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75 lines
2.1 KiB
75 lines
2.1 KiB
/*
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Copyright The Helm Authors.
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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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http://www.apache.org/licenses/LICENSE-2.0
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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 archive
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import (
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"fmt"
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"io"
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"math"
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"os"
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)
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// BudgetedReader tracks cumulative file reads against a size limit.
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type BudgetedReader struct {
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max int64
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remaining int64
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}
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// NewBudgetedReader creates a BudgetedReader with the given maximum total size.
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// The remaining budget is initialized to the maximum.
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func NewBudgetedReader(limit int64) *BudgetedReader {
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return &BudgetedReader{
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max: limit,
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remaining: limit,
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}
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}
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// ReadFileWithBudget reads a file and decrements the remaining budget by the bytes read.
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// It returns an error if the total would exceed the configured maximum.
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// The read is capped via io.LimitReader so a file that grows between stat
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// and read cannot cause unbounded memory allocation.
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func (r *BudgetedReader) ReadFileWithBudget(path string, size int64) ([]byte, error) {
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if size > r.remaining {
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return nil, fmt.Errorf("chart exceeds maximum decompressed size of %d bytes", r.max)
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}
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f, err := os.Open(path)
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if err != nil {
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return nil, err
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}
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defer f.Close()
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// Read at most r.remaining+1 bytes so we can detect over-budget without
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// allocating unbounded memory if the file grew since stat.
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// Clamp to avoid int64 overflow when r.remaining is near math.MaxInt64.
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limit := r.remaining
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if limit < math.MaxInt64 {
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limit++
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}
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data, err := io.ReadAll(io.LimitReader(f, limit))
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if err != nil {
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return nil, err
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}
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if int64(len(data)) > r.remaining {
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return nil, fmt.Errorf("chart exceeds maximum decompressed size of %d bytes", r.max)
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}
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r.remaining -= int64(len(data))
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return data, nil
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}
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