Record dynamic dependencies in .note.dlopen elf section

The data can be used with `dlopen-notes`.
The raw date can be viewed with `objdump -j .note.dlopen -s libSDL3.so.0`

Author: madebr

CMakeLists.txt

@@ -320,6 +320,7 @@ dep_option(SDL_ARMNEON             "Use NEON assembly routines" ON "SDL_ASSEMBLY
 dep_option(SDL_LSX                 "Use LSX assembly routines" ON "SDL_ASSEMBLY;SDL_CPU_LOONGARCH64" OFF)
 dep_option(SDL_LASX                "Use LASX assembly routines" ON "SDL_ASSEMBLY;SDL_CPU_LOONGARCH64" OFF)
 
+dep_option(SDL_DLOPEN_NOTES        "Record dlopen dependencies in .note.dlopen section" TRUE UNIX_SYS OFF)
 set_option(SDL_LIBC                "Use the system C library" ${SDL_LIBC_DEFAULT})
 set_option(SDL_SYSTEM_ICONV        "Use iconv() from system-installed libraries" ${SDL_SYSTEM_ICONV_DEFAULT})
 set_option(SDL_LIBICONV            "Prefer iconv() from libiconv, if available, over libc version" OFF)
@@ -1559,6 +1560,25 @@ elseif(EMSCRIPTEN)
   CheckLibUnwind()
 
 elseif(UNIX AND NOT APPLE AND NOT RISCOS AND NOT HAIKU)
+
+  if(SDL_DLOPEN_NOTES)
+    set(CHECK_ELF_DLNOTES_SRC [==[
+    #ifndef __ELF__
+      ELF DL notes is only supported on ELF platforms
+    #endif
+    __attribute__ ((used,aligned(4),section(".note.dlopen"))) static const struct {
+      struct { int a; int b; int c; } hdr; char name[4]; __attribute__((aligned(4))) char json[24];
+    } dlnote = { { 4, 0x407c0c0aU, 16 }, "FDO", "[\\"a\\":{\\"a\\":\\"1\\",\\"b\\":\\"2\\"}]" };
+    int main(int argc, char *argv[]) {
+      return argc + dlnote.hdr.a;
+    }
+    ]==])
+    check_c_source_compiles("${CHECK_ELF_DLNOTES_SRC}" COMPILER_SUPPORTS_ELFNOTES)
+    if(COMPILER_SUPPORTS_ELFNOTES)
+      set(HAVE_DLOPEN_NOTES TRUE)
+    endif()
+  endif()
+
   if(SDL_AUDIO)
     if(NETBSD)
         set(SDL_AUDIO_DRIVER_NETBSD 1)

docs/README-linux.md

@@ -26,7 +26,7 @@ Ubuntu 22.04+ can also add `libpipewire-0.3-dev libwayland-dev libdecor-0-dev li
 Fedora 35, all available features enabled:
 
     sudo yum install gcc git-core make cmake \
-    alsa-lib-devel pulseaudio-libs-devel nas-devel pipewire-devel \
+    alsa-lib-devel pulseaudio-libs-devel pipewire-devel \
     libX11-devel libXext-devel libXrandr-devel libXcursor-devel libXfixes-devel \
     libXi-devel libXScrnSaver-devel dbus-devel ibus-devel \
     systemd-devel mesa-libGL-devel libxkbcommon-devel mesa-libGLES-devel \

include/build_config/SDL_build_config.h.cmake

@@ -231,6 +231,8 @@
 #cmakedefine HAVE_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR 1
 #cmakedefine HAVE_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR_NP 1
 
+#cmakedefine HAVE_DLOPEN_NOTES 1
+
 /* SDL internal assertion support */
 #cmakedefine SDL_DEFAULT_ASSERT_LEVEL_CONFIGURED 1
 #ifdef SDL_DEFAULT_ASSERT_LEVEL_CONFIGURED

src/SDL_internal.h

@@ -63,6 +63,7 @@
 #include "SDL_build_config.h"
 
 #include "dynapi/SDL_dynapi.h"
+#include "dynapi/SDL_dynapi_dlopennote.h"
 
 #if SDL_DYNAMIC_API
 #include "dynapi/SDL_dynapi_overrides.h"

src/audio/aaudio/SDL_aaudio.c

@@ -53,6 +53,13 @@ struct SDL_PrivateAudioData
 
 #define LIB_AAUDIO_SO "libaaudio.so"
 
