faxien-launcher-universal.py

#!/usr/bin/env python

"""
This Python script will determine what flavor of bootstrapper
to fetch for your system, download it, and optionally run it.

To use this script, run:

python faxien-launcher-universal.py

in a shell. Adjust the filename to match the one you downloaded.
"""

import commands, optparse, os, urllib, re, subprocess, sys, tempfile

VERSION = '0.3.7'

DEFAULT_PREFIX = '/usr/local/lib/erlang'

LISTING_URL = 'http://code.google.com/p/faxien/downloads/list'
FILE_URL = 'http://faxien.googlecode.com/files'

INTERACTIVE = os.isatty(sys.stdin.fileno())

# re to find the filenames
scraper = re.compile(r'_go\(\'detail\?name=(faxien-launcher[^&]*)')

# re to find version numbers in filenames.
# looking for x.x.x-Vx, but the first part is optional
verpat = re.compile(r'-(?:((?:\d+\.)*\d+)-)?V(\d+).sh')

OTP_BASE_ESCRIPT = """\
# escript seems to want this line
main([]) ->
    io:format("~s", [filename:dirname(code:lib_dir())]).
"""


# ioctl_GWINSZ and terminal_size are from Chuck Blake's cls.py
# http://pdos.csail.mit.edu/~cblake/cls/cls.py

def ioctl_GWINSZ(fd):                  #### TABULATION FUNCTIONS
    try:                                ### Discover terminal width
        import fcntl, termios, struct
        cr = struct.unpack('hh', fcntl.ioctl(fd, termios.TIOCGWINSZ, '1234'))
    except:
        return None
    return cr

def terminal_size():                    ### decide on *some* terminal size
    cr = ioctl_GWINSZ(0) or ioctl_GWINSZ(1) or ioctl_GWINSZ(2)  # try open fds
    if not cr:                                                  # ...then ctty
        try:
            fd = os.open(os.ctermid(), os.O_RDONLY)
            cr = ioctl_GWINSZ(fd)
            os.close(fd)
        except:
            pass
    if not cr:                            # env vars or finally defaults
        try:
            cr = (os.environ['LINES'], os.environ['COLUMNS'])
        except:
            cr = (25, 80)
    return int(cr[1]), int(cr[0])         # reverse rows, cols


def get_otp_base():
    """Get the base directory of the default OTP installation or None."""

    fd, script = tempfile.mkstemp(suffix='.erl')
    os.write(fd, OTP_BASE_ESCRIPT)
    os.close(fd)

    try:
        p = subprocess.Popen(['escript', script],
                             stdout=subprocess.PIPE,
                             stderr=subprocess.PIPE)
    except OSError:
        os.remove(script)
        return None

    output, _ = p.communicate()

    os.remove(script)

    if p.returncode != 0:
        return None

    return output


def get_prefix(args):
    """Get the prefix to use for installation."""

    prefix = args and args[0] or ''

    default_prefix = DEFAULT_PREFIX

    if INTERACTIVE and not prefix:
        otp_base = get_otp_base()

        if otp_base is not None:
            msg = 'Install to existing Erlang/OTP? (%s) [Y/n] '
            ans = raw_input(msg % otp_base)
            if ans in ('', 'Y', 'y', 'yes'):
                prefix = otp_base

        if not prefix:
            msg = 'Enter the install prefix: [%s] '
            prefix = raw_input(msg % default_prefix)

    prefix = prefix or default_prefix
    prefix = os.path.abspath(os.path.expanduser(prefix))

    return prefix


def check_prefix(prefix):
    """Check to make sure we can install to the given prefix."""

    first_existing = prefix

    while True:
        if os.path.exists(first_existing):
            break

        up_one = os.path.dirname(first_existing)
        if up_one == first_existing:
            raise Exception('weird. no root path')

        first_existing = up_one

    if not os.path.isdir(first_existing):
        print >>sys.stderr, '%s is not a directory' % first_existing
        sys.exit(1)

    if not os.access(first_existing, os.R_OK | os.W_OK | os.X_OK):
        print >>sys.stderr, 'You do not have permissions to change %s.' % first_existing
        print >>sys.stderr, 'You must either run this script as another user,'
        print >>sys.stderr, 'perhaps using "sudo", or install to another prefix.'
        print >>sys.stderr, 'You can specify an alternate prefix as the first'
        print >>sys.stderr, 'argument to this script.'
        sys.exit(1)


def get_bootstrappers():
    """Return the list of bootstrappers available for download."""

