mirror of
https://github.com/NVIDIA/nvidia-container-toolkit
synced 2024-11-24 21:14:00 +00:00
112 lines
2.8 KiB
Go
112 lines
2.8 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() (*specs.Spec, error) {
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specFile, err := os.Open(s.path)
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if err != nil {
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return nil, 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 nil, 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 s.Spec, 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 specified 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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