github.com/MerlinKodo/gvisor@v0.0.0-20231110090155-957f62ecf90e/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/MerlinKodo/gvisor/pkg/state/pretty"
    23  	"github.com/MerlinKodo/gvisor/pkg/state/statefile"
    24  	"github.com/MerlinKodo/gvisor/runsc/cmd/util"
    25  	"github.com/MerlinKodo/gvisor/runsc/flag"
    26  	"github.com/google/subcommands"
    27  )
    28  
    29  // Statefile implements subcommands.Command for the "statefile" command.
    30  type Statefile struct {
    31  	list   bool
    32  	get    string
    33  	key    string
    34  	output string
    35  	html   bool
    36  }
    37  
    38  // Name implements subcommands.Command.
    39  func (*Statefile) Name() string {
    40  	return "state"
    41  }
    42  
    43  // Synopsis implements subcommands.Command.
    44  func (*Statefile) Synopsis() string {
    45  	return "shows information about a statefile"
    46  }
    47  
    48  // Usage implements subcommands.Command.
    49  func (*Statefile) Usage() string {
    50  	return `statefile [flags] <statefile>`
    51  }
    52  
    53  // SetFlags implements subcommands.Command.
    54  func (s *Statefile) SetFlags(f *flag.FlagSet) {
    55  	f.BoolVar(&s.list, "list", false, "lists the metdata in the statefile.")
    56  	f.StringVar(&s.get, "get", "", "extracts the given metadata key.")
    57  	f.StringVar(&s.key, "key", "", "the integrity key for the file.")
    58  	f.StringVar(&s.output, "output", "", "target to write the result.")
    59  	f.BoolVar(&s.html, "html", false, "outputs in HTML format.")
    60  }
    61  
    62  // Execute implements subcommands.Command.Execute.
    63  func (s *Statefile) Execute(_ context.Context, f *flag.FlagSet, args ...any) subcommands.ExitStatus {
    64  	// Check arguments.
    65  	if s.list && s.get != "" {
    66  		util.Fatalf("error: can't specify -list and -get simultaneously.")
    67  	}
    68  
    69  	// Setup output.
    70  	var output = os.Stdout // Default.
    71  	if s.output != "" {
    72  		f, err := os.OpenFile(s.output, os.O_WRONLY|os.O_TRUNC|os.O_CREATE, 0644)
    73  		if err != nil {
    74  			util.Fatalf("error opening output: %v", err)
    75  		}
    76  		defer func() {
    77  			if err := f.Close(); err != nil {
    78  				util.Fatalf("error flushing output: %v", err)
    79  			}
    80  		}()
    81  		output = f
    82  	}
    83  
    84  	// Open the file.
    85  	if f.NArg() != 1 {
    86  		f.Usage()
    87  		return subcommands.ExitUsageError
    88  	}
    89  	input, err := os.Open(f.Arg(0))
    90  	if err != nil {
    91  		util.Fatalf("error opening input: %v\n", err)
    92  	}
    93  
    94  	if s.html {
    95  		fmt.Fprintf(output, "<html><body>\n")
    96  		defer fmt.Fprintf(output, "</body></html>\n")
    97  	}
    98  
    99  	// Dump the full file?
   100  	if !s.list && s.get == "" {
   101  		var key []byte
   102  		if s.key != "" {
   103  			key = []byte(s.key)
   104  		}
   105  		rc, _, err := statefile.NewReader(input, key)
   106  		if err != nil {
   107  			util.Fatalf("error parsing statefile: %v", err)
   108  		}
   109  		if s.html {
   110  			if err := pretty.PrintHTML(output, rc); err != nil {
   111  				util.Fatalf("error printing state: %v", err)
   112  			}
   113  		} else {
   114  			if err := pretty.PrintText(output, rc); err != nil {
   115  				util.Fatalf("error printing state: %v", err)
   116  			}
   117  		}
   118  		return subcommands.ExitSuccess
   119  	}
   120  
   121  	// Load just the metadata.
   122  	metadata, err := statefile.MetadataUnsafe(input)
   123  	if err != nil {
   124  		util.Fatalf("error reading metadata: %v", err)
   125  	}
   126  
   127  	// Is it a single key?
   128  	if s.get != "" {
   129  		val, ok := metadata[s.get]
   130  		if !ok {
   131  			util.Fatalf("metadata key %s: not found", s.get)
   132  		}
   133  		fmt.Fprintf(output, "%s\n", val)
   134  		return subcommands.ExitSuccess
   135  	}
   136  
   137  	// List all keys.
   138  	if s.html {
   139  		fmt.Fprintf(output, " <ul>\n")
   140  		defer fmt.Fprintf(output, " </ul>\n")
   141  	}
   142  	for key := range metadata {
   143  		if s.html {
   144  			fmt.Fprintf(output, "  <li>%s</li>\n", key)
   145  		} else {
   146  			fmt.Fprintf(output, "%s\n", key)
   147  		}
   148  	}
   149  	return subcommands.ExitSuccess
   150  }