wavetermdev/waveterm · error

append would exceed maximum file size of %d bytes

Error message

append would exceed maximum file size of %d bytes

What it means

The append loop checks that the accumulated buffer plus the newly read chunk stays within remainingSpace = MaxFileSize - info.Size. If the append would push the remote file past the 10MB cap, it fails with 'append would exceed maximum file size of %d bytes'. Unlike error 191 (file already full), this fires mid-stream when the incoming data is too large for the remaining capacity.

Source

Thrown at cmd/wsh/cmd/wshcmd-file.go:298

	if info.Size >= MaxFileSize {
		return fmt.Errorf("file already at maximum size (%d bytes)", MaxFileSize)
	}

	reader := bufio.NewReader(WrappedStdin)
	var buf bytes.Buffer
	remainingSpace := MaxFileSize - info.Size
	for {
		chunk := make([]byte, 8192)
		n, err := reader.Read(chunk)
		if err == io.EOF {
			break
		}
		if err != nil {
			return fmt.Errorf("reading input: %w", err)
		}

		if int64(buf.Len()+n) > remainingSpace {
			return fmt.Errorf("append would exceed maximum file size of %d bytes", MaxFileSize)
		}

		buf.Write(chunk[:n])

		if buf.Len() >= 8192 { // 8KB batch size
			fileData.Data64 = base64.StdEncoding.EncodeToString(buf.Bytes())
			err = wshclient.FileAppendCommand(RpcClient, fileData, &wshrpc.RpcOpts{Timeout: fileTimeout})
			if err != nil {
				return fmt.Errorf("appending to file: %w", err)
			}
			remainingSpace -= int64(buf.Len())
			buf.Reset()
		}
	}

	if buf.Len() > 0 {
		fileData.Data64 = base64.StdEncoding.EncodeToString(buf.Bytes())
		err = wshclient.FileAppendCommand(RpcClient, fileData, &wshrpc.RpcOpts{Timeout: fileTimeout})

View on GitHub (pinned to a4447c1563)

Solutions

1. Pre-check the remote file size and truncate your input to fit the remaining space
2. Rotate: append to a second file once the first approaches 10MB
3. Write the whole payload to a fresh file with 'wsh file write' if combined size exceeds 10MB and old content is replaceable

Example fix

// before
big-stream | wsh file append [block] out.bin   # exceeds remaining space
// after
head -c 5000000 big-stream | wsh file append [block] out.bin  # stay under the cap

info, _ := wshclient.FileInfoCommand(RpcClient, wshrpc.CommandFileData{Info: &wshrpc.FileInfo{Path: path}}, &wshrpc.RpcOpts{Timeout: fileTimeout})
inputSize, _ := streamLen() // e.g. stat of temp input file
if info.Size+inputSize > 10*1024*1024 {
    return fmt.Errorf("append of %d bytes would exceed cap (file at %d)", inputSize, info.Size)
}

func fitsInCap(current, incoming int64) bool {
    return current+incoming <= 10*1024*1024
}

When it happens

Trigger: Piping more than (MaxFileSize - current file size) bytes into 'wsh file append'; the check triggers when buf.Len()+n exceeds remainingSpace, before any batch flush containing the excess.

Common situations: Appending a large log/dataset to a file that already holds several MB; long-running append jobs whose input grows past the cap; not realizing the 10MB cap applies to the resulting file, not the appended portion.

Understand the failure class

Background: "File too large" / "file size exceeds limit" errors: why libraries cap file sizes and how to fix them — this error's family across 46 libraries.

Related errors

• file %s exceeds maximum size of %s for %s files
• file already at maximum size (%d bytes)
• Image too large (>5MB)
• input exceeds maximum file size of %d bytes
• file size (%d bytes) exceeds maximum of %d bytes

AI-assisted analysis of wavetermdev/waveterm@a4447c1563 (2026-09-01). Data as JSON: /api/errors/26af5ee03d08930c. Report an issue: GitHub.