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fix: local BE - don't leave broken files when writing fails #499

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Merged
aawsome merged 1 commit into from
Apr 27, 2026
+121 −69
Merged

fix: local BE - don't leave broken files when writing fails #499

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128 changes: 79 additions & 49 deletions crates/backend/src/local.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -90,6 +90,13 @@ impl LocalBackend {
}
}

fn filename(tpe: FileType, id: &Id) -> String {
match tpe {
FileType::Config => "config".to_string(),
_ => id.to_hex().to_string(),
}
}

/// Path to the given file type and id.
///
/// If the file type is `FileType::Pack`, the id will be used to determine the subdirectory.
Expand All @@ -103,11 +110,7 @@ impl LocalBackend {
///
/// The path to the file.
fn path(&self, tpe: FileType, id: &Id) -> PathBuf {
let hex_id = id.to_hex();
match tpe {
FileType::Config => self.path.join("config"),
_ => self.base_path(tpe, id).join(hex_id),
}
self.base_path(tpe, id).join(Self::filename(tpe, id))
}

/// Call the given command.
Expand Down Expand Up @@ -469,70 +472,97 @@ impl WriteBackend for LocalBackend {
_cacheable: bool,
buf: Bytes,
) -> RusticResult<()> {
trace!("writing tpe: {:?}, id: {}", &tpe, &id);
let filename = self.path(tpe, id);

let parent = self.base_path(tpe, id);
fn write_local_file(filename: &Path, buf: &[u8]) -> RusticResult<()> {
let length = buf.len().try_into().map_err(|err| {
RusticError::with_source(
ErrorKind::Internal,
"Failed to convert length `{length}` to u64.",
err,
)
.attach_context("length", buf.len().to_string())
.ask_report()
})?;

// create parent directory if it does not exist
fs::create_dir_all(&parent).map_err(|err| {
RusticError::with_source(
ErrorKind::InputOutput,
"Failed to create directories `{path}`. Does the directory already exist? Please check the file and try again.",
err,
)
.attach_context("path", parent.display().to_string())
.ask_report()
})?;
let mut file = fs::OpenOptions::new()
.create(true)
.truncate(true)
.write(true)
.open(filename)
.map_err(|err| {
RusticError::with_source(
ErrorKind::InputOutput,
"Failed to open the file `{path}`. Please check the file and try again.",
err,
)
.attach_context("path", filename.to_string_lossy())
})?;

file.set_len(length)
.map_err(|err| {
RusticError::with_source(
ErrorKind::InputOutput,
"Failed to set the length of the file `{path}`. Please check the file and try again.",
err,
)
.attach_context("path", filename.to_string_lossy())
})?;

let mut file = fs::OpenOptions::new()
.create(true)
.truncate(true)
.write(true)
.open(&filename)
.map_err(|err| {
file.write_all(buf).map_err(|err| {
RusticError::with_source(
ErrorKind::InputOutput,
"Failed to write to the buffer: `{path}`. Please check the file and try again.",
err,
)
.attach_context("path", filename.to_string_lossy())
})?;
file.sync_all().map_err(|err| {
RusticError::with_source(
ErrorKind::InputOutput,
"Failed to open the file `{path}`. Please check the file and try again.",
"Failed to sync OS Metadata to disk: `{path}`. Please check the file and try again.",
err,
)
.attach_context("path", filename.to_string_lossy())
})?;
Ok(())
}

file.set_len(buf.len().try_into().map_err(|err| {
RusticError::with_source(
ErrorKind::Internal,
"Failed to convert length `{length}` to u64.",
err,
)
.attach_context("length", buf.len().to_string())
.ask_report()
})?)
.map_err(|err| {
RusticError::with_source(
ErrorKind::InputOutput,
"Failed to set the length of the file `{path}`. Please check the file and try again.",
err,
)
.attach_context("path", filename.to_string_lossy())
})?;
trace!("writing tpe: {:?}, id: {}", &tpe, &id);
let filename = self.path(tpe, id);

let parent = self.base_path(tpe, id);

