Commit 10df615d141 ("add "Send Debug Info" option under Help") added some
debug information that contains the GL_VENDOR, GL_RENDERER and GL_VERSION
strings that are returned by the glGetString() function, and is used by
algorithms to recognize the platform.
But in some GL contexts, these may be NULL which leads to a NULL pointer
dereference when trying to copy the returned strings. Commit 97247dbaecc
("gl1: check for vender/renderer was in the wrong place") later fixed it
for the GL1 driver, but it missed doing the same for the GL driver.
For example, on an Exynos Odroid XU4 with a mali-fdev GL context I get:
$ retroarch -v
[INFO] RetroArch 1.8.5 (Git 8d3f25f)
[INFO] === Build =======================================
[INFO] Capabilities: NEON VFPv3 VFPv4
[INFO] Built: Mar 18 2020
[INFO] Version: 1.8.5
[INFO] Git: 8d3f25f
[INFO] =================================================
[INFO] [Environ]: SET_PIXEL_FORMAT: RGB565.
[INFO] Version of libretro API: 1
[INFO] Compiled against API: 1
[INFO] [Audio]: Set audio input rate to: 30000.00 Hz.
[INFO] [Video]: Video @ 960x720
[INFO] [EGL] Falling back to eglGetDisplay
[INFO] [EGL]: EGL version: 1.4
[INFO] [GL]: Found GL context: mali-fbdev
[INFO] [GL]: Detecting screen resolution 0x0.
[INFO] [EGL]: Current context: 0xf08e20.
[INFO] [GL]: Vendor: (null), Renderer: (null).
[INFO] [GL]: Version: (null).
Segmentation fault (core dumped)
- move shader flags from the video drivers to the context drivers
- rework config_load_shader_preset() from configuration.c into retroarch_load_shader_preset() in retroarch.c with proper compatibility check
- implicitly call retroarch_load_shader_preset() in retroarch_get_shader_preset() once per core/content life cycle
- use video_shader_is_supported() instead of video_driver_test_all_flags() where appropriate
- remove GFX_CTX_FLAGS_NONE because it is meaningless
