Fix -e without specified exit code and fix help text

Otherwise, we call printf() etc. in the signal handler...

README.md

@@ -103,8 +103,16 @@ Install
 ## Debian / Ubuntu
 Latest release can be installed using apt
 ```
-curl -s https://repo.quitesimple.org/repo.quitesimple.org.asc | sudo apt-key add -
-echo "deb https://repo.quitesimple.org/debian/ default main" | sudo tee /etc/apt/sources.list.d/quitesimple.list
+# First, obtain key, assume it's trusted.
+wget -O- https://repo.quitesimple.org/repo.quitesimple.org.asc  | gpg --dearmor > repo.quitesimple.org-keyring.gpg
+cat repo.quitesimple.org-keyring.gpg | sudo tee -a /usr/share/keyrings/repo.quitesimple.org.gpg > /dev/null
+
+#For Debian
+echo "deb [arch=amd64 signed-by=/usr/share/keyrings/repo.quitesimple.org.gpg] https://repo.quitesimple.org/debian/ default main" | sudo tee /etc/apt/sources.list.d/quitesimple.list
+
+#For Ubuntu >=21.10, prefer these sources
+#echo "deb [arch=amd64 signed-by=/usr/share/keyrings/repo.quitesimple.org.gpg] https://repo.quitesimple.org/debian/ $(lsb_release -sc) main" | sudo tee /etc/apt/sources.list.d/quitesimple.list
+
 sudo apt-get update
 sudo apt-get install adhocify
 ```

adhocify.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014-2020 Albert S. <adhocify@quitesimple.org>
+ * Copyright (c) 2014-2024 Albert S. <adhocify@quitesimple.org>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -78,6 +78,8 @@ char *path_logfile = NULL;
 char **script_arguments = NULL; // options to be passed to script we are calling
 size_t n_script_arguments = 0;
 
+volatile sig_atomic_t handle_child_exits = 0;
+
 void *xmalloc(size_t size)
 {
 	void *m = malloc(size);
@@ -509,7 +511,7 @@ void print_usage()
 	printf("--no-forkbomb-check, -b Disable fork bomb detection\n");
 	printf("--ignore, -i            Shell wildcard pattern (see glob(7)) to ignore events on files for which the "
 		   "pattern matches\n");
-	printf("--exit-with-child, -e   Exit when the commands exits. You can also specify a return code (e. g. -e=1 to "
+	printf("--exit-with-child, -e   Exit when the commands exits. You can also specify a return code and negations (e. g. -e'!0' to "
 		   "exit only on errors)\n");
 	printf("\nIf your command should know the file the event occured on, use the {} placeholder when you specify the "
 		   "arguments (like xargs)\n");
@@ -673,10 +675,62 @@ void process_options()
 	}
 }
 
+
+void wait_for_children()
+{
+	while(1)
+	{
+		int status;
+		pid_t p = waitpid(-1, &status, WNOHANG);
+		if(p == 0 || (p == -1 && errno == ECHILD)) // No more children to reap
+		{
+			return;
+		}
+		if(p == -1)
+		{
+			logerror("waitpid failed when handling child exit\n");
+			exit(EXIT_FAILURE);
+		}
+		int adhocify_exit_code = 0;
+		if(WIFEXITED(status))
+		{
+			adhocify_exit_code = WEXITSTATUS(status);
+			if(adhocify_exit_code == 127)
+			{
+				logwrite("command not found, exiting\n");
+				exit(adhocify_exit_code);
+			}
+			if(exit_with_child)
+			{
+				bool must_exit = adhocify_exit_code == awaited_child_exit_code || awaited_child_exit_code == -1;
+				if(negate_child_exit_code)
+				{
+					must_exit = !must_exit;
+				}
+				if(must_exit)
+				{
+					logwrite("command exited with specified exit code, exiting too\n");
+					exit(adhocify_exit_code);
+				}
+			}
+		}
+		if(exit_with_child && WIFSIGNALED(status))
+		{
+			adhocify_exit_code = 128 + WTERMSIG(status); // copy bash's behaviour
+			exit(adhocify_exit_code);
+		}
+	}
+}
+
 void start_monitoring(int ifd)
 {
 	while(1)
 	{
+		if(handle_child_exits)
+		{
+			handle_child_exits = 1;
+			wait_for_children();
+		}
 		int len;
 		int offset = 0;
 		char buf[BUF_SIZE];
@@ -688,7 +742,6 @@ void start_monitoring(int ifd)
 			perror("read");
 			exit(EXIT_FAILURE);
 		}
-
 		while(offset < len)
 		{
 
@@ -699,49 +752,14 @@ void start_monitoring(int ifd)
 	}
 }
 
+
 void child_handler(int signum, siginfo_t *info, void *context)
 {
 	if(signum != SIGCHLD)
 	{
 		return;
 	}
-
-	int status;
-	pid_t p = waitpid(-1, &status, WNOHANG);
-	if(p == -1)
-	{
-		logerror("waitpid failed when handling child exit\n");
-		exit(EXIT_FAILURE);
-	}
-
-	int adhocify_exit_code = 0;
-	if(WIFEXITED(status))
-	{
-		adhocify_exit_code = WEXITSTATUS(status);
-		if(adhocify_exit_code == 127)
-		{
-			logwrite("command not found, exiting\n");
-			exit(adhocify_exit_code);
-		}
-		if(exit_with_child && awaited_child_exit_code > -1)
-		{
-			bool must_exit = adhocify_exit_code == awaited_child_exit_code;
-			if(negate_child_exit_code)
-			{
-				must_exit = !must_exit;
-			}
-			if(must_exit)
-			{
-				logwrite("command exited with specified exit code, exiting too\n");
-				exit(adhocify_exit_code);
-			}
-		}
-	}
-	if(exit_with_child && WIFSIGNALED(status))
-	{
-		adhocify_exit_code = 128 + WTERMSIG(status); // copy bash's behaviour
-		exit(adhocify_exit_code);
-	}
+	handle_child_exits = 1;
 }
 
 void set_signals()