[cfe-commits] [PATCH 1/1] Checking zero byte allocation for realloc() and calloc().

[Cyril Roelandt]

Hello,

Currently, clang can check zero byte allocations for the malloc 
function. I think it should also warn programmers about zero byte 
allocations for the calloc and realloc functions.

Attached is a patch that implements this idea. It checks either the 
first argument of malloc(), or the second argument of realloc(), or both 
arguments of calloc(), looking for a value constrained to 0.

Checking both arguments of calloc() makes the code a little bit ugly, so 
I'll probably need to give it some more work.

You may find a test case attached to this mail :

$ clang --analyze -c -o alloc alloc.c
/tmp/alloc.c:29:16: warning: Call to 'malloc' has an allocation size of 
0 bytes
     int *ptr = malloc(0);
                ^      ~
/tmp/alloc.c:36:16: warning: Call to 'calloc' has an allocation size of 
0 bytes
     int *ptr = calloc(0, sizeof(int));
                ^      ~
/tmp/alloc.c:43:16: warning: Call to 'calloc' has an allocation size of 
0 bytes
     int *ptr = calloc(42, 0);
                ^          ~
/tmp/alloc.c:50:16: warning: Call to 'realloc' has an allocation size of 
0 bytes
     int *ptr = realloc(NULL, 0);
                ^             ~

Looking forward to hearing from you,
Cyril Roelandt.
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