Function fileContext

testutils/simplecheck.go:210–249

(filename string, line, context int)

var fileCache = make(map[string][][]byte)

func fileContext(filename string, line, context int) ([][]byte, int) {
	fileCacheLock.Lock()
	defer fileCacheLock.Unlock()
	lines, ok := fileCache[filename]
	if !ok {
		data, err := os.ReadFile(filename)
		if err != nil {
			// cache errors as nil slice: code below handles it correctly
			// otherwise when missing the source or running as a different user, we try
			// reading the file on each error which is unnecessary
			fileCache[filename] = nil
			return nil, 0
		}
		lines = bytes.Split(data, []byte{'\n'})
		fileCache[filename] = lines
	}

	if lines == nil {
		// cached error from ReadFile: return no lines
		return nil, 0
	}

	line-- // stack trace lines are 1-indexed
	start := line - context
	var idx int
	if start < 0 {
		start = 0
		idx = line
	} else {
		idx = context
	}
	end := line + context + 1
	if line >= len(lines) {
		return nil, 0
	}
	if end > len(lines) {
		end = len(lines)
	}
	return lines[start:end], idx
}