vo_gpu: gl: implement proper extension string search

The existing code in check_ext() avoided false positive due to
sub-strings, but allowed false negatives. Fix this with slightly better
search code, and make it available as function to other source files.
(There are some cases of strstr() still around.)

3 files changed, 23 insertions, 10 deletions

diff --git a/video/out/opengl/common.c b/video/out/opengl/common.c
index db317ee843..be3ff8e438 100644
--- a/video/out/opengl/common.c
+++ b/video/out/opengl/common.c
@@ -31,6 +31,7 @@
 
 #include "common.h"
 #include "common/common.h"
+#include "utils.h"
 
 // This guesses if the current GL context is a suspected software renderer.
 static bool is_software_gl(GL *gl)
@@ -49,14 +50,6 @@ static void GLAPIENTRY dummy_glBindFramebuffer(GLenum target, GLuint framebuffer
     assert(framebuffer == 0);
 }
 
-static bool check_ext(GL *gl, const char *name)
-{
-    const char *exts = gl->extensions;
-    char *s = strstr(exts, name);
-    char *e = s ? s + strlen(name) : NULL;
-    return s && (s == exts || s[-1] == ' ') && (e[0] == ' ' || !e[0]);
-}
-
 #define FN_OFFS(name) offsetof(GL, name)
 
 #define DEF_FN(name)            {FN_OFFS(name), "gl" # name}
@@ -581,8 +574,8 @@ void mpgl_load_functions2(GL *gl, void *(*get_fn)(void *ctx, const char *n),
         if (ver_core)
             must_exist = version >= ver_core;
 
-        if (section->extension && check_ext(gl, section->extension))
-            exists = true;
+        if (section->extension)
+            exists = gl_check_extension(gl->extensions, section->extension);
 
         exists |= must_exist;
         if (!exists)
diff --git a/video/out/opengl/utils.c b/video/out/opengl/utils.c
index 3b296d52de..38982e501e 100644
--- a/video/out/opengl/utils.c
+++ b/video/out/opengl/utils.c
@@ -267,3 +267,21 @@ void gl_set_debug_logger(GL *gl, struct mp_log *log)
     if (gl->DebugMessageCallback)
         gl->DebugMessageCallback(log ? gl_debug_cb : NULL, log);
 }
+
+// Given a GL combined extension string in extensions, find out whether ext
+// is included in it. Basically, a word search.
+bool gl_check_extension(const char *extensions, const char *ext)
+{
+    int len = strlen(ext);
+    const char *cur = extensions;
+    while (cur) {
+        cur = strstr(cur, ext);
+        if (!cur)
+            break;
+        if ((cur == extensions || cur[-1] == ' ') &&
+            (cur[len] == '\0' || cur[len] == ' '))
+            return true;
+        cur += len;
+    }
+    return false;
+}
diff --git a/video/out/opengl/utils.h b/video/out/opengl/utils.h
index 18cab476ed..53127e479e 100644
--- a/video/out/opengl/utils.h
+++ b/video/out/opengl/utils.h
@@ -51,4 +51,6 @@ void gl_vao_draw_data(struct gl_vao *vao, GLenum prim, void *ptr, size_t num);
 
 void gl_set_debug_logger(GL *gl, struct mp_log *log);
 
+bool gl_check_extension(const char *extensions, const char *ext);
+
 #endif