Adding a run_on_exit kernel debugger add-on. It installs a debugger command

"on_exit" with which you can add commands to run when exiting the debugger.
With this you could for example "on_exit sync" and "on_exit shutdown -r" when
your app_server crashed.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@30016 a95241bf-73f2-0310-859d-f6bbb57e9c96

build/jam/HaikuImage

@@ -158,7 +158,7 @@ AddFilesToHaikuImage system add-ons kernel busses usb
 AddFilesToHaikuImage system add-ons kernel console : vga_text ;
 AddFilesToHaikuImage system add-ons kernel debugger
 	: $(X86_ONLY)<kdebug>disasm <kdebug>hangman <kdebug>invalidate_on_exit
-	<kdebug>usb_keyboard ;
+	<kdebug>usb_keyboard <kdebug>run_on_exit ;
 AddFilesToHaikuImage system add-ons kernel file_systems
 	: $(SYSTEM_ADD_ONS_FILE_SYSTEMS) ;
 AddFilesToHaikuImage system add-ons kernel generic

src/add-ons/kernel/debugger/Jamfile

@@ -7,4 +7,5 @@ SubInclude HAIKU_TOP src add-ons kernel debugger disasm ;
 SubInclude HAIKU_TOP src add-ons kernel debugger hangman ;
 SubInclude HAIKU_TOP src add-ons kernel debugger invalidate_on_exit ;
 SubInclude HAIKU_TOP src add-ons kernel debugger laplinkll ;
+SubInclude HAIKU_TOP src add-ons kernel debugger run_on_exit ;
 SubInclude HAIKU_TOP src add-ons kernel debugger usb_keyboard ;

src/add-ons/kernel/debugger/run_on_exit/Jamfile

@@ -0,0 +1,7 @@
+SubDir HAIKU_TOP src add-ons kernel debugger run_on_exit ;
+
+UsePrivateHeaders kernel ;
+
+KernelAddon <kdebug>run_on_exit :
+	run_on_exit.cpp
+	;

src/add-ons/kernel/debugger/run_on_exit/run_on_exit.cpp

@@ -0,0 +1,142 @@
+/*
+ * Copyright 2009, Michael Lotz, mmlr@mlotz.ch
+ * Distributed under the terms of the MIT License.
+ */
+#include <debug.h>
+#include <signal.h>
+#include <string.h>
+#include <image.h>
+
+
+static sem_id sRequestSem = -1;
+static char sCommandBuffer[1024];
+static uint32 sCommandOffset = 0;
+static uint32 sCommandCount = 0;
+
+
+static int32
+run_on_exit_loop(void *data)
+{
+	while (true) {
+		if (acquire_sem(sRequestSem) != B_OK)
+			break;
+
+		char *pointer = sCommandBuffer;
+		while (sCommandCount > 0) {
+			uint8 argCount = (uint8)pointer[0];
+			pointer++;
+
+			const char *args[argCount];
+			for (uint8 i = 0; i < argCount; i++) {
+				args[i] = pointer;
+				uint32 length = strlen(pointer);
+				pointer += length + 1;
+			}
+
+			thread_id thread = load_image(argCount, args, NULL);
+			if (thread >= B_OK)
+				resume_thread(thread);
+			sCommandCount--;
+		}
+
+		sCommandOffset = 0;
+	}
+
+	return 0;
+}
+
+
+static int
+add_run_on_exit_command(int argc, char **argv)
+{
+	if (argc < 2 || strcmp(argv[1], "--help") == 0) {
+		print_debugger_command_usage(argv[0]);
+		return 0;
+	}
+
+	if (argc > 256) {
+		kprintf("too many arguments\n");
+		return 0;
+	}
+
+	size_t totalLength = 1;
+	for (int32 i = 1; i < argc; i++)
+		totalLength += strlen(argv[i]) + 1;
+
+	if (sCommandOffset + totalLength > sizeof(sCommandBuffer)) {
+		kprintf("no space left in command buffer\n");
+		return 0;
+	}
+
+	char *pointer = sCommandBuffer + sCommandOffset;
+	*pointer++ = (char)(argc - 1);
+
+	for (int32 i = 1; i < argc; i++) {
+		strcpy(pointer, argv[i]);
+		pointer += strlen(argv[i]) + 1;
+	}
+
+	sCommandOffset += totalLength;
+	sCommandCount++;
+	return 0;
+}
+
+
+static void
+exit_debugger()
+{
+	if (sCommandCount > 0)
+		release_sem_etc(sRequestSem, 1, B_DO_NOT_RESCHEDULE);
+}
+
+
+static status_t
+std_ops(int32 op, ...)
+{
+	if (op == B_MODULE_INIT) {
+		sRequestSem = create_sem(0, "run_on_exit_request");
+		if (sRequestSem < B_OK)
+			return sRequestSem;
+
+		thread_id thread = spawn_kernel_thread(&run_on_exit_loop,
+			"run_on_exit_loop", B_NORMAL_PRIORITY, NULL);
+		if (thread < B_OK)
+			return thread;
+
+		send_signal_etc(thread, SIGCONT, B_DO_NOT_RESCHEDULE);
+
+		add_debugger_command_etc("on_exit", &add_run_on_exit_command,
+			"Adds a command to be run when leaving the kernel debugger",
+			"<command> [<arguments>]\n"
+			"Adds a command to be run when leaving the kernel debugger.\n", 0);
+
+		return B_OK;
+	} else if (op == B_MODULE_UNINIT) {
+		remove_debugger_command("on_exit", &add_run_on_exit_command);
+		// deleting the sem will also cause the thread to exit
+		delete_sem(sRequestSem);
+		sRequestSem = -1;
+		return B_OK;
+	}
+
+	return B_BAD_VALUE;
+}
+
+
+static struct debugger_module_info sModuleInfo = {
+	{
+		"debugger/run_on_exit/v1",
+		B_KEEP_LOADED,
+		&std_ops
+	},
+
+	NULL,
+	exit_debugger,
+	NULL,
+	NULL
+};
+
+module_info *modules[] = { 
+	(module_info *)&sModuleInfo,
+	NULL
+};