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crt: Change mingw-aligned-malloc.c to be compatible with MS CRT functions

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MS CRT libraries (UCRT, msvcr70+ and os system msvcrt) for functions
_aligned_malloc() and _aligned_offset_malloc() allocate the source buffer
slightly smaller than the mingw-w64 functions in mingw-aligned-malloc.c.
This is because the alignment gap can be used for the user data too.

Do exactly same math calculation in the mingw-w64 implementation as is UCRT
doing. Same calculation is in msvcr70 and probably also in system msvcrt
library (at least different _msize() tests confirms it).

This will allow to call __mingw_aligned_msize() on buffer allocated by
MS CRT _aligned_malloc() function from msvcrt.dll, msvcr70.dll and
msvcrt71.dll CRT libraries. This is very useful because these CRT libraries
do not have _aligned_msize() function and hence mingw-w64 could emulate it
via __mingw_aligned_msize().

Signed-off-by: Martin Storsjö <martin@martin.st>
This commit is contained in:
Pali Rohár 2025-04-08 00:20:45 +02:00 committed by Martin Storsjö
parent b4722cedb3
commit b8a0910a88
1 changed files with 9 additions and 5 deletions
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14
mingw-w64-crt/misc/mingw-aligned-malloc.c
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@ -22,9 +22,10 @@
#define UI(p) ((uintptr_t) (p))
#define CP(p) ((char *) p)
#define GAP(offset) ((0 - offset) & (sizeof (void *) -1))
#define PTR_ALIGN(p0, alignment, offset) \
((void *) (((UI(p0) + (alignment + sizeof(void*)) + offset) \
& (~UI(alignment - 1))) \
((void *) (((UI(p0) + (alignment + GAP(offset) + sizeof(void*)) + offset) \
& (~UI(alignment))) \
- offset))
/* Pointer must sometimes be aligned; assume sizeof(void*) is a power of two. */
@ -44,12 +45,13 @@ __mingw_aligned_offset_malloc (size_t size, size_t alignment, size_t offset)
return ((void *) 0);
if (alignment < sizeof (void *))
alignment = sizeof (void *);
alignment--;
/* Including the extra sizeof(void*) is overkill on a 32-bit
machine, since malloc is already 8-byte aligned, as long
as we enforce alignment >= 8 ...but oh well. */
p0 = malloc (size + (alignment + sizeof (void *)));
p0 = malloc (size + (alignment + GAP (offset) + sizeof (void *)));
if (!p0)
return ((void *) 0);
p = PTR_ALIGN (p0, alignment, offset);
@ -88,6 +90,7 @@ __mingw_aligned_offset_realloc (void *memblock, size_t size,
}
if (alignment < sizeof (void *))
alignment = sizeof (void *);
alignment--;
p0 = ORIG_PTR (memblock);
/* It is an error for the alignment to change. */
@ -95,7 +98,7 @@ __mingw_aligned_offset_realloc (void *memblock, size_t size,
goto bad;
shift = CP (memblock) - CP (p0);
p0 = realloc (p0, size + (alignment + sizeof (void *)));
p0 = realloc (p0, size + (alignment + GAP (offset) + sizeof (void *)));
if (!p0)
return ((void *) 0);
p = PTR_ALIGN (p0, alignment, offset);
@ -131,6 +134,7 @@ __mingw_aligned_msize (void *memblock, size_t alignment, size_t offset)
}
if (alignment < sizeof (void *))
alignment = sizeof (void *);
alignment--;
p0 = ORIG_PTR (memblock);
@ -141,5 +145,5 @@ __mingw_aligned_msize (void *memblock, size_t alignment, size_t offset)
return (size_t)-1;
}
return _msize (p0) - (alignment + sizeof (void *));
return _msize (p0) - (alignment + GAP (offset) + sizeof (void *));
}