CT Google Storage utils to download/upload artifacts for workers

go/auth/auth.go

 package auth
 
 import (
         "fmt"
         "net/http"
         "time"
 
         "code.google.com/p/goauth2/oauth"
         "github.com/oxtoacart/webbrowser"
         "skia.googlesource.com/buildbot.git/go/util"
 )
 
 const (
         // TIMEOUT is the http timeout when making Google Storage requests.
         TIMEOUT = time.Duration(time.Minute)
+        // Supported Cloud storage API OAuth scopes.
+        SCOPE_READ_ONLY    = "https://www.googleapis.com/auth/devstorage.read_only"
+        SCOPE_READ_WRITE   = "https://www.googleapis.com/auth/devstorage.read_write"
+        SCOPE_FULL_CONTROL = "https://www.googleapis.com/auth/devstorage.full_control"
 )
 
 // DefaultOAuthConfig returns the default configuration for oauth.
 // If the given path for the cachefile is empty a default value is
 // used.
 func DefaultOAuthConfig(cacheFilePath string) *oauth.Config {
+        return OAuthConfig(cacheFilePath, SCOPE_READ_ONLY)
+}
+
+// OAuthConfig returns a configuration for oauth with the specified scope.
+// If the given path for the cachefile is empty a default value is used.
+func OAuthConfig(cacheFilePath, scope string) *oauth.Config {
         if cacheFilePath == "" {
                 cacheFilePath = "google_storage_token.data"
         }
-
         return &oauth.Config{
                 ClientId:     "470362608618-nlbqngfl87f4b3mhqqe9ojgaoe11vrld.apps.googleusercontent.com",
                 ClientSecret: "J4YCkfMXFJISGyuBuVEiH60T",
-                Scope:        "https://www.googleapis.com/auth/devstorage.read_only",
+                Scope:        scope,
                 AuthURL:      "https://accounts.google.com/o/oauth2/auth",
                 TokenURL:     "https://accounts.google.com/o/oauth2/token",
                 RedirectURL:  "urn:ietf:wg:oauth:2.0:oob",
                 TokenCache:   oauth.CacheFile(cacheFilePath),
         }
 }
 
 // runFlow runs through a 3LO OAuth 2.0 flow to get credentials for Google Storage.
 func RunFlow(config *oauth.Config) (*http.Client, error) {
         if config == nil {
@@ skipping 15 matching lines @@
                 webbrowser.Open(url)
                 var code string
                 fmt.Scan(&code)
                 if _, err := transport.Exchange(code); err != nil {
                         return nil, err
                 }
         }
 
         return transport.Client(), nil
 }