github.com/SagerNet/gvisor@v0.0.0-20210707092255-7731c139d75c/runsc/cmd/statefile.go (about)

     1  // Copyright 2020 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 cmd
    16  
    17  import (
    18  	"context"
    19  	"fmt"
    20  	"os"
    21  
    22  	"github.com/google/subcommands"
    23  	"github.com/SagerNet/gvisor/pkg/state/pretty"
    24  	"github.com/SagerNet/gvisor/pkg/state/statefile"
    25  	"github.com/SagerNet/gvisor/runsc/flag"
    26  )
    27  
    28  // Statefile implements subcommands.Command for the "statefile" command.
    29  type Statefile struct {
    30  	list   bool
    31  	get    string
    32  	key    string
    33  	output string
    34  	html   bool
    35  }
    36  
    37  // Name implements subcommands.Command.
    38  func (*Statefile) Name() string {
    39  	return "state"
    40  }
    41  
    42  // Synopsis implements subcommands.Command.
    43  func (*Statefile) Synopsis() string {
    44  	return "shows information about a statefile"
    45  }
    46  
    47  // Usage implements subcommands.Command.
    48  func (*Statefile) Usage() string {
    49  	return `statefile [flags] <statefile>`
    50  }
    51  
    52  // SetFlags implements subcommands.Command.
    53  func (s *Statefile) SetFlags(f *flag.FlagSet) {
    54  	f.BoolVar(&s.list, "list", false, "lists the metdata in the statefile.")
    55  	f.StringVar(&s.get, "get", "", "extracts the given metadata key.")
    56  	f.StringVar(&s.key, "key", "", "the integrity key for the file.")
    57  	f.StringVar(&s.output, "output", "", "target to write the result.")
    58  	f.BoolVar(&s.html, "html", false, "outputs in HTML format.")
    59  }
    60  
    61  // Execute implements subcommands.Command.Execute.
    62  func (s *Statefile) Execute(_ context.Context, f *flag.FlagSet, args ...interface{}) subcommands.ExitStatus {
    63  	// Check arguments.
    64  	if s.list && s.get != "" {
    65  		Fatalf("error: can't specify -list and -get simultaneously.")
    66  	}
    67  
    68  	// Setup output.
    69  	var output = os.Stdout // Default.
    70  	if s.output != "" {
    71  		f, err := os.OpenFile(s.output, os.O_WRONLY|os.O_TRUNC|os.O_CREATE, 0644)
    72  		if err != nil {
    73  			Fatalf("error opening output: %v", err)
    74  		}
    75  		defer func() {
    76  			if err := f.Close(); err != nil {
    77  				Fatalf("error flushing output: %v", err)
    78  			}
    79  		}()
    80  		output = f
    81  	}
    82  
    83  	// Open the file.
    84  	if f.NArg() != 1 {
    85  		f.Usage()
    86  		return subcommands.ExitUsageError
    87  	}
    88  	input, err := os.Open(f.Arg(0))
    89  	if err != nil {
    90  		Fatalf("error opening input: %v\n", err)
    91  	}
    92  
    93  	if s.html {
    94  		fmt.Fprintf(output, "<html><body>\n")
    95  		defer fmt.Fprintf(output, "</body></html>\n")
    96  	}
    97  
    98  	// Dump the full file?
    99  	if !s.list && s.get == "" {
   100  		var key []byte
   101  		if s.key != "" {
   102  			key = []byte(s.key)
   103  		}
   104  		rc, _, err := statefile.NewReader(input, key)
   105  		if err != nil {
   106  			Fatalf("error parsing statefile: %v", err)
   107  		}
   108  		if s.html {
   109  			if err := pretty.PrintHTML(output, rc); err != nil {
   110  				Fatalf("error printing state: %v", err)
   111  			}
   112  		} else {
   113  			if err := pretty.PrintText(output, rc); err != nil {
   114  				Fatalf("error printing state: %v", err)
   115  			}
   116  		}
   117  		return subcommands.ExitSuccess
   118  	}
   119  
   120  	// Load just the metadata.
   121  	metadata, err := statefile.MetadataUnsafe(input)
   122  	if err != nil {
   123  		Fatalf("error reading metadata: %v", err)
   124  	}
   125  
   126  	// Is it a single key?
   127  	if s.get != "" {
   128  		val, ok := metadata[s.get]
   129  		if !ok {
   130  			Fatalf("metadata key %s: not found", s.get)
   131  		}
   132  		fmt.Fprintf(output, "%s\n", val)
   133  		return subcommands.ExitSuccess
   134  	}
   135  
   136  	// List all keys.
   137  	if s.html {
   138  		fmt.Fprintf(output, " <ul>\n")
   139  		defer fmt.Fprintf(output, " </ul>\n")
   140  	}
   141  	for key := range metadata {
   142  		if s.html {
   143  			fmt.Fprintf(output, "  <li>%s</li>\n", key)
   144  		} else {
   145  			fmt.Fprintf(output, "%s\n", key)
   146  		}
   147  	}
   148  	return subcommands.ExitSuccess
   149  }