From 26ae9c9f8aebbf4b925649f971f90c0dee047aa9 Mon Sep 17 00:00:00 2001
From: Nicolas George <george@nsup.org>
Date: Mon, 17 Feb 2020 12:59:27 +0100
Subject: lavd/opengl_enc: check strings before parsing them.

Fix a segfault if OpenGL was not initialized before calling
write_header().
---
 libavdevice/opengl_enc.c | 4 ++++
 1 file changed, 4 insertions(+)

(limited to 'libavdevice/opengl_enc.c')

diff --git a/libavdevice/opengl_enc.c b/libavdevice/opengl_enc.c
index fa94345a7c..b07f9c2e43 100644
--- a/libavdevice/opengl_enc.c
+++ b/libavdevice/opengl_enc.c
@@ -588,6 +588,10 @@ static av_cold int opengl_read_limits(AVFormatContext *h)
 
     version = glGetString(GL_VERSION);
     extensions = glGetString(GL_EXTENSIONS);
+    if (!version || !extensions) {
+        av_log(h, AV_LOG_ERROR, "No OpenGL context initialized for the current thread\n");
+        return AVERROR(ENOSYS);
+    }
 
     av_log(h, AV_LOG_DEBUG, "OpenGL version: %s\n", version);
     sscanf(version, "%d.%d", &major, &minor);
-- 
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