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fix(lib): validate every variadic fallback #1049

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Merged
jdx merged 2 commits into from
Aug 19, 2026
Merged

fix(lib): validate every variadic fallback #1049

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8f02fed
fix(lib): validate every variadic fallback
jdx Aug 19, 2026
44d5cd5
fix(lib): enforce fallback value bounds
jdx Aug 19, 2026
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165 changes: 138 additions & 27 deletions lib/src/parse.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -418,31 +418,38 @@ impl<'a> Parser<'a> {
}
if let Some(env_var) = arg.env.as_ref() {
if let Some(env_value) = get_env(env_var) {
validate_choice_value(
let values =
split_fallback_values(std::slice::from_ref(&env_value), arg.delimiter);
validate_choice_values(
ChoiceTarget::arg(arg),
&env_value,
&values,
arg.choices.as_ref(),
custom_env,
)?;
out.args
.insert(Arc::new(arg.clone()), ParseValue::String(env_value));
let parsed = if arg.var {
validate_arg_fallback_count(arg, values.len(), &mut out.errors);
ParseValue::MultiString(values)
} else {
ParseValue::String(values.into_iter().next().unwrap_or_default())
};
out.args.insert(Arc::new(arg.clone()), parsed);
continue;
}
}
if !arg.default.is_empty() {
// Consider var when deciding the type of default return value
if arg.var {
let values = split_fallback_values(&arg.default, arg.delimiter);
validate_arg_fallback_count(arg, values.len(), &mut out.errors);
validate_choice_values(
ChoiceTarget::arg(arg),
&arg.default,
&values,
arg.choices.as_ref(),
custom_env,
)?;
// For var=true, always return a vec (MultiString)
out.args.insert(
Arc::new(arg.clone()),
ParseValue::MultiString(arg.default.clone()),
);
out.args
.insert(Arc::new(arg.clone()), ParseValue::MultiString(values));
} else {
validate_choice_value(
ChoiceTarget::arg(arg),
Expand Down Expand Up @@ -471,14 +478,31 @@ impl<'a> Parser<'a> {
if let Some(env_var) = flag.env.as_ref() {
if let Some(env_value) = get_env(env_var) {
if let Some(arg) = flag.arg.as_ref() {
validate_choice_value(
let values =
split_fallback_values(std::slice::from_ref(&env_value), arg.delimiter);
validate_choice_values(
ChoiceTarget::option(flag),
&env_value,
&values,
arg.choices.as_ref(),
custom_env,
)?;
out.flags
.insert(Arc::clone(flag), ParseValue::String(env_value));
let parsed = if flag.var || arg.var {
if flag.var {
validate_flag_fallback_count(flag, values.len(), &mut out.errors);
}
if arg.var {
validate_flag_arg_fallback_count(
flag,
arg,
values.len(),
&mut out.errors,
);
}
ParseValue::MultiString(values)
} else {
ParseValue::String(values.into_iter().next().unwrap_or_default())
};
out.flags.insert(Arc::clone(flag), parsed);
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} else {
let is_true = matches!(env_value.as_str(), "1" | "true" | "True" | "TRUE");
out.flags
Expand Down Expand Up @@ -1779,6 +1803,84 @@ fn fallback_is_true(value: &str) -> bool {
matches!(value, "1" | "true" | "True" | "TRUE")
}

fn split_fallback_values(values: &[String], delimiter: Option<char>) -> Vec<String> {
match delimiter {
Some(delimiter) => values
.iter()
.flat_map(|value| value.split(delimiter).map(str::to_string))
.collect(),
None => values.to_vec(),
}
}

fn validate_arg_fallback_count(arg: &SpecArg, count: usize, errors: &mut Vec<UsageErr>) {
if let Some(min) = arg.var_min {
if count < min {
errors.push(UsageErr::VarArgTooFew {
name: arg.name.clone(),
min,
got: count,
});
}
}
if let Some(max) = arg.var_max {
if count > max {
errors.push(UsageErr::VarArgTooMany {
name: arg.name.clone(),
max,
got: count,
});
}
}
}

fn validate_flag_fallback_count(flag: &SpecFlag, count: usize, errors: &mut Vec<UsageErr>) {
if let Some(min) = flag.var_min {
if count < min {
errors.push(UsageErr::VarFlagTooFew {
name: flag.name.clone(),
min,
got: count,
});
}
}
if let Some(max) = flag.var_max {
if count > max {
errors.push(UsageErr::VarFlagTooMany {
name: flag.name.clone(),
max,
got: count,
});
}
}
}

fn validate_flag_arg_fallback_count(
flag: &SpecFlag,
arg: &SpecArg,
count: usize,
errors: &mut Vec<UsageErr>,
) {
if let Some(min) = arg.var_min {
if count < min {
errors.push(UsageErr::VarFlagTooFew {
name: flag.name.clone(),
min,
got: count,
});
}
}
if let Some(max) = arg.var_max {
if count > max {
errors.push(UsageErr::VarFlagTooMany {
name: flag.name.clone(),
max,
got: count,
});
}
}
}

