shadow1ng/fscan · error

portfinger_input_empty

Error message

portfinger_input_empty

What it means

fromString trims the input and splits it into lines; if there are no lines at all to process it reports that the input is empty. In practice strings.Split never returns an empty slice, so this is a defensive guard against blank input being handed to probe parsing.

Source

Thrown at core/portfinger/probe_parser.go:76

	}

	// 设置探测器属性
	p.Name = directive.DirectiveName
	p.Data = strings.Split(directive.DirectiveStr, directive.Delimiter)[0]
	p.Protocol = strings.ToLower(strings.TrimSpace(proto))

	return nil
}

// 从字符串解析探测器信息
func (p *Probe) fromString(data string) error {
	var err error

	// 预处理数据
	data = strings.TrimSpace(data)
	lines := strings.Split(data, "\n")
	if len(lines) == 0 {
		return fmt.Errorf("%s", i18n.GetText("portfinger_input_empty"))
	}

	probeStr := lines[0]
	if err := p.parseProbeInfo(probeStr); err != nil {
		return err
	}

	// 解析匹配规则和其他配置
	var matchs []Match
	for _, line := range lines {
		switch {
		case strings.HasPrefix(line, "match "):
			match, matchErr := p.getMatch(line)
			if matchErr != nil {
				continue
			}
			matchs = append(matchs, match)

View on GitHub (pinned to 95cc12e753)

Solutions

1. Check that the probe file exists, is readable, and has non-blank content before calling fromString/Init.
2. Trim/validate the input string in the caller and skip parsing when it is empty.
3. Log or handle the empty-file case explicitly in Init instead of letting it surface as a parse error.
4. Verify file-reading code returns real content (check bytes read) rather than swallowing read errors.

Example fix

// before
p, err := parser.FromString(probeFileContent)
// after
if strings.TrimSpace(probeFileContent) == "" {
    return fmt.Errorf("probe file is empty")
}
p, err := parser.FromString(probeFileContent)

if strings.TrimSpace(probeData) == "" {
    return errors.New("probe input is empty")
}

probe, err := parser.FromString(data)
if err != nil {
    if strings.Contains(err.Error(), "input_empty") {
        return nil // nothing to parse; not fatal
    }
    return err
}

When it happens

Trigger: Calling fromString with an empty or whitespace-only string, e.g. when a probe file is empty, read failed silently, or all content was trimmed away.

Common situations: Empty probe database files, reading a file with only blank lines, a configuration pointing at an empty/placeholder file, or passing an uninitialized string variable.

Understand the failure class

Background: "must not be empty", "cannot be empty" — required-field validation errors across open-source libraries — this error's family across 41 libraries.

Related errors

• portfinger_probe_name_invalid
• portfinger_probe_file_empty
• portfinger_probe_exclude_duplicate
• Parse error: first line must start with "Probe " or "Exclude
• parser_cidr_failed: %w

AI-assisted analysis of shadow1ng/fscan@95cc12e753 (2026-09-06). Data as JSON: /api/errors/f6908240ed882120. Report an issue: GitHub.