From e2619f1dcf6b2749be08f17164c4b50e6924f987 Mon Sep 17 00:00:00 2001 From: "Ryan C. Gordon" Date: Thu, 17 May 2018 12:50:46 -0400 Subject: [PATCH] dynapi: don't let system loader resolve the initializer to the wrong version. 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. --- src/dynapi/SDL_dynapi.c | 34 ++++++++++++++++++++-------------- 1 file changed, 20 insertions(+), 14 deletions(-) diff --git a/src/dynapi/SDL_dynapi.c b/src/dynapi/SDL_dynapi.c index b898826b2f02a..7574cf5f49be5 100644 --- a/src/dynapi/SDL_dynapi.c +++ b/src/dynapi/SDL_dynapi.c @@ -167,15 +167,10 @@ SDL_DYNAPI_VARARGS(,,) #error Write me. #endif - - -/* 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) +/* 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. */ +static Sint32 +initialize_jumptable(Uint32 apiver, void *table, Uint32 tablesize) { 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. :) */ /* Also obviously, we never close the loaded library. */ #if defined(WIN32) || defined(_WIN32) || defined(__CYGWIN__) @@ -260,7 +267,7 @@ static void SDL_InitDynamicAPILocked(void) { 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) { 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: definitely warn user. */ /* 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: definitely warn user. */ /* Just fill in the function pointers from this library. */ - if (entry != SDL_DYNAPI_entry) { - if (!SDL_DYNAPI_entry(SDL_DYNAPI_VERSION, &jump_table, sizeof (jump_table))) { + if (!entry) { + if (!initialize_jumptable(SDL_DYNAPI_VERSION, &jump_table, sizeof (jump_table))) { /* !!! FIXME: now we're screwed. Should definitely abort now. */ } }