non-octal-permissions (RUF064)

Fix is sometimes available.

This rule is unstable and in preview. The --preview flag is required for use.

What it does

Checks for standard library functions which take a numeric mode argument where a non-octal integer literal is passed.

Why is this bad?

Numeric modes are made up of one to four octal digits. Converting a non-octal integer to octal may not be the mode the author intended.

Example

os.chmod("foo", 644)

Use instead:

os.chmod("foo", 0o644)

Fix safety

There are two categories of fix, the first of which is where it looks like the author intended to use an octal literal but the 0o prefix is missing:

os.chmod("foo", 400)
os.chmod("foo", 644)

This class of fix changes runtime behaviour. In the first case, 400 corresponds to 0o620 (u=rw,g=w,o=). As this mode is not deemed likely, it is changed to 0o400 (u=r,go=). Similarly, 644 corresponds to 0o1204 (u=ws,g=,o=r) and is changed to 0o644 (u=rw,go=r).

The second category is decimal literals which are recognised as likely valid but in decimal form:

os.chmod("foo", 256)
os.chmod("foo", 493)

256 corresponds to 0o400 (u=r,go=) and 493 corresponds to 0o755 (u=rwx,go=rx). Both of these fixes keep runtime behavior unchanged. If the original code really intended to use 0o256 (u=w,g=rx,o=rw) instead of 256, this fix should not be accepted.

Fix availability

A fix is only available if the integer literal matches a set of common modes.