libvirt/src/util/memory.c
David Allan 62170b9952 Implement variable length structure allocator
* This patch implements a memory allocator to obtain memory for
  structures whose last member is a variable length array.  C99 refers
  to these variable length objects as structs containing flexible
  array members.
* Fixed macro parentheses per Eric Blake
2010-04-14 00:46:13 -04:00

220 lines
5.6 KiB
C

/*
* memory.c: safer memory allocation
*
* Copyright (C) 2008 Daniel P. Berrange
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#include <config.h>
#include <stdlib.h>
#include <stddef.h>
#include "memory.h"
#if TEST_OOM
static int testMallocNext = 0;
static int testMallocFailFirst = 0;
static int testMallocFailLast = 0;
static void (*testMallocHook)(int, void*) = NULL;
static void *testMallocHookData = NULL;
void virAllocTestInit(void)
{
testMallocNext = 1;
testMallocFailFirst = 0;
testMallocFailLast = 0;
}
int virAllocTestCount(void)
{
return testMallocNext - 1;
}
void virAllocTestHook(void (*func)(int, void*), void *data)
{
testMallocHook = func;
testMallocHookData = data;
}
void virAllocTestOOM(int n, int m)
{
testMallocNext = 1;
testMallocFailFirst = n;
testMallocFailLast = n + m - 1;
}
static int virAllocTestFail(void)
{
int fail = 0;
if (testMallocNext == 0)
return 0;
fail =
testMallocNext >= testMallocFailFirst &&
testMallocNext <= testMallocFailLast;
if (fail && testMallocHook)
(testMallocHook)(testMallocNext, testMallocHookData);
testMallocNext++;
return fail;
}
#endif
/**
* virAlloc:
* @ptrptr: pointer to pointer for address of allocated memory
* @size: number of bytes to allocate
*
* Allocate 'size' bytes of memory. Return the address of the
* allocated memory in 'ptrptr'. The newly allocated memory is
* filled with zeros.
*
* Returns -1 on failure to allocate, zero on success
*/
int virAlloc(void *ptrptr, size_t size)
{
#if TEST_OOM
if (virAllocTestFail()) {
*(void **)ptrptr = NULL;
return -1;
}
#endif
*(void **)ptrptr = calloc(1, size);
if (*(void **)ptrptr == NULL)
return -1;
return 0;
}
/**
* virAllocN:
* @ptrptr: pointer to pointer for address of allocated memory
* @size: number of bytes to allocate
* @count: number of elements to allocate
*
* Allocate an array of memory 'count' elements long,
* each with 'size' bytes. Return the address of the
* allocated memory in 'ptrptr'. The newly allocated
* memory is filled with zeros.
*
* Returns -1 on failure to allocate, zero on success
*/
int virAllocN(void *ptrptr, size_t size, size_t count)
{
#if TEST_OOM
if (virAllocTestFail()) {
*(void **)ptrptr = NULL;
return -1;
}
#endif
*(void**)ptrptr = calloc(count, size);
if (*(void**)ptrptr == NULL)
return -1;
return 0;
}
/**
* virReallocN:
* @ptrptr: pointer to pointer for address of allocated memory
* @size: number of bytes to allocate
* @count: number of elements in array
*
* Resize the block of memory in 'ptrptr' to be an array of
* 'count' elements, each 'size' bytes in length. Update 'ptrptr'
* with the address of the newly allocated memory. On failure,
* 'ptrptr' is not changed and still points to the original memory
* block. The newly allocated memory is filled with zeros.
*
* Returns -1 on failure to allocate, zero on success
*/
int virReallocN(void *ptrptr, size_t size, size_t count)
{
void *tmp;
#if TEST_OOM
if (virAllocTestFail())
return -1;
#endif
if (xalloc_oversized(count, size)) {
errno = ENOMEM;
return -1;
}
tmp = realloc(*(void**)ptrptr, size * count);
if (!tmp && (size * count))
return -1;
*(void**)ptrptr = tmp;
return 0;
}
/**
* Vir_Alloc_Var:
* @ptrptr: pointer to hold address of allocated memory
* @struct_size: size of initial struct
* @element_size: size of array elements
* @count: number of array elements to allocate
*
* Allocate struct_size bytes plus an array of 'count' elements, each
* of size element_size. This sort of allocation is useful for
* receiving the data of certain ioctls and other APIs which return a
* struct in which the last element is an array of undefined length.
* The caller of this type of API is expected to know the length of
* the array that will be returned and allocate a suitable buffer to
* contain the returned data. C99 refers to these variable length
* objects as structs containing flexible array members.
*
* Returns -1 on failure, 0 on success
*/
int virAllocVar(void *ptrptr, size_t struct_size, size_t element_size, size_t count)
{
size_t alloc_size = 0;
#if TEST_OOM
if (virAllocTestFail())
return -1;
#endif
if (VIR_ALLOC_VAR_OVERSIZED(struct_size, count, element_size)) {
errno = ENOMEM;
return -1;
}
alloc_size = struct_size + (element_size * count);
*(void **)ptrptr = calloc(1, alloc_size);
if (*(void **)ptrptr == NULL)
return -1;
return 0;
}
/**
* virFree:
* @ptrptr: pointer to pointer for address of memory to be freed
*
* Release the chunk of memory in the pointer pointed to by
* the 'ptrptr' variable. After release, 'ptrptr' will be
* updated to point to NULL.
*/
void virFree(void *ptrptr)
{
free(*(void**)ptrptr);
*(void**)ptrptr = NULL;
}