support/blob_repeat.h

   1 /* Repeating a memory blob, with alias mapping optimization.
   2    Copyright (C) 2018-2022 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library 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 GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #ifndef SUPPORT_BLOB_REPEAT_H
  20 #define SUPPORT_BLOB_REPEAT_H
  21
  22 #include <stdbool.h>
  23 #include <stddef.h>
  24
  25 struct support_blob_repeat
  26 {
  27   void *start;
  28   size_t size;
  29   bool use_malloc;
  30 };
  31
  32 /* Return an allocation of COUNT elements, each of ELEMENT_SIZE bytes,
  33    initialized with the bytes starting at ELEMENT.  The memory is
  34    writable (and thus counts towards the commit charge).  In case of
  35    on error, all members of the return struct are zero-initialized,
  36    and errno is set accordingly.  */
  37 struct support_blob_repeat support_blob_repeat_allocate (const void *element,
  38                                                          size_t element_size,
  39                                                          size_t count);
  40
  41 /* Like support_blob_repeat_allocate, except that copy-on-write
  42    semantics are disabled.  This means writing to one part of the blob
  43    can affect other parts.  It is possible to map non-shared memory
  44    over parts of the resulting blob using MAP_ANONYMOUS | MAP_FIXED
  45    | MAP_PRIVATE, so that writes to these parts do not affect
  46    others.  */
  47 struct support_blob_repeat support_blob_repeat_allocate_shared
  48   (const void *element, size_t element_size, size_t count);
  49
  50 /* Deallocate the blob created by support_blob_repeat_allocate or
  51    support_blob_repeat_allocate_shared.  */
  52 void support_blob_repeat_free (struct support_blob_repeat *);
  53
  54 #endif /* SUPPORT_BLOB_REPEAT_H */