libvirt/src/util/memory.h

217 lines
7.8 KiB
C
Raw Normal View History

/*
* memory.c: safer memory allocation
*
* Copyright (C) 2010-2011 Red Hat, Inc.
* 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
*
*/
#ifndef __VIR_MEMORY_H_
# define __VIR_MEMORY_H_
# include "internal.h"
/* Return 1 if an array of N objects, each of size S, cannot exist due
to size arithmetic overflow. S must be positive and N must be
nonnegative. This is a macro, not an inline function, so that it
works correctly even when SIZE_MAX < N.
By gnulib convention, SIZE_MAX represents overflow in size
calculations, so the conservative dividend to use here is
SIZE_MAX - 1, since SIZE_MAX might represent an overflowed value.
However, malloc (SIZE_MAX) fails on all known hosts where
sizeof(ptrdiff_t) <= sizeof(size_t), so do not bother to test for
exactly-SIZE_MAX allocations on such hosts; this avoids a test and
branch when S is known to be 1. */
# ifndef xalloc_oversized
# define xalloc_oversized(n, s) \
((size_t) (sizeof(ptrdiff_t) <= sizeof(size_t) ? -1 : -2) / (s) < (n))
# endif
/* Don't call these directly - use the macros below */
int virAlloc(void *ptrptr, size_t size) ATTRIBUTE_RETURN_CHECK
ATTRIBUTE_NONNULL(1);
int virAllocN(void *ptrptr, size_t size, size_t count) ATTRIBUTE_RETURN_CHECK
ATTRIBUTE_NONNULL(1);
int virReallocN(void *ptrptr, size_t size, size_t count) ATTRIBUTE_RETURN_CHECK
ATTRIBUTE_NONNULL(1);
int virExpandN(void *ptrptr, size_t size, size_t *count, size_t add)
ATTRIBUTE_RETURN_CHECK ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(3);
int virResizeN(void *ptrptr, size_t size, size_t *alloc, size_t count,
size_t desired)
ATTRIBUTE_RETURN_CHECK ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(3);
void virShrinkN(void *ptrptr, size_t size, size_t *count, size_t toremove)
ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(3);
int virAllocVar(void *ptrptr,
size_t struct_size,
size_t element_size,
size_t count) ATTRIBUTE_RETURN_CHECK ATTRIBUTE_NONNULL(1);
void virFree(void *ptrptr) ATTRIBUTE_NONNULL(1);
/**
* VIR_ALLOC:
* @ptr: pointer to hold address of allocated memory
*
* Allocate sizeof(*ptr) bytes of memory and store
* the address of allocated memory in 'ptr'. Fill the
* newly allocated memory with zeros.
*
* Returns -1 on failure, 0 on success
*/
# define VIR_ALLOC(ptr) virAlloc(&(ptr), sizeof(*(ptr)))
/**
* VIR_ALLOC_N:
* @ptr: pointer to hold address of allocated memory
* @count: number of elements to allocate
*
* Allocate an array of 'count' elements, each sizeof(*ptr)
* bytes long and store the address of allocated memory in
* 'ptr'. Fill the newly allocated memory with zeros.
*
* Returns -1 on failure, 0 on success
*/
# define VIR_ALLOC_N(ptr, count) virAllocN(&(ptr), sizeof(*(ptr)), (count))
/**
* VIR_REALLOC_N:
* @ptr: pointer to hold address of allocated memory
* @count: number of elements to allocate
*
* Re-allocate an array of 'count' elements, each sizeof(*ptr)
* bytes long and store the address of allocated memory in
* 'ptr'. If 'ptr' grew, the added memory is uninitialized.
*
* Returns -1 on failure, 0 on success
*/
# define VIR_REALLOC_N(ptr, count) virReallocN(&(ptr), sizeof(*(ptr)), (count))
/**
* VIR_EXPAND_N:
* @ptr: pointer to hold address of allocated memory
* @count: variable tracking number of elements currently allocated
* @add: number of elements to add
*
* Re-allocate an array of 'count' elements, each sizeof(*ptr)
* bytes long, to be 'count' + 'add' elements long, then store the
* address of allocated memory in 'ptr' and the new size in 'count'.
