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/* xmalloc.c -- malloc with out of memory checking
Copyright (C) 1990-1996, 2000-2003, 2005-2007, 2012 Free Software
Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
#include <config.h>
/* Specification. */
#include "xalloc.h"
#include <stdlib.h>
#include "error.h"
#include "gettext.h"
#define _(str) gettext (str)
/* Exit value when the requested amount of memory is not available.
The caller may set it to some other value. */
int xmalloc_exit_failure = EXIT_FAILURE;
void
xalloc_die ()
{
error (xmalloc_exit_failure, 0, _("memory exhausted"));
/* _Noreturn cannot be given to error, since it may return if
its first argument is 0. To help compilers understand the
xalloc_die does terminate, call exit. */
exit (EXIT_FAILURE);
}
static void *
fixup_null_alloc (size_t n)
{
void *p;
p = NULL;
if (n == 0)
p = malloc ((size_t) 1);
if (p == NULL)
xalloc_die ();
return p;
}
/* Allocate N bytes of memory dynamically, with error checking. */
void *
xmalloc (size_t n)
{
void *p;
p = malloc (n);
if (p == NULL)
p = fixup_null_alloc (n);
return p;
}
/* Allocate memory for NMEMB elements of SIZE bytes, with error checking.
SIZE must be > 0. */
void *
xnmalloc (size_t nmemb, size_t size)
{
size_t n;
void *p;
if (xalloc_oversized (nmemb, size))
xalloc_die ();
n = nmemb * size;
p = malloc (n);
if (p == NULL)
p = fixup_null_alloc (n);
return p;
}
/* Allocate SIZE bytes of memory dynamically, with error checking,
and zero it. */
void *
xzalloc (size_t size)
{
void *p;
p = xmalloc (size);
memset (p, 0, size);
return p;
}
/* Allocate memory for N elements of S bytes, with error checking,
and zero it. */
void *
xcalloc (size_t n, size_t s)
{
void *p;
p = calloc (n, s);
if (p == NULL)
p = fixup_null_alloc (n);
return p;
}
/* Change the size of an allocated block of memory P to N bytes,
with error checking.
If P is NULL, run xmalloc. */
void *
xrealloc (void *p, size_t n)
{
if (p == NULL)
return xmalloc (n);
p = realloc (p, n);
if (p == NULL)
p = fixup_null_alloc (n);
return p;
}
/* If P is null, allocate a block of at least *PN such objects;
otherwise, reallocate P so that it contains more than *PN objects
each of S bytes. S must be nonzero. Set *PN to the new number of
objects, and return the pointer to the new block. *PN is never set
to zero, and the returned pointer is never null.
Repeated reallocations are guaranteed to make progress, either by
allocating an initial block with a nonzero size, or by allocating a
larger block.
In the following implementation, nonzero sizes are increased by a
factor of approximately 1.5 so that repeated reallocations have
O(N) overall cost rather than O(N**2) cost, but the
specification for this function does not guarantee that rate.
Here is an example of use:
int *p = NULL;
size_t used = 0;
size_t allocated = 0;
void
append_int (int value)
{
if (used == allocated)
p = x2nrealloc (p, &allocated, sizeof *p);
p[used++] = value;
}
This causes x2nrealloc to allocate a block of some nonzero size the
first time it is called.
To have finer-grained control over the initial size, set *PN to a
nonzero value before calling this function with P == NULL. For
example:
int *p = NULL;
size_t used = 0;
size_t allocated = 0;
size_t allocated1 = 1000;
void
append_int (int value)
{
if (used == allocated)
{
p = x2nrealloc (p, &allocated1, sizeof *p);
allocated = allocated1;
}
p[used++] = value;
}
*/
static inline void *
x2nrealloc (void *p, size_t *pn, size_t s)
{
size_t n = *pn;
if (! p)
{
if (! n)
{
/* The approximate size to use for initial small allocation
requests, when the invoking code specifies an old size of
zero. This is the largest "small" request for the GNU C
library malloc. */
enum { DEFAULT_MXFAST = 64 * sizeof (size_t) / 4 };
n = DEFAULT_MXFAST / s;
n += !n;
}
if (xalloc_oversized (n, s))
xalloc_die ();
}
else
{
/* Set N = floor (1.5 * N) + 1 so that progress is made even if N == 0.
Check for overflow, so that N * S stays in both ptrdiff_t and
size_t range. The check may be slightly conservative, but an
exact check isn't worth the trouble. */
if ((PTRDIFF_MAX < SIZE_MAX ? PTRDIFF_MAX : SIZE_MAX) / 3 * 2 / s
<= n)
xalloc_die ();
n += n / 2 + 1;
}
*pn = n;
return xrealloc (p, n * s);
}
/* If P is null, allocate a block of at least *PN bytes; otherwise,
reallocate P so that it contains more than *PN bytes. *PN must be
nonzero unless P is null. Set *PN to the new block's size, and
return the pointer to the new block. *PN is never set to zero, and
the returned pointer is never null. */
void *
x2realloc (void *p, size_t *pn)
{
return x2nrealloc (p, pn, 1);
}
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