file.write_all(&buf).map_err(|err| {
// create parent directory if it does not exist
fs::create_dir_all(&parent)
.map_err(|err| {
RusticError::with_source(
ErrorKind::InputOutput,
"Failed to write to the buffer: `{path}`. Please check the file and try again.",
"Failed to create directories `{path}`. Does the directory already exist? Please check the file and try again.",
err,
)
.attach_context("path", filename.to_string_lossy())
.attach_context("path", parent.display().to_string())
.ask_report()
})?;

file.sync_all().map_err(|err| {
// Write to temporary file
let filename_tmp = parent.join(Self::filename(tpe, id) + "-tmp-");
match write_local_file(&filename_tmp, &buf) {
Ok(file) => file,
Err(err) => {
// Clean-up in case of error
_ = fs::remove_file(&filename_tmp);
return Err(err);
}
}
// rename temporary file to real file
fs::rename(&filename_tmp, &filename).map_err(|err| {
RusticError::with_source(
ErrorKind::InputOutput,
"Failed to sync OS Metadata to disk: `{path}`. Please check the file and try again.",
"Failed to move `{path_tmp}` to `{path}`",
err,
)
.attach_context("path", filename.to_string_lossy())
.attach_context("path_tmp", filename_tmp.display().to_string())
.attach_context("path", filename.display().to_string())
.ask_report()
})?;

if let Some(command) = &self.post_create_command
Expand Down
62 changes: 42 additions & 20 deletions crates/core/src/backend/cache.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@ use std::{
collections::HashMap,
fs::{self, File},
io::{self, Read, Seek, SeekFrom, Write},
path::PathBuf,
path::{Path, PathBuf},
sync::Arc,
};

Expand Down Expand Up @@ -538,10 +538,37 @@ impl Cache {
///
/// * If the file could not be written.
pub fn write_bytes(&self, tpe: FileType, id: &Id, buf: &Bytes) -> RusticResult<()> {
fn write_local_file(filename: &Path, buf: &[u8]) -> RusticResult<()> {
let mut file = fs::OpenOptions::new()
.create(true)
.truncate(true)
.write(true)
.open(filename)
.map_err(|err| {
RusticError::with_source(
ErrorKind::InputOutput,
"Failed to open the file `{path}`.",
err,
)
.attach_context("path", filename.to_string_lossy())
})?;

file.write_all(buf).map_err(|err| {
RusticError::with_source(
ErrorKind::InputOutput,
"Failed to write to the buffer: `{path}`.",
err,
)
.attach_context("path", filename.to_string_lossy())
})?;
Ok(())
}

trace!("cache writing tpe: {:?}, id: {}", &tpe, &id);

let dir = self.dir(tpe, id);

// create parent directory if it does not exist
fs::create_dir_all(&dir).map_err(|err| {
RusticError::with_source(
ErrorKind::InputOutput,
Expand All @@ -554,30 +581,25 @@ impl Cache {
})?;

let filename = self.path(tpe, id);

let mut file = fs::OpenOptions::new()
.create(true)
.truncate(true)
.write(true)
.open(&filename)
.map_err(|err| {
RusticError::with_source(
ErrorKind::InputOutput,
"Failed to open file at `{path}`",
err,
)
.attach_context("path", filename.display().to_string())
})?;

file.write_all(buf).map_err(|err| {
let filename_tmp = dir.join(id.to_hex().to_string() + "-tmp-");
match write_local_file(&filename_tmp, buf) {
Ok(file) => file,
Err(err) => {
// Clean-up in case of error
_ = fs::remove_file(&filename_tmp);
return Err(err);
}
}
// rename temporary file to real file
fs::rename(&filename_tmp, &filename).map_err(|err| {
RusticError::with_source(
ErrorKind::InputOutput,
"Failed to write to buffer at `{path}`",
"Failed to move `{path_tmp}` to `{path}`",
err,
)
.attach_context("path_tmp", filename_tmp.display().to_string())
.attach_context("path", filename.display().to_string())
.attach_context("tpe", tpe.to_string())
.attach_context("id", id.to_string())
.ask_report()
})?;

Ok(())
Expand Down
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