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 #ifdef __cplusplus
  42 extern "C" {
  43 #endif
  44
  45
  46 /* Whether aligned_alloc supports any power-of-two alignment,
  47    returns a nonnull pointer for size-zero allocations,
  48    and sets errno on failure.  */
  49 #if 2 < __GLIBC__ + (16 <= __GLIBC_MINOR__)
  50 # define ALIGNALLOC_VIA_ALIGNED_ALLOC 1
  51 #else
  52 # define ALIGNALLOC_VIA_ALIGNED_ALLOC 0
  53 #endif
  54
  55 /* Work around AddressSanitizer bug.
  56    https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104262
  57    https://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20220124/1001910.html
  58    */
  59 #ifdef __SANITIZE_ADDRESS__
  60 # undef ALIGNALLOC_VIA_ALIGNED_ALLOC
  61 # define ALIGNALLOC_VIA_ALIGNED_ALLOC 0
  62 #endif
  63 #ifdef __has_feature
  64 # if __has_feature (address_sanitizer)
  65 #  undef ALIGNALLOC_VIA_ALIGNED_ALLOC
  66 #  define ALIGNALLOC_VIA_ALIGNED_ALLOC 0
  67 # endif
  68 #endif
  69
  70 #if ALIGNALLOC_VIA_ALIGNED_ALLOC || HAVE_POSIX_MEMALIGN
  71
  72 /* Free storage allocated via alignalloc.  Do nothing if PTR is null.  */
  73
  74 ALIGNALLOC_INLINE void
  75 alignfree (void *ptr)
  76 {
  77   free (ptr);
  78 }
  79
  80 /* Return an ALIGNMENT-aligned pointer to new storage of size SIZE,
  81    or a null pointer (setting errno) if memory is exhausted.
  82    ALIGNMENT must be a power of two.
  83    If SIZE is zero, on success return a unique pointer each time.
  84    To free storage later, call alignfree.  */
  85
  86 ALIGNALLOC_INLINE
  87 _GL_ATTRIBUTE_MALLOC _GL_ATTRIBUTE_ALLOC_SIZE ((2))
  88 /* _GL_ATTRIBUTE_DEALLOC (alignfree, 1) */
  89 void *
  90 alignalloc (idx_t alignment, idx_t size)
  91 {
  92   if ((size_t) -1 < alignment)
  93     alignment = (size_t) -1;
  94   if ((size_t) -1 < size)
  95     size = (size_t) -1;
  96
  97 # if ALIGNALLOC_VIA_ALIGNED_ALLOC
  98   return aligned_alloc (alignment, size);
  99 # else
 100   void *ptr = NULL;
 101   if (alignment < sizeof (void *))
 102     alignment = sizeof (void *);
 103   /* Work around posix_memalign glitch by treating a 0 size as if it were 1,
 104      so that returning NULL is equivalent to failing.  */
 105   errno = posix_memalign (&ptr, alignment, size ? size : 1);
 106 #  if defined __CHERI_PURE_CAPABILITY__
 107   if (ptr != NULL)
 108     ptr = cheri_bounds_set (ptr, size);
 109 #  endif
 110   return ptr;
 111 # endif
 112 }
 113
 114 #else /* ! (ALIGNALLOC_VIA_ALIGNED_ALLOC || HAVE_POSIX_MEMALIGN) */
 115
 116 void alignfree (void *);
 117 void *alignalloc (idx_t, idx_t)
 118   _GL_ATTRIBUTE_MALLOC _GL_ATTRIBUTE_ALLOC_SIZE ((2))
 119   _GL_ATTRIBUTE_DEALLOC (alignfree, 1);
 120
 121 #endif
 122
 123 /* Like alignalloc, but die instead of returning a null pointer.  */
 124 void *xalignalloc (idx_t, idx_t)
 125   _GL_ATTRIBUTE_MALLOC _GL_ATTRIBUTE_ALLOC_SIZE ((2))
 126   _GL_ATTRIBUTE_RETURNS_NONNULL /* _GL_ATTRIBUTE_DEALLOC (alignfree, 1) */;
 127
 128
 129 #ifdef __cplusplus
 130 }
 131 #endif
 132
 133 _GL_INLINE_HEADER_END
 134
 135 #endif /* !ALIGNALLOC_H_ */