Add --cd-datadir setting

2 files changed, 15 insertions, 1 deletions

diff --git a/NEWS b/NEWS
index e01387b..56e3bcf 100644
--- a/NEWS
+++ b/NEWS
@@ -14,6 +14,10 @@ Version 0.19, released UNRELEASED
   This can be used to use Python instead of sh:
   `--shell=/usr/bin/python2 --shell-arg=''`.
 
+* Yarn now supports the `--cd-datadir` setting to have each step run
+  in `DATADIR` instead of `SRCDIR`. The default remains `SRCDIR`, but
+  at some point in the future, the default will probably change.
+
 Version 0.18, released 2015-11-06
 ---------------------------------
 
diff --git a/yarn b/yarn
index c6e32cc..0782a8f 100755
--- a/yarn
+++ b/yarn
@@ -100,6 +100,11 @@ class YarnRunner(cliapp.Application):
             metavar='ARG',
             default=['-xeu'])
 
+        self.settings.boolean(
+            ['cd-datadir'],
+            'change to DATADIR when running commands',
+            default=False)
+
     def stdout(self, msg):
         self.output.write(msg)
         self.output.flush()
@@ -448,6 +453,11 @@ class YarnRunner(cliapp.Application):
         for i, match in enumerate(m.groups('')):
             env['MATCH_%d' % (i+1)] = match
 
+        if self.settings['cd-datadir']:
+            cwd = datadir
+        else:
+            cwd = '.'
+
         fd, shell_script = tempfile.mkstemp()
         os.close(fd)
         with open(shell_script, 'w') as f:
@@ -460,7 +470,7 @@ class YarnRunner(cliapp.Application):
         logging.warning('shell_args: %r', shell_args)
         logging.warning('shell_script: %r', shell_script)
         exit, stdout, stderr = cliapp.runcmd_unchecked(
-            [shell] + shell_args + [shell_script], env=env)
+            [shell] + shell_args + [shell_script], env=env, cwd=cwd)
         os.remove(shell_script)
 
         logging.debug('Exit code: %d' % exit)