root@localhost:/mnt/sdcard/UXP# sh ./mach build
Error running mach:

    ['build']

The error occurred in code that was called by the mach command. This is either
a bug in the called code itself or in the way that mach is calling it.

You should consider filing a bug for this issue.

If filing a bug, please include the full output of mach, including this error
message.

The details of the failure are as follows:

OSError: [Errno 13] Permission denied

  File "/mnt/sdcard/UXP/python/mozbuild/mozbuild/base.py", line 725, in __init__    self._ensure_state_subdir_exists('.')
  File "/mnt/sdcard/UXP/python/mozbuild/mozbuild/base.py", line 435, in _ensure_state_subdir_exists
    path = os.path.join(self.statedir, subdir)
  File "/mnt/sdcard/UXP/python/mozbuild/mozbuild/base.py", line 266, in statedir    return os.path.join(self.topobjdir, '.mozbuild')
  File "/mnt/sdcard/UXP/python/mozbuild/mozbuild/base.py", line 192, in topobjdir
    default='obj-@CONFIG_GUESS@')
  File "/mnt/sdcard/UXP/python/mozbuild/mozbuild/base.py", line 181, in resolve_mozconfig_topobjdir
    self.resolve_config_guess())
  File "/mnt/sdcard/UXP/python/mozbuild/mozbuild/base.py", line 364, in resolve_config_guess
    subprocess.check_output(args, cwd=self.topsrcdir).strip())
  File "/usr/lib/python2.7/subprocess.py", line 216, in check_output
    process = Popen(stdout=PIPE, *popenargs, **kwargs)
  File "/usr/lib/python2.7/subprocess.py", line 394, in __init__
    errread, errwrite)
  File "/usr/lib/python2.7/subprocess.py", line 1047, in _execute_child
    raise child_exception
root@localhost:/mnt/sdcard/UXP#