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feat(etc): backup and replace pre-existing files during activation #359

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170 changes: 140 additions & 30 deletions crates/system-manager-engine/src/activate/etc_files.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,8 @@ fn get_uid_gid_regex() -> &'static regex::Regex {
UID_GID_REGEX.get_or_init(|| regex::Regex::new(r"^\+[0-9]+$").expect("could not compile regex"))
}

const BACKUP_SUFFIX: &str = ".system-manager-backup";

#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
struct EtcFile {
Expand All @@ -40,6 +42,8 @@ struct EtcFile {
group: String,
user: String,
mode: String,
#[serde(default)]
replace_existing: bool,
}

type EtcFiles = HashMap<String, EtcFile>;
Expand Down Expand Up @@ -118,29 +122,68 @@ pub fn deactivate(old_state: FileTree) -> EtcActivationResult {
Ok(final_state)
}

fn backup_path_for(path: &Path) -> PathBuf {
let mut s = path.as_os_str().to_owned();
s.push(BACKUP_SUFFIX);
PathBuf::from(s)
}

fn backup_existing_file(path: &Path) -> anyhow::Result<()> {
let backup_path = backup_path_for(path);
log::info!(
"Backing up existing file {} to {}",
path.display(),
backup_path.display()
);
fs::rename(path, &backup_path)?;
Ok(())
}

fn restore_backup(path: &Path) -> anyhow::Result<()> {
let backup_path = backup_path_for(path);
if backup_path.exists() || backup_path.is_symlink() {
log::info!(
"Restoring backup {} to {}",
backup_path.display(),
path.display()
);
fs::rename(&backup_path, path)?;
} else {
log::warn!(
"Backup file {} not found, cannot restore",
backup_path.display()
);
}
Ok(())
}

fn try_delete_path(path: &Path, status: &FileStatus) -> bool {
fn do_try_delete(path: &Path, status: &FileStatus) -> anyhow::Result<()> {
// exists() returns false for broken symlinks
if path.exists() || path.is_symlink() {
if path.is_symlink() {
remove_link(path)
remove_link(path)?;
} else if path.is_file() {
remove_file(path)
remove_file(path)?;
} else if path.is_dir() {
if path.read_dir()?.next().is_none() {
remove_dir(path)
remove_dir(path)?;
} else {
if let FileStatus::Managed = status {
if matches!(status, FileStatus::Managed | FileStatus::ManagedWithBackup) {
log::warn!("Managed directory not empty, ignoring: {}", path.display());
}
Ok(())
return Ok(());
}
} else {
anyhow::bail!("Unsupported file type! {}", path.display())
}
} else {
Ok(())
}

if *status == FileStatus::ManagedWithBackup {
restore_backup(path)?;
}

Ok(())
}

log::debug!("Deactivating: {}", path.display());
Expand Down Expand Up @@ -198,6 +241,7 @@ fn create_etc_link<P>(
etc_dir: &Path,
state: FileTree,
old_state: &FileTree,
replace_existing: bool,
) -> EtcActivationResult
where
P: AsRef<Path>,
Expand All @@ -209,6 +253,7 @@ where
state: FileTree,
old_state: &FileTree,
upwards_path: &Path,
replace_existing: bool,
) -> EtcActivationResult {
let link_path = etc_dir.join(link_target);
// Create the dir if it doesn't exist yet
Expand All @@ -232,6 +277,7 @@ where
state,
old_state,
&upwards_path.join(".."),
replace_existing,
);
match new_state {
Ok(new_state) => new_state,
Expand Down Expand Up @@ -260,12 +306,42 @@ where
.is_some()
}

/// Check whether link_path is inside a systemd .wants or .requires directory.
fn is_inside_systemd_dependency_dir(link_path: &Path) -> bool {
link_path
.parent()
.map(|parent| {
parent
.extension()
.filter(|ext| ["wants", "requires"].iter().any(|other| other == ext))
.is_some()
&& parent
.parent()
.map(|pp| pp.ends_with("systemd/system"))
.unwrap_or(false)
})
.unwrap_or(false)
}

fn backup_and_link(
target: &Path,
link_path: &Path,
dir_state: FileTree,
) -> EtcActivationResult {
backup_existing_file(link_path)
.map_err(|e| ActivationError::with_partial_result(dir_state.clone(), e))?;
create_link(target, link_path)
.map_err(|e| ActivationError::with_partial_result(dir_state.clone(), e))?;
Ok(dir_state.register_backed_up_entry(link_path))
}

