Unset Mozilla environment variables when launching files and URLs (#4983)

Fixes #4981

chrome/content/zotero/xpcom/fileHandlers.js

@@ -149,6 +149,7 @@ Zotero.FileHandlers = {
 		handler = handler || systemHandler;
 		if (handler) {
 			if (Zotero.isMac) {
+				Zotero.Utilities.Internal.Environment.clearMozillaVariables();
 				try {
 					await Zotero.Utilities.Internal.exec('/usr/bin/open', ['-a', handler, path]);
 					return true;
@@ -156,6 +157,9 @@ Zotero.FileHandlers = {
 				catch (e) {
 					Zotero.logError(e);
 				}
+				finally {
+					Zotero.Utilities.Internal.Environment.restoreMozillaVariables();
+				}
 			}
 			
 			try {
@@ -498,8 +502,13 @@ Zotero.FileHandlers = {
 		if (!Zotero.File.pathToFile(command).isExecutable()) {
 			throw new Error(`${command} is not an executable`);
 		}
+		
+		Zotero.Utilities.Internal.Environment.clearMozillaVariables();
+		
 		// Do not await
-		Zotero.Utilities.Internal.exec(command, args);
+		var promise = Zotero.Utilities.Internal.exec(command, args);
+		
+		promise.finally(() => Zotero.Utilities.Internal.Environment.restoreMozillaVariables());
 	},
 };
 

chrome/content/zotero/xpcom/utilities_internal.js

@@ -2899,6 +2899,85 @@ Zotero.Utilities.Internal.getProcessID = function () {
 };
 
 
+Zotero.Utilities.Internal.Environment = {
+	/**
+	 * Unset an environment variable
+	 *
+	 * Since nsIEnvironment doesn't have an unset method
+	 */
+	unset: function (varName) {
+		Components.utils.import("resource://gre/modules/ctypes.jsm");
+		
+		let lib;
+		let result;
+		let success;
+		// Windows
+		// https://learn.microsoft.com/en-us/windows/win32/api/processenv/nf-processenv-setenvironmentvariablew
+		if (Zotero.isWin) {
+			lib = ctypes.open("kernel32.dll");
+			let SetEnvironmentVariable = lib.declare(
+				"SetEnvironmentVariableW",
+				ctypes.winapi_abi,
+				ctypes.int, // Return type
+				ctypes.char16_t.ptr, // Argument type: LPCTSTR (variable name)
+				ctypes.char16_t.ptr // Argument type: LPCTSTR (value, NULL to unset)
+			);
+			result = SetEnvironmentVariable(varName, null);
+			success = result != 0; // "If the function succeeds, the return value is nonzero."
+		}
+		// macOS or Linux
+		else {
+			lib = ctypes.open(Zotero.isMac ? "/usr/lib/libSystem.dylib" : "libc.so.6");
+			let unsetenv = lib.declare(
+				"unsetenv",
+				ctypes.default_abi,
+				ctypes.int, // Return type
+				ctypes.char.ptr // Argument type: const char *
+			);
+			result = unsetenv(varName);
+			success = result == 0;
+		}
+		
+		// Check the result
+		if (success) {
+			//Zotero.debug(`Unset environment variable ${varName}`);
+		}
+		else {
+			Zotero.logError(`Failed to unset environment variable ${varName} (${result})`);
+		}
+		
+		lib.close();
+	},
+	
+	/**
+	 * Clear the Mozilla environment variables that we changed in the launcher
+	 *
+	 * Call this before launching another process that might be Firefox so that we don't end up
+	 * using the wrong Firefox profile when launching URLs or PDFs. On Windows, it's not necessary
+	 * to call this when launching URLs, only processes.
+	 *
+	 * https://github.com/zotero/zotero/issues/4981
+	 */
+	clearMozillaVariables: function () {
+		this.unset("MOZ_ALLOW_DOWNGRADE");
+		this.unset("MOZ_LEGACY_PROFILES");
+	},
+	
+	/**
+	 * Re-set the Mozilla environment variables that we changed in the launcher
+	 *
+	 * Call this in a finally() after using unsetMozillaVariables(). This mostly isn't necessary,
+	 * since most new launches of Zotero would use the modified launcher, but a restart on Linux
+	 * skips our shell script where we set these variables.
+	 */
+	restoreMozillaVariables: function () {
+		var env = Cc["@mozilla.org/process/environment;1"].getService(Ci.nsIEnvironment);
+		env.set("MOZ_ALLOW_DOWNGRADE", "1");
+		env.set("MOZ_LEGACY_PROFILES", "1");
+	},
+};
+
+
 /**
  *  Base64 encode / decode
  *  From http://www.webtoolkit.info/

