lib/alignalloc.h

   1 /* aligned memory allocation
   2
   3    Copyright 2022-2024 Free Software Foundation, Inc.
   4
   5    This file is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU Lesser General Public License as
   7    published by the Free Software Foundation; either version 2.1 of the
   8    License, or (at your option) any later version.
   9
  10    This file is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public License
  16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18 /* Written by Paul Eggert.  */
  19
  20 #ifndef ALIGNALLOC_H_
  21 #define ALIGNALLOC_H_
  22
  23 /* This file uses _GL_INLINE_HEADER_BEGIN, _GL_INLINE, _GL_ATTRIBUTE_ALLOC_SIZE,
  24    _GL_ATTRIBUTE_MALLOC, _GL_ATTRIBUTE_RETURNS_NONNULL, HAVE_POSIX_MEMALIGN.  */
  25 #if !_GL_CONFIG_H_INCLUDED
  26  #error "Please include config.h first."
  27 #endif
  28
  29 #include <errno.h>
  30 #include <stdlib.h>
  31 #include "idx.h"
  32 #if defined __CHERI_PURE_CAPABILITY__
  33 # include <cheri.h>
  34 #endif
  35
  36 _GL_INLINE_HEADER_BEGIN
  37 #ifndef ALIGNALLOC_INLINE
  38 # define ALIGNALLOC_INLINE _GL_INLINE
  39 #endif
  40
  41 /* Whether aligned_alloc supports any power-of-two alignment,
  42    returns a nonnull pointer for size-zero allocations,
  43    and sets errno on failure.  */
  44 #if 2 < __GLIBC__ + (16 <= __GLIBC_MINOR__)
  45 # define ALIGNALLOC_VIA_ALIGNED_ALLOC 1
  46 #else
  47 # define ALIGNALLOC_VIA_ALIGNED_ALLOC 0
  48 #endif
  49
  50 /* Work around AddressSanitizer bug.
  51    https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104262
  52    https://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20220124/1001910.html
  53    */
  54 #ifdef __SANITIZE_ADDRESS__
  55 # undef ALIGNALLOC_VIA_ALIGNED_ALLOC
  56 # define ALIGNALLOC_VIA_ALIGNED_ALLOC 0
  57 #endif
  58 #ifdef __has_feature
  59 # if __has_feature (address_sanitizer)
  60 #  undef ALIGNALLOC_VIA_ALIGNED_ALLOC
  61 #  define ALIGNALLOC_VIA_ALIGNED_ALLOC 0
  62 # endif
  63 #endif
  64
  65 #if ALIGNALLOC_VIA_ALIGNED_ALLOC || HAVE_POSIX_MEMALIGN
  66
  67 /* Free storage allocated via alignalloc.  Do nothing if PTR is null.  */
  68
  69 ALIGNALLOC_INLINE void
  70 alignfree (void *ptr)
  71 {
  72   free (ptr);
  73 }
  74
  75 /* Return an ALIGNMENT-aligned pointer to new storage of size SIZE,
  76    or a null pointer (setting errno) if memory is exhausted.
  77    ALIGNMENT must be a power of two.
  78    If SIZE is zero, on success return a unique pointer each time.
  79    To free storage later, call alignfree.  */
  80
  81 ALIGNALLOC_INLINE
  82 _GL_ATTRIBUTE_MALLOC _GL_ATTRIBUTE_ALLOC_SIZE ((2))
  83 /* _GL_ATTRIBUTE_DEALLOC (alignfree, 1) */
  84 void *
  85 alignalloc (idx_t alignment, idx_t size)
  86 {
  87   if ((size_t) -1 < alignment)
  88     alignment = (size_t) -1;
  89   if ((size_t) -1 < size)
  90     size = (size_t) -1;
  91
  92 # if ALIGNALLOC_VIA_ALIGNED_ALLOC
  93   return aligned_alloc (alignment, size);
  94 # else
  95   void *ptr = NULL;
  96   if (alignment < sizeof (void *))
  97     alignment = sizeof (void *);
  98   errno = posix_memalign (&ptr, alignment, size | !size);
  99 #  if defined __CHERI_PURE_CAPABILITY__
 100   if (ptr != NULL)
 101     ptr = cheri_bounds_set (ptr, size);
 102 #  endif
 103   return ptr;
 104 # endif
 105 }
 106
 107 #else /* ! (ALIGNALLOC_VIA_ALIGNED_ALLOC || HAVE_POSIX_MEMALIGN) */
 108
 109 void alignfree (void *);
 110 void *alignalloc (idx_t, idx_t)
 111   _GL_ATTRIBUTE_MALLOC _GL_ATTRIBUTE_ALLOC_SIZE ((2))
 112   _GL_ATTRIBUTE_DEALLOC (alignfree, 1);
 113
 114 #endif
 115
 116 /* Like alignalloc, but die instead of returning a null pointer.  */
 117 void *xalignalloc (idx_t, idx_t)
 118   _GL_ATTRIBUTE_MALLOC _GL_ATTRIBUTE_ALLOC_SIZE ((2))
 119   _GL_ATTRIBUTE_RETURNS_NONNULL /* _GL_ATTRIBUTE_DEALLOC (alignfree, 1) */;
 120
 121 _GL_INLINE_HEADER_END
 122
 123 #endif /* !ALIGNALLOC_H_ */