{"record":{"id":"1c162d1d86e9e174","repo":"ReFirmLabs/binwalk","slug":"failed-to-print-help-output","errorCode":null,"errorMessage":"Failed to print help output","messagePattern":"Failed to print help output","errorType":"panic","errorClass":null,"httpStatus":null,"severity":"error","filePath":"src/cliparser.rs","lineNumber":76,"sourceCode":"    /// Only scan for these signatures\n    #[arg(short = 'y', long, value_delimiter = ',', num_args = 1.., conflicts_with = \"exclude\")]\n    pub include: Option<Vec<String>>,\n\n    /// Extract files/folders to a custom directory\n    #[arg(short, long, default_value = \"extractions\")]\n    pub directory: String,\n\n    /// Path to the file to analyze\n    pub file_name: Option<String>,\n}\n\npub fn parse() -> CliArgs {\n    let args = CliArgs::parse();\n\n    if std::env::args().len() == 1 {\n        CliArgs::command()\n            .print_help()\n            .expect(\"Failed to print help output\");\n        std::process::exit(0);\n    }\n\n    args\n}\n","sourceCodeStart":58,"sourceCodeEnd":82,"githubUrl":"https://github.com/ReFirmLabs/binwalk/blob/26713972e3f9f52dc37d4a421c4554b0bd9e82ef/src/cliparser.rs#L58-L82","documentation":"In parse(), if the process was invoked with no arguments, the code tries to print the clap command's help text and exits. This expect() fires only if clap's print_help() fails while writing help output (an I/O error on stdout/stderr).","triggerScenarios":"Calling the binary with zero arguments AND the write of help text to stdout fails (closed/broken stdout pipe, e.g. `binary | head -0`, or a full/unavailable output stream).","commonSituations":"Piping output into a closed consumer; running in a stripped environment where stdout is not writable; embedding parse() in a test harness with redirected/closed stdio.","solutions":["Check that stdout is writable and the downstream pipe consumer is alive","Run the binary normally (with arguments) so this no-args help path isn't taken","Replace expect with graceful handling: print a note to stderr and exit with a proper code if help can't be printed","Verify clap version behavior — in newer clap, use `Cli::command().print_help()` result explicitly rather than expect"],"exampleFix":"// before\nCliArgs::command()\n    .print_help()\n    .expect(\"Failed to print help output\");\n// after\nif CliArgs::command().print_help().is_err() {\n    eprintln!(\"Failed to print help output\");\n    std::process::exit(1);\n}","handlingStrategy":"try-catch","validationCode":"if std::env::args().len() == 1 && std::io::stdout().write(&[]).is_err() {\n    eprintln!(\"stdout is not writable\");\n    std::process::exit(1);\n}","typeGuard":null,"tryCatchPattern":"if let Err(e) = CliArgs::command().print_help() {\n    eprintln!(\"Failed to print help: {e}\");\n    std::process::exit(1);\n}","preventionTips":["Handle print_help()'s Result instead of expect()ing it","Avoid invoking with a closed stdout pipe (e.g. `| head` with no reads)","Test no-argument startup in CI with normal stdio","Consider clap's built-in arg_required_else_help(true) instead of manual parsing"],"tags":["rust","cli","clap","io"],"backgroundTag":"file-write-failed","analyzedSha":"26713972e3f9f52dc37d4a421c4554b0bd9e82ef","analyzedAt":"2026-09-06T21:38:04.941Z","contentChangedAt":"2026-09-06T21:38:04.941Z","schemaVersion":2},"datasetVersion":"2026-09-14T05:17:10.506Z"}