[Cocci] Can I pass a variable from a Python script in one rule to another rule in the same .cocci file?

[Cocci] Can I pass a variable from a Python script in one rule to another rule in the same .cocci file?

[Timur Tabi]

In one rule, I have some Python code that parses a string literal to
see what it looks like.  If I detect a specific pattern, then I want
another rule (that has no Python code) to act differently.

More specifically, if a string literal passed as a parameter to
DBG_PRINTF() starts with "NVRM: ", then I want my script to replace
DBG_PRINTF with NV_PRINTF.  This works today.

If the string does not begin with "NVRM:", however, then I want
DBG_PRINTF changed to NV_PRINTF_EX instead.

If this can't work, an alternative would be to create a second script
that handles DBG_PRINTF to NV_PRINTF_EX.  However, it would need to
abort the change if the Python script detects that NVRM: doesn't
exist.  So is there a way for Python to return a value that says,
"Woah, stop and undo everything you just did!"
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Re: [Cocci] Can I pass a variable from a Python script in one rule to another rule in the same .cocci file?

[Julia Lawall]

On Fri, 4 Jan 2019, Timur Tabi wrote:

> In one rule, I have some Python code that parses a string literal to
> see what it looks like.  If I detect a specific pattern, then I want
> another rule (that has no Python code) to act differently.
>
> More specifically, if a string literal passed as a parameter to
> DBG_PRINTF() starts with "NVRM: ", then I want my script to replace
> DBG_PRINTF with NV_PRINTF.  This works today.
>
> If the string does not begin with "NVRM:", however, then I want
> DBG_PRINTF changed to NV_PRINTF_EX instead.
>
> If this can't work, an alternative would be to create a second script
> that handles DBG_PRINTF to NV_PRINTF_EX.  However, it would need to
> abort the change if the Python script detects that NVRM: doesn't
> exist.  So is there a way for Python to return a value that says,
> "Woah, stop and undo everything you just did!"

I think that you want to use cocci.include_match(False)

In your python script, make the checks that you want, and then if you are
not satisfied with the results, use cocci.include_match(False) to get the
curent match of the metavariables to disappear.  You may need to rematch
something to get the information needed for the second change option.

julia

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