mirror of
https://github.com/NVIDIA/nvidia-container-toolkit
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4177fddcc4
This change imports the modifying runtime abstraction from the experimental branch. This encapsulates the checks for whether modification is required, and forwards the loaded spec to the specified modifier. This allows for the same code to be reused when performing more complex modifications. Signed-off-by: Evan Lezar <elezar@nvidia.com>
112 lines
2.7 KiB
Go
112 lines
2.7 KiB
Go
/*
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# Copyright (c) 2021, NVIDIA CORPORATION. All rights reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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*/
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package oci
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import (
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"encoding/json"
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"fmt"
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"io"
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"os"
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"github.com/opencontainers/runtime-spec/specs-go"
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)
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type fileSpec struct {
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memorySpec
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path string
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}
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var _ Spec = (*fileSpec)(nil)
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// NewFileSpec creates an object that encapsulates a file-backed OCI spec.
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// This can be used to read from the file, modify the spec, and write to the
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// same file.
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func NewFileSpec(filepath string) Spec {
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oci := fileSpec{
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path: filepath,
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}
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return &oci
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}
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// Load reads the contents of an OCI spec from file to be referenced internally.
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// The file is opened "read-only"
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func (s *fileSpec) Load() error {
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specFile, err := os.Open(s.path)
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if err != nil {
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return fmt.Errorf("error opening OCI specification file: %v", err)
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}
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defer specFile.Close()
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spec, err := loadFrom(specFile)
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if err != nil {
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return fmt.Errorf("error loading OCI specification from file: %v", err)
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}
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s.Spec = spec
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return nil
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}
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// loadFrom reads the contents of the OCI spec from the specified io.Reader.
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func loadFrom(reader io.Reader) (*specs.Spec, error) {
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decoder := json.NewDecoder(reader)
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var spec specs.Spec
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err := decoder.Decode(&spec)
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if err != nil {
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return nil, fmt.Errorf("error reading OCI specification: %v", err)
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}
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return &spec, nil
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}
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// Modify applies the specified SpecModifier to the stored OCI specification.
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func (s *fileSpec) Modify(m SpecModifier) error {
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return s.memorySpec.Modify(m)
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}
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// Flush writes the stored OCI specification to the filepath specifed by the path member.
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// The file is truncated upon opening, overwriting any existing contents.
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func (s fileSpec) Flush() error {
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if s.Spec == nil {
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return fmt.Errorf("no OCI specification loaded")
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}
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specFile, err := os.Create(s.path)
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if err != nil {
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return fmt.Errorf("error opening OCI specification file: %v", err)
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}
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defer specFile.Close()
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return flushTo(s.Spec, specFile)
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}
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// flushTo writes the stored OCI specification to the specified io.Writer.
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func flushTo(spec *specs.Spec, writer io.Writer) error {
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if spec == nil {
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return nil
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}
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encoder := json.NewEncoder(writer)
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err := encoder.Encode(spec)
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if err != nil {
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return fmt.Errorf("error writing OCI specification: %v", err)
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}
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return nil
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}
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