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Posts tagged with 'msi'

mandel

Following my last post regarding how to list all installed applications using python here is the code that one will require to remove an installed msi from a Windows machine using python.

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class MsiException(Exception):
    """Raised when there are issues with the msi actions."""
 
 
def uninstall_product(uid):
    """Will remove the old beta from the users machine."""
    # we use the msi lib to be able to uninstall apps
    property_name = u'LocalPackage'
    uninstall_path = get_property_for_product(uid, property_name)
    if uninstall_path is not None:
        # lets remove the package.
        command_line = u'REMOVE=ALL'
        result = windll.msi.MsiInstallProductW(uninstall_path, command_line)
        if result != ERROR_SUCCESS:
            raise MsiException('Could not remove product %s' % uid)

The missing functions can be found in the last post about the topic.

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mandel

The new Ubuntu One Windows client is very close to be released (we have already been sending the new code to our beta testers) and in order to make life easier to new user we wanted to provide a migration script that will allow the user migrate his data to the new client and uninstall the old one. In order to be able to know if the old msi is present in the system we had to use the Windows Installer SDK to query the installed applications and find if the old Ubuntu One client is present.

The following code is a small script that contains the functions to query the installed software in the system which is very similar to the script found in WiLstPrd.vbs but using python instead of VB and ctypes.

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# This scripts allows to get a list of all installed products in a windows
# machine. The code uses ctypes becuase there were a number of issues when
# trying to achieve the same win win32com.client
from collections import namedtuple
from ctypes import byref, create_unicode_buffer, windll
from ctypes.wintypes import DWORD
from itertools import count
 
# defined at http://msdn.microsoft.com/en-us/library/aa370101(v=VS.85).aspx
UID_BUFFER_SIZE = 39
PROPERTY_BUFFER_SIZE = 256 
ERROR_MORE_DATA = 234
ERROR_INVALID_PARAMETER = 87
ERROR_SUCCESS = 0
ERROR_NO_MORE_ITEMS = 259 
ERROR_UNKNOWN_PRODUCT = 1605 
 
# diff propoerties of a product, not all products have all properties
PRODUCT_PROPERTIES = [u'Language',
                      u'ProductName',
                      u'PackageCode',
                      u'Transforms',
                      u'AssignmentType',
                      u'PackageName',
                      u'InstalledProductName',
                      u'VersionString',
                      u'RegCompany',
                      u'RegOwner',
                      u'ProductID',
                      u'ProductIcon',
                      u'InstallLocation',
                      u'InstallSource',
                      u'InstallDate',
                      u'Publisher',
                      u'LocalPackage',
                      u'HelpLink',
                      u'HelpTelephone',
                      u'URLInfoAbout',
                      u'URLUpdateInfo',] 
 
# class to be used for python users :)
Product = namedtuple('Product', PRODUCT_PROPERTIES)
 
 
def get_property_for_product(product, property, buf_size=PROPERTY_BUFFER_SIZE):
    """Retruns the value of a fiven property from a product."""
    property_buffer = create_unicode_buffer(buf_size)
    size = DWORD(buf_size)
    result = windll.msi.MsiGetProductInfoW(product, property, property_buffer,
                                           byref(size))
    if result == ERROR_MORE_DATA:
        return get_property_for_product(product, property,
                2 * buf_size)
    elif result == ERROR_SUCCESS:
        return property_buffer.value
    else:
        return None
 
 
def populate_product(uid):
    """Return a Product with the different present data."""
    properties = []
    for property in PRODUCT_PROPERTIES:
        properties.append(get_property_for_product(uid, property))
    return Product(*properties) 
 
 
def get_installed_products_uids():
    """Returns a list with all the different uid of the installed apps."""
    # enum will return an error code according to the result of the app
    products = []
    for i in count(0):
        uid_buffer = create_unicode_buffer(UID_BUFFER_SIZE)
        result = windll.msi.MsiEnumProductsW(i, uid_buffer)
        if result == ERROR_NO_MORE_ITEMS:
            # done interating over the collection
            break
        products.append(uid_buffer.value)
    return products
 
 
def get_installed_products():
    """Returns a collection of products that are installed in the system."""
    products = []
    for puid in  get_installed_products_uids():
        products.append(populate_product(puid))
    return products 
 
 
def is_product_installed_uid(uid):
    """Return if a product with the given id is installed.
 
    uid Most be a unicode object with the uid of the product using
    the following format {uid}
    """
    # we try to get the VersisonString for the uid, if we get an error it means
    # that the product is not installed in the system.
    buf_size = 256
    uid_buffer = create_unicode_buffer(uid)
    property = u'VersionString'
    property_buffer = create_unicode_buffer(buf_size)
    size = DWORD(buf_size)
    result = windll.msi.MsiGetProductInfoW(uid_buffer, property, property_buffer,
                                           byref(size))
    if result == ERROR_UNKNOWN_PRODUCT:
        return False
    else:
        return True

The above code will allow a python developer to check which products are installed on Windows as well as to know if a product with the given UID is indeed installed.

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