57 lines
1.6 KiB
Go
57 lines
1.6 KiB
Go
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// Copyright 2022 Google Inc. 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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package main
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import (
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"bufio"
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"fmt"
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"io"
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"os"
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"strings"
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)
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const hashPrefix = "# pg_map_hash: "
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const hashTypePrefix = "SHA-256 "
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const commentPrefix = "#"
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// r8Identifier extracts the hash from the comments of a dictionary produced by R8. It returns
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// an empty identifier if no matching comment was found before the first non-comment line.
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func r8Identifier(filename string) (string, error) {
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f, err := os.Open(filename)
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if err != nil {
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return "", fmt.Errorf("failed to open %s: %w", filename, err)
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}
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defer f.Close()
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return extractR8CompilerHash(f)
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}
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func extractR8CompilerHash(r io.Reader) (string, error) {
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s := bufio.NewScanner(r)
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for s.Scan() {
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line := s.Text()
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if strings.HasPrefix(line, hashPrefix) {
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hash := strings.TrimPrefix(line, hashPrefix)
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if !strings.HasPrefix(hash, hashTypePrefix) {
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return "", fmt.Errorf("invalid hash type found in %q", line)
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}
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return strings.TrimPrefix(hash, hashTypePrefix), nil
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} else if !strings.HasPrefix(line, commentPrefix) {
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break
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}
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}
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return "", nil
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}
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