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62170b9952
* 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
146 lines
4.9 KiB
C
146 lines
4.9 KiB
C
/*
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* memory.c: safer memory allocation
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*
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* Copyright (C) 2008 Daniel P. Berrange
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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*/
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#ifndef __VIR_MEMORY_H_
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# define __VIR_MEMORY_H_
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# include "internal.h"
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/* Return 1 if an array of N objects, each of size S, cannot exist due
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to size arithmetic overflow. S must be positive and N must be
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nonnegative. This is a macro, not an inline function, so that it
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works correctly even when SIZE_MAX < N.
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By gnulib convention, SIZE_MAX represents overflow in size
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calculations, so the conservative dividend to use here is
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SIZE_MAX - 1, since SIZE_MAX might represent an overflowed value.
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However, malloc (SIZE_MAX) fails on all known hosts where
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sizeof (ptrdiff_t) <= sizeof (size_t), so do not bother to test for
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exactly-SIZE_MAX allocations on such hosts; this avoids a test and
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branch when S is known to be 1. */
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# ifndef xalloc_oversized
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# define xalloc_oversized(n, s) \
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((size_t) (sizeof (ptrdiff_t) <= sizeof (size_t) ? -1 : -2) / (s) < (n))
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# endif
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/* Don't call these directly - use the macros below */
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int virAlloc(void *ptrptr, size_t size) ATTRIBUTE_RETURN_CHECK;
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int virAllocN(void *ptrptr, size_t size, size_t count) ATTRIBUTE_RETURN_CHECK;
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int virReallocN(void *ptrptr, size_t size, size_t count) ATTRIBUTE_RETURN_CHECK;
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int virAllocVar(void *ptrptr,
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size_t struct_size,
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size_t element_size,
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size_t count) ATTRIBUTE_RETURN_CHECK;
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void virFree(void *ptrptr);
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/**
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* VIR_ALLOC:
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* @ptr: pointer to hold address of allocated memory
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*
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* Allocate sizeof(*ptr) bytes of memory and store
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* the address of allocated memory in 'ptr'. Fill the
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* newly allocated memory with zeros.
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*
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* Returns -1 on failure, 0 on success
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*/
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# define VIR_ALLOC(ptr) virAlloc(&(ptr), sizeof(*(ptr)))
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/**
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* VIR_ALLOC_N:
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* @ptr: pointer to hold address of allocated memory
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* @count: number of elements to allocate
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*
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* Allocate an array of 'count' elements, each sizeof(*ptr)
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* bytes long and store the address of allocated memory in
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* 'ptr'. Fill the newly allocated memory with zeros.
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*
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* Returns -1 on failure, 0 on success
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*/
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# define VIR_ALLOC_N(ptr, count) virAllocN(&(ptr), sizeof(*(ptr)), (count))
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/**
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* VIR_REALLOC_N:
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* @ptr: pointer to hold address of allocated memory
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* @count: number of elements to allocate
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*
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* Re-allocate an array of 'count' elements, each sizeof(*ptr)
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* bytes long and store the address of allocated memory in
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* 'ptr'. Fill the newly allocated memory with zeros
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*
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* Returns -1 on failure, 0 on success
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*/
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# define VIR_REALLOC_N(ptr, count) virReallocN(&(ptr), sizeof(*(ptr)), (count))
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/*
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* VIR_ALLOC_VAR_OVERSIZED:
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* @M: size of base structure
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* @N: number of array elements in trailing array
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* @S: size of trailing array elements
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*
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* Check to make sure that the requested allocation will not cause
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* arithmetic overflow in the allocation size. The check is
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* essentially the same as that in gnulib's xalloc_oversized.
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*/
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#define VIR_ALLOC_VAR_OVERSIZED(M, N, S) ((((size_t)-1) - (M)) / (S) < (N))
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/**
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* VIR_ALLOC_VAR:
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* @ptr: pointer to hold address of allocated memory
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* @type: element type of trailing array
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* @count: number of array elements to allocate
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*
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* Allocate sizeof(*ptr) bytes plus an array of 'count' elements, each
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* sizeof('type'). This sort of allocation is useful for receiving
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* the data of certain ioctls and other APIs which return a struct in
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* which the last element is an array of undefined length. The caller
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* of this type of API is expected to know the length of the array
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* that will be returned and allocate a suitable buffer to contain the
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* returned data. C99 refers to these variable length objects as
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* structs containing flexible array members.
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* Returns -1 on failure, 0 on success
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*/
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#define VIR_ALLOC_VAR(ptr, type, count) virAllocVar(&(ptr), sizeof(*(ptr)), sizeof(type), (count))
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/**
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* VIR_FREE:
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* @ptr: pointer holding address to be freed
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*
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* Free the memory stored in 'ptr' and update to point
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* to NULL.
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*/
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# define VIR_FREE(ptr) virFree(&(ptr))
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# if TEST_OOM
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void virAllocTestInit(void);
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int virAllocTestCount(void);
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void virAllocTestOOM(int n, int m);
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void virAllocTestHook(void (*func)(int, void*), void *data);
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# endif
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#endif /* __VIR_MEMORY_H_ */
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