Prevent statfs from hanging the app for more than half a second in the face of...

Prevent statfs from hanging the app for more than half a second in the face of broken network filesystems. Issue 6110

sources/NSFileManager+iTerm.h

@@ -37,7 +37,8 @@
 // Returns YES if the file exists on a local (non-network) filesystem.
 - (BOOL)fileExistsAtPathLocally:(NSString *)filename
-         additionalNetworkPaths:(NSArray<NSString *> *)additionalNetworkpaths;
+         additionalNetworkPaths:(NSArray<NSString *> *)additionalNetworkpaths
+                       timedOut:(BOOL *)timedOut;
 - (BOOL)fileHasForbiddenPrefix:(NSString *)filename
         additionalNetworkPaths:(NSArray<NSString *> *)additionalNetworkpaths;

sources/NSFileManager+iTerm.m

@@ -227,17 +227,46 @@ NSString * const DirectoryLocationDomain = @"DirectoryLocationDomain";
 }
 - (BOOL)fileExistsAtPathLocally:(NSString *)filename
-         additionalNetworkPaths:(NSArray<NSString *> *)additionalNetworkPaths {
+         additionalNetworkPaths:(NSArray<NSString *> *)additionalNetworkPaths
+                       timedOut:(BOOL *)timedOutPtr {
     if ([self fileHasForbiddenPrefix:filename additionalNetworkPaths:additionalNetworkPaths]) {
         return NO;
     }
-    struct statfs buf;
-    int rc = statfs([filename UTF8String], &buf);
-    if (rc != 0 || (buf.f_flags & MNT_LOCAL)) {
-        return [self fileExistsAtPath:filename];
-    } else {
-        return NO;
+    static dispatch_queue_t statfsQueue;
+    static dispatch_once_t onceToken;
+    dispatch_once(&onceToken, ^{
+        statfsQueue = dispatch_queue_create("com.iterm2.statfs", NULL);
+    });
+
+    // Do statfs in a background thread because it can hang when you're using certain network file systems.
+    __block BOOL ok = NO;
+    dispatch_group_t group = dispatch_group_create();
+    dispatch_group_enter(group);
+    [filename retain];
+    dispatch_async(statfsQueue, ^{
+        struct statfs buf;
+        int rc = statfs([filename UTF8String], &buf);
+        if (rc != 0 || (buf.f_flags & MNT_LOCAL)) {
+            ok = [self fileExistsAtPath:filename];
+        } else {
+            ok = NO;
+        }
+        [filename release];
+        dispatch_group_leave(group);
+    });
+
+    // Wait up to half a second for the statfs to finish.
+    long timedOut = dispatch_group_wait(group,
+                                        dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.5 * NSEC_PER_SEC)));
+    dispatch_release(group);
+    if (timedOutPtr) {
+        *timedOutPtr = !!timedOut;
     }
+    if (timedOut) {
+        DLog(@"Timed out doing statfs on %@", filename);
+    }
+    return timedOut ? NO : ok;
 }
 @end
+

sources/iTermSemanticHistoryController.h

@@ -48,7 +48,8 @@ extern NSString *const kSemanticHistoryWorkingDirectorySubstitutionKey;
 - (NSString *)getFullPath:(NSString *)path
          workingDirectory:(NSString *)workingDirectory
                lineNumber:(NSString **)lineNumber
-             columnNumber:(NSString **)columnNumber;
+             columnNumber:(NSString **)columnNumber
+                 timedOut:(BOOL *)timedOut;
 // Opens the file at the relative |path| (which may include :lineNumber) in |workingDirectory|.
 // The |substitutions| dictionary is used to expand \references in the command to run (gotten from

