Enhance logging output for safeSetTimes() when the client runtime user does not the file requiring timestamp change (#3654)

Improve diagnostics and reduce alarm for filesystem timestamp permission failures. Timestamp update failures due to permission issues (e.g., EPERM) are now reported as warnings with clearer guidance, including detection of file owner vs. client runtime user UID mismatches. This helps users quickly identify common causes such as multi-user or Samba-created files without implying a fatal or critical client error.

.github/actions/spelling/allow.txt

@@ -90,6 +90,7 @@ concated
 confdir
 constness
 controllen
+cpath
 crt
 Cstrip
 ctl
@@ -141,6 +142,7 @@ envp
 eopkg
 epel
 epfd
+errnos
 eselect
 estr
 eventfd

src/util.d

@@ -3,7 +3,7 @@ module util;
 
 // What does this module require to function?
 import core.memory;
-import core.stdc.errno : ENOENT, EINTR, EBUSY, EXDEV, EAGAIN;
+import core.stdc.errno : ENOENT, EINTR, EBUSY, EXDEV, EAGAIN, EPERM, EACCES, EROFS;
 import core.stdc.stdlib;
 import core.stdc.string;
 import core.sys.posix.pwd;
@@ -68,7 +68,8 @@ shared static this() {
 enum FsErrorSeverity {
 	warning,
 	error,
-    fatal
+	fatal,
+	permission
 }
 
 // Creates a safe backup of the given item, and only performs the function if not in a --dry-run scenario.
@@ -1066,6 +1067,7 @@ void displayFileSystemErrorMessage(string message, string callingFunction, strin
 
 	// Header prefix for logging accuracy
 	string headerPrefix = severity == FsErrorSeverity.warning ? "WARNING"
+					  : severity == FsErrorSeverity.permission ? "WARNING"
 					  : severity == FsErrorSeverity.fatal ? "FATAL"
 					  : "ERROR";
 	
@@ -1114,7 +1116,8 @@ void displayFileSystemErrorMessage(string message, string callingFunction, strin
 		addLogEntry("  Error Message:     No error message available");
 	}
 
-	// Disk space diagnostics (best-effort)
+	// Disk space diagnostics (best-effort) - if this is not a permission issue
+	if (severity != FsErrorSeverity.permission) {
 		// We intentionally probe both the current directory and the target path directory when possible.
 		try {
 			// Always check the current working directory as a baseline
@@ -1156,30 +1159,40 @@ void displayFileSystemErrorMessage(string message, string callingFunction, strin
 			// Handle exceptions from disk space check or type conversion
 			addLogEntry("  NOTE: Exception during disk space check: " ~ e.msg);
 		}
+	}
 	
 	// Add note for WARNING messages
-	if (headerPrefix == "WARNING") {
+	if (severity == FsErrorSeverity.warning) {
 		addLogEntry();
-		addLogEntry("NOTE: This error is non-fatal; the client will continue to operate, but this may affect future operations if not resolved");
+		addLogEntry("NOTE: This warning is non-fatal; the client will continue to operate, but this may affect future operations if not resolved");
+		addLogEntry();
+	}
+	
+	// Add note for filesystem permission messages
+	if (severity == FsErrorSeverity.permission) {
+		addLogEntry();
+		addLogEntry("NOTE: Sync will continue. This file’s timestamps could not be updated because the effective user does not own the file.");
+		addLogEntry("      Potential Fix:");
+		addLogEntry("           Run the client as the file owner, or change ownership of the sync tree so it is owned by the user running the client.");
+		addLogEntry("      Learn more about File Ownership:");
+		addLogEntry("           https://www.redhat.com/en/blog/linux-file-permissions-explained");
+		addLogEntry("           https://unix.stackexchange.com/questions/191940/difference-between-owner-root-and-ruid-euid");
 		addLogEntry();
 	}
 	
 	// Add note for ERROR messages
-	if (headerPrefix == "ERROR") {
+	if (severity == FsErrorSeverity.error) {
 		addLogEntry();
 		addLogEntry("NOTE: This error requires attention; the client may continue running, but functionality is impaired and the issue should be resolved.");
 		addLogEntry();
 	}
 	
 	// Add note for FATAL messages
-	if (headerPrefix == "FATAL") {
+	if (severity == FsErrorSeverity.fatal) {
 		addLogEntry();
 		addLogEntry("NOTE: This error is fatal; the client cannot continue and this issue must be corrected before retrying. The client will now attempt to exit in a safe and orderly manner.");
 		addLogEntry();
 	}
-	
-	// Separate this block from surrounding log output 
-	addLogEntry();
 }
 
 // Display the POSIX Error Message
@@ -2103,9 +2116,57 @@ private bool safeGetTimes(string path, out SysTime accessTime, out SysTime modTi
 	return false;
 }
 
