Context support for GUI-driven clients and relays by abakum · Pull Request #1038 · schollz/croc

abakum · 2025-12-26T06:29:19Z

#943
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
...
c, err:=NewCtx(ctx, Options{...})
...
go func() {
c.Send(...)
donechan <- true
}()
go func() {
<-cancelchan
cancel()
}()
...
go func() {
c.Receive()
donechan <- true
}()
go func() {
<-cancelchan
cancel()
}()
...

Copilot

Pull request overview

This pull request adds context support for GUI-driven clients and relays, enabling graceful cancellation of long-running operations in the croc file transfer application. The implementation introduces context-aware versions of key functions and proper cleanup mechanisms.

Changes:

Added context-aware file hashing functionality (HashFileCtx) that can be canceled mid-operation
Implemented context-based TCP server management with graceful shutdown support
Integrated context cancellation throughout the croc client lifecycle (Send/Receive operations)

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 15 comments.

Show a summary per file

File	Description
src/utils/ctx.go	New file implementing context-aware file hashing with cancellation support
src/utils/utils_test.go	Comprehensive tests for HashFileCtx covering cancellation scenarios
src/utils/utils.go	Minor fallback improvement for GetLocalIPs
src/tcp/ctx.go	Context management for TCP server with graceful shutdown
src/tcp/tcp.go	Refactored TCP server to use context-based lifecycle management
src/tcp/tcp_test.go	Tests for context-aware TCP server and various edge cases
src/croc/ctx.go	Context support for croc client operations
src/croc/croc.go	Integrated context cancellation throughout client lifecycle
src/croc/croc_test.go	Tests for context cancellation in various transfer scenarios

Comments suppressed due to low confidence (1)

src/utils/ctx.go:1

There's a race condition here. The context could be canceled between the select statement (line 46) and the ReadAt call (line 50), or between the ReadAt call and the context check (line 51). While this won't cause corruption, it creates inconsistent behavior. Consider using a non-blocking select after the read to check if cancellation occurred during the operation.

// ctx.go

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Copilot · 2026-01-16T14:54:19Z

src/utils/ctx.go

+		bar.Add(0)
+	}
+
+	b, err := imopartial.SumSectionReader(sr)


The variable imopartial is not defined in this file. It's defined in utils.go but not imported here. Either import it from utils.go by making it accessible, or define it locally in ctx.go.

Copilot · 2026-01-16T14:54:19Z

src/utils/ctx.go

+		bar.Add(0) // Start the spinner
+	}
+
+	b, err := imofull.SumSectionReader(sr)


The variable imofull is not defined in this file. It's defined in utils.go but not imported here. Either import it from utils.go by making it accessible, or define it locally in ctx.go.

Copilot · 2026-01-16T14:54:19Z

src/tcp/tcp.go

+	// stopRoomCleanup chan struct{}
+	// replaced by stop ctx.go


Remove commented-out code rather than leaving it with a note. The version control system preserves this history.

Copilot · 2026-01-16T14:54:19Z

src/tcp/tcp.go

 	s.roomTTL = DEFAULT_ROOM_TTL
 	s.debugLevel = DEFAULT_LOG_LEVEL
-	s.stopRoomCleanup = make(chan struct{})
+	// s.stopRoomCleanup = make(chan struct{}) replaced by stop


Remove commented-out code rather than leaving it with a note. The version control system preserves this history.

Suggested change

// s.stopRoomCleanup = make(chan struct{}) replaced by stop

Copilot · 2026-01-16T14:54:20Z

src/tcp/tcp.go

+		defer s.stop.wg.Done()
+		s.deleteOldRooms()
+	}()
+	// defer s.stopRoomDeletion()


Remove commented-out code rather than leaving it with a note. The version control system preserves this history.

Copilot · 2026-01-16T14:54:21Z

src/utils/ctx.go

+func (c *ctxFile) Seek(offset int64, whence int) (n int64, err error) {
+	select {
+	case <-c.ctx.Done():
+		return 0, c.ctx.Err()
+	default:
+		n, err = c.f.Seek(offset, whence)
+		if c.ctx.Err() != nil {
+			return 0, c.ctx.Err()
+		}
+		return n, err
+	}
+}


There's a race condition here. The context could be canceled between the select statement (line 60) and the Seek call (line 64), or between the Seek call and the context check (line 65). While this won't cause corruption, it creates inconsistent behavior. Consider using a non-blocking select after the seek to check if cancellation occurred during the operation.

Copilot · 2026-01-16T14:54:22Z

src/tcp/tcp.go

+	go func() {
+		dc := &net.Dialer{
+			Timeout: 100 * time.Millisecond,
+		}
+		if conn, err := dc.DialContext(s.stop.ctx, network, addr); err == nil {
+			log.Debugf("started TCP server on %s", addr)
+			conn.Close()
+		} else {
+			log.Errorf("started TCP server on %s : %v", addr, err)
+			s.stop.Cancel()
+		}
+	}()


This goroutine is fired-and-forgotten without any synchronization. If the main function returns before this goroutine completes, it may not execute fully. Consider adding this to the WaitGroup or using a synchronization mechanism to ensure proper cleanup.

Copilot · 2026-01-16T14:54:22Z

src/croc/croc.go

+	defer func() {
+		if r := recover(); r != nil {
+			if c.stop.gui {
+				log.Errorf("panic: %v", r)
+				c.stop.Cancel()
+			} else {
+				panic(r)
+			}
+		}
+	}()


Suppressing panics in GUI mode can hide serious bugs. Consider logging the full stack trace with debug.Stack() to aid debugging, and potentially returning an error from this function instead of silently recovering.

Copilot · 2026-01-16T14:54:22Z

src/croc/croc.go

+	defer func() {
+		if r := recover(); r != nil {
+			if c.stop.gui {
+				log.Errorf("panic: %v", r)
+				c.stop.Cancel()
+			} else {
+				panic(r)
+			}
+		}
+	}()


Suppressing panics in GUI mode can hide serious bugs. Consider logging the full stack trace with debug.Stack() to aid debugging, and potentially returning an error from this function instead of silently recovering.

Copilot · 2026-01-16T14:54:22Z

src/croc/croc.go

+		if r := recover(); r != nil {
+			if c.stop.gui {
+				log.Errorf("panic: %v", r)
+				c.stop.Cancel()
+			} else {
+				panic(r)
+			}
+		}


Suppressing panics in GUI mode can hide serious bugs. Consider logging the full stack trace with debug.Stack() to aid debugging, and potentially returning an error from this function instead of silently recovering.

abakum · 2026-01-16T15:30:17Z

\8^) https://chat.deepseek.com/share/16belxb9r2bmmnw9je

abakum · 2026-03-08T10:30:16Z

This code works. Zack, please try it out to believe it. https://github.com/abakum/crocgui

schollz · 2026-03-08T13:04:23Z

@abakum are you building a croc gui?

abakum added 3 commits December 26, 2025 00:51

Context support for GUI-driven clients and relays

70fd035

Context cancellation for hashing.

fb2b8d4

Use LocalIP() on error in GetLocalIPs() helps for hosts with android

c64ab79

schollz requested a review from Copilot January 16, 2026 14:49

Copilot started reviewing on behalf of schollz January 16, 2026 14:50 View session

Copilot AI reviewed Jan 16, 2026

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updateIfSenderChannelSecured

668ca1e

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abakum commented Dec 26, 2025

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Pull request overview

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abakum commented Jan 16, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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abakum commented Mar 8, 2026

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schollz commented Mar 8, 2026

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abakum commented Jan 16, 2026 •

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