swap* routines conflict with OpenBSD swap(3) macros

Question

swap* routines conflict with OpenBSD swap(3) macros

Closed this issue 10 months ago · 12 comments

https://man.openbsd.org/swap16.3

/usr/ports/pobj/noson-2.12.6/noson-2.12.6/noson/src/private/byteorder.h:57:23: error: redefinition of '__uint16_t' as different kind of symbol
static inline int16_t swap16(int16_t val)
                      ^

I haven't looked as to why noson needs its own routines for this and/or which one should be used, but a simple fix to unbreak the build is prepending #undef swap16 to the function definition in byteorder.h -- same problem for swap32().

Full build failure log, in case that helps: https://gist.github.com/klemensn/cc23726ee6231c0708720905003168c2

Answer 1 · 2024-02-10T12:04:47.000Z

noson-app has the same problem.

Answer 2 · 2024-02-13T13:15:04.000Z

I will have a look on this issue on BSD. In others Unix like , the function swap16 is declared in header sys/endian.h. It seems some top includes load this header on OpenBSD. The resolution could be to rename my functions or to prefix them in an anonymous namespace.

Answer 3 · 2024-02-14T13:33:27.000Z

I pushed a new commit , and a new release 2.12.7. It should help to fix this issue.

Answer 4 · 2024-02-14T14:57:28.000Z

Still fails on OpenBSD/amd64 7.4-current with clang and libstd++16.0.6:

FAILED: noson/CMakeFiles/noson.dir/src/private/byteorder.cpp.o 
/usr/ports/pobj/noson-2.12.7/bin/c++ -Dnoson_EXPORTS -I/usr/ports/pobj/noson-2.12.7/build-amd64/noson/public/noson -I/usr/ports/pobj/noson-2.12.7/build-amd64/noson/public -I/usr/ports/pobj/noson-2.12.7/noson-2.12.7/noson/src -isystem /usr/local/include -O2 -pipe -DNDEBUG -std=gnu++11 -fPIC -MD -MT noson/CMakeFiles/noson.dir/src/private/byteorder.cpp.o -MF noson/CMakeFiles/noson.dir/src/private/byteorder.cpp.o.d -o noson/CMakeFiles/noson.dir/src/private/byteorder.cpp.o -c /usr/ports/pobj/noson-2.12.7/noson-2.12.7/noson/src/private/byteorder.cpp
In file included from /usr/ports/pobj/noson-2.12.7/noson-2.12.7/noson/src/private/byteorder.cpp:19:
/usr/ports/pobj/noson-2.12.7/noson-2.12.7/noson/src/private/byteorder.h:61:1: warning: inline variables are a C++17 extension [-Wc++17-extensions]
inline int16_t swap16(int16_t val)
^
/usr/ports/pobj/noson-2.12.7/noson-2.12.7/noson/src/private/byteorder.h:61:23: error: unexpected type name 'int16_t': expected expression
inline int16_t swap16(int16_t val)
                      ^
/usr/ports/pobj/noson-2.12.7/noson-2.12.7/noson/src/private/byteorder.h:61:31: error: expected ')'
inline int16_t swap16(int16_t val)
                              ^
/usr/ports/pobj/noson-2.12.7/noson-2.12.7/noson/src/private/byteorder.h:61:16: note: to match this '('
inline int16_t swap16(int16_t val)
               ^
/usr/include/sys/endian.h:70:19: note: expanded from macro 'swap16'
#define swap16(x) __swap16(x)
                  ^
/usr/include/sys/_endian.h:87:35: note: expanded from macro '__swap16'
        (__uint16_t)(__builtin_constant_p(x) ? __swap16gen(x) : __swap16md(x))
                                         ^
In file included from /usr/ports/pobj/noson-2.12.7/noson-2.12.7/noson/src/private/byteorder.cpp:19:
/usr/ports/pobj/noson-2.12.7/noson-2.12.7/noson/src/private/byteorder.h:61:23: error: unexpected type name 'int16_t': expected expression
inline int16_t swap16(int16_t val)
                      ^
/usr/ports/pobj/noson-2.12.7/noson-2.12.7/noson/src/private/byteorder.h:61:31: error: expected ')'
inline int16_t swap16(int16_t val)
                              ^
/usr/ports/pobj/noson-2.12.7/noson-2.12.7/noson/src/private/byteorder.h:61:16: note: to match this '('
inline int16_t swap16(int16_t val)
               ^
/usr/include/sys/endian.h:70:19: note: expanded from macro 'swap16'
#define swap16(x) __swap16(x)
                  ^
/usr/include/sys/_endian.h:87:41: note: expanded from macro '__swap16'
        (__uint16_t)(__builtin_constant_p(x) ? __swap16gen(x) : __swap16md(x))
                                               ^
/usr/include/sys/_endian.h:49:31: note: expanded from macro '__swap16gen'
    (__uint16_t)(((__uint16_t)(x) & 0xffU) << 8 | ((__uint16_t)(x) & 0xff00U) >> 8)
                              ^
In file included from /usr/ports/pobj/noson-2.12.7/noson-2.12.7/noson/src/private/byteorder.cpp:19:
/usr/ports/pobj/noson-2.12.7/noson-2.12.7/noson/src/private/byteorder.h:61:23: error: unexpected type name 'int16_t': expected expression
inline int16_t swap16(int16_t val)
                      ^
/usr/ports/pobj/noson-2.12.7/noson-2.12.7/noson/src/private/byteorder.h:61:31: error: expected ')'
inline int16_t swap16(int16_t val)
                              ^
/usr/ports/pobj/noson-2.12.7/noson-2.12.7/noson/src/private/byteorder.h:61:16: note: to match this '('
inline int16_t swap16(int16_t val)
               ^
/usr/include/sys/endian.h:70:19: note: expanded from macro 'swap16'
#define swap16(x) __swap16(x)
                  ^
/usr/include/sys/_endian.h:87:41: note: expanded from macro '__swap16'
        (__uint16_t)(__builtin_constant_p(x) ? __swap16gen(x) : __swap16md(x))
                                               ^
/usr/include/sys/_endian.h:49:64: note: expanded from macro '__swap16gen'
    (__uint16_t)(((__uint16_t)(x) & 0xffU) << 8 | ((__uint16_t)(x) & 0xff00U) >> 8)
                                                               ^
In file included from /usr/ports/pobj/noson-2.12.7/noson-2.12.7/noson/src/private/byteorder.cpp:19:
/usr/ports/pobj/noson-2.12.7/noson-2.12.7/noson/src/private/byteorder.h:61:23: error: unexpected type name 'int16_t': expected expression
inline int16_t swap16(int16_t val)
                      ^
/usr/ports/pobj/noson-2.12.7/noson-2.12.7/noson/src/private/byteorder.h:61:31: error: expected ')'
inline int16_t swap16(int16_t val)
                              ^
/usr/ports/pobj/noson-2.12.7/noson-2.12.7/noson/src/private/byteorder.h:61:16: note: to match this '('
inline int16_t swap16(int16_t val)
               ^
/usr/include/sys/endian.h:70:19: note: expanded from macro 'swap16'
#define swap16(x) __swap16(x)
                  ^
/usr/include/sys/_endian.h:87:68: note: expanded from macro '__swap16'
        (__uint16_t)(__builtin_constant_p(x) ? __swap16gen(x) : __swap16md(x))
                                                                          ^
In file included from /usr/ports/pobj/noson-2.12.7/noson-2.12.7/noson/src/private/byteorder.cpp:19:
/usr/ports/pobj/noson-2.12.7/noson-2.12.7/noson/src/private/byteorder.h:61:35: error: expected ';' after top level declarator
inline int16_t swap16(int16_t val)
                                  ^
                                  ;
/usr/ports/pobj/noson-2.12.7/noson-2.12.7/noson/src/private/byteorder.cpp:26:13: error: no member named '__endianess__' in namespace 'SONOS'
int NSROOT::__endianess__ = test_endianess();
    ~~~~~~~~^
1 warning and 10 errors generated.