    page = urllib.urlopen(LISTING_URL).read()

    bootstrappers = list(set(scraper.findall(page)))
    bootstrappers.sort()
    return bootstrappers


def choose_bootstrapper(bootstrappers):
    """Present a menu for the user to choose a bootstrapper and return
    the bootstrapper chosen."""

    if not INTERACTIVE:
        print >>sys.stderr, 'choose mode in a non-interactive environment'
        sys.exit(1)

    while True:
        print
        print 'Choose a bootstrapper from the list:'
        for i, bootstrapper in enumerate(bootstrappers):
            print ' %d: %s' % (i + 1, bootstrapper)

        ans = raw_input('[%d-%d] ' % (1, len(bootstrappers)))

        if not ans:
            print 'Aborting.'
            sys.exit(1)

        ans = ans.isdigit() and int(ans) or None

        if ans and ans >= 1 and ans <= len(bootstrappers):
            return bootstrappers[ans-1]

        print
        print 'Please enter a number between %d and %d.' % (1, len(bootstrappers))


def make_version_tuple(input):
    """Turn a non-empty version string into a tuple of integers."""
    if not input:
        return ()
    return tuple([int(n) for n in input.split('.')])


def determine_bootstrapper(options, bootstrappers):
    """Determine which bootstrapper to use based on the options."""
    if options.choose:
        return choose_bootstrapper(bootstrappers)

    if not options.os_version:
        if (options.machine, options.kernel) == (None, None):
            status, output = commands.getstatusoutput('uname -r')
            if status != 0:
                print 'Cannot determine os version.'
                sys.exit(1)
            options.os_version = output.split('-')[0]

    options.os_version = make_version_tuple(options.os_version)

    if not options.machine:
        status, output = commands.getstatusoutput('uname -m')
        if status != 0:
            print 'Cannot determine machine type.'
            sys.exit(1)
        options.machine = output

    if not options.kernel:
        status, output = commands.getstatusoutput('uname -s')
        if status != 0:
            print 'Cannot determine kernel name.'
            sys.exit(1)
        options.kernel = output

    options.machine = options.machine.replace(' ', '-')
    options.kernel = options.kernel.replace(' ', '-')

    prefix = 'faxien-launcher-%s-%s' % (options.machine, options.kernel)

    # find potential bootstrappers
    matches = [b for b in bootstrappers if b.startswith(prefix)]

    # search for version numbers
    matches = [(verpat.search(b), b) for b in matches]

    # grab the version numbers, cull filenames with no matches
    matches = [(m.group(2), m.group(1), b) for m, b in matches if m]

    # tupleize them for sorting
    matches = [(int(boot_version), make_version_tuple(os_version), b)
               for boot_version, os_version, b in matches]

    # exclude os versions later than ours
    matches = [(boot_version, os_version, b) for boot_version, os_version, b in matches
               if os_version <= options.os_version]

    # latest version will be last after sort
    matches.sort()

    if matches:
        return matches[-1][-1]

    msg = 'There is no bootstrapper for the architecture "%s"' % options.machine
    print >>sys.stderr, msg

    msg = 'and the operating system "%s (%s)".\n'
    msg %= (options.kernel, '.'.join([str(n) for n in options.os_version]))
    print >>sys.stderr, msg

    print >>sys.stderr, 'You can see the complete list of available bootstrappers'
    print >>sys.stderr, 'by running this program with the --choose argument.\n'
    print >>sys.stderr, 'For help, post to the erlware-questions mailing list:'
    print >>sys.stderr, '    http://groups.google.com/group/erlware-questions'
    sys.exit(1)


