cipd: Refactor client to make it more readable.

go/src/infra/tools/cipd/common/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
+/*
+Package common defines structures and functions used by all other cipd/ packages.
+*/
+package common
 
 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"
+// Pin uniquely identifies an instance of some package.
+type Pin struct {
+        PackageName string `json:"package"`
+        InstanceID  string `json:"instance_id"`
+}
 
-// 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"`
+// String converts pin to a human readable string.
+func (pin Pin) String() string {
+        return fmt.Sprintf("%s:%s", pin.PackageName, pin.InstanceID)
 }
 
 // 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
 }
 
+// ValidatePin returns error if package name of instance id of a pin are not valid.
+func ValidatePin(pin Pin) error {
+        if err := ValidatePackageName(pin.PackageName); err != nil {
+                return err
+        }
+        if err := ValidateInstanceID(pin.InstanceID); err != nil {
+                return err
+        }
+        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"
-}