Add an explanatory comment for a surprisingly-unused field.

[fips] / glwrap.c

diff --git a/glwrap.c b/glwrap.c
index a7d62c5c1ef2be57d650591302923197c0fbb05f..3c751cc4e19832aa49d55516b8b38b00aea9033b 100644 (file)
--- a/glwrap.c
+++ b/glwrap.c
@@ -19,6 +19,8 @@
  * THE SOFTWARE.
  */
 
+#include "dlwrap.h"
+
 /* The prototypes for some OpenGL functions changed at one point from:
  *
  *     const void* *indices
@@ -45,26 +47,65 @@
 
 #include "metrics.h"
 
-#include "dlwrap.h"
-
 static int inside_new_list = 0;
 
+static void *gl_handle;
+
+void
+glwrap_set_gl_handle (void *handle)
+{
+       if (gl_handle == NULL)
+               gl_handle = handle;
+}
+
 void *
 glwrap_lookup (char *name)
 {
-       const char *libgl_filename = "libGL.so.1";
-       static void *libgl_handle = NULL;
-
-       if (! libgl_handle) {
-               libgl_handle = dlwrap_real_dlopen (libgl_filename, RTLD_NOW | RTLD_DEEPBIND);
-               if (! libgl_handle) {
-                       fprintf (stderr, "Error: Failed to dlopen %s\n",
-                                libgl_filename);
-                       exit (1);
+       void *ret;
+
+       /* We don't call dlopen here to find the library in which to
+        * perform a dlsym lookup. That's because the application may
+        * be loading libGL.so or libGLESv2.so for its OpenGL symbols.
+        *
+        * So we instead watch for one of those filenames to go by in
+        * our dlopen wrapper, which will then call
+        * glwrap_set_gl_handle to give us the handle to use here.
+        *
+        * If the application hasn't called dlopen on a "libGL"
+        * library, then presumably the application is linked directly
+        * to an OpenGL implementation. In this case, we can use
+        * RTLD_NEXT to find the symbol.
+        *
+        * But just in case, we also let the user override that by
+        * specifying the FIPS_LIBGL environment variable to the path
+        * of the real libGL.so library that fips should dlopen here.
+        */
+       if (gl_handle == NULL) {
+               const char *path;
+
+               path = getenv ("FIPS_LIBGL");
+               if (path) {
+                       gl_handle = dlopen (path, RTLD_LAZY);
+
+                       if (gl_handle == NULL) {
+                               fprintf (stderr, "Failed to dlopen FIPS_LIBGL: "
+                                        "%s\n", path);
+                               exit (1);
+                       }
+               } else {
+                       gl_handle = RTLD_NEXT;
                }
        }
 
-       return dlwrap_real_dlsym (libgl_handle, name);
+       ret = dlwrap_real_dlsym (gl_handle, name);
+
+       if (ret == NULL) {
+               fprintf (stderr, "Error: glwrap_lookup failed to dlsym %s\n",
+                        name);
+               exit (1);
+       }
+
+       return ret;
 }
 
 /* Execute an OpenGL call and time it with a GPU metrics counter. */