Add ability to stop print dialog canceler

Author: piroor

PrintCancelerTalk/cb_query.c

@@ -1,6 +1,7 @@
 #include <Windows.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <tlhelp32.h>
 #include "internal.h"
 
 static int get_PrintCancelerExtensionExecfile(char *buf, DWORD size)
@@ -52,7 +53,7 @@ static int start_monitoring(char *browser, char *path)
 	return 0;
 }
 
-int cb_query(char *cmd)
+int cb_query_start(char *cmd)
 {
 	char path[MAX_PATH];
 	char *browser;
@@ -63,7 +64,7 @@ int cb_query(char *cmd)
 	}
 
 	/*
-	 *  Q edge
+	 *  B edge
 	 *    ----
 	 */
 	browser = cmd + 2;
@@ -77,3 +78,85 @@ int cb_query(char *cmd)
 	talk_response("{\"status\":\"OK\"}");
 	return 0;
 }
+
+static int stop_monitoring(char *browser, char *path)
+{
+	HANDLE hSnap;
+	PROCESSENTRY32 pe32;
+
+	hSnap = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
+	if (hSnap == INVALID_HANDLE_VALUE) {
+		fprintf(stderr, "CreateToolhelp32Snapshot failed (%lu)\n", GetLastError());
+		return -1;
+	}
+
+	pe32.dwSize = sizeof(PROCESSENTRY32);
+
+	if (!Process32First(hSnap, &pe32)) {
+		fprintf(stderr, "Process32First failed (%lu)\n", GetLastError());
+		CloseHandle(hSnap);
+		return -1;
+	}
+
+	int stopped = 0;
+
+	do {
+		HANDLE hProc = OpenProcess(PROCESS_QUERY_LIMITED_INFORMATION | PROCESS_TERMINATE,
+		                           FALSE,
+		                           pe32.th32ProcessID);
+		if (!hProc) {
+			continue;
+		}
+
+		char procPath[MAX_PATH];
+		DWORD size = sizeof(procPath);
+
+		if (QueryFullProcessImageNameA(hProc, 0, procPath, &size)) {
+			if (_stricmp(procPath, path) == 0) {
+				if (TerminateProcess(hProc, 0)) {
+					stopped = 1;
+				} else {
+					fprintf(stderr, "TerminateProcess failed (%lu)\n", GetLastError());
+				}
+			}
+		}
+
+		CloseHandle(hProc);
+
+	} while (Process32Next(hSnap, &pe32));
+
+	CloseHandle(hSnap);
+
+	if (!stopped) {
+		fprintf(stderr, "No matching process for '%s'\n", path);
+		return -1;
+	}
+
+	return 0;
+}
+
+int cb_query_stop(char *cmd)
+{
+	char path[MAX_PATH];
+	char *browser;
+
+	if (strlen(cmd) < 3) {
+		fprintf(stderr, "command too short '%s'", cmd);
+		return -1;
+	}
+
+	/*
+	 *  E edge
+	 *    ----
+	 */
+	browser = cmd + 2;
+
+	if (get_PrintCancelerExtensionExecfile(path, MAX_PATH) < 0)
+		return -1;
+
+	if (stop_monitoring(browser, path) < 0)
+		return -1;
+
+	talk_response("{\"status\":\"OK\"}");
+	return 0;
+}

PrintCancelerTalk/main.c

@@ -143,15 +143,20 @@ int main(int argc, char *argv[])
 	 *
 	 *  "C edge"
 	 *    ... Read and return PrintCanceler.ini.
-	 *  "Q edge
-	 *    ... Open PrintCanceler for edge.
+	 *  "B edge
+	 *    ... Start (begin) PrintCanceler for edge.
+	 *  "E edge
+	 *    ... Stop (end) PrintCanceler for edge.
 	 */
 	switch (cmd[0]) {
 	case 'C':
 	    ret = cb_config(cmd);
 	    break;
-	case 'Q':
-	    ret = cb_query(cmd);
+	case 'B':
+	    ret = cb_query_start(cmd);
+	    break;
+	case 'E':
+	    ret = cb_query_stop(cmd);
 	    break;
 	default:
 	    fprintf(stderr, "unknown command '%s'", cmd);

webextensions/edge/background.js

@@ -23,9 +23,16 @@ chrome.scripting.registerContentScripts([{
 
 chrome.runtime.onMessage.addListener((message, _sender, _sendResponse) => {
   console.log('accept message.');
-  if (message === 'cancel') {
-    const query = new String('Q ' + BROWSER);
-    chrome.runtime.sendNativeMessage(SERVER_NAME, query);
+  switch (message?.type) {
+    case 'deny': {
+      const query = new String('B ' + BROWSER);
+      chrome.runtime.sendNativeMessage(SERVER_NAME, query);
+    }; break;
+
+    case 'allow': {
+      const query = new String('E ' + BROWSER);
+      chrome.runtime.sendNativeMessage(SERVER_NAME, query);
+    }; break;
   }
   return true;
 });

webextensions/edge/content-isolated.js

@@ -4,7 +4,11 @@ window.addEventListener('beforeprint', _event => {
   const isPrintEnabled = window.isPrintEnabled;
   window.isPrintEnabled = false;
   if (!isPrintEnabled) {
-    chrome.runtime.sendMessage({ type: 'cancel' }, _response => {
+    chrome.runtime.sendMessage({ type: 'deny' }, _response => {
+    });
+  }
+  else {
+    chrome.runtime.sendMessage({ type: 'allow' }, _response => {
     });
   }
 });