wget/lib/xmalloc.c

341 lines
8.2 KiB
C

/* xmalloc.c -- malloc with out of memory checking
Copyright (C) 1990-2000, 2002-2006, 2008-2023 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>
#define XALLOC_INLINE _GL_EXTERN_INLINE
#include "xalloc.h"
#include "ialloc.h"
#include "minmax.h"
#include <stdckdint.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
static void * _GL_ATTRIBUTE_PURE
nonnull (void *p)
{
if (!p)
xalloc_die ();
return p;
}
/* Allocate S bytes of memory dynamically, with error checking. */
void *
xmalloc (size_t s)
{
return nonnull (malloc (s));
}
void *
ximalloc (idx_t s)
{
return nonnull (imalloc (s));
}
char *
xcharalloc (size_t n)
{
return XNMALLOC (n, char);
}
/* Change the size of an allocated block of memory P to S bytes,
with error checking. */
void *
xrealloc (void *p, size_t s)
{
void *r = realloc (p, s);
if (!r && (!p || s))
xalloc_die ();
return r;
}
void *
xirealloc (void *p, idx_t s)
{
return nonnull (irealloc (p, s));
}
/* Change the size of an allocated block of memory P to an array of N
objects each of S bytes, with error checking. */
void *
xreallocarray (void *p, size_t n, size_t s)
{
void *r = reallocarray (p, n, s);
if (!r && (!p || (n && s)))
xalloc_die ();
return r;
}
void *
xireallocarray (void *p, idx_t n, idx_t s)
{
return nonnull (ireallocarray (p, n, s));
}
/* Allocate an array of N objects, each with S bytes of memory,
dynamically, with error checking. S must be nonzero. */
void *
xnmalloc (size_t n, size_t s)
{
return xreallocarray (NULL, n, s);
}
void *
xinmalloc (idx_t n, idx_t s)
{
return xireallocarray (NULL, n, s);
}
/* If P is null, allocate a block of at least *PS bytes; otherwise,
reallocate P so that it contains more than *PS bytes. *PS must be
nonzero unless P is null. Set *PS to the new block's size, and
return the pointer to the new block. *PS is never set to zero, and
the returned pointer is never null. */
void *
x2realloc (void *p, size_t *ps)
{
return x2nrealloc (p, ps, 1);
}
/* 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;
}
*/
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;
}
}
else
{
/* Set N = floor (1.5 * N) + 1 to make progress even if N == 0. */
if (ckd_add (&n, n, (n >> 1) + 1))
xalloc_die ();
}
p = xreallocarray (p, n, s);
*pn = n;
return p;
}
/* Grow PA, which points to an array of *PN items, and return the
location of the reallocated array, updating *PN to reflect its
new size. The new array will contain at least N_INCR_MIN more
items, but will not contain more than N_MAX items total.
S is the size of each item, in bytes.
S and N_INCR_MIN must be positive. *PN must be
nonnegative. If N_MAX is -1, it is treated as if it were
infinity.
If PA is null, then allocate a new array instead of reallocating
the old one.
Thus, to grow an array A without saving its old contents, do
{ free (A); A = xpalloc (NULL, &AITEMS, ...); }. */
void *
xpalloc (void *pa, idx_t *pn, idx_t n_incr_min, ptrdiff_t n_max, idx_t s)
{
idx_t n0 = *pn;
/* The approximate size to use for initial small allocation
requests. This is the largest "small" request for the GNU C
library malloc. */
enum { DEFAULT_MXFAST = 64 * sizeof (size_t) / 4 };
/* If the array is tiny, grow it to about (but no greater than)
DEFAULT_MXFAST bytes. Otherwise, grow it by about 50%.
Adjust the growth according to three constraints: N_INCR_MIN,
N_MAX, and what the C language can represent safely. */
idx_t n;
if (ckd_add (&n, n0, n0 >> 1))
n = IDX_MAX;
if (0 <= n_max && n_max < n)
n = n_max;
/* NBYTES is of a type suitable for holding the count of bytes in an object.
This is typically idx_t, but it should be size_t on (theoretical?)
platforms where SIZE_MAX < IDX_MAX so xpalloc does not pass
values greater than SIZE_MAX to xrealloc. */
#if IDX_MAX <= SIZE_MAX
idx_t nbytes;
#else
size_t nbytes;
#endif
idx_t adjusted_nbytes
= (ckd_mul (&nbytes, n, s)
? MIN (IDX_MAX, SIZE_MAX)
: nbytes < DEFAULT_MXFAST ? DEFAULT_MXFAST : 0);
if (adjusted_nbytes)
{
n = adjusted_nbytes / s;
nbytes = adjusted_nbytes - adjusted_nbytes % s;
}
if (! pa)
*pn = 0;
if (n - n0 < n_incr_min
&& (ckd_add (&n, n0, n_incr_min)
|| (0 <= n_max && n_max < n)
|| ckd_mul (&nbytes, n, s)))
xalloc_die ();
pa = xrealloc (pa, nbytes);
*pn = n;
return pa;
}
/* Allocate S bytes of zeroed memory dynamically, with error checking.
There's no need for xnzalloc (N, S), since it would be equivalent
to xcalloc (N, S). */
void *
xzalloc (size_t s)
{
return xcalloc (s, 1);
}
void *
xizalloc (idx_t s)
{
return xicalloc (s, 1);
}
/* Allocate zeroed memory for N elements of S bytes, with error
checking. S must be nonzero. */
void *
xcalloc (size_t n, size_t s)
{
return nonnull (calloc (n, s));
}
void *
xicalloc (idx_t n, idx_t s)
{
return nonnull (icalloc (n, s));
}
/* Clone an object P of size S, with error checking. There's no need
for xnmemdup (P, N, S), since xmemdup (P, N * S) works without any
need for an arithmetic overflow check. */
void *
xmemdup (void const *p, size_t s)
{
return memcpy (xmalloc (s), p, s);
}
void *
ximemdup (void const *p, idx_t s)
{
return memcpy (ximalloc (s), p, s);
}
/* Clone an object P of size S, with error checking. Append
a terminating NUL byte. */
char *
ximemdup0 (void const *p, idx_t s)
{
char *result = ximalloc (s + 1);
result[s] = 0;
return memcpy (result, p, s);
}
/* Clone STRING. */
char *
xstrdup (char const *string)
{
return xmemdup (string, strlen (string) + 1);
}