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Commit 91d06f0c authored by Yuya Nishihara's avatar Yuya Nishihara
Browse files

rust-chg: add helper to pack environment variables

On my machine, "printenv | wc -c" says 3422. That's the only reason why
the initial buffer capacity is set to 4kB.

Differential Revision: https://phab.mercurial-scm.org/D8363
parent 0a2516efc463
......@@ -5,7 +5,7 @@
//! Utility for parsing and building command-server messages.
use bytes::Bytes;
use bytes::{BufMut, Bytes, BytesMut};
use std::error;
use std::ffi::{OsStr, OsString};
use std::io;
......@@ -67,6 +67,45 @@ fn parse_command_type(value: &[u8]) -> io::Result<CommandType> {
}
}
// allocate large buffer as environment variables can be quite long
const INITIAL_PACKED_ENV_VARS_CAPACITY: usize = 4096;
/// Packs environment variables of platform encoding into bytes.
///
/// # Panics
///
/// Panics if key or value contains `\0` character, or key contains '='
/// character.
pub fn pack_env_vars_os<I, P>(vars: I) -> Bytes
where
I: IntoIterator<Item = (P, P)>,
P: AsRef<OsStr>,
{
let mut vars_iter = vars.into_iter();
if let Some((k, v)) = vars_iter.next() {
let mut dst = BytesMut::with_capacity(INITIAL_PACKED_ENV_VARS_CAPACITY);
pack_env_into(&mut dst, k.as_ref(), v.as_ref());
for (k, v) in vars_iter {
dst.reserve(1);
dst.put_u8(b'\0');
pack_env_into(&mut dst, k.as_ref(), v.as_ref());
}
dst.freeze()
} else {
Bytes::new()
}
}
fn pack_env_into(dst: &mut BytesMut, k: &OsStr, v: &OsStr) {
assert!(!k.as_bytes().contains(&0), "key shouldn't contain NUL");
assert!(!k.as_bytes().contains(&b'='), "key shouldn't contain '='");
assert!(!v.as_bytes().contains(&0), "value shouldn't contain NUL");
dst.reserve(k.as_bytes().len() + 1 + v.as_bytes().len());
dst.put_slice(k.as_bytes());
dst.put_u8(b'=');
dst.put_slice(v.as_bytes());
}
fn decode_latin1<S>(s: S) -> String
where
S: AsRef<[u8]>,
......@@ -85,6 +124,7 @@ where
mod tests {
use super::*;
use std::os::unix::ffi::OsStringExt;
use std::panic;
#[test]
fn parse_command_spec_good() {
......@@ -127,7 +167,66 @@ mod tests {
assert!(parse_command_spec(Bytes::from_static(b"paper\0less")).is_err());
}
#[test]
fn pack_env_vars_os_good() {
assert_eq!(
pack_env_vars_os(vec![] as Vec<(OsString, OsString)>),
Bytes::new()
);
assert_eq!(
pack_env_vars_os(vec![os_string_pair_from(b"FOO", b"bar")]),
Bytes::from_static(b"FOO=bar")
);
assert_eq!(
pack_env_vars_os(vec![
os_string_pair_from(b"FOO", b""),
os_string_pair_from(b"BAR", b"baz")
]),
Bytes::from_static(b"FOO=\0BAR=baz")
);
}
#[test]
fn pack_env_vars_os_large_key() {
let mut buf = vec![b'A'; INITIAL_PACKED_ENV_VARS_CAPACITY];
let envs = vec![os_string_pair_from(&buf, b"")];
buf.push(b'=');
assert_eq!(pack_env_vars_os(envs), Bytes::from(buf));
}
#[test]
fn pack_env_vars_os_large_value() {
let mut buf = vec![b'A', b'='];
buf.resize(INITIAL_PACKED_ENV_VARS_CAPACITY + 1, b'a');
let envs = vec![os_string_pair_from(&buf[..1], &buf[2..])];
assert_eq!(pack_env_vars_os(envs), Bytes::from(buf));
}
#[test]
fn pack_env_vars_os_nul_eq() {
assert!(panic::catch_unwind(|| {
pack_env_vars_os(vec![os_string_pair_from(b"\0", b"")])
})
.is_err());
assert!(panic::catch_unwind(|| {
pack_env_vars_os(vec![os_string_pair_from(b"FOO", b"\0bar")])
})
.is_err());
assert!(panic::catch_unwind(|| {
pack_env_vars_os(vec![os_string_pair_from(b"FO=", b"bar")])
})
.is_err());
assert_eq!(
pack_env_vars_os(vec![os_string_pair_from(b"FOO", b"=ba")]),
Bytes::from_static(b"FOO==ba")
);
}
fn os_string_from(s: &[u8]) -> OsString {
OsString::from_vec(s.to_vec())
}
fn os_string_pair_from(k: &[u8], v: &[u8]) -> (OsString, OsString) {
(os_string_from(k), os_string_from(v))
}
}
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