c6acfe86c7
conflicts due to radically different approaches to security and bug fixes. In some cases I re-started from the vendor version and reimplemented our patches. Fortunately, this is not enabled by default in -current.
272 lines
7.6 KiB
C++
272 lines
7.6 KiB
C++
/* xalloc.h -- malloc with out-of-memory checking
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Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
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1999, 2000, 2003, 2004, 2006, 2007 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software Foundation,
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Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
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#ifndef XALLOC_H_
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# define XALLOC_H_
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# include <stddef.h>
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# ifdef __cplusplus
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extern "C" {
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# endif
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# ifndef __attribute__
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# if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 8) || __STRICT_ANSI__
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# define __attribute__(x)
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# endif
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# endif
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# ifndef ATTRIBUTE_NORETURN
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# define ATTRIBUTE_NORETURN __attribute__ ((__noreturn__))
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# endif
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/* This function is always triggered when memory is exhausted.
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It must be defined by the application, either explicitly
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or by using gnulib's xalloc-die module. This is the
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function to call when one wants the program to die because of a
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memory allocation failure. */
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extern void xalloc_die (void) ATTRIBUTE_NORETURN;
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void *xmalloc (size_t s);
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void *xzalloc (size_t s);
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void *xcalloc (size_t n, size_t s);
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void *xrealloc (void *p, size_t s);
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void *x2realloc (void *p, size_t *pn);
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void *xmemdup (void const *p, size_t s);
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char *xstrdup (char const *str);
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/* Return 1 if an array of N objects, each of size S, cannot exist due
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to size arithmetic overflow. S must be positive and N must be
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nonnegative. This is a macro, not an inline function, so that it
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works correctly even when SIZE_MAX < N.
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By gnulib convention, SIZE_MAX represents overflow in size
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calculations, so the conservative dividend to use here is
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SIZE_MAX - 1, since SIZE_MAX might represent an overflowed value.
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However, malloc (SIZE_MAX) fails on all known hosts where
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sizeof (ptrdiff_t) <= sizeof (size_t), so do not bother to test for
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exactly-SIZE_MAX allocations on such hosts; this avoids a test and
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branch when S is known to be 1. */
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# define xalloc_oversized(n, s) \
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((size_t) (sizeof (ptrdiff_t) <= sizeof (size_t) ? -1 : -2) / (s) < (n))
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/* In the following macros, T must be an elementary or structure/union or
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typedef'ed type, or a pointer to such a type. To apply one of the
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following macros to a function pointer or array type, you need to typedef
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it first and use the typedef name. */
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/* Allocate an object of type T dynamically, with error checking. */
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/* extern t *XMALLOC (typename t); */
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# define XMALLOC(t) ((t *) xmalloc (sizeof (t)))
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/* Allocate memory for N elements of type T, with error checking. */
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/* extern t *XNMALLOC (size_t n, typename t); */
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# define XNMALLOC(n, t) \
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((t *) (sizeof (t) == 1 ? xmalloc (n) : xnmalloc (n, sizeof (t))))
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/* Allocate an object of type T dynamically, with error checking,
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and zero it. */
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/* extern t *XZALLOC (typename t); */
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# define XZALLOC(t) ((t *) xzalloc (sizeof (t)))
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/* Allocate memory for N elements of type T, with error checking,
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and zero it. */
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/* extern t *XCALLOC (size_t n, typename t); */
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# define XCALLOC(n, t) \
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((t *) (sizeof (t) == 1 ? xzalloc (n) : xcalloc (n, sizeof (t))))
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# if HAVE_INLINE
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# define static_inline static inline
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# else
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void *xnmalloc (size_t n, size_t s);
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void *xnrealloc (void *p, size_t n, size_t s);
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void *x2nrealloc (void *p, size_t *pn, size_t s);
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char *xcharalloc (size_t n);
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# endif
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# ifdef static_inline
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/* Allocate an array of N objects, each with S bytes of memory,
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dynamically, with error checking. S must be nonzero. */
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static_inline void *
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xnmalloc (size_t n, size_t s)
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{
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if (xalloc_oversized (n, s))
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xalloc_die ();
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return xmalloc (n * s);
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}
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/* Change the size of an allocated block of memory P to an array of N
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objects each of S bytes, with error checking. S must be nonzero. */
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static_inline void *
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xnrealloc (void *p, size_t n, size_t s)
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{
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if (xalloc_oversized (n, s))
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xalloc_die ();
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return xrealloc (p, n * s);
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}
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/* If P is null, allocate a block of at least *PN such objects;
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otherwise, reallocate P so that it contains more than *PN objects
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each of S bytes. *PN must be nonzero unless P is null, and S must
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be nonzero. Set *PN to the new number of objects, and return the
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pointer to the new block. *PN is never set to zero, and the
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returned pointer is never null.
