1 /* -*- buffer-read-only: t -*- vi: set ro: */ 2 /* DO NOT EDIT! GENERATED AUTOMATICALLY! */ 3 /* Safe automatic memory allocation. 4 Copyright (C) 2003-2007, 2009-2011 Free Software Foundation, Inc. 5 Written by Bruno Haible <bruno@clisp.org>, 2003. 6 7 This program is free software; you can redistribute it and/or modify 8 it under the terms of the GNU General Public License as published by 9 the Free Software Foundation; either version 3, or (at your option) 10 any later version. 11 12 This program is distributed in the hope that it will be useful, 13 but WITHOUT ANY WARRANTY; without even the implied warranty of 14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 GNU General Public License for more details. 16 17 You should have received a copy of the GNU General Public License 18 along with this program; if not, write to the Free Software Foundation, 19 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ 20 21 #ifndef _MALLOCA_H 22 #define _MALLOCA_H 23 24 #include <alloca.h> 25 #include <stddef.h> 26 #include <stdlib.h> 27 28 29 #ifdef __cplusplus 30 extern "C" { 31 #endif 32 33 34 /* safe_alloca(N) is equivalent to alloca(N) when it is safe to call 35 alloca(N); otherwise it returns NULL. It either returns N bytes of 36 memory allocated on the stack, that lasts until the function returns, 37 or NULL. 38 Use of safe_alloca should be avoided: 39 - inside arguments of function calls - undefined behaviour, 40 - in inline functions - the allocation may actually last until the 41 calling function returns. 42 */ 43 #if HAVE_ALLOCA 44 /* The OS usually guarantees only one guard page at the bottom of the stack, 45 and a page size can be as small as 4096 bytes. So we cannot safely 46 allocate anything larger than 4096 bytes. Also care for the possibility 47 of a few compiler-allocated temporary stack slots. 48 This must be a macro, not an inline function. */ 49 # define safe_alloca(N) ((N) < 4032 ? alloca (N) : NULL) 50 #else 51 # define safe_alloca(N) ((void) (N), NULL) 52 #endif 53 54 /* malloca(N) is a safe variant of alloca(N). It allocates N bytes of 55 memory allocated on the stack, that must be freed using freea() before 56 the function returns. Upon failure, it returns NULL. */ 57 #if HAVE_ALLOCA 58 # define malloca(N) \ 59 ((N) < 4032 - sa_increment \ 60 ? (void *) ((char *) alloca ((N) + sa_increment) + sa_increment) \ 61 : mmalloca (N)) 62 #else 63 # define malloca(N) \ 64 mmalloca (N) 65 #endif 66 extern void * mmalloca (size_t n); 67 68 /* Free a block of memory allocated through malloca(). */ 69 #if HAVE_ALLOCA 70 extern void freea (void *p); 71 #else 72 # define freea free 73 #endif 74 75 /* nmalloca(N,S) is an overflow-safe variant of malloca (N * S). 76 It allocates an array of N objects, each with S bytes of memory, 77 on the stack. S must be positive and N must be nonnegative. 78 The array must be freed using freea() before the function returns. */ 79 #if 1 80 /* Cf. the definition of xalloc_oversized. */ 81 # define nmalloca(n, s) \ 82 ((n) > (size_t) (sizeof (ptrdiff_t) <= sizeof (size_t) ? -1 : -2) / (s) \ 83 ? NULL \ 84 : malloca ((n) * (s))) 85 #else 86 extern void * nmalloca (size_t n, size_t s); 87 #endif 88 89 90 #ifdef __cplusplus 91 } 92 #endif 93 94 95 /* ------------------- Auxiliary, non-public definitions ------------------- */ 96 97 /* Determine the alignment of a type at compile time. */ 98 #if defined __GNUC__ 99 # define sa_alignof __alignof__ 100 #elif defined __cplusplus 101 template <class type> struct sa_alignof_helper { char __slot1; type __slot2; }; 102 # define sa_alignof(type) offsetof (sa_alignof_helper<type>, __slot2) 103 #elif defined __hpux 104 /* Work around a HP-UX 10.20 cc bug with enums constants defined as offsetof 105 values. */ 106 # define sa_alignof(type) (sizeof (type) <= 4 ? 4 : 8) 107 #elif defined _AIX 108 /* Work around an AIX 3.2.5 xlc bug with enums constants defined as offsetof 109 values. */ 110 # define sa_alignof(type) (sizeof (type) <= 4 ? 4 : 8) 111 #else 112 # define sa_alignof(type) offsetof (struct { char __slot1; type __slot2; }, __slot2) 113 #endif 114 115 enum 116 { 117 /* The desired alignment of memory allocations is the maximum alignment 118 among all elementary types. */ 119 sa_alignment_long = sa_alignof (long), 120 sa_alignment_double = sa_alignof (double), 121 #if HAVE_LONG_LONG_INT 122 sa_alignment_longlong = sa_alignof (long long), 123 #endif 124 sa_alignment_longdouble = sa_alignof (long double), 125 sa_alignment_max = ((sa_alignment_long - 1) | (sa_alignment_double - 1) 126 #if HAVE_LONG_LONG_INT 127 | (sa_alignment_longlong - 1) 128 #endif 129 | (sa_alignment_longdouble - 1) 130 ) + 1, 131 /* The increment that guarantees room for a magic word must be >= sizeof (int) 132 and a multiple of sa_alignment_max. */ 133 sa_increment = ((sizeof (int) + sa_alignment_max - 1) / sa_alignment_max) * sa_alignment_max 134 }; 135 136 #endif /* _MALLOCA_H */ 137