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90d761eeb2
We can exploit the fact that gcc warns about int-to-pointer conversion in ternary cond?(void*):(int) in order to prevent future mistakes of calling VIR_FREE on a scalar lvalue. For example, between commits158ba873and802e2df, we would have had this warning: cc1: warnings being treated as errors remote.c: In function 'remoteDispatchListNetworks': remote.c:3684:70: error: pointer/integer type mismatch in conditional expression There are still a number of places that malloc into a const char*; while it would probably be worth scrubbing them to use char* instead, that is a separate patch, so we have to cast away const in VIR_FREE for now. * src/util/memory.h (VIR_FREE): Make gcc warn about integers. Iteratively developed from a patch by Christophe Fergeau.
217 lines
7.8 KiB
C
217 lines
7.8 KiB
C
/*
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* memory.c: safer memory allocation
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*
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* Copyright (C) 2010-2011 Red Hat, Inc.
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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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ATTRIBUTE_NONNULL(1);
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int virAllocN(void *ptrptr, size_t size, size_t count) ATTRIBUTE_RETURN_CHECK
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ATTRIBUTE_NONNULL(1);
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int virReallocN(void *ptrptr, size_t size, size_t count) ATTRIBUTE_RETURN_CHECK
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ATTRIBUTE_NONNULL(1);
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int virExpandN(void *ptrptr, size_t size, size_t *count, size_t add)
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ATTRIBUTE_RETURN_CHECK ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(3);
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int virResizeN(void *ptrptr, size_t size, size_t *alloc, size_t count,
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size_t desired)
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ATTRIBUTE_RETURN_CHECK ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(3);
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void virShrinkN(void *ptrptr, size_t size, size_t *count, size_t toremove)
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ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(3);
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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 ATTRIBUTE_NONNULL(1);
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void virFree(void *ptrptr) ATTRIBUTE_NONNULL(1);
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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'. If 'ptr' grew, the added memory is uninitialized.
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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_EXPAND_N:
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* @ptr: pointer to hold address of allocated memory
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* @count: variable tracking number of elements currently allocated
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* @add: number of elements to add
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*
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* Re-allocate an array of 'count' elements, each sizeof(*ptr)
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* bytes long, to be 'count' + 'add' elements long, then store the
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* address of allocated memory in 'ptr' and the new size in 'count'.
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* The new elements are filled with zero.
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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_EXPAND_N(ptr, count, add) \
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virExpandN(&(ptr), sizeof(*(ptr)), &(count), add)
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/**
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* VIR_RESIZE_N:
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* @ptr: pointer to hold address of allocated memory
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* @alloc: variable tracking number of elements currently allocated
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* @count: number of elements currently in use
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* @add: minimum number of elements to additionally support
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*
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* Blindly using VIR_EXPAND_N(array, alloc, 1) in a loop scales
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* quadratically, because every iteration must copy contents from
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* all prior iterations. But amortized linear scaling can be achieved
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* by tracking allocation size separately from the number of used
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* elements, and growing geometrically only as needed.
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*
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* If 'count' + 'add' is larger than 'alloc', then geometrically reallocate
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* the array of 'alloc' elements, each sizeof(*ptr) bytes long, and store
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* the address of allocated memory in 'ptr' and the new size in 'alloc'.
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* The new elements are filled with zero.
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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_RESIZE_N(ptr, alloc, count, add) \
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virResizeN(&(ptr), sizeof(*(ptr)), &(alloc), count, add)
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/**
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* VIR_SHRINK_N:
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* @ptr: pointer to hold address of allocated memory
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* @count: variable tracking number of elements currently allocated
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* @remove: number of elements to remove
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*
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* Re-allocate an array of 'count' elements, each sizeof(*ptr)
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* bytes long, to be 'count' - 'remove' elements long, then store the
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* address of allocated memory in 'ptr' and the new size in 'count'.
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* If 'count' <= 'remove', the entire array is freed.
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*
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* No return value.
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*/
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# define VIR_SHRINK_N(ptr, count, remove) \
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virShrinkN(&(ptr), sizeof(*(ptr)), &(count), remove)
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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) \
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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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/* The ternary ensures that ptr is a pointer and not an integer type,
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* while evaluating ptr only once. For now, we intentionally cast
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* away const, since a number of callers safely pass const char *.
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*/
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# define VIR_FREE(ptr) virFree((void *) (1 ? (const void *) &(ptr) : (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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