github.com/sagernet/gvisor@v0.0.0-20240428053021-e691de28565f/pkg/usermem/bytes_io_unsafe.go (about)

     1  // Copyright 2018 The gVisor Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package usermem
    16  
    17  import (
    18  	"unsafe"
    19  
    20  	"github.com/sagernet/gvisor/pkg/atomicbitops"
    21  	"github.com/sagernet/gvisor/pkg/context"
    22  	"github.com/sagernet/gvisor/pkg/hostarch"
    23  )
    24  
    25  // SwapUint32 implements IO.SwapUint32.
    26  func (b *BytesIO) SwapUint32(ctx context.Context, addr hostarch.Addr, new uint32, opts IOOpts) (uint32, error) {
    27  	if _, rngErr := b.rangeCheck(addr, 4); rngErr != nil {
    28  		return 0, rngErr
    29  	}
    30  	return (*atomicbitops.Uint32)(unsafe.Pointer(&b.Bytes[int(addr)])).Swap(new), nil
    31  
    32  }
    33  
    34  // CompareAndSwapUint32 implements IO.CompareAndSwapUint32.
    35  func (b *BytesIO) CompareAndSwapUint32(ctx context.Context, addr hostarch.Addr, old, new uint32, opts IOOpts) (uint32, error) {
    36  	if _, rngErr := b.rangeCheck(addr, 4); rngErr != nil {
    37  		return 0, rngErr
    38  	}
    39  	return atomicbitops.CompareAndSwapUint32((*atomicbitops.Uint32)(unsafe.Pointer(&b.Bytes[int(addr)])), old, new), nil
    40  }
    41  
    42  // LoadUint32 implements IO.LoadUint32.
    43  func (b *BytesIO) LoadUint32(ctx context.Context, addr hostarch.Addr, opts IOOpts) (uint32, error) {
    44  	if _, err := b.rangeCheck(addr, 4); err != nil {
    45  		return 0, err
    46  	}
    47  	return (*atomicbitops.Uint32)(unsafe.Pointer(&b.Bytes[int(addr)])).Load(), nil
    48  }