diff options
author | Paul Eggert <[email protected]> | 2011-04-17 21:41:29 -0700 |
---|---|---|
committer | Paul Eggert <[email protected]> | 2011-04-17 21:41:29 -0700 |
commit | 36372bf93fc75b5f85d04007268e98840d1699c5 (patch) | |
tree | bd15d9623db1c58cbac99a5b3b40590fee8703c9 /src/alloc.c | |
parent | c7bda33cad5112de8c093dce0eaf62c84fb32063 (diff) |
* alloc.c: Remove unportable assumptions about struct layout.
(SDATA_SELECTOR, SDATA_DATA_OFFSET): New macros.
(SDATA_OF_STRING, SDATA_SIZE, allocate_string_data):
(allocate_vectorlike, make_pure_vector): Use the new macros,
plus offsetof, to remove unportable assumptions about struct layout.
These assumptions hold on all porting targets that I know of, but
they are not guaranteed, they're easy to remove, and removing them
makes further changes easier.
Diffstat (limited to 'src/alloc.c')
-rw-r--r-- | src/alloc.c | 32 |
1 files changed, 13 insertions, 19 deletions
diff --git a/src/alloc.c b/src/alloc.c index 2d1c8ffe70..fbc075be3b 100644 --- a/src/alloc.c +++ b/src/alloc.c @@ -1517,6 +1517,7 @@ struct sdata #define SDATA_NBYTES(S) (S)->nbytes #define SDATA_DATA(S) (S)->data +#define SDATA_SELECTOR(member) member #else /* not GC_CHECK_STRING_BYTES */ @@ -1531,8 +1532,11 @@ struct sdata #define SDATA_NBYTES(S) (S)->u.nbytes #define SDATA_DATA(S) (S)->u.data +#define SDATA_SELECTOR(member) u.member #endif /* not GC_CHECK_STRING_BYTES */ + +#define SDATA_DATA_OFFSET offsetof (struct sdata, SDATA_SELECTOR (data)) }; @@ -1608,18 +1612,7 @@ static EMACS_INT total_string_size; a pointer to the `u.data' member of its sdata structure; the structure starts at a constant offset in front of that. */ -#ifdef GC_CHECK_STRING_BYTES - -#define SDATA_OF_STRING(S) \ - ((struct sdata *) ((S)->data - sizeof (struct Lisp_String *) \ - - sizeof (EMACS_INT))) - -#else /* not GC_CHECK_STRING_BYTES */ - -#define SDATA_OF_STRING(S) \ - ((struct sdata *) ((S)->data - sizeof (struct Lisp_String *))) - -#endif /* not GC_CHECK_STRING_BYTES */ +#define SDATA_OF_STRING(S) ((struct sdata *) ((S)->data - SDATA_DATA_OFFSET)) #ifdef GC_CHECK_STRING_OVERRUN @@ -1643,17 +1636,16 @@ static char const string_overrun_cookie[GC_STRING_OVERRUN_COOKIE_SIZE] = #ifdef GC_CHECK_STRING_BYTES #define SDATA_SIZE(NBYTES) \ - ((sizeof (struct Lisp_String *) \ + ((SDATA_DATA_OFFSET \ + (NBYTES) + 1 \ - + sizeof (EMACS_INT) \ + sizeof (EMACS_INT) - 1) \ & ~(sizeof (EMACS_INT) - 1)) #else /* not GC_CHECK_STRING_BYTES */ #define SDATA_SIZE(NBYTES) \ - ((sizeof (struct Lisp_String *) \ - + (NBYTES) + 1 \ + ((SDATA_DATA_OFFSET \ + + max (NBYTES, sizeof (EMACS_INT) - 1) + 1 \ + sizeof (EMACS_INT) - 1) \ & ~(sizeof (EMACS_INT) - 1)) @@ -1877,7 +1869,7 @@ allocate_string_data (struct Lisp_String *s, if (nbytes > LARGE_STRING_BYTES) { - size_t size = sizeof *b - sizeof (struct sdata) + needed; + size_t size = offsetof (struct sblock, first_data) + needed; #ifdef DOUG_LEA_MALLOC /* Prevent mmap'ing the chunk. Lisp data may not be mmap'ed @@ -2807,7 +2799,8 @@ allocate_vectorlike (EMACS_INT len) /* This gets triggered by code which I haven't bothered to fix. --Stef */ /* eassert (!handling_signal); */ - nbytes = sizeof *p + (len - 1) * sizeof p->contents[0]; + nbytes = (offsetof (struct Lisp_Vector, contents) + + len * sizeof p->contents[0]); p = (struct Lisp_Vector *) lisp_malloc (nbytes, MEM_TYPE_VECTORLIKE); #ifdef DOUG_LEA_MALLOC @@ -4735,7 +4728,8 @@ make_pure_vector (EMACS_INT len) { Lisp_Object new; struct Lisp_Vector *p; - size_t size = sizeof *p + (len - 1) * sizeof (Lisp_Object); + size_t size = (offsetof (struct Lisp_Vector, contents) + + len * sizeof (Lisp_Object)); p = (struct Lisp_Vector *) pure_alloc (size, Lisp_Vectorlike); XSETVECTOR (new, p); |