webbrowser.py cannot use a non-standard browser under MacOS

[mmaass-x]

Bug report

Bug description:

webbrowser.py reads the environment variable "BROWSER" to find executable using "_synthesize".
This does not work with macOS, where the browser is open by either

/Applications/Google\ Chrome.app/Contents/MacOS/Google\ Chrome

or

open -a "Google Chrome"

it doesn't match the list of configured browsers

Workaround is to create a zsh script in the path called 'chrome':

#!/bin/zsh
#
open -a "Google Chrome.app" $

"_synthesize" needs to be fixed.

CPython versions tested on:

3.11

Operating systems tested on:

macOS

Linked PRs

• gh-113539: Enable using $BROWSER to reorder default seach order in webbrowser.py #113561

[ronaldoussoren]

It might be better to tweak the code that calls _synthesize, using the already registered browsers when available (which would lead to using the registration for MacOSXOSAScript at the start of register_standard_browsers. That likely needs changes as well because this currently tries to start chrome using the following shell command:

osascript -e 'tell application "chrome" 
                         activate
                         open location "https://www.python.org"
                       end'

I don't have Chrome installed, could you check if this command opens the python website for you? If not, try the same with "chrome" replaced by "google chrome".

[sobolevn]

@ronaldoussoren I have chrome installed on macos, it does not work for me:

» osascript -e 'tell application "chrome" 
                         activate
                         open location "https://www.python.org"
                       end'
52:60: execution error: Cannot open application "chrome". (-1728)

But, this one works:

» osascript -e 'tell application "google chrome" 
                         activate
                         open location "https://www.python.org"
                       end'

Also works with: firefox, safari (I don't have any other browsers).

[ronaldoussoren]

The diff below seems to work, but I haven't fully thought through the consequences on platforms other than macOS. That's why I haven't created a PR at this time.

diff --git a/Lib/webbrowser.py b/Lib/webbrowser.py
index 636e8ca459..310c6d58ce 100755
--- a/Lib/webbrowser.py
+++ b/Lib/webbrowser.py
@@ -114,7 +114,21 @@ def _synthesize(browser, *, preferred=False):
     executable for the requested browser, return [None, None].
 
     """
-    cmd = browser.split()[0]
+    parts = browser.split()
+    if len(parts) == 1:
+        # Assume this the name of a registered command, use
+        # that unless it is a GenericBrowser.
+        try:
+            command = _browsers[browser.lower()]
+        except KeyError:
+            pass
+
+        else:
+            if not isinstance(command[1], GenericBrowser):
+                _tryorder.insert(0, browser.lower())
+                return [None, command[1]]
+
+    cmd = parts[0]
     if not shutil.which(cmd):
         return [None, None]
     name = os.path.basename(cmd)
@@ -466,9 +480,10 @@ def register_standard_browsers():
 
     if sys.platform == 'darwin':
         register("MacOSX", None, MacOSXOSAScript('default'))
-        register("chrome", None, MacOSXOSAScript('chrome'))
+        register("chrome", None, MacOSXOSAScript('google chrome'))
         register("firefox", None, MacOSXOSAScript('firefox'))
         register("safari", None, MacOSXOSAScript('safari'))
+        register("safari-preview", None, MacOSXOSAScript('safari technology preview'))
         # OS X can use below Unix support (but we prefer using the OS X
         # specific stuff)

Ignore the registration of "safari-preview", I added that because that's the only alternative browser on the system I'm working on. A PR for this issue should not contain that.

[ronaldoussoren]

I've added a PR and I'm being very conservative with this: the PR phrasing and documentation changes assume this is a new feature and not a bug fix.

The reason is that the documentation for webbrowser module mentions that values in the $BROWSER search list refer to command-lines:

If the environment variable BROWSER exists, it is interpreted as the os.pathsep-separated list of browsers to try ahead of the platform defaults. When the value of a list part contains the string %s, then it is interpreted as a literal browser command line to be used with the argument URL substituted for %s; if the part does not contain %s, it is simply interpreted as the name of the browser to launch. 1

[micseydel]

Any update or recommended workaround for this? @sobolevn's osascript works for me by itself, and from within a script, but the webbrowser module doesn't seem to use it even when it's on my PATH.

[hugovk]

This will be in the next release (3.14.0b1) in a couple of weeks.

[micseydel]

@hugovk thanks for the update. Is there a recommended workaround for affected versions?