon(const Arg *arg);
+@@ -259,6 +261,7 @@ static void (*handler[LASTEvent]) (XEvent *) = {
+ 	[UnmapNotify] = unmapnotify
+ };
+ static Atom wmatom[WMLast], netatom[NetLast];
++static int restart = 0;
+ static int running = 1;
+ static Cur *cursor[CurLast];
+ static Clr **scheme;
+@@ -1257,6 +1260,7 @@ propertynotify(XEvent *e)
+ void
+ quit(const Arg *arg)
+ {
++	if(arg->i) restart = 1;
+ 	running = 0;
+ }
+ 
+@@ -1552,6 +1556,9 @@ setup(void)
+ 	/* clean up any zombies (inherited from .xinitrc etc) immediately */
+ 	while (waitpid(-1, NULL, WNOHANG) > 0);
+ 
++	signal(SIGHUP, sighup);
++	signal(SIGTERM, sigterm);
++
+ 	/* init screen */
+ 	screen = DefaultScreen(dpy);
+ 	sw = DisplayWidth(dpy, screen);
+@@ -1643,6 +1650,20 @@ showhide(Client *c)
+ 	}
+ }
+ 
++void
++sighup(int unused)
++{
++	Arg a = {.i = 1};
++	quit(&a);
++}
++
++void
++sigterm(int unused)
++{
++	Arg a = {.i = 0};
++	quit(&a);
++}
++
+ void
+ spawn(const Arg *arg)
+ {
+@@ -2158,6 +2179,7 @@ main(int argc, char *argv[])
+ #endif /* __OpenBSD__ */
+ 	scan();
+ 	run();
++	if(restart) execvp(argv[0], argv);
+ 	cleanup();
+ 	XCloseDisplay(dpy);
+ 	return EXIT_SUCCESS;