mirror of https://github.com/knative/pkg.git
130 lines
3.9 KiB
Go
130 lines
3.9 KiB
Go
/*
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Copyright 2018 The Knative 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 changeset
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import (
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"bufio"
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"fmt"
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"io/ioutil"
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"os"
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"path/filepath"
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"regexp"
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"strings"
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)
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const (
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commitIDFile = "HEAD"
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koDataPathEnvName = "KO_DATA_PATH"
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// packedRefsFile is a file containing a list of refs, used to compact the
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// list of refs instead of storing them on the filesystem directly.
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// See https://git-scm.com/docs/git-pack-refs
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packedRefsFile = "packed-refs"
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)
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var commitIDRE = regexp.MustCompile(`^[a-f0-9]{40}$`)
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// Get tries to fetch the first 7 digitals of GitHub commit ID from HEAD file in
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// KO_DATA_PATH. If it fails, it returns the error it gets.
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func Get() (string, error) {
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data, err := readFileFromKoData(commitIDFile)
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if err != nil {
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return "", err
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}
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commitID := strings.TrimSpace(string(data))
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if rID := strings.TrimPrefix(commitID, "ref: "); rID != commitID {
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// First try to read from the direct ref file - e.g. refs/heads/main
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data, err := readFileFromKoData(rID)
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if err != nil {
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if !os.IsNotExist(err) {
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return "", err
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}
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// Ref file didn't exist - it might be contained in the packed-refs
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// file.
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var pferr error
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data, pferr = findPackedRef(rID)
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// Only return the sub-error if the packed-refs file exists, otherwise
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// just let the original error return (e.g. treat it as if we didn't
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// even attempt the operation). This is primarily to keep the error
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// messages clean.
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if pferr != nil {
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if os.IsNotExist(pferr) {
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return "", err
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}
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return "", pferr
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}
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}
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commitID = strings.TrimSpace(string(data))
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}
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if commitIDRE.MatchString(commitID) {
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return commitID[:7], nil
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}
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return "", fmt.Errorf("%q is not a valid GitHub commit ID", commitID)
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}
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// readFileFromKoData tries to read data as string from the file with given name
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// under KO_DATA_PATH then returns the content as string. The file is expected
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// to be wrapped into the container from /kodata by ko. If it fails, returns
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// the error it gets.
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func readFileFromKoData(filename string) ([]byte, error) {
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f, err := koDataFile(filename)
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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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return ioutil.ReadAll(f)
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}
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// readFileFromKoData tries to open the file with given name under KO_DATA_PATH.
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// The file is expected to be wrapped into the container from /kodata by ko.
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// If it fails, returns the error it gets.
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func koDataFile(filename string) (*os.File, error) {
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koDataPath := os.Getenv(koDataPathEnvName)
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if koDataPath == "" {
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return nil, fmt.Errorf("%q does not exist or is empty", koDataPathEnvName)
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}
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return os.Open(filepath.Join(koDataPath, filename))
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}
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// findPackedRef searches the packed-ref file for ref values.
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// This can happen if the # of refs in a repo grows too much - git will try
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// and condense them into a file.
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// See https://git-scm.com/docs/git-pack-refs
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func findPackedRef(ref string) ([]byte, error) {
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f, err := koDataFile(packedRefsFile)
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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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scanner := bufio.NewScanner(f)
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for scanner.Scan() {
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// We only care about lines with `<commit> <ref>` pairs.
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// Why this might happen:
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// 1. Lines starting with ^ refer to unpeeled tag SHAs
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// (e.g. the commits pointed to by annotated tags)
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s := strings.Split(scanner.Text(), " ")
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if len(s) != 2 {
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continue
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}
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if ref == s[1] {
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return []byte(s[0]), nil
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}
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}
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return nil, fmt.Errorf("%q ref not found in packed-refs", ref)
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}
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