github.com/SagerNet/gvisor@v0.0.0-20210707092255-7731c139d75c/tools/verity/measure_tool_unsafe.go (about)

     1  // Copyright 2021 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  package main
    15  
    16  import (
    17  	"encoding/hex"
    18  	"fmt"
    19  	"os"
    20  	"syscall"
    21  	"unsafe"
    22  
    23  	"github.com/SagerNet/gvisor/pkg/abi/linux"
    24  )
    25  
    26  // measure prints the hash of path to stdout.
    27  func measure(path string) error {
    28  	f, err := os.Open(path)
    29  	if err != nil {
    30  		return err
    31  	}
    32  	var digest digest
    33  	digest.metadata.DigestSize = maxDigestSize
    34  	if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, uintptr(f.Fd()), uintptr(linux.FS_IOC_MEASURE_VERITY), uintptr(unsafe.Pointer(&digest))); err != 0 {
    35  		return err
    36  	}
    37  	fmt.Fprintf(os.Stdout, "%s\n", hex.EncodeToString(digest.digest[:digest.metadata.DigestSize]))
    38  	return err
    39  }