libpurple backend hangs when MySQL support is enabled

[vitalyster]

Started from 84814a1 it hangs there:

#0  0x00007f76ab2aa4db in pthread_join (threadid=140147412866816, thread_return=0x0) at pthread_join.c:92
#1  0x00007f76a911babc in my_thread_global_init () from /usr/lib/x86_64-linux-gnu/libmysqlclient.so.18
#2  0x00007f76a91195d0 in my_init () from /usr/lib/x86_64-linux-gnu/libmysqlclient.so.18
#3  0x00007f76acc049ba in call_init (l=<optimized out>, argc=argc@entry=9, argv=argv@entry=0x7ffc0ded0ab8, env=env@entry=0x7ffc0ded0b08) at dl-init.c:78
#4  0x00007f76acc04aa3 in call_init (env=0x7ffc0ded0b08, argv=0x7ffc0ded0ab8, argc=9, l=<optimized out>) at dl-init.c:36
#5  _dl_init (main_map=main_map@entry=0x1c53a40, argc=9, argv=0x7ffc0ded0ab8, env=0x7ffc0ded0b08) at dl-init.c:126
#6  0x00007f76acc08c08 in dl_open_worker (a=a@entry=0x7ffc0ded0078) at dl-open.c:577
#7  0x00007f76acc04874 in _dl_catch_error (objname=objname@entry=0x7ffc0ded0068, errstring=errstring@entry=0x7ffc0ded0070,
    mallocedp=mallocedp@entry=0x7ffc0ded0067, operate=operate@entry=0x7f76acc08930 <dl_open_worker>, args=args@entry=0x7ffc0ded0078) at dl-error.c:187
#8  0x00007f76acc083fb in _dl_open (file=0x1c52d90 "/usr/lib/purple-2/perl.so", mode=-2147483646, caller_dlopen=<optimized out>, nsid=-2, argc=9,
    argv=0x7ffc0ded0ab8, env=0x7ffc0ded0b08) at dl-open.c:661
#9  0x00007f76a786502b in dlopen_doit (a=a@entry=0x7ffc0ded0290) at dlopen.c:66
#10 0x00007f76acc04874 in _dl_catch_error (objname=0x1c4c940, errstring=0x1c4c948, mallocedp=0x1c4c938, operate=0x7f76a7864fd0 <dlopen_doit>,
    args=0x7ffc0ded0290) at dl-error.c:187
#11 0x00007f76a78655dd in _dlerror_run (operate=operate@entry=0x7f76a7864fd0 <dlopen_doit>, args=args@entry=0x7ffc0ded0290) at dlerror.c:163
#12 0x00007f76a78650c1 in __dlopen (file=<optimized out>, mode=<optimized out>) at dlopen.c:87
#13 0x00007f76aba04942 in g_module_open () from /usr/lib/x86_64-linux-gnu/libgmodule-2.0.so.0
#14 0x00007f76ac194c8d in purple_plugin_probe () from /usr/lib/libpurple.so.0
#15 0x00007f76ac1952de in purple_plugins_probe () from /usr/lib/libpurple.so.0
#16 0x00007f76ac177dc8 in purple_core_init () from /usr/lib/libpurple.so.0
#17 0x000000000044be32 in initPurple () at /home/vt/spectrum2/packaging/debian/spectrum2-2163-55221a7/backends/libpurple/main.cpp:2136
#18 0x000000000044d16f in main (argc=9, argv=0x7ffc0ded0ab8) at /home/vt/spectrum2/packaging/debian/spectrum2-2163-55221a7/backends/libpurple/main.cpp:2279

Disabling MySQL support prevent hanging.

[vitalyster]

related https://bugs.mysql.com/bug.php?id=71646

[vitalyster]

libmariadbclient does not have this problem

[dequis]

libmysqlclient 5.6 and 5.7 don't have this problem either.

libmysqlclient 5.5 does have this problem.

[dequis]

The part of that commit that breaks it is adding transport to target_link_libraries of the libpurple backend.

diff --git a/backends/libpurple/CMakeLists.txt b/backends/libpurple/CMakeLists.txt
index cbf2575..0a15fd2 100644
--- a/backends/libpurple/CMakeLists.txt
+++ b/backends/libpurple/CMakeLists.txt
@@ -7,7 +7,7 @@ if(MSVC)
 target_link_libraries(spectrum2_libpurple_backend sqlite3 ${PURPLE_LIBRARY} ${GLIB2_LIBRARIES} ${LIBXML2_LIBRARIES} ${EVENT_LIBRARIES} transport-plugin ${PROTOBUF_LIBRARY})
 else()
        if (NOT WIN32)
-       target_link_libraries(spectrum2_libpurple_backend ${PURPLE_LIBRARY} ${GLIB2_LIBRARIES} ${EVENT_LIBRARIES} transport-plugin pthread)
+       target_link_libraries(spectrum2_libpurple_backend transport ${PURPLE_LIBRARY} ${GLIB2_LIBRARIES} ${EVENT_LIBRARIES} transport-plugin pthread)
        else()
        target_link_libraries(spectrum2_libpurple_backend ${PURPLE_LIBRARY} ${GLIB2_LIBRARIES} ${EVENT_LIBRARIES} transport-plugin)
        endif()

[vitalyster]

libpurple backend now have access to db, so db libraries must be linked

[vitalyster]

I just realized: when using libpurple with mysql private headers in path it includes plugin.h from mysql private headers. (newer mysql doesn't have plugin.h) How to prevent this?

[vitalyster]

replacing #include <plugin.h> with #include "plugin.h" in libpurple.h fixes the problem