+use crate::env;
use crate::ffi::OsStr;
-use crate::path::Prefix;
+use crate::io;
+use crate::path::{Path, PathBuf, Prefix};
#[inline]
pub fn is_sep_byte(b: u8) -> bool {
pub const MAIN_SEP_STR: &str = "/";
pub const MAIN_SEP: char = '/';
+
+/// Make a POSIX path absolute without changing its semantics.
+pub(crate) fn absolute(path: &Path) -> io::Result<PathBuf> {
+ // This is mostly a wrapper around collecting `Path::components`, with
+ // exceptions made where this conflicts with the POSIX specification.
+ // See 4.13 Pathname Resolution, IEEE Std 1003.1-2017
+ // https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap04.html#tag_04_13
+
+ // Get the components, skipping the redundant leading "." component if it exists.
+ let mut components = path.strip_prefix(".").unwrap_or(path).components();
+ let path_os = path.as_os_str().bytes();
+
+ let mut normalized = if path.is_absolute() {
+ // "If a pathname begins with two successive <slash> characters, the
+ // first component following the leading <slash> characters may be
+ // interpreted in an implementation-defined manner, although more than
+ // two leading <slash> characters shall be treated as a single <slash>
+ // character."
+ if path_os.starts_with(b"//") && !path_os.starts_with(b"///") {
+ components.next();
+ PathBuf::from("//")
+ } else {
+ PathBuf::new()
+ }
+ } else {
+ env::current_dir()?
+ };
+ normalized.extend(components);
+
+ // "Interfaces using pathname resolution may specify additional constraints
+ // when a pathname that does not name an existing directory contains at
+ // least one non- <slash> character and contains one or more trailing
+ // <slash> characters".
+ // A trailing <slash> is also meaningful if "a symbolic link is
+ // encountered during pathname resolution".
+ if path_os.ends_with(b"/") {
+ normalized.push("");
+ }
+
+ Ok(normalized)
+}