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From: Mats Kindahl <mats.kindahl@gmail.com>
To: cocci@inria.fr
Subject: [cocci] How to add error handling code before first use
Date: Mon, 11 Nov 2024 20:59:51 +0100	[thread overview]
Message-ID: <f59fb941-f9a9-455c-a369-f764e33323e8@gmail.com> (raw)

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Hi again,

I am trying to match code like the following and add error handling to it:

    #include <postgres.h>

    void foo(Oid id) {
       HeapTuple tuple;
       Form_pg_proc fd;

       tuple = SearchSysCache1(PROCOID, ObjectIdGetDatum(id));
       fd = (Form_pg_proc)GETSTRUCT(tuple);

       if (strcmp("magic", NameStr(fd->proname)) != 0)
         printf("Bad magic\n");
    }

The semantic patch I have for this is:

    @@
    identifier tuple;
    expression id, cache;
    statement S;
    @@
       tuple = SearchSysCache1(cache, ObjectIdGetDatum(id));
       ... when != tuple
    (
       if (<+... HeapTupleIsValid(tuple) ...+>) S
    |
    + if (!HeapTupleIsValid(tuple))
    +   elog(ERROR, "cache lookup failed for %u", id);
       (<+...tuple...+>);
    )

However, when executing spatch, I get the following error:

    mats@abzu:~/lang/cocci/postgres$ spatch --all-includes --sp-file
    heap_tuple.cocci code/heap_tuple.c
    init_defs_builtins: /usr/lib/coccinelle/standard.h
    before [[Tag29 ("{", 0)]; [Tag22 ((Tag1 ((Tag5 (("if", (11, 2, 0, 0,
    " "), Tag2 (0), 0), ("(", (11, 5, 0, 0, " "), Tag2 (0), 0), (Tag9
    ((Tag3 (((
    ((("HeapTupleIsValid", (11, 7, 0, 0, ""), Tag2 (0), 0)), 11, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0)), 11, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 1, 0),
    ("(", (11, 23, 0, 0, ""), Tag2 (0), 0), ([(((Tag1 ((("rule starting
    on line 1", "tuple"), (11, 24, 0, 0, ""), Tag2 (0), 0), 1, 0, 0),
    11, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0)), 11, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 1, 0)], 11, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0), (")", (11,
    29, 0, 0,
    ""), Tag2 (0), 0)), 11, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0), (6,
    (11, 6, 0, 0, ""), Tag2 (0), 0)), 11, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 1, 0),
    (")", (11, 30, 0, 0, ""), Tag2 (0), 0)), 11, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 1, 0), (Tag8 ((Tag4 (((Tag3 (((((("elog", (12, 4, 0, 0, "
       "), Ta
    g2 (0), 0)), 12, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0)), 12, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0), ("(", (12, 8, 0, 0, ""), Tag2 (0),
    0), ([((
    ((("ERROR", (12, 9, 0, 0, ""), Tag2 (0), 0)), 12, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 1, 0)), 12, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0);
    (Tag26 (("
    ,", (12, 14, 0, 0, ""), Tag2 (0), 0)), 12, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 1, 0); (Tag1 ((("cache lookup failed for %u", 4), (12, 16,
    0, 0, " ")
    , Tag2 (0), 0)), 12, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0); (Tag26
    ((",", (12, 44, 0, 0, ""), Tag2 (0), 0)), 12, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0
    , 1, 0); (Tag22 ((("rule starting on line 1", "id"), (12, 46, 0, 0,
    " "), Tag2 (0), 0), 1, 0, 0, 0, 0, 0), 12, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 1
    , 0)], 12, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0), (")", (12, 48, 0,
    0, ""), Tag2 (0), 0)), 12, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0)),
    (";", (1
    2, 49, 0, 0, ""), Tag2 (0), 0)), 12, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 1, 0)), 12, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0), (0, 0, 0,
    Tag1 (0, 0)))
    , 11, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0))]]
    context tree should not have bad code before

First, what is causing the error?

Second, is the semantic patch supposed to work or is another method 
preferred?

Best wishes,
Mats Kindahl

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next             reply	other threads:[~2024-11-11 20:00 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-11-11 19:59 Mats Kindahl [this message]
2024-11-11 22:36 ` [cocci] How to add error handling code before first use Julia Lawall
2024-11-13 15:13   ` Julia Lawall
2024-11-13 17:38     ` Mats Kindahl

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