Answer 5 · 2024-02-14T18:02:36.000Z

mmm, it builds without issue on FreeBSD. The problem is the OS header uses some macros to rename internal function (i.e swap16 etc), and the preprocessor apply those macros to rename my private functions. that's ugly.

Answer 6 · 2024-02-14T19:21:28.000Z

I reverted the repo (noson and noson-app) to the previous tags. The issue is not in the source, but in the OS headers.
The build shouldn't include "sys/endian.h".

What is the release of OpenBSD ?

Answer 7 · 2024-02-14T19:23:31.000Z

What is the release of OpenBSD ?

7.4 is the latest stable version: https://www.openbsd.org/

Answer 8 · 2024-02-14T19:45:11.000Z

In header "sys/endian.h" of OpenBSD, we find:

#if __BSD_VISIBLE
#define swap16(x) __swap16(x)
#define swap32(x) __swap32(x)
#define swap64(x) __swap64(x)

Please try to build the app without the definition "__BSD_VISIBLE". Those things are not compliant.
Maybe you have to specify a flag to be in "compatible mode".

Answer 9 · 2024-02-14T19:58:14.000Z

I haven't looked as to why noson needs its own routines for this and/or which one should be used, but a simple fix to unbreak the build is prepending #undef swap16 to the function definition in byteorder.h -- same problem for swap32().

I cannot prepending with undef all the bunch of functions declared in the sources. The OS headers shouldn't declare macros without prefix "__" for names not used in the standards (i.e printf etc).
So, the flag "__BSD_VISIBLE" exists to enable some special stuff of OpenBSD. Those stuff must be disabled.

Edit: Others standard declaration are needed in the section. So it shouldn't be disabled :(

Edit: Those routines aren't standard, and many OSes don't provide them. Only Linux GNU, and FreeBSD provide them, but without the same naming: Linux = bswap_16 , FreeBSD = bswap16 ... etc. For those reasons many app using byte processing (audio, video) have their own routines.

Answer 10 · 2024-02-14T21:21:43.000Z

@klemensn , could you provide a PR with the required changes if you succeed to build using "ifdef/undef" ???
i.e:

#ifdef swap16
#undef swap16
#endif
...

Here the file is "src/private/byteorder.h". In the project "noson-app", the same file is in "backend/NosonMediaScanner/byteorder.h".

Thanks

Answer 11 · 2024-02-15T17:16:31.000Z

I had a look about the same issue for other products, and there is a bunch of media app that get this issue on OpenBSD. The maintainers have choosen to rename their routines. So maybe it is the good choice, until the next collision ...

edit: I pushed the commit

Answer 12 · 2024-02-16T00:38:49.000Z

Thanks, both noson and noson-app now build on OpenBSD without any local patches.