47 lines
1.5 KiB
Rust
47 lines
1.5 KiB
Rust
use std::env::{var, VarError::*};
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use std::ffi::OsString;
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use std::fmt;
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use std::path::{is_separator, PathBuf};
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const CREDENTIALS_DIRECTORY: &str = "CREDENTIALS_DIRECTORY";
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/// Takes a systemd credential ID. If the environment variable
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/// `CREDENTIALS_DIRECTORY` is set and valid Unicode, and the file corresponding
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/// to the credential exists, returns the path of the file corresponding to the
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/// credential.
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///
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/// Absence of the environment variable and inexistence of the file are handled
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/// gracefully returning `Ok(None)`.
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pub fn path(id: &str) -> Result<Option<PathBuf>, PathError> {
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use PathError::*;
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if id.contains(is_separator) {
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return Err(InvalidCredentialId { id: id.to_owned() });
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}
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let credential = match var(CREDENTIALS_DIRECTORY) {
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Err(NotUnicode(os)) => return Err(EnvVarNotUnicode { os }),
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Err(NotPresent) => return Ok(None),
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Ok(env) => PathBuf::from(env).join(id),
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};
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Ok(credential.exists().then_some(credential))
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}
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/// The error returned by [`path`].
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#[derive(Debug)]
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pub enum PathError {
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InvalidCredentialId { id: String },
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EnvVarNotUnicode { os: OsString },
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}
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impl fmt::Display for PathError {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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use PathError::*;
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match self {
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InvalidCredentialId { id } => write!(f, "The systemd credential ID '{id}' is invalid."),
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EnvVarNotUnicode { os } => write!(f, "The value of environment variable '{CREDENTIALS_DIRECTORY}' is not valid Unicode (it lossily translates to '{}').", os.to_string_lossy()),
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}
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}
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}
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