webbrowser.open incomplete on Windows

[joncwchao]

BPO	8232
Nosy	@pfmoore, @tjguk, @bitdancer, @zware, @eryksun, @zooba, @PedanticHacker, @Mariatta
Dependencies	bpo-43538: [Windows] support args and cwd in os.startfile()
Files	webbrowserdebug.py webbrowserfix.patch webbrowserfix2.patch webbrowserfix3.patch webbrowserfix3.patch webbrowserfix4.patch webbrowserfix5.patch webbrowserfix6.patch 25005_1.patch 8232_1.patch

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2010-03-25.18:32:39.567>
labels = ['type-bug', 'library', '3.10', 'OS-windows']
title = 'webbrowser.open incomplete on Windows'
updated_at = <Date 2021-03-18.07:42:50.864>
user = 'https://bugs.python.org/joncwchao'

bugs.python.org fields:

activity = <Date 2021-03-18.07:42:50.864>
actor = 'eryksun'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)', 'Windows']
creation = <Date 2010-03-25.18:32:39.567>
creator = 'joncwchao'
dependencies = ['43538']
files = ['36110', '36265', '39525', '39533', '39534', '39590', '39626', '39650', '40384', '40393']
hgrepos = []
issue_num = 8232
keywords = ['patch']
message_count = 55.0
messages = ['101725', '101728', '101732', '126265', '224057', '224060', '224796', '241047', '241057', '244219', '244298', '244299', '244606', '244769', '244784', '244843', '244851', '244959', '244968', '244986', '245364', '245372', '245374', '245377', '245382', '245385', '245386', '245387', '245388', '245389', '245390', '245391', '245392', '245393', '245394', '245396', '245398', '245399', '245400', '245401', '245404', '245405', '250067', '250072', '250074', '250112', '250114', '250115', '250117', '250121', '250135', '261704', '290930', '290935', '388993']
nosy_count = 13.0
nosy_names = ['paul.moore', 'tim.golden', 'Arfrever', 'r.david.murray', 'joncwchao', 'devplayer', 'python-dev', 'zach.ware', 'eryksun', 'steve.dower', 'jbmilam', 'PedanticHacker', 'Mariatta']
pr_nums = []
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue8232'
versions = ['Python 3.10']

[joncwchao]

webbrowser.open(), webbrowser.open_new(), and webbrowser.open_new_tab() all do the exact same thing, regardless of the flags that I set. In Firefox, open('www.google.com', new=0), open_new('www.google.com'), and open_new_tab('www.google.com') all open either three new www.google.com tabs (if "Open new windows in a new tab instead" is selected in FF options) or three new www.google.com windows (if "Open new windows in a new tab instead" is not selected in FF options). In Internet Explorer, three new www.google.com tabs are created.

The issue exhibits itself the same way whether or not I have the browser open before running the script.

Environment was a Windows Vista 32-bit machine, running Python 3.1.2.

Example script reads:
import webbrowser
import time
ff = webbrowser.get('firefox')
ff.open('www.google.com', new=0)
time.sleep(3)
ff.open_new('www.google.com')
time.sleep(3)
ff.open_new_tab('www.google.com')

[briancurtin]

On Windows, the WindowsDefault class gets used and it doesn't make use of anything other than the URL (no 'new' or 'autoraise'). All it does is pass the URL onto os.startfile.

It should make a better attempt at running the URL. Patches welcome, or I'll try to come up with one shortly.

[briancurtin]

Minor correction: BackgroundBrowser gets used in this case, but it still lacks in the same area and causes what you are seeing.

[devplayer]

Don't forget to check if the MS Internet Explorer's advanced option to open new URLS in a seperate windows effects this. Users can have this advanced setting set differently on different computers(or even accounts). Also different browser versions call that option by different names. And I think there may even be a way to turn off tabs altogether, so check that too.

[jbmilam]

In order to fix the issue I added on to the WindowsDefault class so that it is the main browser class for windows platforms as opposed to being a default when no other browser is given. I gave the class an init where it specifies specific flags for firefox, chrome, and internet explorer (from what I could find there aren't really new window or new tab flags for internet explorer). If the flags for other browsers are known they should be easy to add to this section.

        def __init__(self,browser = "windows-default"):
            # Grab the different flags for the different browser types
            browser.lower()
            self.browsername = browser
            # If get() is used without arguments browser will be passed None
            if browser == "windows_default" or browser == None:
                self.cmd = "start"
            elif browser == 'iexplore' or browser == 'internet explorer':
                self.cmd = "start iexplore"
                self.newwindow = ""
                self.newtab = ""
            elif browser == "chrome":
                self.cmd = "start chrome.exe"
                self.newwindow = "-new-window"
                self.newtab = "-new-tab"
            elif browser == "firefox":
                self.cmd = "start firefox.exe"
                self.newwindow = "-new-window"
                self.newtab = "-new-tab"
            else:
                raise Error('The browser you entered (%s) is not currently supported on windows' % browser)

In the open method of the WindowsDefault class I changed how the browser is opened by building a command from the flags and the cmd for the specific browser and used subprocess,call.

