implement user switching

This was documented (incorrectly) and not implemented for either
the master/worker or single process cases.  Implement and test
all (with mocks, so not fully-tested).

4 files changed, 20 insertions, 27 deletions

diff --git a/lib/yahns/config.rb b/lib/yahns/config.rb
index 6d8945a..ebc3bda 100644
--- a/lib/yahns/config.rb
+++ b/lib/yahns/config.rb
@@ -158,7 +158,7 @@ class Yahns::Config # :nodoc:
   # if the Worker#user method is not called in the after_fork hooks
   # +group+ is optional and will not change if unspecified.
   def user(user, group = nil)
-    var = :user
+    var = _check_in_block(nil, :user)
     @block and raise "#{var} is not valid inside #{@block.type}"
     # raises ArgumentError on invalid user/group
     Etc.getpwnam(user)
@@ -385,7 +385,7 @@ class Yahns::Config # :nodoc:
       io.sync = true
     end
 
-    [ :logger, :pid, :worker_processes,
+    [ :logger, :pid, :worker_processes, :user,
       :worker_atfork_prepare, :worker_atfork_parent, :worker_atfork_child
     ].each do |var|
       val = @set[var]
diff --git a/lib/yahns/server.rb b/lib/yahns/server.rb
index fea310c..a2af745 100644
--- a/lib/yahns/server.rb
+++ b/lib/yahns/server.rb
@@ -10,6 +10,7 @@ class Yahns::Server # :nodoc:
                  :CHLD ]
   attr_accessor :daemon_pipe
   attr_accessor :logger
+  attr_writer :user
   attr_writer :worker_processes
   attr_writer :worker_atfork_prepare
   attr_writer :worker_atfork_parent
@@ -60,10 +61,26 @@ class Yahns::Server # :nodoc:
     if @worker_processes
       require 'yahns/server_mp'
       extend Yahns::ServerMP
+    else
+      switch_user(*@user) if @user
     end
     self
   end
 
+  def switch_user(user, group = nil)
+    # we do not protect the caller, checking Process.euid == 0 is
+    # insufficient because modern systems have fine-grained
+    # capabilities.  Let the caller handle any and all errors.
+    uid = Etc.getpwnam(user).uid
+    gid = Etc.getgrnam(group).gid if group
+    Yahns::Log.chown_all(uid, gid)
+    if gid && Process.egid != gid
+      Process.initgroups(user, gid)
+      Process::GID.change_privilege(gid)
+    end
+    Process.euid != uid and Process::UID.change_privilege(uid)
+  end
+
   def drop_acceptors
     @listeners.delete_if(&:ac_quit)
   end
diff --git a/lib/yahns/server_mp.rb b/lib/yahns/server_mp.rb
index c8e1989..be24152 100644
--- a/lib/yahns/server_mp.rb
+++ b/lib/yahns/server_mp.rb
@@ -46,7 +46,7 @@ module Yahns::ServerMP # :nodoc:
     Yahns::START.clear
     @sev.close
     @sev = Yahns::Sigevent.new
-    worker.user(*@user) if @user
+    switch_user(*@user) if @user
     @user = @workers = nil
     @worker_atfork_child.each(&:call) if @worker_atfork_child
     @worker_atfork_child = @worker_atfork_parent = @worker_atfork_prepare = nil
diff --git a/lib/yahns/worker.rb b/lib/yahns/worker.rb
index 980f7bd..0d25acc 100644
--- a/lib/yahns/worker.rb
+++ b/lib/yahns/worker.rb
@@ -31,28 +31,4 @@ class Yahns::Worker # :nodoc:
   def ==(other_nr) # :nodoc:
     @nr == other_nr
   end
-
-  # Changes the worker process to the specified +user+ and +group+
-  # This is only intended to be called from within the worker
-  # process from the +after_fork+ hook.  This should be called in
-  # the +after_fork+ hook after any privileged functions need to be
-  # run (e.g. to set per-worker CPU affinity, niceness, etc)
-  #
-  # Any and all errors raised within this method will be propagated
-  # directly back to the caller (usually the +after_fork+ hook.
-  # These errors commonly include ArgumentError for specifying an
-  # invalid user/group and Errno::EPERM for insufficient privileges
-  def user(user, group = nil)
-    # we do not protect the caller, checking Process.euid == 0 is
-    # insufficient because modern systems have fine-grained
-    # capabilities.  Let the caller handle any and all errors.
-    uid = Etc.getpwnam(user).uid
-    gid = Etc.getgrnam(group).gid if group
-    Yahns::Log.chown_all(uid, gid)
-    if gid && Process.egid != gid
-      Process.initgroups(user, gid)
-      Process::GID.change_privilege(gid)
-    end
-    Process.euid != uid and Process::UID.change_privilege(uid)
-  end
 end