1 /* -*- buffer-read-only: t -*- vi: set ro: */
2 /* DO NOT EDIT! GENERATED AUTOMATICALLY! */
3 /* Safe automatic memory allocation.
4 Copyright (C) 2003-2007, 2009-2013 Free Software Foundation, Inc.
5 Written by Bruno Haible <bruno@clisp.org>, 2003.
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)
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.
17 You should have received a copy of the GNU General Public License
18 along with this program; if not, see <http://www.gnu.org/licenses/>. */
33 /* safe_alloca(N) is equivalent to alloca(N) when it is safe to call
34 alloca(N); otherwise it returns NULL. It either returns N bytes of
35 memory allocated on the stack, that lasts until the function returns,
37 Use of safe_alloca should be avoided:
38 - inside arguments of function calls - undefined behaviour,
39 - in inline functions - the allocation may actually last until the
40 calling function returns.
43 /* The OS usually guarantees only one guard page at the bottom of the stack,
44 and a page size can be as small as 4096 bytes. So we cannot safely
45 allocate anything larger than 4096 bytes. Also care for the possibility
46 of a few compiler-allocated temporary stack slots.
47 This must be a macro, not a function. */
48 # define safe_alloca(N) ((N) < 4032 ? alloca (N) : NULL)
50 # define safe_alloca(N) ((void) (N), NULL)
53 /* malloca(N) is a safe variant of alloca(N). It allocates N bytes of
54 memory allocated on the stack, that must be freed using freea() before
55 the function returns. Upon failure, it returns NULL. */
58 ((N) < 4032 - sa_increment \
59 ? (void *) ((char *) alloca ((N) + sa_increment) + sa_increment) \
65 extern void * mmalloca (size_t n);
67 /* Free a block of memory allocated through malloca(). */
69 extern void freea (void *p);
74 /* nmalloca(N,S) is an overflow-safe variant of malloca (N * S).
75 It allocates an array of N objects, each with S bytes of memory,
76 on the stack. S must be positive and N must be nonnegative.
77 The array must be freed using freea() before the function returns. */
79 /* Cf. the definition of xalloc_oversized. */
80 # define nmalloca(n, s) \
81 ((n) > (size_t) (sizeof (ptrdiff_t) <= sizeof (size_t) ? -1 : -2) / (s) \
83 : malloca ((n) * (s)))
85 extern void * nmalloca (size_t n, size_t s);
94 /* ------------------- Auxiliary, non-public definitions ------------------- */
96 /* Determine the alignment of a type at compile time. */
97 #if defined __GNUC__ || defined __IBM__ALIGNOF__
98 # define sa_alignof __alignof__
99 #elif defined __cplusplus
100 template <class type> struct sa_alignof_helper { char __slot1; type __slot2; };
101 # define sa_alignof(type) offsetof (sa_alignof_helper<type>, __slot2)
103 /* Work around a HP-UX 10.20 cc bug with enums constants defined as offsetof
105 # define sa_alignof(type) (sizeof (type) <= 4 ? 4 : 8)
107 /* Work around an AIX 3.2.5 xlc bug with enums constants defined as offsetof
109 # define sa_alignof(type) (sizeof (type) <= 4 ? 4 : 8)
111 # define sa_alignof(type) offsetof (struct { char __slot1; type __slot2; }, __slot2)
116 /* The desired alignment of memory allocations is the maximum alignment
117 among all elementary types. */
118 sa_alignment_long = sa_alignof (long),
119 sa_alignment_double = sa_alignof (double),
120 #if HAVE_LONG_LONG_INT
121 sa_alignment_longlong = sa_alignof (long long),
123 sa_alignment_longdouble = sa_alignof (long double),
124 sa_alignment_max = ((sa_alignment_long - 1) | (sa_alignment_double - 1)
125 #if HAVE_LONG_LONG_INT
126 | (sa_alignment_longlong - 1)
128 | (sa_alignment_longdouble - 1)
130 /* The increment that guarantees room for a magic word must be >= sizeof (int)
131 and a multiple of sa_alignment_max. */
132 sa_increment = ((sizeof (int) + sa_alignment_max - 1) / sa_alignment_max) * sa_alignment_max
135 #endif /* _MALLOCA_H */