cipd: Refactor client to make it more readable.

go/src/infra/tools/cipd/common.go

-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-package cipd
-
-import (
-        "encoding/json"
-        "fmt"
-        "io"
-        "io/ioutil"
-        "regexp"
-        "strings"
-
-        "infra/libs/build"
-)
-
-// Name of the directory inside the package reserved for cipd stuff.
-const packageServiceDir = ".cipdpkg"
-
-// Name of the directory inside an installation root reserved for cipd stuff.
-const siteServiceDir = ".cipd"
-
-// packageNameRe is a regular expression for a package name: <word>/<word/<word>
-// Package names must be lower case.
-var packageNameRe = regexp.MustCompile(`^([a-z0-9_\-]+/)*[a-z0-9_\-]+$`)
-
-// instanceTagKeyRe is a regular expression for a tag key.
-var instanceTagKeyRe = regexp.MustCompile(`^[a-z0-9_\-]+$`)
-
-// Name of the manifest file inside the package.
-const manifestName = packageServiceDir + "/manifest.json"
-
-// Format version to write to the manifest file.
-const manifestFormatVersion = "1"
-
-// Manifest defines structure of manifest.json file.
-type Manifest struct {
-        FormatVersion string `json:"format_version"`
-        PackageName   string `json:"package_name"`
-}
-
-// ValidatePackageName returns error if a string doesn't look like a valid package name.
-func ValidatePackageName(name string) error {
-        if !packageNameRe.MatchString(name) {
-                return fmt.Errorf("Invalid package name: %s", name)
-        }
-        return nil
-}
-
-// ValidateInstanceID returns error if a string doesn't look like a valid package instance id.
-func ValidateInstanceID(s string) error {
-        // Instance id is SHA1 hex digest currently.
-        if len(s) != 40 {
-                return fmt.Errorf("Not a valid package instance ID \"%s\": not 40 bytes", s)
-        }
-        for _, c := range s {
-                if !((c >= '0' && c <= '9') || (c >= 'a' && c <= 'f')) {
-                        return fmt.Errorf("Not a valid package instance ID \"%s\": wrong char %c", s, c)
-                }
-        }
-        return nil
-}
-
-// ValidateInstanceTag returns error if a string doesn't look like a valid tag.
-func ValidateInstanceTag(t string) error {
-        chunks := strings.SplitN(t, ":", 2)
-        if len(chunks) != 2 {
-                return fmt.Errorf("The string %q doesn't look like a tag (a key:value pair)", t)
-        }
-        if len(t) > 400 {
-                return fmt.Errorf("The tag is too long: %q", t)
-        }
-        if !instanceTagKeyRe.MatchString(chunks[0]) {
-                return fmt.Errorf("Invalid tag key in %q. Should be a lowercase word.", t)
-        }
-        return nil
-}
-
-// DefaultServiceURL returns URL to a backend to use by default.
-func DefaultServiceURL() string {
-        if build.ReleaseBuild {
-                return "https://chrome-infra-packages.appspot.com"
-        }
-        return "https://chrome-infra-packages-dev.appspot.com"
-}
-
-// readManifest reads and decodes manifest JSON from io.Reader.
-func readManifest(r io.Reader) (Manifest, error) {
-        blob, err := ioutil.ReadAll(r)
-        if err != nil {
-                return Manifest{}, err
-        }
-        manifest := Manifest{}
-        err = json.Unmarshal(blob, &manifest)
-        if err != nil {
-                return Manifest{}, err
-        }
-        return manifest, nil
-}
-
-// writeManifest encodes and writes manifest JSON to io.Writer.
-func writeManifest(m *Manifest, w io.Writer) error {
-        data, err := json.MarshalIndent(m, "", "  ")
-        if err != nil {
-                return err
-        }
-        _, err = w.Write(data)
-        return err
-}
-
-// userAgent returns user agent string to send with each request.
-func userAgent() string {
-        if build.ReleaseBuild {
-                return "cipd 1.0 release"
-        }
-        return "cipd 1.0 testing"
-}