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Auto merge of #75428 - the8472:fix-copy-eopnotsupp, r=joshtriplett
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Workarounds for copy_file_range issues

fixes #75387
fixes #75446
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bors committed Sep 5, 2020
2 parents 04f44fb + 4ddedd5 commit de921ab
Showing 1 changed file with 17 additions and 10 deletions.
27 changes: 17 additions & 10 deletions library/std/src/sys/unix/fs.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1140,14 +1140,14 @@ pub fn copy(from: &Path, to: &Path) -> io::Result<u64> {
}

let (mut reader, reader_metadata) = open_from(from)?;
let len = reader_metadata.len();
let max_len = u64::MAX;
let (mut writer, _) = open_to_and_set_permissions(to, reader_metadata)?;

let has_copy_file_range = HAS_COPY_FILE_RANGE.load(Ordering::Relaxed);
let mut written = 0u64;
while written < len {
while written < max_len {
let copy_result = if has_copy_file_range {
let bytes_to_copy = cmp::min(len - written, usize::MAX as u64) as usize;
let bytes_to_copy = cmp::min(max_len - written, usize::MAX as u64) as usize;
let copy_result = unsafe {
// We actually don't have to adjust the offsets,
// because copy_file_range adjusts the file offset automatically
Expand All @@ -1162,7 +1162,7 @@ pub fn copy(from: &Path, to: &Path) -> io::Result<u64> {
};
if let Err(ref copy_err) = copy_result {
match copy_err.raw_os_error() {
Some(libc::ENOSYS) | Some(libc::EPERM) => {
Some(libc::ENOSYS | libc::EPERM | libc::EOPNOTSUPP) => {
HAS_COPY_FILE_RANGE.store(false, Ordering::Relaxed);
}
_ => {}
Expand All @@ -1173,18 +1173,25 @@ pub fn copy(from: &Path, to: &Path) -> io::Result<u64> {
Err(io::Error::from_raw_os_error(libc::ENOSYS))
};
match copy_result {
Ok(0) if written == 0 => {
// fallback to work around several kernel bugs where copy_file_range will fail to
// copy any bytes and return 0 instead of an error if
// - reading virtual files from the proc filesystem which appear to have 0 size
// but are not empty. noted in coreutils to affect kernels at least up to 5.6.19.
// - copying from an overlay filesystem in docker. reported to occur on fedora 32.
return io::copy(&mut reader, &mut writer);
}
Ok(0) => return Ok(written), // reached EOF
Ok(ret) => written += ret as u64,
Err(err) => {
match err.raw_os_error() {
Some(os_err)
if os_err == libc::ENOSYS
|| os_err == libc::EXDEV
|| os_err == libc::EINVAL
|| os_err == libc::EPERM =>
{
Some(
libc::ENOSYS | libc::EXDEV | libc::EINVAL | libc::EPERM | libc::EOPNOTSUPP,
) => {
// Try fallback io::copy if either:
// - Kernel version is < 4.5 (ENOSYS)
// - Files are mounted on different fs (EXDEV)
// - copy_file_range is broken in various ways on RHEL/CentOS 7 (EOPNOTSUPP)
// - copy_file_range is disallowed, for example by seccomp (EPERM)
// - copy_file_range cannot be used with pipes or device nodes (EINVAL)
assert_eq!(written, 0);
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