diff options
Diffstat (limited to 'Include/pyport.h')
| -rw-r--r-- | Include/pyport.h | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/Include/pyport.h b/Include/pyport.h index 271ec431a3..a831b264f9 100644 --- a/Include/pyport.h +++ b/Include/pyport.h @@ -366,8 +366,16 @@ extern double hypot(double, double); #endif #ifdef MALLOC_ZERO_RETURNS_NULL -/* XXX Always allocate one extra byte, since some malloc's return NULL - XXX for malloc(0) or realloc(p, 0). */ +/* Allocate an extra byte if the platform malloc(0) returns NULL. + Caution: this bears no relation to whether realloc(p, 0) returns NULL + when p != NULL. Even on platforms where malloc(0) does not return NULL, + realloc(p, 0) may act like free(p) and return NULL. Examples include + Windows, and Python's own obmalloc.c (as of 2-Mar-2002). For whatever + reason, our docs promise that PyMem_Realloc(p, 0) won't act like + free(p) or return NULL, so realloc() calls may have to be hacked + too, but MALLOC_ZERO_RETURNS_NULL's state is irrelevant to realloc (it + needs a different hack). +*/ #define _PyMem_EXTRA 1 #else #define _PyMem_EXTRA 0 |