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c9a85af319
The Coverity static analyzer was generating many false positives for the unary operation inside the VIR_FREE() definition as it was trying to evaluate the else portion of the "?:" even though the if portion was (1). Signed-off-by: Eric Blake <eblake@redhat.com>
391 lines
16 KiB
C
391 lines
16 KiB
C
/*
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* viralloc.h: safer memory allocation
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*
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* Copyright (C) 2010-2013 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, see
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* <http://www.gnu.org/licenses/>.
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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 virInsertElementsN(void *ptrptr, size_t size, size_t at, size_t *countptr,
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size_t add, void *newelem,
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bool clearOriginal, bool inPlace)
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ATTRIBUTE_RETURN_CHECK ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(4);
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int virDeleteElementsN(void *ptrptr, size_t size, size_t at, size_t *countptr,
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size_t remove, bool inPlace)
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ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(4);
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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_TYPEMATCH:
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*
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* The following macro seems a bit cryptic, so it needs a thorough
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* explanation. Its purpose is to check for assignment compatibility
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* and identical size between two values without creating any side
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* effects (by doing something silly like actually assigning one to
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* the other). Note that it takes advantage of the C89-guaranteed
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* property of sizeof() - it cannot have any side effects, so anything
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* that happens inside sizeof() will not have any effect at runtime.
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*
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* VIR_TYPEMATCH evaluates to "1" if the two passed values are both
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* assignment-compatible and the same size, and otherwise generates a
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* compile-time error. It determines the result by performing the
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* following three operations:
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*
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* * sizeof(*(a) = *(b)) assures that *a and *b are
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* assignment-compatible (they may still have a different size
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* though! e.g. longVar = intVar) (If not, there is a compile-time
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* error. If so, the result of that subexpression is sizeof(*(a)),
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* i.e. one element of the array)
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*
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* * sizeof(*(a) = *(b)) == sizeof(*(b)) checks if *a and *b are also
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* of the same size (so that, e.g. you don't accidentally copy an
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* int plus the random bytes following it into an array of long). It
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* evaluates to 1 if they are the same, and 0 otherwise.
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*
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* * sizeof(char[2 * (result of previous step) - 1]) evaluates to 1
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* if the previous step was successful (char [(2*1) - 1] i.e.
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* char[1]), or generates a compile error if it wasn't successful
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* (char[2*0 -1] i.e. char[-1], which isn't valid in C).
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*
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* So VIR_TYPECHECK(a, b) will either abort the compile with an error,
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* or evaluate to "1", and in the meantime check that we've actually
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* added the correct &'s and/or *'s to the arguments. (Whew!)
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*/
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# define VIR_TYPEMATCH(a, b) \
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sizeof(char[2 * (sizeof(*(a) = *(b)) == sizeof(*(b))) - 1])
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/**
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* VIR_INSERT_ELEMENT:
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* @ptr: pointer to array of objects (*not* ptr to ptr)
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* @at: index within array where new elements should be added
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* @count: variable tracking number of elements currently allocated
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* @newelem: the new element to move into place (*not* a pointer to
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* the element, but the element itself).
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* (the original will be zeroed out if successful)
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*
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* Re-allocate an array of 'count' elements, each sizeof(*ptr) bytes
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* long, to be 'count' + 1 elements long, then appropriately move
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* the elements starting at ptr[at] up by 1 element, copy the
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* item 'newelem' into ptr[at], then store the address of
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* allocated memory in 'ptr' and the new size in 'count'.
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*
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* VIR_INSERT_ELEMENT_COPY is identical, but doesn't clear out the
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* original element to 0 on success, so there are two copies of the
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* element. This is useful if the "element" is actually just a
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* pointer to the real data, and you want to maintain a reference to
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* it for use after the insert is completed; but if the "element" is
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* an object that points to other allocated memory, having multiple
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* copies can cause problems (e.g. double free).
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*
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* VIR_INSERT_ELEMENT_*INPLACE are identical, but assume any necessary
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* memory re-allocation has already been done.
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*
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* VIR_INSERT_ELEMENT_* all need to send "1" as the "add" argument to
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* virInsertElementsN (which has the currently-unused capability of
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* inserting multiple items at once). We use this to our advantage by
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* replacing it with VIR_TYPECHECK(ptr, &newelem) so that we can be
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* assured ptr and &newelem are of compatible types.
