syncthing/lib/fs/basicfs_copy_range.go

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// Copyright (C) 2020 The Syncthing Authors.
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this file,
// You can obtain one at https://mozilla.org/MPL/2.0/.
package fs
import (
"syscall"
)
type copyRangeImplementationBasicFile func(src, dst basicFile, srcOffset, dstOffset, size int64) error
func copyRangeImplementationForBasicFile(impl copyRangeImplementationBasicFile) copyRangeImplementation {
return func(src, dst File, srcOffset, dstOffset, size int64) error {
src = unwrap(src)
dst = unwrap(dst)
// Then see if it's basic files
srcFile, srcOk := src.(basicFile)
dstFile, dstOk := dst.(basicFile)
if !srcOk || !dstOk {
return syscall.ENOTSUP
}
return impl(srcFile, dstFile, srcOffset, dstOffset, size)
}
}
func withFileDescriptors(first, second basicFile, fn func(first, second uintptr) (int, error)) (int, error) {
fc, err := first.SyscallConn()
if err != nil {
return 0, err
}
sc, err := second.SyscallConn()
if err != nil {
return 0, err
}
var n int
var ferr, serr, fnerr error
ferr = fc.Control(func(first uintptr) {
serr = sc.Control(func(second uintptr) {
n, fnerr = fn(first, second)
})
})
if ferr != nil {
return n, ferr
}
if serr != nil {
return n, serr
}
return n, fnerr
}
func unwrap(f File) File {
for {
if wrapped, ok := f.(interface{ unwrap() File }); ok {
f = wrapped.unwrap()
} else {
return f
}
}
}