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#include "alloc.h"
#include <errno.h>
#include <limits.h>
#include <stdlib.h>
#include "byte.h"
#define ALIGNMENT 16 /* XXX: assuming that this alignment is enough */
#define SPACE 4096 /* must be multiple of ALIGNMENT */
#define space ((char *)realspace)
/**
@file alloc.c
@authors djb, feh, jmh
@ref qmail
@brief Generic allocation of heap memory
*/
typedef union {
char irrelevant[ALIGNMENT];
double d;
} aligned;
static aligned realspace[SPACE / ALIGNMENT];
static unsigned int avail = SPACE; /* multiple of ALIGNMENT; 0<=avail<=SPACE */
void *alloc(unsigned int n)
{
char *x;
/* Guninski exploit + patch from Qualys (CVE-2005-1513) */
if (n >= (INT_MAX >> 3)) {
errno = ENOMEM;
return 0;
}
n = ALIGNMENT + n - (n & (ALIGNMENT - 1)); /* XXX: could overflow */
if (n <= avail) {
avail -= n;
return space + avail;
}
x = malloc(n);
if (!x) errno = ENOMEM;
return x;
}
void alloc_free(void *x)
{
if (x >= space)
if (x < space + SPACE) return; /* XXX: assuming that pointers are flat */
free(x);
}
int alloc_re(void *a, unsigned int m, unsigned int n)
{
char **x = a;
char *y;
y = alloc(n);
if (!y) return 0;
byte_copy(y, m, *x);
qfree(*x);
*x = y;
return 1;
}
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