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nasm_delete(): ugly hack to make it side-effect-free

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Use an ugly hack to make nasm_delete() side effect free.  This assumes
all pointers have the same internal NULL pointer representation as
void *, however, we already assume zero-initialized memory will
represent a NULL pointer, so hopefully this is okay on any platform we
actually care about.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
This commit is contained in:
H. Peter Anvin
2017-01-24 14:04:44 -08:00
parent 75f2c1e131
commit a92a7dce5e
1 changed files with 14 additions and 3 deletions
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17
include/nasmlib.h
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@@ -153,13 +153,24 @@ void nasm_free(void *);
char * safe_alloc nasm_strdup(const char *);
char * safe_alloc nasm_strndup(const char *, size_t);
/* Assert the argument is a pointer without evaluating it */
#define nasm_assert_pointer(p) ((void)sizeof(*(p)))
#define nasm_new(p) ((p) = nasm_zalloc(sizeof(*(p))))
#define nasm_newn(p,n) ((p) = nasm_calloc(sizeof(*(p)),(n)))
/*
* Careful: nasm_delete() is not side-effect safe.
* Any ideas how to fix that?
* This is broken on platforms where there are pointers which don't
* match void * in their internal layout. It unfortunately also
* loses any "const" part of the argument, although hopefully the
* compiler will warn in that case.
*/
#define nasm_delete(p) do { nasm_free(p); (p) = NULL; } while (0)
#define nasm_delete(p) \
do { \
void **_pp = (void **)&(p); \
nasm_assert_pointer(p); \
nasm_free(*_pp); \
*_pp = NULL; \
} while (0)
#define nasm_zero(p) (memset((p), 0, sizeof(*(p))))
/*