Applied OpenGL 3.2+ fix patch

from kbranigan/Simple-OpenGL-Image-Library#17

src/soil.c

@@ -80,6 +80,58 @@ int query_DXT_capability( void );
 #define SOIL_RGBA_S3TC_DXT5		0x83F3
 typedef void (APIENTRY * P_SOIL_GLCOMPRESSEDTEXIMAGE2DPROC) (GLenum target, GLint level, GLenum internalformat, GLsizei width, GLsizei height, GLint border, GLsizei imageSize, const GLvoid * data);
 P_SOIL_GLCOMPRESSEDTEXIMAGE2DPROC soilGlCompressedTexImage2D = NULL;
+typedef const GLubyte* (APIENTRY * P_SOIL_GLGETSTRINGIPROC) (GLenum name, GLuint index);
+
+/**
+https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=727175
+
+"Most SOIL functions crash if OpenGL context is 3.2+ core profile. SOIL calls
+glGetString with a value that is no longer valid, and then sends the returned
+null pointer to strstr.
+
+This patch checks the OpenGL version at runtime, and uses a glGetString function
+that is appropriate and available. It doesn't crash if, for whatever reason,
+glGetString returns a null pointer."
+
+- Thanks to Brandon!
+
+**/
+static int SOIL_internal_has_OGL_capability(const char * cap)
+{
+	int i;
+	GLint num_ext;
+	const GLubyte * ext_string;
+	int major_version;
+
+	const GLubyte * ver_string = glGetString(GL_VERSION);
+	if (ver_string)
+		 major_version = atoi((const char *) ver_string);
+	else
+		major_version = 0;
+
+	P_SOIL_GLGETSTRINGIPROC soilGlGetStringi =
+		(P_SOIL_GLGETSTRINGIPROC) glXGetProcAddressARB((const GLubyte *) "glGetStringi");
+
+	if (major_version >= 3 && soilGlGetStringi) {
+		/* OpenGL 3.0+ */
+		glGetIntegerv(GL_NUM_EXTENSIONS, &num_ext);
+		for (i = 0; i < num_ext; i++) {
+			ext_string = soilGlGetStringi(GL_EXTENSIONS, i);
+			if (ext_string && !strcmp((const char *) ext_string, cap)) {
+				return GL_TRUE;
+			}
+		}
+	}
+	else {
+		/* OpenGL < 3.0 */
+		ext_string = glGetString(GL_EXTENSIONS);
+		if (ext_string && strstr((const char *) ext_string, cap)) {
+			return GL_TRUE;
+		}
+	}
+	return GL_FALSE;
+}
+
 unsigned int SOIL_direct_load_DDS(
 		const char *filename,
 		unsigned int reuse_texture_ID,
@@ -1876,10 +1928,7 @@ int query_NPOT_capability( void )
 	if( has_NPOT_capability == SOIL_CAPABILITY_UNKNOWN )
 	{
 		/*	we haven't yet checked for the capability, do so	*/
-		if(
-			(NULL == strstr( (char const*)glGetString( GL_EXTENSIONS ),
-				"GL_ARB_texture_non_power_of_two" ) )
-			)
+		if(!SOIL_internal_has_OGL_capability("GL_ARB_texture_non_power_of_two"))
 		{
 			/*	not there, flag the failure	*/
 			has_NPOT_capability = SOIL_CAPABILITY_NONE;
@@ -1900,14 +1949,11 @@ int query_tex_rectangle_capability( void )
 	{
 		/*	we haven't yet checked for the capability, do so	*/
 		if(
-			(NULL == strstr( (char const*)glGetString( GL_EXTENSIONS ),
-				"GL_ARB_texture_rectangle" ) )
+			(!SOIL_internal_has_OGL_capability("GL_ARB_texture_rectangle" ))
 		&&
-			(NULL == strstr( (char const*)glGetString( GL_EXTENSIONS ),
-				"GL_EXT_texture_rectangle" ) )
+			(!SOIL_internal_has_OGL_capability("GL_EXT_texture_rectangle"))
 		&&
-			(NULL == strstr( (char const*)glGetString( GL_EXTENSIONS ),
-				"GL_NV_texture_rectangle" ) )
+			(!SOIL_internal_has_OGL_capability("GL_NV_texture_rectangle" ))
 			)
 		{
 			/*	not there, flag the failure	*/
@@ -1929,11 +1975,9 @@ int query_cubemap_capability( void )
 	{
 		/*	we haven't yet checked for the capability, do so	*/
 		if(
-			(NULL == strstr( (char const*)glGetString( GL_EXTENSIONS ),
-				"GL_ARB_texture_cube_map" ) )
+			(!SOIL_internal_has_OGL_capability("GL_ARB_texture_cube_map"))
 		&&
-			(NULL == strstr( (char const*)glGetString( GL_EXTENSIONS ),
-				"GL_EXT_texture_cube_map" ) )
+			(!SOIL_internal_has_OGL_capability("GL_EXT_texture_cube_map"))
 			)
 		{
 			/*	not there, flag the failure	*/
@@ -1954,9 +1998,7 @@ int query_DXT_capability( void )
 	if( has_DXT_capability == SOIL_CAPABILITY_UNKNOWN )
 	{
 		/*	we haven't yet checked for the capability, do so	*/
-		if( NULL == strstr(
-				(char const*)glGetString( GL_EXTENSIONS ),
-				"GL_EXT_texture_compression_s3tc" ) )
+		if(!SOIL_internal_has_OGL_capability("GL_EXT_texture_compression_s3tc"))
 		{
 			/*	not there, flag the failure	*/
 			has_DXT_capability = SOIL_CAPABILITY_NONE;