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use std::fs::read;
use std::path::{Path, PathBuf};
/// Name of tag file.
pub const CACHEDIR_TAG: &str = "CACHEDIR.TAG";
/// Prefix of contents of tag file.
pub const TAG: &str = "Signature: 8a477f597d28d172789f06886806bc55";
/// Is a given file a cache directory tag?
pub fn is_cachedir_tag(filename: &Path) -> Result<bool, CacheDirError> {
// Is the filename OK?
if let Some(basename) = filename.file_name() {
if basename != CACHEDIR_TAG {
return Ok(false);
}
}
// Does the file exist? It's OK if it doesn't, but we don't want
// to try to read it if it doesn't.
if !filename.exists() {
return Ok(false);
}
// Does the file start with the right prefix?
let data = read(filename).map_err(|e| CacheDirError::Read(filename.into(), e))?;
if data.len() >= TAG.len() {
Ok(&data[..TAG.len()] == TAG.as_bytes())
} else {
Ok(false)
}
}
#[derive(Debug, thiserror::Error)]
pub enum CacheDirError {
#[error("failed to read file {0}")]
Read(PathBuf, #[source] std::io::Error),
#[error("failed to write file {0}")]
Write(PathBuf, #[source] std::io::Error),
#[error("failed to delete file {0}")]
Remove(PathBuf, #[source] std::io::Error),
#[error(transparent)]
WalkDir(#[from] walkdir::Error),
}
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