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mv: use RENAME_NOREPLACE when we can #7832

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mv: use RENAME_NOREPLACE when we can #7832

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1 change: 1 addition & 0 deletions Cargo.lock
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1 change: 1 addition & 0 deletions src/uu/mv/Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,7 @@ clap = { workspace = true }
fs_extra = { workspace = true }
indicatif = { workspace = true }
libc = { workspace = true }
nix = { workspace = true }
thiserror = { workspace = true }
uucore = { workspace = true, features = [
"backup-control",
Expand Down
102 changes: 67 additions & 35 deletions src/uu/mv/src/mv.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,13 +3,15 @@
// For the full copyright and license information, please view the LICENSE
// file that was distributed with this source code.

// spell-checker:ignore (ToDO) sourcepath targetpath nushell canonicalized
// spell-checker:ignore NOREPLACE TOCTOU canonicalized nushell renameat sourcepath targetpath

mod error;

use clap::builder::ValueParser;
use clap::{Arg, ArgAction, ArgMatches, Command, error::ErrorKind};
use indicatif::{MultiProgress, ProgressBar, ProgressStyle};
#[cfg(all(target_os = "linux", target_env = "gnu"))]
use nix::{errno::Errno, fcntl};

use std::collections::HashSet;
use std::env;
Expand Down Expand Up @@ -596,23 +598,42 @@ fn rename(
) -> io::Result<()> {
let mut backup_path = None;

if to.exists() {
if opts.update == UpdateMode::None {
if opts.debug {
println!("skipped {}", to.quote());
}
return Ok(());
}

if (opts.update == UpdateMode::IfOlder)
&& fs::metadata(from)?.modified()? <= fs::metadata(to)?.modified()?
{
return Ok(());
let already_exists = if opts.overwrite == OverwriteMode::Force
&& opts.update == UpdateMode::All
&& opts.backup == BackupMode::None
{
// fast path, no need to check for overwrites
rename_with_fallback(from, to, multi_progress)?;
false
} else {
// try to move without overwriting
match rename_no_replace(from, to, multi_progress) {
Ok(()) => false,
Err(e) if e.kind() == io::ErrorKind::AlreadyExists => true,
Err(e) => Err(e)?,
}
};

if opts.update == UpdateMode::NoneFail {
let err_msg = format!("not replacing {}", to.quote());
return Err(io::Error::other(err_msg));
if already_exists {
match opts.update {
UpdateMode::None => {
if opts.debug {
println!("skipped {}", to.quote());
}
return Ok(());
}
UpdateMode::IfOlder => {
if fs::metadata(from)?.modified()? <= fs::metadata(to)?.modified()? {
return Ok(());
}
// There's a TOCTOU here, if `to` gets replaced with a newer version.
// I don't think there's a way to fix it.
}
UpdateMode::NoneFail => {
let err_msg = format!("not replacing {}", to.quote());
return Err(io::Error::other(err_msg));
}
UpdateMode::All => {}
}

match opts.overwrite {
Expand All @@ -634,21 +655,17 @@ fn rename(
if let Some(ref backup_path) = backup_path {
rename_with_fallback(to, backup_path, multi_progress)?;
}
}

// "to" may no longer exist if it was backed up
if to.exists() && to.is_dir() {
// normalize behavior between *nix and windows
if from.is_dir() {
if is_empty_dir(to) {
fs::remove_dir(to)?;
} else {
return Err(io::Error::other("Directory not empty"));
}
#[cfg(windows)]
// older versions of windows don't handle this automatically,
// see std::fs::rename docs
if to.is_dir() && from.is_dir() {
// this checks if dir is empty for us, and returns the appropriate error if not
fs::remove_dir(to)?;
}
}

rename_with_fallback(from, to, multi_progress)?;
rename_with_fallback(from, to, multi_progress)?;
}

if opts.verbose {
let message = match backup_path {
Expand Down Expand Up @@ -681,6 +698,28 @@ fn is_fifo(_filetype: fs::FileType) -> bool {
false
}

/// Attempts to use atomic renaming that avoids overwriting files, if available from the OS,
/// otherwise checks if `to` exists and calls `rename_with_fallback` (allowing races).
/// In either case, returns `io::ErrorKind::AlreadyExists` kind if `to` exists.
fn rename_no_replace(
from: &Path,
to: &Path,
multi_progress: Option<&MultiProgress>,
) -> io::Result<()> {
#[cfg(all(target_os = "linux", target_env = "gnu"))]
match fcntl::renameat2(None, from, None, to, fcntl::RenameFlags::RENAME_NOREPLACE) {
Ok(()) => return Ok(()),
Err(Errno::EINVAL) => {} // could be unsupported on platform, continue
Err(e) => Err(e)?,
}

if to.exists() {
Err(io::Error::from(io::ErrorKind::AlreadyExists))
} else {
rename_with_fallback(from, to, multi_progress)
}
}

/// A wrapper around `fs::rename`, so that if it fails, we try falling back on
/// copying and removing.
fn rename_with_fallback(
Expand Down Expand Up @@ -855,13 +894,6 @@ fn rename_file_fallback(from: &Path, to: &Path) -> io::Result<()> {
Ok(())
}

fn is_empty_dir(path: &Path) -> bool {
match fs::read_dir(path) {
Ok(contents) => contents.peekable().peek().is_none(),
Err(_e) => false,
}
}

/// Checks if a file can be deleted by attempting to open it with delete permissions.
#[cfg(windows)]
fn can_delete_file(path: &Path) -> Result<bool, io::Error> {
Expand Down
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