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//go:build linux || darwin || freebsd || netbsd
package archive
import (
"errors"
"fmt"
"io/fs"
"golang.org/x/sys/unix"
)
// lgetxattr retrieves the value of the extended attribute identified by attr
// and associated with the given path in the file system.
// It returns a nil slice and nil error if the xattr is not set.
func lgetxattr(path string, attr string) ([]byte, error) {
// Start with a 128 length byte array
dest := make([]byte, 128)
sz, err := unix.Lgetxattr(path, attr, dest)
for errors.Is(err, unix.ERANGE) {
// Buffer too small, use zero-sized buffer to get the actual size
sz, err = unix.Lgetxattr(path, attr, []byte{})
if err != nil {
return nil, wrapPathError("lgetxattr", path, attr, err)
}
dest = make([]byte, sz)
sz, err = unix.Lgetxattr(path, attr, dest)
}
if err != nil {
if errors.Is(err, noattr) {
return nil, nil
}
return nil, wrapPathError("lgetxattr", path, attr, err)
}
return dest[:sz], nil
}
// lsetxattr sets the value of the extended attribute identified by attr
// and associated with the given path in the file system.
func lsetxattr(path string, attr string, data []byte, flags int) error {
return wrapPathError("lsetxattr", path, attr, unix.Lsetxattr(path, attr, data, flags))
}
func wrapPathError(op, path, attr string, err error) error {
if err == nil {
return nil
}
return &fs.PathError{Op: op, Path: path, Err: fmt.Errorf("xattr %q: %w", attr, err)}
}
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