[Cocci] using cocci to switch to formatted log/print function

[George McCollister <george.mccollister@gmail.com>]

Hello,

I'm working with an old code base that makes excessive use of the
following sort of construct:

char display[128];

...

snprintf(display, sizeof(display), "example log message %d", i);
log_buffer(level, strlen(display)+1, display);

I'd like to replace this mess with a single call to a function named
log_formatted(). This involves moving the format string and arguments
passed to snprintf into the log_formatted() call, removing snprintf
call and (here's where it gets a bit tricky) remove the buffer if it
isn't used for anything else.

I have this all working with the following script with the caveat that
running it on moderately complicated source files makes it never
finish (after an hour or so the spatch process crashes with a stack
overflow error).
I've tried --no-loops which seem to speed things up but complicated
source files still result in it never finishing.

@r1@
type T;
identifier disp;
expression level;
expression list prnt;
@@

{
... when any
(
T disp[...];
|
T disp[...]="";
)
<+...
  snprintf(disp, sizeof(disp), prnt);
... when != disp
- log_buffer(level, strlen(disp)+1, disp);
+ log_formatted(level, prnt);
...+>
}

// Only remove the display variable and snprintf if there are no
// other references to the variable.

@r2 depends on r1@
type r1.T;
identifier r1.disp;
expression list r1.prnt;
@@

{
... when any
(
- T disp[...];
|
- T disp[...]="";
)
<+... when != disp
- snprintf(disp, sizeof(disp), prnt);
...+>
}


Any suggestions on changes to my script that would make this work on
lengthy source files would be greatly appreciated!

Thanks,
George McCollister
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