Re: How can I tell if a file has been updated upstream?

[Timur Tabi <timur@freescale.com>]

On Fri, Feb 5, 2010 at 10:23 AM, Timur Tabi <timur@freescale.com> wrote:
> Is there a way for me to tell if a particular file in my repository
> has an update in the upstream repository?

Thanks to everyone who replied.  Here's what I came up with:

def check_for_updates():
    # Get the path to our script.  This should be a git repository.
    script_path = os.path.dirname(os.path.realpath(__file__))

    # Determine the upstream URL
    p = subprocess.Popen(['git', 'config', '-f', script_path + '/.git/config',
        '--get', 'remote.origin.url'],
        shell=False, stdout=subprocess.PIPE, stderr=open(os.devnull, 'w'))
    url = p.communicate()[0].strip()
    if not url:
        # The script is not running from a git repository
        return

    # Determine the HEAD of the upstream repository
    p = subprocess.Popen(['git', 'ls-remote', url, 'HEAD'],
        shell=False, stdout=subprocess.PIPE, stderr=open(os.devnull, 'w'))
    sha = p.communicate()[0].split()
    if not sha:
        # Something is wrong with the upstream repository
        return
    sha = sha[0] # The SHA of the upstream head

    # Check if the remote SHA is in the local repository.
    # git --git-dir=/home/b04825/bin/.git show-ref HEAD
    p = subprocess.Popen(['git', '--git-dir=' + script_path + '/.git',
        'log', '-1', sha],
        shell=False, stdout=subprocess.PIPE, stderr=open(os.devnull, 'w'))
    if not p.communicate()[0]:
        # If we can't find the SHA locally, then it means that the local
        # repository is out of date.  We pretend that it means that this script
        # is out of date.
        print 'There is an update for this script available.  Please
pull from the remote'
        print 'repository (e.g. "cd %s; git pull")' % script_path

-- 
Timur Tabi
Linux kernel developer at Freescale