SPINNER = "-\|/"
TERMINAL_SIZE = None

def progress_bar(block_count, block_size, total_bytes):
    """Progress hook for urllib.urlretrieve.
    With an interactive shell, display a progress bar for download progress."""
    if not INTERACTIVE:
        return

    if block_count % 10 != 0:
        return

    count = block_count // 10

    progress_length = max(0, TERMINAL_SIZE[0] - 6)

    bytes = block_count * block_size

    num_bars = progress_length * (bytes / float(total_bytes))
    num_bars = int(num_bars)

    if num_bars:
        last_bars = progress_length * ((bytes - (block_size * 10)) / float(total_bytes))
        last_bars = int(last_bars)
        new_bars = '=' * (num_bars - last_bars)
    else:
        new_bars = ''

    percent = 100 * (bytes / float(total_bytes))
    percent = ' %3d%%' % round(percent)

    sys.stdout.write('\b\b\b\b\b\b' + new_bars + SPINNER[count % len(SPINNER)] + percent)
    sys.stdout.flush()


def already_downloaded(bootstrapper):
    """Return True if the given bootstrap file has already been downloaded."""
    if not os.path.exists(bootstrapper):
        return False

    url = '%s/%s' % (FILE_URL, bootstrapper)

    content_length = urllib.urlopen(url).info().getheader('Content-Length')
    if not content_length or not content_length.isdigit():
        return False

    content_length = int(content_length)

    current_size = os.stat(bootstrapper).st_size

    return content_length == current_size


def download_bootstrapper(bootstrapper):
    """Fetch the given bootstrap file from the website. Return the file location."""
    global TERMINAL_SIZE
    if INTERACTIVE:
        TERMINAL_SIZE = terminal_size()

    url = '%s/%s' % (FILE_URL, bootstrapper)

    print 'Downloading %s' % url

    if INTERACTIVE:
        sys.stdout.write(SPINNER[0] + '    %')

    urllib.urlretrieve(url, bootstrapper, reporthook=progress_bar)[0]

    print
    print 'Download done.'


if __name__ == '__main__':
    usage = """%prog [options] [prefix]

    Without options, this script will download the latest version of
    the Faxien bootstrapper for your system and optionally run it.
    Additional options allow you to override the default choice or
    choose a specific bootstrapper from the list of available ones.

    For more information on Erlware, see http://erlware.org

    For help, contact the erlware-questions mailing list here:

        http://groups.google.com/group/erlware-questions
    """

    parser = optparse.OptionParser(usage=usage)

    help = 'run the bootstrapper after download'
    parser.add_option("-r", "--autorun", dest="autorun", action='store_true', help=help)

    help = 'let me choose my bootstrapper from the current available'
    parser.add_option("-c", "--choose", dest="choose", action='store_true', help=help)

    help = 'the type of computer you are running. By default, the output of "uname -m"'
    parser.add_option("-m", "--machine", dest="machine", help=help)

    help = 'the name of the kernel you are running. By default, the output of "uname -s"'
    parser.add_option("-k", "--kernel", dest="kernel", help=help)

    help = 'the version of the kernel you are running. By default, the output of "uname -r", excluding everything after and including the first "-" character.'
    parser.add_option("-o", "--os-version", dest="os_version", help=help)

    help = 'print version information for the universal bootstrapper'
    parser.add_option("-v", "--version", action='store_true', help=help)

    options, args = parser.parse_args()

    if len(args) > 1:
        parser.error('bad arguments')

    if options.version:
        print 'Faxien universal bootstrapper version %s.' % VERSION
        sys.exit()

    prefix = get_prefix(args)

    print 'Using prefix:', prefix

    check_prefix(prefix)

    print 'Fetching list of current bootstrappers from %s' % LISTING_URL
    bootstrappers = get_bootstrappers()

    bootstrapper = determine_bootstrapper(options, bootstrappers)

    if already_downloaded(bootstrapper):
        print 'Already downloaded', bootstrapper
    else:
        download_bootstrapper(bootstrapper)

    command = 'sh %s %s' % (bootstrapper, prefix)

    if INTERACTIVE and not options.autorun:
        ans = raw_input('Do you want to run the bootstrapper now? ([y]/n) ')
        if ans.lower() not in ('', 'y'):
            print "To run the bootstrapper yourself, use this command:"
            print command
            sys.exit()

    if not INTERACTIVE and not options.autorun:
        sys.exit()

    print 'Running:', command
    os.system(command)