            # Format the command for optional arguments and add the url
            if new == 1:
                self.cmd += " " + self.newwindow
            elif new == 2:
                self.cmd += " " + self.newtab
            self.cmd += " " + url

            subprocess.call(self.cmd,shell = True)

This allows the user to input different new arguments to open a new window or new tab like the documentation says they should be able to do. I added a little bit to the beginning of the get function so that it passes its argument to the WindowsDefault class and returns that object on Windows systems.

    # Let the windows default class handle different browsers on windows
    if sys.platform[:3] == "win":
        return WindowsDefault(using)

This adds some of the desired compatibility but does not completely address the module's issues. I did not see a way to open a web page in a currently open page on any of the browsers, just new windows and new tabs (when no flags are passed the browsers default to one of these two options). Also the _isexecutable function's attempt at windows compatibility is still not working because I was unsure of how to use just a string of a browser name like 'chrome' to determine if a file is on a system. This leaves _tryorder not properly containing the browsers on the system. This leaves the module's open, open_new and open_new_tab not properly working either just the WindowsDefault open method.
Any feed back and direction from here is most welcome.

[jbmilam]

How the _isexecutable function is set up now it would require a full path name in order to be able to tell if a specific browser is on the system. The area under platform support for windows checks for multiple browsers using this function but only passes it browser names and so it always returns false and does not add any browsers to _tryorder. I found a way to fix this using os.walk so that the simple strings of the browser names like "firefox.exe" is able to actually able to be found on the system. This method is rather slow though and the module wants to check for 8 browsers when imported.

[jbmilam]

I got rid of the __init__ for the WindowsDefault class that I asked about earlier and changed it to match the sub-classing model that the Unix browsers use. This caused some changes in the get function too. Due to the _isexecutable still not completely working, the get function is hard coded for chrome, internet explorer and firefox for windows systems. This is my first attempt at making a patch file so if it is incorrect please bear with me.

[zooba]

Some hints about finding browsers on Windows.

When browsers are installed, they should register themselves in HKEY_LOCAL_MACHINE\SOFTWARE\Clients\StartMenuInternet so that users can change their default browser through the OS.

On 64-bit systems, this is always in the 64-bit registry, so to open it you need OpenKeyEx and the KEY_WOW64_64KEY flag.

Each subkey of the key represents one browser, and the key name is a moniker while the default value of each subkey is a user-friendly name.

Under each subkey is a shell\open\command key that has the path for the browser in the default value. As far as I can tell this must be the path and cannot contain command-line arguments, and it may optionally have quotes (to handle spaces in the path).

I'd expect browsers to provide command-line arguments for opening in an existing window or a new one, but they will differ between browsers. and will require individual research (though it looks like the attached patch has some of them).

[eryksun]

register themselves in HKEY_LOCAL_MACHINE\SOFTWARE\
Clients\StartMenuInternet so that users can change their
default browser through the OS. On 64-bit systems, this
is always in the 64-bit registry

According to "Registry Keys Affected by WOW64", the "Clients" key is redirected in Vista and shared in Windows 7.

https://msdn.microsoft.com/en-us/library/aa384253

    import winreg

    HKLM = winreg.HKEY_LOCAL_MACHINE
    subkey = r'Software\Clients\StartMenuInternet'
    read32 = winreg.KEY_READ | winreg.KEY_WOW64_32KEY
    read64 = winreg.KEY_READ | winreg.KEY_WOW64_64KEY

    key32 = winreg.OpenKey(HKLM, subkey, access=read32)
    key64 = winreg.OpenKey(HKLM, subkey, access=read64)
    # This should be true in Windows 7.
    assert winreg.QueryInfoKey(key32) == winreg.QueryInfoKey(key64)

I don't have a Vista installation to confirm that it's really redirected. If so, it's important to enumerate the WOW64 redirected key as well, since 32-bit browsers are still common on Windows.

[jbmilam]

I kept the changes to the WindowsDefault.open() method and used and extended eryksun's code to build the browser list using the registry. Also I added support for a few more browsers. Some of the browsers I could not find ways to differentiate between opening a new window or new tab using command line flags. This also removed the hardcoding I had put in the get function.

[jbmilam]

I went ahead and took the assert statement out and added support for vista using a union of sets for both the 32 bit and 64 bit locations.

[jbmilam]

On second thought no type testing is required if sets are used because the union will take out duplicates anyways and so I removed the type testing and left in the set union code.