sources/iTermSemanticHistoryController.m

@@ -43,9 +43,10 @@ NSString *const kSemanticHistoryWorkingDirectorySubstitutionKey = @"semanticHist
 @synthesize prefs = prefs_;
 @synthesize delegate = delegate_;
-- (BOOL)fileExistsAtPathLocally:(NSString *)path {
+- (BOOL)fileExistsAtPathLocally:(NSString *)path timedOut:(BOOL *)timedOut {
     return [self.fileManager fileExistsAtPathLocally:path
-                              additionalNetworkPaths:[[iTermAdvancedSettingsModel pathsToIgnore] componentsSeparatedByString:@","]];
+                              additionalNetworkPaths:[[iTermAdvancedSettingsModel pathsToIgnore] componentsSeparatedByString:@","]
+                                            timedOut:timedOut];
 }
 - (BOOL)fileHasForbiddenPrefix:(NSString *)path {
@@ -56,7 +57,8 @@ NSString *const kSemanticHistoryWorkingDirectorySubstitutionKey = @"semanticHist
 - (NSString *)getFullPath:(NSString *)path
          workingDirectory:(NSString *)workingDirectory
                lineNumber:(NSString **)lineNumber
-             columnNumber:(NSString **)columnNumber {
+             columnNumber:(NSString **)columnNumber
+                 timedOut:(BOOL *)timedOut {
     DLog(@"Check if %@ is a valid path in %@", path, workingDirectory);
     NSString *origPath = path;
     // TODO(chendo): Move regex, define capture semantics in config file/prefs
@@ -104,7 +106,7 @@ NSString *const kSemanticHistoryWorkingDirectorySubstitutionKey = @"semanticHist
     // be stat()ed, although they were always stat()ed because of unintentional
     // disk access in the old code.
-    if ([self fileExistsAtPathLocally:path]) {
+    if ([self fileExistsAtPathLocally:path timedOut:timedOut]) {
         DLog(@"    YES: A file exists at %@", path);
         NSURL *url = [NSURL fileURLWithPath:path];
@@ -117,6 +119,9 @@ NSString *const kSemanticHistoryWorkingDirectorySubstitutionKey = @"semanticHist
             return nil;
         }
         return path;
+    } else if (*timedOut) {
+        DLog(@"     NO: timed out");
+        return nil;
     }
     // If path doesn't exist and it starts with "a/" or "b/" (from `diff`).
@@ -130,7 +135,8 @@ NSString *const kSemanticHistoryWorkingDirectorySubstitutionKey = @"semanticHist
         return [self getFullPath:origPath
                 workingDirectory:workingDirectory
                       lineNumber:lineNumber
-                    columnNumber:columnNumber];
+                    columnNumber:columnNumber
+                        timedOut:timedOut];
     }
     DLog(@"     NO: no valid path found");
@@ -331,7 +337,11 @@ NSString *const kSemanticHistoryWorkingDirectorySubstitutionKey = @"semanticHist
     BOOL isRawAction = [prefs_[kSemanticHistoryActionKey] isEqualToString:kSemanticHistoryRawCommandAction];
     if (!isRawAction) {
-        path = [self getFullPath:path workingDirectory:workingDirectory lineNumber:&lineNumber columnNumber:&columnNumber];
+        BOOL timedOut;
+        path = [self getFullPath:path workingDirectory:workingDirectory
+                      lineNumber:&lineNumber
+                    columnNumber:&columnNumber
+                        timedOut:&timedOut];
         DLog(@"Not a raw action. New path is %@, line number is %@", path, lineNumber);
     }
@@ -444,7 +454,8 @@ NSString *const kSemanticHistoryWorkingDirectorySubstitutionKey = @"semanticHist
                            charsTakenFromPrefix:(int *)charsTakenFromPrefixPtr
                            charsTakenFromSuffix:(int *)suffixChars
                                  trimWhitespace:(BOOL)trimWhitespace {
-    BOOL workingDirectoryIsOk = [self fileExistsAtPathLocally:workingDirectory];
+    BOOL timedOut;
+    BOOL workingDirectoryIsOk = [self fileExistsAtPathLocally:workingDirectory timedOut:&timedOut];
     if (!workingDirectoryIsOk) {
         DLog(@"Working directory %@ is a network share or doesn't exist. Not using it for context.",
              workingDirectory);
@@ -507,7 +518,16 @@ NSString *const kSemanticHistoryWorkingDirectorySubstitutionKey = @"semanticHist
             for (NSString *modifiedPossiblePath in [self pathsFromPath:trimmedPath byRemovingBadSuffixes:questionableSuffixes]) {
                 BOOL exists = NO;
                 if (workingDirectoryIsOk || [modifiedPossiblePath hasPrefix:@"/"]) {
-                    exists = ([self getFullPath:modifiedPossiblePath workingDirectory:workingDirectory lineNumber:NULL columnNumber:NULL] != nil);
+                    BOOL timedOut = NO;
+                    exists = ([self getFullPath:modifiedPossiblePath
+                               workingDirectory:workingDirectory
+                                     lineNumber:NULL
+                                   columnNumber:NULL
+                                       timedOut:&timedOut] != nil);
+                    if (timedOut) {
+                        DLog(@"Timed out checking path %@ in %@", modifiedPossiblePath, workingDirectory);
+                        return nil;
+                    }
                 }
                 if (exists) {
                     if (charsTakenFromPrefixPtr) {

sources/iTermURLActionFactory.m

@@ -196,10 +196,12 @@
         range.columnWindow = extractor.logicalWindow;
         action.range = range;
+        BOOL timedOut;
         action.fullPath = [semanticHistoryController getFullPath:filename
                                                 workingDirectory:workingDirectory
                                                       lineNumber:NULL
-                                                    columnNumber:NULL];
+                                                    columnNumber:NULL
+                                                        timedOut:&timedOut];
         action.workingDirectory = workingDirectory;
         return action;
     }