gvisor.dev/gvisor@v0.0.0-20240520182842-f9d4d51c7e0f/runsc/cmd/fd_mapping.go (about)

     1  // Copyright 2023 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  	"fmt"
    19  	"strconv"
    20  	"strings"
    21  
    22  	"gvisor.dev/gvisor/runsc/boot"
    23  )
    24  
    25  // fdMappings can be used with flags that appear multiple times.
    26  type fdMappings []boot.FDMapping
    27  
    28  // String implements flag.Value.
    29  func (i *fdMappings) String() string {
    30  	var mappings []string
    31  	for _, m := range *i {
    32  		mappings = append(mappings, fmt.Sprintf("%v:%v", m.Host, m.Guest))
    33  	}
    34  	return strings.Join(mappings, ",")
    35  }
    36  
    37  // Get implements flag.Value.
    38  func (i *fdMappings) Get() any {
    39  	return i
    40  }
    41  
    42  // GetArray returns an array of mappings.
    43  func (i *fdMappings) GetArray() []boot.FDMapping {
    44  	return *i
    45  }
    46  
    47  // Set implements flag.Value and appends a mapping from the command line to the
    48  // mappings array. Set(String()) should be idempotent.
    49  func (i *fdMappings) Set(s string) error {
    50  	for _, m := range strings.Split(s, ",") {
    51  		split := strings.Split(m, ":")
    52  		if len(split) != 2 {
    53  			// Split returns a slice of length 1 if its first argument does not
    54  			// contain the separator. An additional length check is not necessary.
    55  			// In case no separator is used and the argument is a valid integer, we
    56  			// assume that host FD and guest FD should be identical.
    57  			fd, err := strconv.Atoi(split[0])
    58  			if err != nil {
    59  				return fmt.Errorf("invalid flag value: must be an integer or a mapping of format M:N")
    60  			}
    61  			*i = append(*i, boot.FDMapping{
    62  				Host:  fd,
    63  				Guest: fd,
    64  			})
    65  			return nil
    66  		}
    67  
    68  		fdHost, err := strconv.Atoi(split[0])
    69  		if err != nil {
    70  			return fmt.Errorf("invalid flag host value: %v", err)
    71  		}
    72  		if fdHost < 0 {
    73  			return fmt.Errorf("flag host value must be >= 0: %d", fdHost)
    74  		}
    75  
    76  		fdGuest, err := strconv.Atoi(split[1])
    77  		if err != nil {
    78  			return fmt.Errorf("invalid flag guest value: %v", err)
    79  		}
    80  		if fdGuest < 0 {
    81  			return fmt.Errorf("flag guest value must be >= 0: %d", fdGuest)
    82  		}
    83  
    84  		*i = append(*i, boot.FDMapping{
    85  			Host:  fdHost,
    86  			Guest: fdGuest,
    87  		})
    88  	}
    89  	return nil
    90  }