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*
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* Returns -1 on failure, 0 on success
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*
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*
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*/
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# define VIR_INSERT_ELEMENT(ptr, at, count, newelem) \
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virInsertElementsN(&(ptr), sizeof(*(ptr)), at, &(count), \
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VIR_TYPEMATCH(ptr, &(newelem)), &(newelem), true, false)
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# define VIR_INSERT_ELEMENT_COPY(ptr, at, count, newelem) \
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virInsertElementsN(&(ptr), sizeof(*(ptr)), at, &(count), \
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VIR_TYPEMATCH(ptr, &(newelem)), &(newelem), false, false)
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# define VIR_INSERT_ELEMENT_INPLACE(ptr, at, count, newelem) \
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virInsertElementsN(&(ptr), sizeof(*(ptr)), at, &(count), \
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VIR_TYPEMATCH(ptr, &(newelem)), &(newelem), true, true)
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# define VIR_INSERT_ELEMENT_COPY_INPLACE(ptr, at, count, newelem) \
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virInsertElementsN(&(ptr), sizeof(*(ptr)), at, &(count), \
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VIR_TYPEMATCH(ptr, &(newelem)), &(newelem), false, true)
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/**
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* VIR_APPEND_ELEMENT:
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* @ptr: pointer to array of objects (*not* ptr to ptr)
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* @count: variable tracking number of elements currently allocated
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* @newelem: the new element to move into place (*not* a pointer to
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* the element, but the element itself).
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* (the original will be zeroed out if successful)
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*
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* Re-allocate an array of 'count' elements, each sizeof(*ptr) bytes
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* long, to be 'count' + 1 elements long, then copy the item from
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* 'newelem' into ptr[count+1], and store the address of allocated
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* memory in 'ptr' and the new size in 'count'. If 'newelem' is NULL,
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* the new element at ptr[at] is instead filled with zero.
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*
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* VIR_APPEND_ELEMENT_COPY is identical, but doesn't clear out the
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* original element to 0 on success, so there are two copies of the
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* element. This is useful if the "element" is actually just a
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* pointer to the real data, and you want to maintain a reference to
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* it for use after the append is completed; but if the "element" is
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* an object that points to other allocated memory, having multiple
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* copies can cause problems (e.g. double free).
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*
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* VIR_APPEND_ELEMENT_*INPLACE are identical, but assume any
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* necessary memory re-allocation has already been done.
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*
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* VIR_APPEND_ELEMENT_* all need to send "1" as the "add" argument to
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* virInsertElementsN (which has the currently-unused capability of
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* inserting multiple items at once). We use this to our advantage by
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* replacing it with VIR_TYPECHECK(ptr, &newelem) so that we can be
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* assured ptr and &newelem are of compatible types.
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*
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* Returns -1 on failure, 0 on success
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*
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*
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*/
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# define VIR_APPEND_ELEMENT(ptr, count, newelem) \
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virInsertElementsN(&(ptr), sizeof(*(ptr)), count, &(count), \
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VIR_TYPEMATCH(ptr, &(newelem)), &(newelem), true, false)
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# define VIR_APPEND_ELEMENT_COPY(ptr, count, newelem) \
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virInsertElementsN(&(ptr), sizeof(*(ptr)), count, &(count), \
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VIR_TYPEMATCH(ptr, &(newelem)), &(newelem), false, false)
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# define VIR_APPEND_ELEMENT_INPLACE(ptr, count, newelem) \
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virInsertElementsN(&(ptr), sizeof(*(ptr)), count, &(count), \
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VIR_TYPEMATCH(ptr, &(newelem)), &(newelem), true, true)
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# define VIR_APPEND_ELEMENT_COPY_INPLACE(ptr, count, newelem) \
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virInsertElementsN(&(ptr), sizeof(*(ptr)), count, &(count), \
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VIR_TYPEMATCH(ptr, &(newelem)), &(newelem), false, true)
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/**
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* VIR_DELETE_ELEMENT:
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* @ptr: pointer to array of objects (*not* ptr to ptr)
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* @at: index within array where new elements should be deleted
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* @count: variable tracking number of elements currently allocated
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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' - 1 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' <= 1, the entire array is freed.
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*
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* VIR_DELETE_ELEMENT_INPLACE is identical, but assumes any
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* necessary memory re-allocation will be done later.
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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_DELETE_ELEMENT(ptr, at, count) \
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virDeleteElementsN(&(ptr), sizeof(*(ptr)), at, &(count), 1, false)
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# define VIR_DELETE_ELEMENT_INPLACE(ptr, at, count) \
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virDeleteElementsN(&(ptr), sizeof(*(ptr)), at, &(count), 1, true)
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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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# if !STATIC_ANALYSIS
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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. This gives us extra compiler
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* safety when compiling under gcc. 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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# else
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/* The Coverity static analyzer considers the else path of the "?:" and
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* flags the VIR_FREE() of the address of the address of memory as a
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* RESOURCE_LEAK resulting in numerous false positives (eg, VIR_FREE(&ptr))
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*/
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# define VIR_FREE(ptr) virFree((void *) &(ptr))
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# endif
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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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