+// Some errnos are 'expected' in the wild (permissions, RO mounts, immutable files)
+// What is this errno
+private bool isExpectedPermissionStyleErrno(int err) {
+    // Return true of this is an expected error due to permission issues
+    return err == EPERM || err == EACCES || err == EROFS;
+}
+
+// Helper function to determine path mismatch against UID|GID and process effective UID
+private bool getPathOwnerMismatch(string path, out uint fileUid, out uint effectiveUid) {
+	version (Posix) {
+		stat_t st;
+
+		// Default outputs
+		fileUid = 0;
+		effectiveUid = cast(uint) geteuid();
+
+		try {
+			// absolutePath can throw; keep this helper non-throwing
+			auto fullPath = absolutePath(path);
+
+			// Ensure we pass a NUL-terminated string to the C API
+			auto cpath = toStringz(fullPath);
+
+			if (lstat(cpath, &st) != 0) {
+				if (debugLogging) {
+					addLogEntry("getPathOwnerMismatch(): lstat() failed for '" ~ path ~ "'", ["debug"]);
+				}
+				return false;
+			}
+
+			fileUid = cast(uint) st.st_uid;
+			// effectiveUid already set above
+			return fileUid != effectiveUid;
+
+		} catch (Exception e) {
+			if (debugLogging) {
+				addLogEntry("getPathOwnerMismatch(): exception for '" ~ path ~ "': " ~ e.msg, ["debug"]);
+			}
+			return false;
+		}
+	} else {
+		fileUid = 0;
+		effectiveUid = 0;
+		return false;
+	}
+}
+
 // Retry wrapper for setTimes()
 private bool safeSetTimes(string path, SysTime accessTime, SysTime modTime, string thisFunctionName) {
-	int maxAttempts = 5;
+	
+	enum int maxAttempts = 5;
 
 	foreach (attempt; 0 .. maxAttempts) {
 		try {
@@ -2117,18 +2178,72 @@ private bool safeSetTimes(string path, SysTime accessTime, SysTime modTime, stri
 				return false;
 			}
 
+			// Transient filesystem error: retry with backoff
 			if (isTransientErrno(e.errno)) {
-				// slightly longer backoff here is fine too, but keep it simple/consistent
+				if (debugLogging) {
+					// Log that we hit a transient error when doing debugging, otherwise nothing
+					addLogEntry("safeSetTimes() transient filesystem error response: " ~ e.msg ~ "\n - Attempting retry for setTimes()", ["debug"]);
+				}
+				// Backoff and retry
 				Thread.sleep(dur!"msecs"(15 * (attempt + 1)));
 				continue;
 			}
 
+			// Non-transient: special-case common permission errors
+			// The user running the client needs to be the owner of the files if the client needs to set explicit timestamps
+			// See https://github.com/abraunegg/onedrive/issues/3651 for details
+			if (isExpectedPermissionStyleErrno(e.errno)) {
+				// Configure application message to display
+				string permissionErrorMessage = "Unable to set local file timestamps (mtime/atime): Operation not permitted";
+				if (e.errno == EPERM) {
+					permissionErrorMessage = permissionErrorMessage ~ " (EPERM)";
+				}
+				
+				if (e.errno == EACCES) {
+					permissionErrorMessage = permissionErrorMessage ~ " (EACCES)";
+				}
+				
+				if (e.errno == EROFS) {
+					permissionErrorMessage = permissionErrorMessage ~ " (EROFS)";
+				}
+				
+				// Get extra details if required
+				string extraHint;
+				uint fileUid;
+				uint effectiveUid;
+				
+				if (e.errno == EPERM && getPathOwnerMismatch(path, fileUid, effectiveUid)) {
+					extraHint =
+						"\nThe onedrive client user does not own this file. onedrive user effective UID=" ~ to!string(effectiveUid) ~ ", file owner UID=" ~ to!string(fileUid) ~ "." ~
+						"\nOn Unix-like systems, setting explicit file timestamps typically requires the process to be the file owner or run with sufficient privileges.";
+					
+					// Update permissionErrorMessage to add extraHint
+					permissionErrorMessage = permissionErrorMessage ~ extraHint;
+				}
+				
+				// If we are doing --verbose or --debug display this file system error
+				if (verboseLogging) {
+					// Display applicable message for the user regarding permission error on path
+					displayFileSystemErrorMessage(
+						permissionErrorMessage,
+						thisFunctionName,
+						path,
+						FsErrorSeverity.permission
+					);
+				}
+				
+				// It is pointless attempting a re-try in this scenario as those conditions will not change by retrying 15ms later.
+				return false;
+			}
+
+			// Everything else: preserve existing behaviour
 			displayFileSystemErrorMessage(e.msg, thisFunctionName, path);
 			return false;
 		}
 	}
 
-	displayFileSystemErrorMessage("Failed to set file timestamps after retries", thisFunctionName, path);
+	// Only reached if transient errors never resolved
+	displayFileSystemErrorMessage("Failed to set path timestamps after retries", thisFunctionName, path);
 	return false;
 }