EIC code displayed by LXR master/​include/​glib-2.0/​glib/​galloca.h	Source navigation Diff markup Identifier search General search
	Version: master test Revert   Change

File indexing completed on 2026-05-06 08:41:16

 /* GLIB - Library of useful routines for C programming
  * Copyright (C) 1995-1997  Peter Mattis, Spencer Kimball and Josh MacDonald
  *
  * SPDX-License-Identifier: LGPL-2.1-or-later
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  */
 
 /*
  * Modified by the GLib Team and others 1997-2000.  See the AUTHORS
  * file for a list of people on the GLib Team.  See the ChangeLog
  * files for a list of changes.  These files are distributed with
  * GLib at ftp://ftp.gtk.org/pub/gtk/.
  */
 
 #ifndef __G_ALLOCA_H__
 #define __G_ALLOCA_H__
 
 #if !defined (__GLIB_H_INSIDE__) && !defined (GLIB_COMPILATION)
 #error "Only <glib.h> can be included directly."
 #endif
 
 #include <glib/gtypes.h>
 #include <string.h>
 
 #if defined(__BIONIC__) && defined (GLIB_HAVE_ALLOCA_H)
 # include <alloca.h>
 #elif defined(__GNUC__)
 /* GCC does the right thing */
 # undef alloca
 # define alloca(size)   __builtin_alloca (size)
 #elif defined (GLIB_HAVE_ALLOCA_H)
 /* a native and working alloca.h is there */ 
 # include <alloca.h>
 #else /* !__GNUC__ && !GLIB_HAVE_ALLOCA_H */
 # if defined(_MSC_VER) || defined(__DMC__)
 #  include <malloc.h>
 #  define alloca _alloca
 # else /* !_MSC_VER && !__DMC__ */
 #  ifdef _AIX
 #   pragma alloca
 #  else /* !_AIX */
 #   ifndef alloca /* predefined by HP cc +Olibcalls */
 G_BEGIN_DECLS
 char *alloca ();
 G_END_DECLS
 #   endif /* !alloca */
 #  endif /* !_AIX */
 # endif /* !_MSC_VER && !__DMC__ */
 #endif /* !__GNUC__ && !GLIB_HAVE_ALLOCA_H */
 
 /**
  * g_alloca:
  * @size: number of bytes to allocate.
  * 
  * Allocates @size bytes on the stack; these bytes will be freed when the current
  * stack frame is cleaned up. This macro essentially just wraps the alloca()
  * function present on most UNIX variants.
  * Thus it provides the same advantages and pitfalls as alloca():
  *
  * - alloca() is very fast, as on most systems it's implemented by just adjusting
  *   the stack pointer register.
  *
  * - It doesn't cause any memory fragmentation, within its scope, separate alloca()
  *   blocks just build up and are released together at function end.
  *
  * - Allocation sizes have to fit into the current stack frame. For instance in a
  *   threaded environment on Linux, the per-thread stack size is limited to 2 Megabytes,
  *   so be sparse with alloca() uses.
  *
  * - Allocation failure due to insufficient stack space is not indicated with a %NULL
  *   return like e.g. with malloc(). Instead, most systems probably handle it the same
  *   way as out of stack space situations from infinite function recursion, i.e.
  *   with a segmentation fault.
  *
  * - Allowing @size to be specified by an untrusted party would allow for them
  *   to trigger a segmentation fault by specifying a large size, leading to a
  *   denial of service vulnerability. @size must always be entirely under the
  *   control of the program.
  *
  * - Special care has to be taken when mixing alloca() with GNU C variable sized arrays.
  *   Stack space allocated with alloca() in the same scope as a variable sized array
  *   will be freed together with the variable sized array upon exit of that scope, and
  *   not upon exit of the enclosing function scope.
  * 
  * Returns: space for @size bytes, allocated on the stack
  */
 #define g_alloca(size)       alloca (size)
 
 /**
  * g_alloca0:
  * @size: number of bytes to allocate.
  *
  * Wraps g_alloca() and initializes allocated memory to zeroes.
  * If @size is `0` it returns %NULL.
  *
  * Note that the @size argument will be evaluated multiple times.
  *
  * Returns: (nullable) (transfer full): space for @size bytes, allocated on the stack
  *
  * Since: 2.72
  */
 #define g_alloca0(size)  ((size) == 0 ? NULL : memset (g_alloca (size), 0, (size)))
 
 /**
  * g_newa:
  * @struct_type: Type of memory chunks to be allocated
  * @n_structs: Number of chunks to be allocated
  * 
  * Wraps g_alloca() in a more typesafe manner.
  * 
  * As mentioned in the documentation for g_alloca(), @n_structs must always be
  * entirely under the control of the program, or you may introduce a denial of
  * service vulnerability. In addition, the multiplication of @struct_type by
  * @n_structs is not checked, so an overflow may lead to a remote code execution
  * vulnerability.
  *
  * Returns: Pointer to stack space for @n_structs chunks of type @struct_type
  */
 #define g_newa(struct_type, n_structs)  ((struct_type*) g_alloca (sizeof (struct_type) * (gsize) (n_structs)))
 
 /**
  * g_newa0:
  * @struct_type: the type of the elements to allocate.
  * @n_structs: the number of elements to allocate.
  *
  * Wraps g_alloca0() in a more typesafe manner.
  *
  * Returns: (nullable) (transfer full): Pointer to stack space for @n_structs
  *   chunks of type @struct_type
  *
  * Since: 2.72
  */
 #define g_newa0(struct_type, n_structs)  ((struct_type*) g_alloca0 (sizeof (struct_type) * (gsize) (n_structs)))
 
 #endif /* __G_ALLOCA_H__ */

This page was automatically generated by the 2.3.7 LXR engine. The LXR team