fn go(
link_target: &Path,
etc_dir: &Path,
state: FileTree,
old_state: &FileTree,
upwards_path: &Path,
replace_existing: bool,
) -> EtcActivationResult {
let link_path = etc_dir.join(link_target);
let dir_state = create_dir_recursively(link_path.parent().unwrap(), state)?;
Expand All @@ -278,14 +354,20 @@ where
|| is_systemd_dependency_dir(&absolute_target)
{
if absolute_target.is_dir() {
// Auto-replace inside .wants/.requires directories
let effective_replace =
replace_existing || is_systemd_dependency_dir(&absolute_target);
link_dir_contents(
link_target,
&absolute_target,
etc_dir,
dir_state,
old_state,
upwards_path,
effective_replace,
)
} else if replace_existing || is_inside_systemd_dependency_dir(&link_path) {
backup_and_link(&target, &link_path, dir_state)
} else {
Err(ActivationError::with_partial_result(
dir_state,
Expand All @@ -300,14 +382,20 @@ where
{
log::debug!("Link {} up to date.", link_path.display());
Ok(dir_state.register_managed_entry(&link_path))
} else if link_path.exists() && !old_state.is_managed(&link_path) {
Err(ActivationError::with_partial_result(
dir_state,
anyhow::anyhow!("Unmanaged path already exists in filesystem, please remove it and run system-manager again: {}",
link_path.display()),
))
} else if (link_path.exists() || link_path.is_symlink())
&& !old_state.is_managed(&link_path)
{
if replace_existing || is_inside_systemd_dependency_dir(&link_path) {
backup_and_link(&target, &link_path, dir_state)
} else {
Err(ActivationError::with_partial_result(
dir_state,
anyhow::anyhow!("Unmanaged path already exists in filesystem, please remove it and run system-manager again: {}",
link_path.display()),
))
}
} else {
let result = if link_path.exists() {
let result = if link_path.exists() || link_path.is_symlink() {
fs::remove_file(&link_path)
.map_err(|e| ActivationError::with_partial_result(dir_state.clone(), e))
} else {
Expand All @@ -330,6 +418,7 @@ where
state,
old_state,
Path::new("."),
replace_existing,
)
}

Expand All @@ -341,7 +430,13 @@ fn create_etc_entry(
) -> EtcActivationResult {
if entry.mode == "symlink" {
if let Some(path::Component::Normal(link_target)) = entry.target.components().next() {
create_etc_link(&link_target, etc_dir, state, old_state)
create_etc_link(
&link_target,
etc_dir,
state,
old_state,
entry.replace_existing,
)
} else {
Err(ActivationError::with_partial_result(
state,
Expand All @@ -357,7 +452,14 @@ fn create_etc_entry(
entry,
old_state,
) {
Ok(_) => Ok(new_state.register_managed_entry(&target_path)),
Ok(backed_up) => {
let register = if backed_up {
FileTree::register_backed_up_entry
} else {
FileTree::register_managed_entry
};
Ok(register(new_state, &target_path))
}
Err(e) => Err(ActivationError::with_partial_result(new_state, e)),
}
}
Expand Down Expand Up @@ -456,25 +558,33 @@ fn find_gid(entry: &EtcFile) -> anyhow::Result<u32> {
}
}

/// Copy a file from source to target. Returns `Ok(true)` if a pre-existing
/// file was backed up, `Ok(false)` if no backup was needed.
fn copy_file(
source: &Path,
target: &Path,
entry: &EtcFile,
old_state: &FileTree,
) -> anyhow::Result<()> {
) -> anyhow::Result<bool> {
let exists = target.try_exists()?;
if !exists || old_state.is_managed(target) {
log::debug!(
"Copying file {} to {}...",
source.display(),
target.display()
);
fs::copy(source, target)?;
let mode_int = u32::from_str_radix(&entry.mode, 8)?;
fs::set_permissions(target, Permissions::from_mode(mode_int))?;
unixfs::chown(target, Some(find_uid(entry)?), Some(find_gid(entry)?))?;
Ok(())
let backed_up = if exists && !old_state.is_managed(target) {
if entry.replace_existing {
backup_existing_file(target)?;
true
} else {
anyhow::bail!("File {} already exists, ignoring.", target.display());
}
} else {
anyhow::bail!("File {} already exists, ignoring.", target.display());
}
false
};
log::debug!(
"Copying file {} to {}...",
source.display(),
target.display()
);
fs::copy(source, target)?;
let mode_int = u32::from_str_radix(&entry.mode, 8)?;
fs::set_permissions(target, Permissions::from_mode(mode_int))?;
unixfs::chown(target, Some(find_uid(entry)?), Some(find_gid(entry)?))?;
Ok(backed_up)
}
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