The size of a single allocation performed by av_malloc() or av_realloc()
is supposed to be bounded by max_alloc_size, which defaults to INT_MAX
and can be set by the user; yet currently this is not completely
honoured: The actual value used is max_alloc_size - 32. How this came
to be can only be understood historically:
a) 0ecca7a49f disallowed allocations
> INT_MAX. At that time the size parameter of av_malloc() was an
unsigned and the commentary added ("lets disallow possible ambiguous
cases") indicates that this was done as a precaution against calling the
functions with negative int values. Genuinely limiting the size of
allocations to INT_MAX doesn't seem to have been the intention given
that at this time the memalign hack introduced in commit
da9b170c6f (which when enabled increased
the size of allocations slightly so that one can return a correctly
aligned pointer that actually does not point to the beginning of the
allocated buffer) was already present.
b) Said memalign hack allocated 17 bytes more than actually desired, yet
allocating 16 bytes more is actually enough and so this was changed in
a9493601638b048c44751956d2360f215918800c; this commit also replaced
INT_MAX by INT_MAX - 16 (and made the limit therefore a limit on the size
of the allocated buffer), but kept the comment, although there is nothing
ambiguous about allocating (INT_MAX - 16)..INT_MAX.
c) 13dfce3d44 then increased 16 to 32 for
AVX, 6b4c0be558 replaced INT_MAX by
MAX_MALLOC_SIZE (which was of course defined to be INT_MAX) and
5a8e994287 added max_alloc_size and made
it user-selectable.
d) 4fb311c804 then dropped the memalign
hack, yet it kept the -32 (probably because the comment about ambiguous
cases was still present?), although it is no longer needed at all after
this commit. Therefore this commit removes it and uses max_alloc_size
directly.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
Do not limit the array allocation functions and av_calloc() to allocations
of INT_MAX, instead depend on max_alloc_size like av_malloc().
Allows a workaround for ticket #7140.
Inlining public functions hardcodes their implementation into the ABI,
so it should be avoided unless there is a very good reason for it. No
such reason exists in this case.
The original code assumes av_realloc() will free ptr if size is zero.
The assumes is incorrect now.
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
internal.h is difficult to use due to circular dependancies
mem.h is a public header ff_* is not public
Alternative solutions probably are possible too
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This uses explicit memory copying to read and write pointer to pointers
of arbitrary object types. This works provided that the architecture
uses the same representation for all pointer types (the previous code
made that assumption already anyway).
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
av_dynarray_add_nofree function have similar functionality
as existing av_dynarray_add, but it doesn't deallocate memory
on fails.
Signed-off-by: Lukasz Marek <lukasz.m.luki@gmail.com>
This makes sure that pointers from av_strdup are reallocable,
which is used in av_dict_set if the AV_DICT_APPEND flag is set.
Nothing should rely on pointers from av_strdup being aligned.
Signed-off-by: Martin Storsjö <martin@martin.st>
- Add special cases for offsets of 2, 3, or 4 bytes. This means the
offset is always >4 in the generic case, allowing 32-bit copies to
be used there.
- Don't use memcpy() for sizes less than 16 bytes.
Signed-off-by: Mans Rullgard <mans@mansr.com>
The check uses check_func_header, since this function is
conditionally available depending on the targeted MSVCRT
version.
Signed-off-by: Martin Storsjö <martin@martin.st>
Overwriting the av_malloc etc. functions is not easily
possible anymore, even for systems that support overriding
symbols in shared libraries in principle.
Signed-off-by: Reimar Döffinger <Reimar.Doeffinger@gmx.de>
Plain POSIX malloc(0) is allowed to return either NULL or a
non-NULL pointer. The calling code should be ready to handle
a NULL return as a correct return (instead of a failure) if the size
to allocate was 0 - this makes sure the condition is handled
in a consistent way across platforms.
This also avoids calling posix_memalign(&ptr, 32, 0) on OS X,
which returns an invalid pointer (a non-NULL pointer that causes
crashes when passed to av_free).
Abort in debug mode, to help track down issues related to
incorrect handling of this case.
Signed-off-by: Martin Storsjö <martin@martin.st>
Andreas Rheinhardt
Carl Eugen Hoyos
Michael Niedermayer
James Darnley
Anton Khirnov
Diego Biurrun
Timothy Gu
Zhao Zhili
Michael Niedermayer
Rémi Denis-Courmont
Lukasz Marek
Nicolas George
Martin Storsjö
Luca Barbato
Stefano Sabatini
Fabrizio Gennari
Mans Rullgard
Clément Bœsch
Ronald S. Bultje
Reimar Döffinger
Alex Converse
Hanspeter Niederstrasser