[Cocci] Checking uniqueness for source code positions during SmPL data processing

[Markus Elfring <Markus.Elfring@web.de>]

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Hello,

I reported that I am trying a specific source code analysis out again.
Information can be imported also into database tables for such a purpose.
I observed a primary key constraint violation for my data processing attempt.
Useful background information can be found for a topic like
“Checking the handling of unique keys/indexes”.
https://groups.google.com/d/msg/sqlalchemy/klmUwiirIQw/LDeeRTcshQ4J

A corresponding aspect can trigger an usual development challenge.
The transaction fails if questionable data were detected. It seems to be hard
to find the single inappropriate data set out by SQL programming interfaces.

Thus I developed the attached script variant for the semantic patch language.
Another test result points interesting details out, doesn't it?


elfring@Sonne:~/Projekte/Linux/next-patched> time spatch ~/Projekte/Coccinelle/janitor/list_duplicate_statement_pairs_from_if_branches5.cocci drivers/media/dvb-frontends/stv0297.c
…
A duplicate key was passed.
function: stv0297_readreg
file: drivers/media/dvb-frontends/stv0297.c
line: 87
column: 4
Traceback (most recent call last):
  File "<string>", line 4, in <module>
  File "<string>", line 26, in store_statements
RuntimeError
exn while in timeout_function
Error in Python script, line 34, file …

real	0m0,606s
user	0m0,541s
sys	0m0,037s


By the way: I would like to point out once more that the code from
the SmPL rule “initialize” is 18 lines long and the definition for
the function “store_statements” starts at line 4 originally.


The implementation of the function “stv0297_readreg” contains two statements
which are repeated in three if branches for the desired exception handling.
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/media/dvb-frontends/stv0297.c?id=085b7755808aa11f78ab9377257e1dad2e6fa4bb#n66


Now I wonder about the shown software behaviour again when the corresponding
source code position should be unique based on the specified data fields.
How can affected software areas be improved further?

Regards,
Markus

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@initialize:python@
@@
import sys
mapping = {}

def store_statements(fun, source, s1, s2):
    """Add data to an internal table."""
    for place in source:
       key = (fun, place.file, place.line, int(place.column) + 1)
       if key in mapping:
          sys.stderr.write("""A duplicate key was passed.
function: %s
file: %s
line: %s
column: %d
""" % key)
          raise RuntimeError
       else:
          mapping[key] = (s1, s2)

@searching@
identifier work;
statement s1, s2;
position pos;
type T;
@@
 T work(...)
 {
 ... when any
 if (...)
 {
 ... when any
 s1@pos
 s2
 }
 ... when any
 }

@script:python collection@
fun << searching.work;
s1 << searching.s1;
s2 << searching.s2;
place << searching.pos;
@@
store_statements(fun, place, s1, s2)

@finalize:python@
@@
entries = len(mapping)

if entries > 0:
   from collections import Counter
   counts = Counter()

   for k, v in mapping.items():
      counts[(v[0], v[1], k[0], k[1])] += 1

   delimiter = "|"
   duplicates = {}

   for k, v in counts.items():
      if v > 1:
         duplicates[k] = v

   if len(duplicates.keys()) > 0:
      sys.stdout.write(delimiter.join(["statement1",
                                       "statement2",
                                       '"function name"',
                                       '"source file"',
                                       "incidence"]))
      sys.stdout.write("\r\n")

      for k, v in duplicates.items():
         sys.stdout.write(delimiter.join([k[0], k[1], k[2], k[3], str(v)]))
         sys.stdout.write("\r\n")
   else:
      sys.stderr.write("Duplicate statements were not determined from "
                       + str(entries) + " records.\n")
      sys.stderr.write(delimiter.join(["statement1",
                                       "statement2",
                                       '"function name"',
                                       '"source file"',
                                       "line"]))
      sys.stderr.write("\r\n")

      for k, v in counts.items():
         sys.stdout.write(delimiter.join([v[0], v[1], k[1], k[0], k[2]]))
         sys.stderr.write("\r\n")
else:
   sys.stderr.write("No result for this analysis!\n")

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