gvisor.dev/gvisor@v0.0.0-20240520182842-f9d4d51c7e0f/pkg/sentry/fsimpl/iouringfs/iouringfs_unsafe.go (about)

     1  // Copyright 2022 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 iouringfs
    16  
    17  import (
    18  	"fmt"
    19  	"unsafe"
    20  
    21  	"gvisor.dev/gvisor/pkg/atomicbitops"
    22  )
    23  
    24  func atomicUint32AtOffset(buf []byte, offset int) *atomicbitops.Uint32 {
    25  	const sizeOfUint32 int = 4
    26  	if offset+sizeOfUint32 > len(buf) || offset < 0 {
    27  		panic(fmt.Sprintf("cast at offset %d for slice of len %d would result in overrun", offset, len(buf)))
    28  	}
    29  	if offset%sizeOfUint32 != 0 {
    30  		panic(fmt.Sprintf("cast at offset %d would produce unaligned pointer", offset))
    31  	}
    32  	return (*atomicbitops.Uint32)(unsafe.Pointer(&buf[offset]))
    33  }