Special characters in database password are not escaped correctly on Windows platforms

[djangoproject.com@…]

​https://github.com/django/django/blob/master/django/db/backends/mysql/client.py#L38

On Windows platforms, the database client command line is composed as a string, but no escaping whatsoever is performed on the parameters. Database configuration can contain special characters (especially the password), which would require escaping.

Real-life case: ​http://stackoverflow.com/questions/22280126/sign-in-database-password-in-django

[djangoproject.com@…]

Proposed fix:
​https://github.com/django/django/pull/2412

[Baptiste Mispelon]

Hi,

It seems that the different codepath on windows was added as a result of #10357.

Looking at the discussion (especially comment number 3 [1]), it seems that using subprocess was considered at the time but it wasn't used because it was incompatible with Python 2.3 which was supported at the time.

The patch looks good and cleans things up nicely but I don't have access to a windows box to make sure it actually works.
I'm also concerned about a potential for subtle differences between os.execp and subprocess.call. The documentation of os.execp [2] is a bit hard to read and as a result, I can't really tell exactly what differences there are between the two.

Still, I'll mark this ticket as accepted, if only on the basis that using os.system(" ".join(args)) is clearly wrong.

Thanks.

[1] https://code.djangoproject.com/ticket/10357#comment:3
[2] ​http://docs.python.org/2/library/os.html?highlight=os.execvp#os.execvp

[Mihail Milushev]

From the ​subprocess.call docs:

The full function signature is the same as that of the Popen constructor - this functions passes all supplied arguments directly through to that interface.

From the ​subprocess.Popen docs:

Execute a child program in a new process. On Unix, the class uses os.execvp()-like behavior to execute the child program. On Windows, the class uses the Windows CreateProcess() function.

Sounds to me subprocess.call and os.execvp are explicitly meant to be compatible on Unix, and on Windows os.execvp isn't an option anyway.

[ANUBHAV JOSHI]

If only you could add a test to your PR, we can test the new implementation.

[Mihail Milushev]

I would, but I'm not really sure how to approach testing this change. The fact that there are zero existing tests for the DatabaseClient implementations does not help either — it seems historical changes to backends.*.client.DatabaseClient have never included a testcase.

[Tim Graham <timograham@…>]

In bf5382c6e549d78da9f7029cd86686459b52eaed:

Fixed #22234 -- Replaced OS-specific code with subprocess.call() in dbshell.

This fixes escaping of special characters on Windows.