Fix Bug #3478: Fix application crash after deleting file locally (#3481)

* Fix application crash after deleting file locally by removing a TOCTTOU (Time-of-check to time-of-use) race condition when deleting a file.
* Improve inotify removal messaging when exiting application to avoid confusion

src/main.d

@@ -1061,6 +1061,9 @@ int main(string[] cliArgs) {
 					} else {
 						addLogEntry("Cannot delete remote item: " ~ e.msg, ["info", "notify"]);
 					}
+				} catch (FileException e) {
+					// Path is gone locally, log and continue.
+					addLogEntry("ERROR: The local file system returned an error with the following message: " ~ e.msg, ["verbose"]);
 				} catch (Exception e) {
 					addLogEntry("Cannot delete remote item: " ~ e.msg, ["info", "notify"]);
 				}

src/monitor.d

@@ -511,7 +511,7 @@ final class Monitor {
 		synchronized(inotifyMutex) {
 			int ret = worker.removeInotifyWatch(wd);
 			if (ret < 0) throw new MonitorException("inotify_rm_watch failed");
-			if (verboseLogging) {addLogEntry("Monitored directory removed: " ~ to!string(wdToDirName[wd]), ["verbose"]);}
+			if (verboseLogging) {addLogEntry("Stopped monitoring directory (inotify watch removed): " ~ to!string(wdToDirName[wd]), ["verbose"]);}
 			wdToDirName.remove(wd);
 		}
 	}
@@ -524,7 +524,7 @@ final class Monitor {
 				int ret = worker.removeInotifyWatch(wd);
 				if (ret < 0) throw new MonitorException("inotify_rm_watch failed");
 				wdToDirName.remove(wd);
-				if (verboseLogging) {addLogEntry("Monitored directory removed: " ~ dirname, ["verbose"]);}
+				if (verboseLogging) {addLogEntry("Stopped monitoring directory (inotify watch removed): " ~ dirname, ["verbose"]);}
 			}
 		}
 	}

src/sync.d

@@ -4582,13 +4582,13 @@ class SyncEngine {
 					// Perform the action
 					if (!dryRun) {
 						if (isFile(path)) {
-							remove(path);
+							safeRemove(path);
 						} else {
 							try {
 								// Remove any children of this path if they still exist
 								// Resolve 'Directory not empty' error when deleting local files
 								foreach (DirEntry child; dirEntries(path, SpanMode.depth, false)) {
-									attrIsDir(child.linkAttributes) ? rmdir(child.name) : remove(child.name);
+									attrIsDir(child.linkAttributes) ? rmdir(child.name) : safeRemove(child.name);
 								}
 								// Remove the path now that it is empty of children
 								rmdirRecurse(path);
@@ -7629,7 +7629,7 @@ class SyncEngine {
 										// No --dry-run ... process local delete
 										if (exists(child)) {
 											try {
-												attrIsDir(child.linkAttributes) ? rmdir(child.name) : remove(child.name);
+												attrIsDir(child.linkAttributes) ? rmdir(child.name) : safeRemove(child.name);
 											} catch (FileException e) {
 												// display the error message
 												displayFileSystemErrorMessage(e.msg, thisFunctionName);
@@ -9561,7 +9561,7 @@ class SyncEngine {
 				if (verboseLogging) {addLogEntry("File upload session failed - invalid calculation of fragment size", ["verbose"]);}
 
 				if (exists(threadUploadSessionFilePath)) {
-					remove(threadUploadSessionFilePath);
+					safeRemove(threadUploadSessionFilePath);
 				}
 				// set uploadResponse to null as error
 				uploadResponse = null;
@@ -9736,7 +9736,7 @@ class SyncEngine {
 
 				// cleanup session data
 				if (exists(threadUploadSessionFilePath)) {
-					remove(threadUploadSessionFilePath);
+					safeRemove(threadUploadSessionFilePath);
 				}
 				// set uploadResponse to null as error
 				uploadResponse = null;
@@ -9753,7 +9753,7 @@ class SyncEngine {
 
 		// Remove session file if it exists		
 		if (exists(threadUploadSessionFilePath)) {
-			remove(threadUploadSessionFilePath);
+			safeRemove(threadUploadSessionFilePath);
 		}
 
 		// Display function processing time if configured to do so
@@ -11423,6 +11423,9 @@ class SyncEngine {
 			} else {
 				uploadDeletedItem(dbItem, path);
 			}
+		} catch (FileException e) {
+			// filesystem generated an error message - display error message
+			displayFileSystemErrorMessage(e.msg, thisFunctionName);
 		} catch (OneDriveException e) {
 			if (e.httpStatusCode == 404) {
 				addLogEntry(e.msg);
@@ -12733,7 +12736,7 @@ class SyncEngine {
 				// cleanup session path
 				if (exists(sessionFilePath)) {
 					if (!dryRun) {
-						remove(sessionFilePath);
+						safeRemove(sessionFilePath);
 					}
 				}
 			}
@@ -12787,7 +12790,7 @@ class SyncEngine {
 				// Cleanup 'resume_download' file
 				if (exists(resumeDownloadFile)) {
 					if (!dryRun) {
-						remove(resumeDownloadFile);
+						safeRemove(resumeDownloadFile);
 					}
 				}
 			}

src/util.d

@@ -3,6 +3,7 @@ module util;
 
 // What does this module require to function?
 import core.stdc.stdlib: EXIT_SUCCESS, EXIT_FAILURE, exit;
+import core.stdc.errno : ENOENT;
 import std.base64;
 import std.conv;
 import std.digest.crc;
@@ -172,7 +173,21 @@ void safeRename(const(char)[] oldPath, const(char)[] newPath, bool dryRun) {
 
 // Deletes the specified file without throwing an exception if it does not exists
 void safeRemove(const(char)[] path) {
-	if (exists(path)) remove(path);
+	// Set this function name
+	string thisFunctionName = format("%s.%s", strip(__MODULE__) , strip(getFunctionName!({})));
+	
+	// Attempt the local deletion
+	try {
+		// Attempt once; no pre-check to avoid TOCTTOU
+		remove(path);				// attempt once, no pre-check
+		return;						// removed
+	} catch (FileException e) {
+		if (e.errno == ENOENT) {	// already gone → fine
+			return;					// nothing to do
+		}
+		// Anything else is noteworthy (EISDIR, EACCES, etc.)
+		displayFileSystemErrorMessage(e.msg, thisFunctionName);
+	}
 }
 
 // Returns the SHA1 hash hex string of a file, or an empty string on failure