Function truncateLines

agent/agentproc/headtail.go:261–303

truncateLines scans the input line by line and truncates any line longer than MaxLineLength.

(s string)

// truncateLines scans the input line by line and truncates
// any line longer than MaxLineLength.
func truncateLines(s string) string {
	if len(s) <= MaxLineLength {
		// Fast path: if the entire string is shorter than
		// the max line length, no line can exceed it.
		return s
	}

	var b strings.Builder
	b.Grow(len(s))

	for len(s) > 0 {
		idx := strings.IndexByte(s, '\n')
		var line string
		if idx == -1 {
			line = s
			s = ""
		} else {
			line = s[:idx]
			s = s[idx+1:]
		}

		if len(line) > MaxLineLength {
			// Truncate preserving the suffix length so the
			// total does not exceed a reasonable size.
			cut := MaxLineLength - len(lineTruncationSuffix)
			if cut < 0 {
				cut = 0
			}
			_, _ = b.WriteString(line[:cut])
			_, _ = b.WriteString(lineTruncationSuffix)
		} else {
			_, _ = b.WriteString(line)
		}

		// Re-add the newline unless this was the final
		// segment without a trailing newline.
		if idx != -1 {
			_ = b.WriteByte('\n')
		}
	}

	return b.String()
}

// Close marks the buffer as closed and wakes any waiters.
// This is called when the process exits.