set the current working directory in the chroot

This patch allows you to set the current working directory (in the
chroot) before running a command with --chroot.  This avoids the need to
pass shell snippets ('cd /some/path && /run/cmd') to mock when running a
command that expects to executed from a certain directory.  It's useful
when using --copyin to setup the environment before running a command.

>From e4071d1d41a62ccf4461dfab958f9325edf30c97 Mon Sep 17 00:00:00 2001
From: Mike Bonnet <mikeb@redhat.com>
Date: Thu, 24 Jan 2008 17:09:06 -0500
Subject: [PATCH] optionally set the current working directory (in the chroot) before running command with --chroot

Signed-off-by: Michael E Brown <mebrown@michaels-house.net>

2 files changed, 15 insertions, 6 deletions

diff --git a/py/mock.py b/py/mock.py
index f422a33..d5afbbe 100755
--- a/py/mock.py
+++ b/py/mock.py
@@ -152,6 +152,10 @@ def command_parse(config_opts):
                            " seconds ")
     parser.add_option("--unpriv", action="store_true", default=False,
                       help="Drop privileges before running command when using --chroot")
+    parser.add_option("--cwd", action="store", default=None,
+                      metavar="DIR",
+                      help="Change to the specified directory (relative to the chroot)"
+                           " before running command when using --chroot")
 
     # verbosity
     parser.add_option("-v", "--verbose", action="store_const", const=2,
@@ -536,9 +540,9 @@ def main(ret):
             chroot._mountall()
             if options.unpriv:
                 chroot.doChroot(args, shell=shell,
-                                uid=chroot.chrootuid, gid=chroot.chrootgid)
+                                uid=chroot.chrootuid, gid=chroot.chrootgid, cwd=options.cwd)
             else:
-                chroot.doChroot(args, shell=shell)
+                chroot.doChroot(args, shell=shell, cwd=options.cwd)
         finally:
             chroot._umountall()
 
diff --git a/py/mock/util.py b/py/mock/util.py
index f93f98b..65cc995 100644
--- a/py/mock/util.py
+++ b/py/mock/util.py
@@ -201,6 +201,10 @@ def condChroot(chrootPath):
         os.chroot(chrootPath)
         uid.setresuid(saved['ruid'], saved['euid'])
 
+def condChdir(cwd):
+    if cwd is not None:
+        os.chdir(cwd)
+
 def condDropPrivs(uid, gid):
     if gid is not None:
         os.setregid(gid, gid)
@@ -245,12 +249,12 @@ def logOutput(fds, logger, returnOutput=1, start=0, timeout=0):
 # The "Not-as-complicated" version
 #
 decorate(traceLog())
-def do(command, shell=False, chrootPath=None, timeout=0, raiseExc=True, returnOutput=0, uid=None, gid=None, personality=None, *args, **kargs):
+def do(command, shell=False, chrootPath=None, cwd=None, timeout=0, raiseExc=True, returnOutput=0, uid=None, gid=None, personality=None, *args, **kargs):
 
     logger = kargs.get("logger", getLog())
     output = ""
     start = time.time()
-    preexec = ChildPreExec(personality, chrootPath, uid, gid)
+    preexec = ChildPreExec(personality, chrootPath, cwd, uid, gid)
     try:
         child = None
         logger.debug("Executing command: %s" % command)
@@ -292,9 +296,10 @@ def do(command, shell=False, chrootPath=None, timeout=0, raiseExc=True, returnOu
     return output
 
 class ChildPreExec(object):
-    def __init__(self, personality, chrootPath, uid, gid):
+    def __init__(self, personality, chrootPath, cwd, uid, gid):
         self.personality = personality
         self.chrootPath  = chrootPath
+        self.cwd = cwd
         self.uid = uid
         self.gid = gid
 
@@ -303,4 +308,4 @@ class ChildPreExec(object):
         condPersonality(self.personality)
         condChroot(self.chrootPath)
         condDropPrivs(self.uid, self.gid)
-
+        condChdir(self.cwd)