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Repeated reallocations are guaranteed to make progress, either by
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allocating an initial block with a nonzero size, or by allocating a
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larger block.
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In the following implementation, nonzero sizes are increased by a
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factor of approximately 1.5 so that repeated reallocations have
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O(N) overall cost rather than O(N**2) cost, but the
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specification for this function does not guarantee that rate.
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Here is an example of use:
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int *p = NULL;
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size_t used = 0;
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size_t allocated = 0;
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void
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append_int (int value)
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{
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if (used == allocated)
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p = x2nrealloc (p, &allocated, sizeof *p);
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p[used++] = value;
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}
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This causes x2nrealloc to allocate a block of some nonzero size the
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first time it is called.
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To have finer-grained control over the initial size, set *PN to a
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nonzero value before calling this function with P == NULL. For
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example:
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int *p = NULL;
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size_t used = 0;
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size_t allocated = 0;
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size_t allocated1 = 1000;
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void
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append_int (int value)
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{
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if (used == allocated)
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{
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p = x2nrealloc (p, &allocated1, sizeof *p);
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allocated = allocated1;
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}
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p[used++] = value;
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}
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*/
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static_inline void *
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x2nrealloc (void *p, size_t *pn, size_t s)
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{
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size_t n = *pn;
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if (! p)
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{
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if (! n)
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{
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/* The approximate size to use for initial small allocation
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requests, when the invoking code specifies an old size of
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zero. 64 bytes is the largest "small" request for the
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GNU C library malloc. */
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enum { DEFAULT_MXFAST = 64 };
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n = DEFAULT_MXFAST / s;
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n += !n;
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}
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}
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else
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{
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/* Set N = ceil (1.5 * N) so that progress is made if N == 1.
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Check for overflow, so that N * S stays in size_t range.
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The check is slightly conservative, but an exact check isn't
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worth the trouble. */
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if ((size_t) -1 / 3 * 2 / s <= n)
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xalloc_die ();
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n += (n + 1) / 2;
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}
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*pn = n;
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return xrealloc (p, n * s);
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}
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/* Return a pointer to a new buffer of N bytes. This is like xmalloc,
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except it returns char *. */
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static_inline char *
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xcharalloc (size_t n)
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{
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return XNMALLOC (n, char);
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}
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# endif
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# ifdef __cplusplus
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}
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/* C++ does not allow conversions from void * to other pointer types
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without a cast. Use templates to work around the problem when
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possible. */
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template <typename T> inline T *
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xrealloc (T *p, size_t s)
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{
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return (T *) xrealloc ((void *) p, s);
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}
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template <typename T> inline T *
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xnrealloc (T *p, size_t n, size_t s)
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{
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return (T *) xnrealloc ((void *) p, n, s);
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}
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template <typename T> inline T *
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x2realloc (T *p, size_t *pn)
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{
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return (T *) x2realloc ((void *) p, pn);
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}
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template <typename T> inline T *
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x2nrealloc (T *p, size_t *pn, size_t s)
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{
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return (T *) x2nrealloc ((void *) p, pn, s);
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}
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template <typename T> inline T *
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xmemdup (T const *p, size_t s)
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{
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return (T *) xmemdup ((void const *) p, s);
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}
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# endif
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#endif /* !XALLOC_H_ */
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