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use crate::cache;
use ignore::Walk;
use std::{
fs,
fs::{File, Metadata},
io::{Seek, SeekFrom, Write},
os::unix::fs::PermissionsExt,
path::Path,
};
use tar::{Builder, Header};
// Add a file to a tar archive.
fn add_file<P: AsRef<Path>, Q: AsRef<Path>, R: AsRef<Path>, W: Write>(
builder: &mut Builder<W>,
metadata: &Metadata,
path: P,
source_dir: Q,
destination_dir: R,
file_hashes: &mut Vec<String>,
) -> Result<(), String> {
// Compute the source and destination paths.
let source = source_dir.as_ref().join(&path);
let mut destination = destination_dir.as_ref().join(&path);
// Tar archives must contain only relative paths. But for our purposes, the
// paths will be relative to the filesystem root. [tag:destination_absolute]
if destination.starts_with("/") {
// The `unwrap` is safe due to [ref:destination_absolute]
destination = destination.strip_prefix("/").unwrap().to_owned();
}
// Determine if the file has the executable bit set.
let mode = metadata.permissions().mode();
let executable = mode & 0o1 > 0 || mode & 0o10 > 0 || mode & 0o100 > 0;
// Construct a tar header for this file.
let mut header = Header::new_gnu();
header.set_mode(if executable { 0o777 } else { 0o666 });
header.set_size(metadata.len());
// Open the file so we can compute the hash of its contents.
let mut file = File::open(&source).map_err(|e| {
format!(
"Unable to open file `{}`. Details: {}",
&source.to_string_lossy(),
e
)
})?;
// Compute the hash of the file contents and metadata.
file_hashes.push(cache::extend(
&cache::extend(
&cache::hash_str(&path.as_ref().to_string_lossy().to_string()),
&cache::hash_read(&mut file)?,
),
if executable { "+x" } else { "-x" },
));
// Jump back to the beginning of the file so the tar builder can read it.
file.seek(SeekFrom::Start(0)).map_err(|e| {
format!(
"Unable to seek file `{}`. Details: {}",
&source.to_string_lossy(),
e
)
})?;
// Add the file to the archive and return.
builder.append_data(&mut header, destination, file).unwrap();
Ok(())
}
// Construct a tar archive and return a hash of its contents. The `source_dir`
// and `destination_dir` are expected to be absolute paths [tag:src_dest_abs].
pub fn create<W: Write, P: AsRef<Path>, Q: AsRef<Path>, R: AsRef<Path>>(
writer: W,
paths: &[P],
source_dir: Q,
destination_dir: R,
) -> Result<(W, String), String> {
// This vector will store all the hashes of the contents and metadata of all
// the files in the archive. In the end, we will sort this vector and then
// take the hash of the whole thing.
let mut file_hashes = vec![];
// This builder will be responsible for writing to the tar file.
let mut builder = Builder::new(writer);
builder.follow_symlinks(false);
// Add each path to the archive.
for path in paths {
// Compute the source path.
let source_path = source_dir.as_ref().join(path);
// Fetch the filesystem metadata for this path.
let metadata = fs::metadata(&source_path).map_err(|e| {
format!(
"Unable to fetch filesystem metadata for `{}`. Details: {}",
&source_path.to_string_lossy(),
e
)
})?;
// Check if the path is a directory.
if metadata.is_dir() {
// The path is a directory, so we need to traverse it.
for entry in Walk::new(&source_path) {
// Fetch the filesystem metadata for this entry.
let entry = entry.map_err(|e| {
format!(
"Unable to traverse directory `{}`. Details: {}",
&source_path.to_string_lossy(),
e
)
})?;
let entry_metadata = entry.metadata().map_err(|e| {
format!(
"Unable to fetch filesystem metadata for `{}`. Details: {}",
&source_path.to_string_lossy(),
e
)
})?;
// Only add files to the archive. Here, `file_type()` should always
// return a `Some`. It could only return `None` if the file represents
// STDIN, and that isn't the case here.
if entry.file_type().unwrap().is_file() {
// Add the file to the archive.
add_file(
&mut builder,
&entry_metadata,
entry
.path()
.canonicalize()
.map_err(|e| {
format!(
"Unable to canonicalize path `{}`. Details: {}",
&entry.path().to_string_lossy(),
e
)
})?
.strip_prefix(source_dir.as_ref())
.map_err(|e| {
format!(
"Unable to relativize path `{}` with respect to `{}`. Details: {}",
&entry.path().to_string_lossy(),
&source_dir.as_ref().to_string_lossy(),
e
)
})?,
&source_dir,
&destination_dir,
&mut file_hashes,
)?;
}
}
} else {
// The path is a file. Add it to the archive.
add_file(
&mut builder,
&metadata,
path,
&source_dir,
&destination_dir,
&mut file_hashes,
)?;
}
}
// Sort the file hashes to ensure the directory traversal order doesn't
// matter.
file_hashes.sort();
// Return the tar file and the hash of its contents.
Ok((
builder
.into_inner()
.map_err(|e| format!("Error writing tar archive. Details: {}", e))?,
file_hashes
.iter()
.fold(cache::hash_str(""), |acc, x| cache::extend(&acc, x)),
))
}