/// Bind a fallback the way an unconditional `default` does: one value, or several
/// for `var`, and choices checked the same way.
fn bind_flag_fallback(
Expand All @@ -1790,30 +1892,39 @@ fn bind_flag_fallback(
if values.is_empty() {
return Ok(());
}
if flag.var {
if let Some(arg) = flag.arg.as_ref() {
if let Some(arg) = flag.arg.as_ref() {
let values = split_fallback_values(values, arg.delimiter);
if flag.var || arg.var {
if flag.var {
validate_flag_fallback_count(flag, values.len(), &mut out.errors);
}
if arg.var {
validate_flag_arg_fallback_count(flag, arg, values.len(), &mut out.errors);
}
validate_choice_values(
ChoiceTarget::option(flag),
values,
&values,
arg.choices.as_ref(),
custom_env,
)?;
out.flags
.insert(Arc::clone(flag), ParseValue::MultiString(values.to_vec()));
.insert(Arc::clone(flag), ParseValue::MultiString(values));
} else {
let bools: Vec<bool> = values.iter().map(|s| fallback_is_true(s)).collect();
let value = values.into_iter().next().unwrap_or_default();
validate_choice_value(
ChoiceTarget::option(flag),
&value,
arg.choices.as_ref(),
custom_env,
)?;
out.flags
.insert(Arc::clone(flag), ParseValue::MultiBool(bools));
.insert(Arc::clone(flag), ParseValue::String(value));
}
} else if let Some(arg) = flag.arg.as_ref() {
validate_choice_value(
ChoiceTarget::option(flag),
&values[0],
arg.choices.as_ref(),
custom_env,
)?;
} else if flag.var {
validate_flag_fallback_count(flag, values.len(), &mut out.errors);
let bools: Vec<bool> = values.iter().map(|s| fallback_is_true(s)).collect();
out.flags
.insert(Arc::clone(flag), ParseValue::String(values[0].clone()));
.insert(Arc::clone(flag), ParseValue::MultiBool(bools));
} else {
out.flags.insert(
Arc::clone(flag),
Expand Down
41 changes: 39 additions & 2 deletions lib/src/spec/arg.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -659,17 +659,54 @@ arg "[port]" env="PORT" validate="int(value) > 0" validate_error="port must be p
flag "--mode" default="bad" {
arg "<mode>" validate="value == 'good'" validate_error="mode must be good"
}
arg "[ports]..." env="PORTS" var=#true var_max=1 delimiter="," validate="int(value) > 0" validate_error="all ports must be positive"
flag "--levels" env="LEVELS" {
arg "<level>..." var=#true var_max=1 delimiter="," validate="value == 'good'" validate_error="all levels must be good"
}
flag "--modes" default="good,bad" {
arg "<mode>..." var=#true var_max=1 delimiter="," validate="value == 'good'" validate_error="all modes must be good"
}
flag "--conditional" {
default_if "--trigger" "good,bad"
arg "<conditional>..." var=#true var_max=1 delimiter="," validate="value == 'good'" validate_error="all conditional values must be good"
}
flag "--repeats <repeat>" env="REPEATS" var=#true var_max=1 delimiter=","
flag "--trigger"
"#
.parse()
.unwrap();
let env = HashMap::from([("PORT".to_string(), "0".to_string())]);
let env = HashMap::from([
("PORT".to_string(), "0".to_string()),
("PORTS".to_string(), "1,0".to_string()),
("LEVELS".to_string(), "good,bad".to_string()),
("REPEATS".to_string(), "one,two".to_string()),
]);
let error = Parser::new(&spec)
.with_env(env)
.parse(&["ex".to_string()])
.parse(&["ex".to_string(), "--trigger".to_string()])
.unwrap_err();
let error = error.to_string();
assert!(error.contains("port must be positive"), "{error}");
assert!(error.contains("mode must be good"), "{error}");
assert!(error.contains("all ports must be positive"), "{error}");
assert!(error.contains("all levels must be good"), "{error}");
assert!(error.contains("all modes must be good"), "{error}");
assert!(
error.contains("all conditional values must be good"),
"{error}"
);
assert!(
error.contains("Variadic argument <ports> accepts at most 1 value(s), got 2"),
"{error}"
);
for flag in ["levels", "modes", "conditional", "repeats"] {
assert!(
error.contains(&format!(
"Variadic flag --{flag} accepts at most 1 value(s), got 2"
)),
"{error}"
);
}
}
}

Expand Down