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use super::parse::{SectionName, SectionOccurrence};
use super::{Config, ConfigError, Entry};
// A deterministic allowance for each synthetic section, entry and membership index. This is a
// logical work budget, not a promise about allocator overhead.
const ASSIGNMENT_BYTES: usize = 128;
impl Config {
/// Decodes counted environment pairs followed by legacy `GIT_CONFIG_PARAMETERS` assignments.
///
/// Unlike [`Self::from_environment`], this accepts both Git command-environment encodings.
/// Legacy assignments use single-quoted `key=value` or separately quoted `key` and `value`.
/// Values are literal bytes; implicit and explicitly empty values remain distinct. Each
/// assignment forms its own synthetic section, in input order. [`Self::resolve`] attaches
/// runtime provenance when this result is supplied as [`super::ConfigInputs::environment`];
/// explicit command entries follow it. No shell, file or process environment is accessed.
///
/// `max_pairs` bounds the combined number of assignments. `max_bytes` counts all supplied
/// COUNT, KEY, VALUE and PARAMETERS bytes plus 128 logical bytes per assignment. Checks precede
/// decoder-owned retention and decoding copies. The supplier owns allocation of its returned
/// buffers and should bound that allocation independently. The byte budget is not a measurement
/// of heap use; decoded output is no larger than the supplied bytes, apart from bounded
/// metadata.
///
/// # Errors
///
/// Returns counted-pair errors before examining legacy parameters, or legacy quoting/key/NUL
/// errors. Resource exhaustion reports `environment pair limit` or `environment byte limit`.
/// Error `line` is the one-based assignment ordinal, continuing after the counted pairs;
/// count and whole-input byte errors use line 1. Raw input values are never included in errors.
///
/// # Examples
///
/// ```
/// use girt::Config;
/// let config = Config::from_command_environment(
/// |key| (key == "GIT_CONFIG_PARAMETERS").then(|| b"'core.flag' 'core.value'=''".to_vec()),
/// 2,
/// 1024,
/// )?;
/// assert_eq!(config.value("core", None, "flag"), Some(None));
/// assert_eq!(
/// config.value("core", None, "value"),
/// Some(Some(b"".as_slice()))
/// );
/// # Ok::<(), girt::ConfigError>(())
/// ```
pub fn from_command_environment(
mut get: impl FnMut(&str) -> Option<Vec<u8>>,
max_pairs: usize,
max_bytes: usize,
) -> Result<Self, ConfigError> {
let mut remaining = max_bytes;
let mut exhausted = false;
let counted = Self::from_environment(
|key| {
let value = get(key)?;
let metadata = if key.starts_with("GIT_CONFIG_VALUE_") {
ASSIGNMENT_BYTES
} else {
0
};
let charge = value.len().checked_add(metadata);
let available = charge.and_then(|charge| remaining.checked_sub(charge));
match available {
Some(bytes) => {
remaining = bytes;
Some(value)
}
None => {
exhausted = true;
None
}
}
},
max_pairs,
);
if exhausted {
return Err(error(1, "environment byte limit"));
}
let mut config = counted?;
let parameters = get("GIT_CONFIG_PARAMETERS").unwrap_or_default();
remaining = remaining
.checked_sub(parameters.len())
.ok_or_else(|| error(1, "environment byte limit"))?;
let mut rest = parameters.as_slice();
while !rest.is_empty() {
let index = config.entries.len();
let line = index.saturating_add(1);
if index >= max_pairs {
return Err(error(line, "environment pair limit"));
}
remaining = remaining
.checked_sub(ASSIGNMENT_BYTES)
.ok_or_else(|| error(line, "environment byte limit"))?;
let mut key = quoted(&mut rest, line)?;
let value = if let Some(after) = rest.strip_prefix(b"=") {
rest = after;
Some(if rest.first() == Some(&b'\'') {
quoted(&mut rest, line)?
} else {
Vec::new()
})
} else if let Some(equal) = key.iter().position(|&byte| byte == b'=') {
let value = key.split_off(equal + 1);
key.pop();
Some(value)
} else {
None
};
if rest.first().is_some_and(|byte| !byte.is_ascii_whitespace()) {
return Err(error(line, "invalid command environment quoting"));
}
append_assignment(&mut config, &key, value, line)?;
rest = rest.trim_ascii_start();
}
Ok(config)
}
}
fn error(line: usize, reason: &'static str) -> ConfigError {
ConfigError { line, reason }
}
/// Decode Git's single-quote encoding, including escaped quote and bang between quoted spans.
fn quoted(input: &mut &[u8], line: usize) -> Result<Vec<u8>, ConfigError> {
let invalid = || error(line, "invalid command environment quoting");
let mut rest = input.strip_prefix(b"'").ok_or_else(invalid)?;
let mut value = Vec::new();
loop {
let (span, after) = crate::bytes::split_once(rest, b'\'').ok_or_else(invalid)?;
value.extend_from_slice(span);
rest = after;
if let [b'\\', escaped @ (b'\'' | b'!'), b'\'', after @ ..] = rest {
value.push(*escaped);
rest = after;
} else {
*input = rest;
return Ok(value);
}
}
}
fn append_assignment(
config: &mut Config,
key: &[u8],
value: Option<Vec<u8>>,
line: usize,
) -> Result<(), ConfigError> {
let invalid = || error(line, "invalid command environment key or value");
let (section, subsection, name) = crate::bytes::config_key(key).ok_or_else(invalid)?;
if section.is_empty()
|| !section
.iter()
.all(|byte| byte.is_ascii_alphanumeric() || *byte == b'-')
|| !name.first().is_some_and(u8::is_ascii_alphabetic)
|| !name
.iter()
.all(|byte| byte.is_ascii_alphanumeric() || *byte == b'-')
|| key.contains(&0)
|| value.as_ref().is_some_and(|value| value.contains(&0))
{
return Err(invalid());
}
let subsection = subsection.map(<[u8]>::to_vec);
let index = config.entries.len();
config.occurrences.push(SectionOccurrence {
name: SectionName {
section: section.to_vec(),
subsection: subsection.clone(),
},
start: index,
entries: vec![index],
});
config.entries.push(Entry {
section: section.to_vec(),
subsection,
name: name.to_vec(),
value,
line,
origin: None,
});
Ok(())
}
#[cfg(test)]
mod tests;