+SDL_ELF_NOTE_DLOPEN(elfnote_aaudio,
+    "audio-aaudio",
+    "Support for audio through AAudio",
+    SDL_ELF_NOTE_DLOPEN_PRIORITY_SUGGESTED,
+    LIB_AAUDIO_SO
+);
+
 typedef struct AAUDIO_Data
 {
     SDL_SharedObject *handle;
@@ -308,8 +315,8 @@ static bool BuildAAudioStream(SDL_AudioDevice *device)
     ctx.AAudioStreamBuilder_setFormat(builder, format);
     ctx.AAudioStreamBuilder_setSampleRate(builder, device->spec.freq);
     ctx.AAudioStreamBuilder_setChannelCount(builder, device->spec.channels);
-	
-    // If no specific buffer size has been requested, the device will pick the optimal 
+
+    // If no specific buffer size has been requested, the device will pick the optimal
 	if(SDL_GetHint(SDL_HINT_AUDIO_DEVICE_SAMPLE_FRAMES)) {
 	    ctx.AAudioStreamBuilder_setBufferCapacityInFrames(builder, 2 * device->sample_frames); // AAudio requires that the buffer capacity is at least
 	    ctx.AAudioStreamBuilder_setFramesPerDataCallback(builder, device->sample_frames);      // twice the size of the data callback buffer size

src/audio/alsa/SDL_alsa_audio.c

@@ -207,6 +207,13 @@ static bool load_alsa_syms(void)
 
 #ifdef SDL_AUDIO_DRIVER_ALSA_DYNAMIC
 
+SDL_ELF_NOTE_DLOPEN(elfnote_alsa,
+    "audio-libalsa",
+    "Support for audio through libalsa",
+    SDL_ELF_NOTE_DLOPEN_PRIORITY_SUGGESTED,
+    SDL_AUDIO_DRIVER_ALSA_DYNAMIC
+);
+
 static void UnloadALSALibrary(void)
 {
     if (alsa_handle) {

src/audio/jack/SDL_jackaudio.c

@@ -50,6 +50,13 @@ static bool load_jack_syms(void);
 
 #ifdef SDL_AUDIO_DRIVER_JACK_DYNAMIC
 
+SDL_ELF_NOTE_DLOPEN(elfnote_libjack,
+    "audio-libjack",
+    "Support for audio through libjack",
+    SDL_ELF_NOTE_DLOPEN_PRIORITY_SUGGESTED,
+    SDL_AUDIO_DRIVER_JACK_DYNAMIC
+);
+
 static const char *jack_library = SDL_AUDIO_DRIVER_JACK_DYNAMIC;
 static SDL_SharedObject *jack_handle = NULL;
 

src/audio/pipewire/SDL_pipewire.c

@@ -93,6 +93,13 @@ static int (*PIPEWIRE_pw_properties_setf)(struct pw_properties *, const char *,
 
 #ifdef SDL_AUDIO_DRIVER_PIPEWIRE_DYNAMIC
 
+SDL_ELF_NOTE_DLOPEN(elfnote_pipewire,
+    "audio-libpipewire",
+    "Support for audio through libpipewire",
+    SDL_ELF_NOTE_DLOPEN_PRIORITY_SUGGESTED,
+    SDL_AUDIO_DRIVER_PIPEWIRE_DYNAMIC
+);
+
 static const char *pipewire_library = SDL_AUDIO_DRIVER_PIPEWIRE_DYNAMIC;
 static SDL_SharedObject *pipewire_handle = NULL;
 

src/audio/pulseaudio/SDL_pulseaudio.c

@@ -133,6 +133,13 @@ static bool load_pulseaudio_syms(void);
 
 #ifdef SDL_AUDIO_DRIVER_PULSEAUDIO_DYNAMIC
 
+SDL_ELF_NOTE_DLOPEN(elfnote_pulseaudio,
+    "audio-libpulseaudio",
+    "Support for audio through libpulseaudio",
+    SDL_ELF_NOTE_DLOPEN_PRIORITY_SUGGESTED,
+    SDL_AUDIO_DRIVER_PULSEAUDIO_DYNAMIC
+);
+
 static const char *pulseaudio_library = SDL_AUDIO_DRIVER_PULSEAUDIO_DYNAMIC;
 static SDL_SharedObject *pulseaudio_handle = NULL;
 

src/audio/sndio/SDL_sndioaudio.c

@@ -108,6 +108,13 @@ static bool load_sndio_syms(void)
 
 #ifdef SDL_AUDIO_DRIVER_SNDIO_DYNAMIC
 
+SDL_ELF_NOTE_DLOPEN(elfnote_pipewire,
+    "audio-libsndio",
+    "Support for audio through libsndio",
+    SDL_ELF_NOTE_DLOPEN_PRIORITY_SUGGESTED,
+    SDL_AUDIO_DRIVER_SNDIO_DYNAMIC
+);
+
 static void UnloadSNDIOLibrary(void)
 {
     if (sndio_handle) {