chrome/content/zotero/xpcom/zotero.js

@@ -992,6 +992,9 @@ Services.scriptloader.loadSubScript("resource://zotero/polyfill.js");
 	 */
 	this.launchFile = function (file) {
 		file = Zotero.File.pathToFile(file);
+		
+		Zotero.Utilities.Internal.Environment.clearMozillaVariables();
+		
 		try {
 			Zotero.debug("Launching " + file.path);
 			file.launch();
@@ -1034,6 +1037,9 @@ Services.scriptloader.loadSubScript("resource://zotero/polyfill.js");
 				);
 			}
 		}
+		finally {
+			Zotero.Utilities.Internal.Environment.restoreMozillaVariables();
+		}
 	};
 	
 	
@@ -1058,8 +1064,12 @@ Services.scriptloader.loadSubScript("resource://zotero/polyfill.js");
 			args = [filePath];
 		}
 		
+		Zotero.Utilities.Internal.Environment.clearMozillaVariables();
+		
 		// Async, but we don't want to block
-		Zotero.Utilities.Internal.exec(applicationPath, args);
+		var promise = Zotero.Utilities.Internal.exec(applicationPath, args);
+		
+		promise.finally(() => Zotero.Utilities.Internal.Environment.restoreMozillaVariables());
 	};
 	
 	
@@ -1089,12 +1099,29 @@ Services.scriptloader.loadSubScript("resource://zotero/polyfill.js");
 				if (!found.value) {
 					throw new Error(`Handler not found for '${scheme}' URLs`);
 				}
-				svc.loadURI(Services.io.newURI(url, null, null));
+				try {
+					if (!Zotero.isWin) {
+						Zotero.Utilities.Internal.Environment.clearMozillaVariables();
+					}
+					
+					svc.loadURI(Services.io.newURI(url, null, null));
+				}
+				finally {
+					if (!Zotero.isWin) {
+						Zotero.Utilities.Internal.Environment.restoreMozillaVariables();
+					}
+				}
 				return;
 			}
 		}
 		
+		var mozCleared = false;
 		try {
+			if (!Zotero.isWin) {
+				Zotero.Utilities.Internal.Environment.clearMozillaVariables();
+				mozCleared = true;
+			}
+			
 			var uri = Services.io.newURI(url, null, null);
 			var handler = Components.classes['@mozilla.org/uriloader/external-protocol-service;1']
 							.getService(Components.interfaces.nsIExternalProtocolService)
@@ -1119,6 +1146,11 @@ Services.scriptloader.loadSubScript("resource://zotero/polyfill.js");
 					+ "check extensions.zotero." + pref + " in about:config");
 			}
 			
+			if (!mozCleared) {
+				Zotero.Utilities.Internal.Environment.clearMozillaVariables();
+				mozCleared = true;
+			}
+			
 			var proc = Components.classes["@mozilla.org/process/util;1"]
 							.createInstance(Components.interfaces.nsIProcess);
 			proc.init(exec);
@@ -1126,6 +1158,11 @@ Services.scriptloader.loadSubScript("resource://zotero/polyfill.js");
 			var args = [url];
 			proc.runw(false, args, args.length);
 		}
+		finally {
+			if (mozCleared) {
+				Zotero.Utilities.Internal.Environment.restoreMozillaVariables();
+			}
+		}
 	}