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dynapi: don't let system loader resolve the initializer to the wrong version.

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Fixes problems launching Firewatch on Linux (which statically links SDL but
also dynamically loads a system-wide copy from a plugin shared library) with
a newer SDL build.
This commit is contained in:
Ryan C. Gordon 2018-05-17 12:50:46 -04:00
parent 425149f47b
commit e2619f1dcf
1 changed files with 20 additions and 14 deletions
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34
src/dynapi/SDL_dynapi.c
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@ -167,15 +167,10 @@ SDL_DYNAPI_VARARGS(,,)
#error Write me. #error Write me.
#endif #endif
/* we make this a static function so we can call the correct one without the
system's dynamic linker resolving to the wrong version of this. */
/* Here's the exported entry point that fills in the jump table. */ static Sint32
/* Use specific types when an "int" might suffice to keep this sane. */ initialize_jumptable(Uint32 apiver, void *table, Uint32 tablesize)
typedef Sint32 (SDLCALL *SDL_DYNAPI_ENTRYFN)(Uint32 apiver, void *table, Uint32 tablesize);
extern DECLSPEC Sint32 SDLCALL SDL_DYNAPI_entry(Uint32, void *, Uint32);
Sint32
SDL_DYNAPI_entry(Uint32 apiver, void *table, Uint32 tablesize)
{ {
SDL_DYNAPI_jump_table *output_jump_table = (SDL_DYNAPI_jump_table *) table; SDL_DYNAPI_jump_table *output_jump_table = (SDL_DYNAPI_jump_table *) table;
@ -202,6 +197,18 @@ SDL_DYNAPI_entry(Uint32 apiver, void *table, Uint32 tablesize)
} }
/* Here's the exported entry point that fills in the jump table. */
/* Use specific types when an "int" might suffice to keep this sane. */
typedef Sint32 (SDLCALL *SDL_DYNAPI_ENTRYFN)(Uint32 apiver, void *table, Uint32 tablesize);
extern DECLSPEC Sint32 SDLCALL SDL_DYNAPI_entry(Uint32, void *, Uint32);
Sint32
SDL_DYNAPI_entry(Uint32 apiver, void *table, Uint32 tablesize)
{
return initialize_jumptable(apiver, table, tablesize);
}
/* Obviously we can't use SDL_LoadObject() to load SDL. :) */ /* Obviously we can't use SDL_LoadObject() to load SDL. :) */
/* Also obviously, we never close the loaded library. */ /* Also obviously, we never close the loaded library. */
#if defined(WIN32) || defined(_WIN32) || defined(__CYGWIN__) #if defined(WIN32) || defined(_WIN32) || defined(__CYGWIN__)
@ -260,7 +267,7 @@ static void
SDL_InitDynamicAPILocked(void) SDL_InitDynamicAPILocked(void)
{ {
const char *libname = SDL_getenv_REAL("SDL_DYNAMIC_API"); const char *libname = SDL_getenv_REAL("SDL_DYNAMIC_API");
SDL_DYNAPI_ENTRYFN entry = SDL_DYNAPI_entry; /* funcs from here by default. */ SDL_DYNAPI_ENTRYFN entry = NULL; /* funcs from here by default. */
if (libname) { if (libname) {
entry = (SDL_DYNAPI_ENTRYFN) get_sdlapi_entry(libname, "SDL_DYNAPI_entry"); entry = (SDL_DYNAPI_ENTRYFN) get_sdlapi_entry(libname, "SDL_DYNAPI_entry");
@ -268,16 +275,15 @@ SDL_InitDynamicAPILocked(void)
/* !!! FIXME: fail to startup here instead? */ /* !!! FIXME: fail to startup here instead? */
/* !!! FIXME: definitely warn user. */ /* !!! FIXME: definitely warn user. */
/* Just fill in the function pointers from this library. */ /* Just fill in the function pointers from this library. */
entry = SDL_DYNAPI_entry;
} }
} }
if (entry(SDL_DYNAPI_VERSION, &jump_table, sizeof (jump_table)) < 0) { if (!entry || (entry(SDL_DYNAPI_VERSION, &jump_table, sizeof (jump_table)) < 0)) {
/* !!! FIXME: fail to startup here instead? */ /* !!! FIXME: fail to startup here instead? */
/* !!! FIXME: definitely warn user. */ /* !!! FIXME: definitely warn user. */
/* Just fill in the function pointers from this library. */ /* Just fill in the function pointers from this library. */
if (entry != SDL_DYNAPI_entry) { if (!entry) {
if (!SDL_DYNAPI_entry(SDL_DYNAPI_VERSION, &jump_table, sizeof (jump_table))) { if (!initialize_jumptable(SDL_DYNAPI_VERSION, &jump_table, sizeof (jump_table))) {
/* !!! FIXME: now we're screwed. Should definitely abort now. */ /* !!! FIXME: now we're screwed. Should definitely abort now. */
} }
} }