Make Process do prctl(PR_SET_PDEATHSIG)

This means that nanosm managed process will also predictably die if nanosm is killed.

README.md

@@ -6,9 +6,9 @@ Written in C++20, using epoll (without helper libraries), to stay nice and smol
 
 # Why write this?
 
-Because `app &` then `exec wm` is impressively awful. What if your WM crashes, or your panel? Guess you lose them!
+Because `app &` then `exec wm` in `.xinitrc` is impressively awful. What if your WM crashes, or your panel? Guess you lose them!
 
-And if your WM crashes? Your whole xorg server goes with it, meaning so does everything else.
+And if your WM crashes? Your whole Xorg server goes with it, meaning so does everything else.
 
 A more robust solution that's still small and easy to setup (read: Not written in bash) is clearly a better idea.
 
@@ -28,4 +28,7 @@ $ ninja -C build
 # Configuration
 
 - Copy `/usr/share/doc/nanosm/nanosm.toml` to `~/.config/nanosm/` and edit it to your liking/setup.
+- Remove the applications you added to your `nanosm.toml` from your `.xinitrc`, since nanosm will handle them
 - Add `exec nanosm` to the end of your `.xinitrc`.
+- ...
+- Profit?

src/Process.cpp

@@ -3,6 +3,7 @@
 #include <linux/sched.h>
 #include <sched.h>
 #include <signal.h>
+#include <sys/prctl.h>
 #include <sys/types.h>
 
 #include "WordExp.hpp"
@@ -49,6 +50,12 @@ namespace nanosm {
 			for(usize i = 0; i < exp.words.size(); ++i)
 				argv[i] = exp.words[i].data();
 
+			// Ensure that if nanosm (the parent) dies, we die along with it
+			if(prctl(PR_SET_PDEATHSIG, SIGTERM) == -1) {
+				perror("Process pre-exec: prctl(PR_SET_PDEATHSIG)");
+				exit(1);
+			}
+
 			exit(execvp(exp.words[0].data(), argv.data()));
 		} else {
 			// Parent: monitor the pidfd by adding ourselves to the event loop now