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Ensure 8-byte aligned memory allocation on MS-Windows 9X

Browse Source 
* src/w32heap.c (init_heap): Redirect malloc, realloc, and free to
special functions on Windows 9X.  Refuse to dump Emacs on Windows 9X.
(malloc_after_dump_9x, realloc_after_dump_9x)
(free_after_dump_9x): New functions.  (Bug#22379)  See also
http://lists.gnu.org/archive/html/emacs-devel/2016-01/msg00852.html
for more details about the original problem.

* nt/inc/ms-w32.h (malloc_after_dump_9x, realloc_after_dump_9x)
(free_after_dump_9x): Add prototypes.

Copyright-paperwork-exempt: yes
This commit is contained in:
Jussi Lahdenniemi 2016-01-16 11:11:12 +02:00 committed by Eli Zaretskii
parent 39afa422ad
commit 15c23aaf83
2 changed files with 87 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
nt/inc/ms-w32.h
View File

@ -457,6 +457,10 @@ extern void *malloc_after_dump(size_t);
extern void *realloc_after_dump(void *, size_t);
extern void free_after_dump(void *);
extern void *malloc_after_dump_9x(size_t);
extern void *realloc_after_dump_9x(void *, size_t);
extern void free_after_dump_9x(void *);
extern malloc_fn the_malloc_fn;
extern realloc_fn the_realloc_fn;
extern free_fn the_free_fn;

89
src/w32heap.c
View File

@ -258,9 +258,18 @@ init_heap (void)
}
#endif
the_malloc_fn = malloc_after_dump;
the_realloc_fn = realloc_after_dump;
the_free_fn = free_after_dump;
if (os_subtype == OS_9X)
{
the_malloc_fn = malloc_after_dump_9x;
the_realloc_fn = realloc_after_dump_9x;
the_free_fn = free_after_dump_9x;
}
else
{
the_malloc_fn = malloc_after_dump;
the_realloc_fn = realloc_after_dump;
the_free_fn = free_after_dump;
}
}
else
{
@ -291,9 +300,18 @@ init_heap (void)
exit (-1);
}
heap = s_pfn_Rtl_Create_Heap (0, data_region_base, 0, 0, NULL, &params);
the_malloc_fn = malloc_before_dump;
the_realloc_fn = realloc_before_dump;
the_free_fn = free_before_dump;
if (os_subtype == OS_9X)
{
fprintf (stderr, "Cannot dump Emacs on Windows 9X; exiting.\n");
exit (-1);
}
else
{
the_malloc_fn = malloc_before_dump;
the_realloc_fn = realloc_before_dump;
the_free_fn = free_before_dump;
}
}
/* Update system version information to match current system. */
@ -504,6 +522,65 @@ free_before_dump (void *ptr)
}
}
/* On Windows 9X, HeapAlloc may return pointers that are not aligned
on 8-byte boundary, alignment which is required by the Lisp memory
management. To circumvent this problem, manually enforce alignment
on Windows 9X. */
void *
malloc_after_dump_9x (size_t size)
{
void *p = malloc_after_dump (size + 8);
void *pa;
if (p == NULL)
return p;
pa = (void*)(((intptr_t)p + 8) & ~7);
*((void**)pa-1) = p;
return pa;
}
void *
realloc_after_dump_9x (void *ptr, size_t size)
{
if (FREEABLE_P (ptr))
{
void *po = *((void**)ptr-1);
void *p;
void *pa;
p = realloc_after_dump (po, size + 8);
if (p == NULL)
return p;
pa = (void*)(((intptr_t)p + 8) & ~7);
if (ptr != NULL &&
(char*)pa - (char*)p != (char*)ptr - (char*)po)
{
/* Handle the case where alignment in pre-realloc and
post-realloc blocks does not match. */
MoveMemory (pa, (void*)((char*)p + ((char*)ptr - (char*)po)), size);
}
*((void**)pa-1) = p;
return pa;
}
else
{
/* Non-freeable pointers have no alignment-enforcing header
(since dumping is not allowed on Windows 9X). */
void* p = malloc_after_dump_9x (size);
if (p != NULL)
CopyMemory (p, ptr, size);
return p;
}
}
void
free_after_dump_9x (void *ptr)
{
if (FREEABLE_P (ptr))
{
free_after_dump (*((void**)ptr-1));
}
}
#ifdef ENABLE_CHECKING
void
report_temacs_memory_usage (void)