* The new elements are filled with zero.
*
* Returns -1 on failure, 0 on success
*/
# define VIR_EXPAND_N(ptr, count, add) \
virExpandN(&(ptr), sizeof(*(ptr)), &(count), add)
/**
* VIR_RESIZE_N:
* @ptr: pointer to hold address of allocated memory
* @alloc: variable tracking number of elements currently allocated
* @count: number of elements currently in use
* @add: minimum number of elements to additionally support
*
* Blindly using VIR_EXPAND_N(array, alloc, 1) in a loop scales
* quadratically, because every iteration must copy contents from
* all prior iterations. But amortized linear scaling can be achieved
* by tracking allocation size separately from the number of used
* elements, and growing geometrically only as needed.
*
* If 'count' + 'add' is larger than 'alloc', then geometrically reallocate
* the array of 'alloc' elements, each sizeof(*ptr) bytes long, and store
* the address of allocated memory in 'ptr' and the new size in 'alloc'.
* The new elements are filled with zero.
*
* Returns -1 on failure, 0 on success
*/
# define VIR_RESIZE_N(ptr, alloc, count, add) \
virResizeN(&(ptr), sizeof(*(ptr)), &(alloc), count, add)
/**
* VIR_SHRINK_N:
* @ptr: pointer to hold address of allocated memory
* @count: variable tracking number of elements currently allocated
* @remove: number of elements to remove
*
* Re-allocate an array of 'count' elements, each sizeof(*ptr)
* bytes long, to be 'count' - 'remove' elements long, then store the
* address of allocated memory in 'ptr' and the new size in 'count'.
* If 'count' <= 'remove', the entire array is freed.
*
* No return value.
*/
# define VIR_SHRINK_N(ptr, count, remove) \
virShrinkN(&(ptr), sizeof(*(ptr)), &(count), remove)
/*
* VIR_ALLOC_VAR_OVERSIZED:
* @M: size of base structure
* @N: number of array elements in trailing array
* @S: size of trailing array elements
*
* Check to make sure that the requested allocation will not cause
* arithmetic overflow in the allocation size. The check is
* essentially the same as that in gnulib's xalloc_oversized.
*/
# define VIR_ALLOC_VAR_OVERSIZED(M, N, S) ((((size_t)-1) - (M)) / (S) < (N))
/**
* VIR_ALLOC_VAR:
* @ptr: pointer to hold address of allocated memory
* @type: element type of trailing array
* @count: number of array elements to allocate
*
* Allocate sizeof(*ptr) bytes plus an array of 'count' elements, each
* sizeof('type'). 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
*/
# define VIR_ALLOC_VAR(ptr, type, count) \
virAllocVar(&(ptr), sizeof(*(ptr)), sizeof(type), (count))
/**
* VIR_FREE:
* @ptr: pointer holding address to be freed
*
* Free the memory stored in 'ptr' and update to point
* to NULL.
*/
/* The ternary ensures that ptr is a pointer and not an integer type,
* while evaluating ptr only once. For now, we intentionally cast
* away const, since a number of callers safely pass const char *.
*/
# define VIR_FREE(ptr) virFree((void *) (1 ? (const void *) &(ptr) : (ptr)))
2008-05-29 15:13:07 +00:00
# if TEST_OOM
2008-05-29 15:13:07 +00:00
void virAllocTestInit(void);
int virAllocTestCount(void);
void virAllocTestOOM(int n, int m);
2008-05-29 18:47:00 +00:00
void virAllocTestHook(void (*func)(int, void*), void *data);
# endif
2008-05-29 15:13:07 +00:00
#endif /* __VIR_MEMORY_H_ */