feat(OutputBuffer): expose scanner buffer size configuration#1
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sherlant wants to merge 3 commits into
Open
feat(OutputBuffer): expose scanner buffer size configuration#1sherlant wants to merge 3 commits into
sherlant wants to merge 3 commits into
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added 3 commits
May 13, 2026 16:15
OutputBuffer.Lines() used bufio.NewScanner with its default 64KB token limit. Lines exceeding that size caused silent truncation: s.Scan() returned false with bufio.ErrTooLong, but the error was never checked, so all subsequent output was lost without any indication. - Adds SetScannerBufferSize(n int) on OutputBuffer to override the limit - Adds Err() on OutputBuffer to surface scanner errors to callers - Propagates Options.LineBufferSize (already used by OutputStream) to OutputBuffer in NewCmdOptions, for both Buffered and CombinedOutput modes - Propagates the buffer size through Clone() - Adds tests covering the truncation behaviour and the new API
When OutputBuffer.Lines() encounters a line exceeding the scanner buffer size, the error is now surfaced in Status.Error once the command finishes, so callers using the Cmd API detect the truncation without having to access OutputBuffer directly.
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Problem
OutputBuffer.Lines()usesbufio.NewScannerwith its default 64KB token limit. When a line exceeds that size,s.Scan()returnsfalsewithbufio.ErrTooLong, but the error was never checked — causing silent truncation of all subsequent output with no indication of failure.Options.LineBufferSizealready existed forOutputStreambut was not propagated toOutputBuffer, making it impossible to work around this issue.Changes
OutputBuffer.SetScannerBufferSize(n int)— sets the maximum token size for the internalbufio.Scanner; default remainsbufio.MaxScanTokenSize(64KB) for backwards compatibilityOutputBuffer.Err() error— surfaces any scanner error (e.g.bufio.ErrTooLong) to the callerOptions.LineBufferSizeis now propagated toOutputBufferinNewCmdOptions, for bothBufferedandCombinedOutputmodesClone()propagates the configured buffer size to the clonedCmdOptions.LineBufferSizepropagation, andClone()propagationTest plan
go test ./...passes (32 tests)TestOutputBufferLongLineTruncation— verifiesErr()is set on overflowTestOutputBufferSetScannerBufferSize— verifies large lines work after enlarging the bufferTestOutputBufferLineBufferSizeOption— verifiesOptions.LineBufferSizereachesOutputBufferTestOutputBufferClonePropagatesScannerBufSize— verifiesClone()preserves the setting