Preventing the use of discouraged or 'insecure' external functions
through defines in an internal header is not a good solution. The
header is not guaranteed to be included universally which makes
overlooking bad use of said functions during review more likely.
There are cases were those functions either are the most straight
forward solution or even have to be used. Using malloc or free is
required if the allocation or release is done by other libraries.
- 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>
Unlike YASM, NASM only looks for include files in the current
directory, not in the directory that included files reside in.
Signed-off-by: Diego Biurrun <diego@biurrun.de>
In addition to the recent tables mess, the AVOption defaults behavior
changed, so an old lavc used with a new lavu will get completely messed
up defaults.
Earlier versions of for instance of libavcodec expect this symbol to be
present in libavutil. This commit can be reverted after the next major
bump.
New shared builds of avcodec will link to the internal copy of the
table within that library, so those builds won't rely on this table
being present in avutil any longer either.
Signed-off-by: Martin Storsjö <martin@martin.st>
These tables are used for instance by older versions of libavcodec and
need to remain visible until the next SONAME bump.
Signed-off-by: Martin Storsjö <martin@martin.st>
This removes inline av_log2 and av_log2_16bit from the public API,
instead exporting them as regular functions. In-tree code still
gets the inline and otherwise optimised variants.
Signed-off-by: Mans Rullgard <mans@mansr.com>
This requires the makedef perl script by Derek, from the
c89-to-c99 repo. That scripts produces a .def file, listing
the symbols to be exported, based on the gcc version scripts
and the built object files.
To properly load non-function symbols from DLL files, the
data symbol declarations need to have the attribute
__declspec(dllimport) when building the calling code. (On mingw,
the linker can fix this up automatically, which is why it has not
been an issue so far. If this attribute is omitted, linking
actually succeeds, but reads from the table will not produce the
desired results at runtime.)
MSVC seems to manage to link DLLs (and run properly) even if
this attribute is present while building the library itself
(which normally isn't recommended) - other object files in the
same library manage to link to the symbol (with a small warning
at link time, like "warning LNK4049: locally defined symbol
_avpriv_mpa_bitrate_tab imported" - it doesn't seem to be possible
to squelch this warning), and the definition of the tables
themselves produce a warning that can be squelched ("warning C4273:
'avpriv_mpa_bitrate_tab' : inconsistent dll linkage, see previous
definition of 'avpriv_mpa_bitrate_tab').
In this setup, mingw isn't able to link object files that refer to
data symbols with __declspec(dllimport) without those symbols
actually being linked via a DLL (linking avcodec.dll ends up with
errors like "undefined reference to `__imp__avpriv_mpa_freq_tab'").
The dllimport declspec isn't needed at all in mingw, so we simply
choose not to declare it for other compilers than MSVC that requires
it. (If ICL support later requires it, the condition can be extended
later to include both of them.)
This also implies that code that is built to link to a certain
library as a DLL can't link to the same library as a static library.
Therefore, we only allow building either static or shared but not
both at the same time. (That is, static libraries as such can be,
and actually are, built - this is used for linking the test tools to
internal symbols in the libraries - but e.g. libavformat built to
link to libavcodec as a DLL cannot link statically to libavcodec.)
Also, linking to DLLs is slightly different from linking to shared
libraries on other platforms. DLLs use a thing called import
libraries, which is basically a stub library allowing the linker
to know which symbols exist in the DLL and what name the DLL will
have at runtime.
In mingw/gcc, the import library is usually named libfoo.dll.a,
which goes next to a static library named libfoo.a. This allows
gcc to pick the dynamic one, if available, from the normal -lfoo
switches, just as it does for libfoo.a vs libfoo.so on Unix. On
MSVC however, you need to literally specify the name of the import
library instead of the static library.
Signed-off-by: Martin Storsjö <martin@martin.st>
Add a configure function to pull in a compat object and set up
redirects in one operation. This avoids duplicating conditions
across configure and makefiles.
Signed-off-by: Mans Rullgard <mans@mansr.com>
