Close #898 Get and cache the uid/gid values early

2 files changed, 39 insertions, 10 deletions

diff --git a/lib/utils/uid-number.js b/lib/utils/uid-number.js
index 27fa9e27b..59952ffd0 100644
--- a/lib/utils/uid-number.js
+++ b/lib/utils/uid-number.js
@@ -1,11 +1,18 @@
 module.exports = uidNumber
 
+// This module calls into bin/npm-get-uid-gid.js, which sets the
+// uid and gid to the supplied argument, in order to find out their
+// numeric value.  This can't be done in the main node process,
+// because otherwise npm would be running as that user.
+
 var exec = require("./exec")
   , path = require("path")
   , log = require("./log")
   , constants = require("constants")
   , npm = require("../../npm")
   , uidSupport = process.getuid && process.setuid
+  , uidCache = {}
+  , gidCache = {}
 
 function uidNumber (uid, gid, cb) {
   if (!uidSupport || npm.config.get("unsafe-perm")) return cb()
@@ -15,9 +22,14 @@ function uidNumber (uid, gid, cb) {
   if (uid == null) uid = process.getuid()
   if (!isNaN(gid)) gid = +gid
   if (!isNaN(uid)) uid = +uid
+
+  if (uidCache[uid]) uid = uidCache[uid]
+  if (gidCache[gid]) gid = gidCache[gid]
+
   if (typeof gid === "number" && typeof uid === "number") {
     return cb(null, uid, gid)
   }
+
   var getter = path.join(__dirname, "..", "..", "bin", "npm-get-uid-gid.js")
   return exec( process.execPath, [getter, uid, gid], process.env, false
              , null, process.getuid(), process.getgid()
@@ -36,6 +48,8 @@ function uidNumber (uid, gid, cb) {
     }
     if (isNaN(out.uid) || isNaN(out.gid)) return cb(new Error(
       "Could not get uid/gid: "+JSON.stringify(out)))
+    uidCache[uid] = out.uid
+    uidCache[gid] = out.gid
     cb(null, out.uid, out.gid)
   })
 }
diff --git a/npm.js b/npm.js
index 88ee93555..917efd06b 100644
--- a/npm.js
+++ b/npm.js
@@ -22,6 +22,7 @@ var EventEmitter = require("events").EventEmitter
   , which = require("./lib/utils/which")
   , semver = require("semver")
   , findPrefix = require("./lib/utils/find-prefix")
+  , getUid = require("./lib/utils/uid-number")
 
 npm.commands = {}
 npm.ELIFECYCLE = {}
@@ -200,16 +201,30 @@ npm.load = function (conf, cb_) {
       } else {
         p = npm.config.get("prefix")
       }
-      // try to guess at a good node_modules location.
-      findPrefix(p, function (er, p) {
-        if (er) return handleError(er)
-        Object.defineProperty(npm, "prefix",
-          { get : function () { return p }
-          , set : function (r) { return p = r }
-          , enumerable : true
-          })
-        return cb()
-      })
+
+      // if we're not in unsafe-perm mode, then figure out who
+      // to run stuff as.  Do this first, to support `npm update npm -g`
+      if (!npm.config.get("unsafe-perm")) {
+        getUid( npm.config.get("user"), npm.config.get("group")
+              , function (er, uid, gid) {
+          if (er) return log.er(cb, "Could not get uid/gid")(er)
+          next()
+        })
+      } else next()
+
+      function next () {
+        // try to guess at a good node_modules location.
+        findPrefix(p, function (er, p) {
+          if (er) return handleError(er)
+          Object.defineProperty(npm, "prefix",
+            { get : function () { return p }
+            , set : function (r) { return p = r }
+            , enumerable : true
+            })
+          return cb()
+        })
+      }
+
     })
   })
 }