Add glaze-find-libegl programs.

[glaze] / glaze-find-libegl.c

diff --git a/glaze-find-libegl.c b/glaze-find-libegl.c
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+/* Copyright © 2014, Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#define _GNU_SOURCE
+#include <dlfcn.h>
+
+#include <stdio.h>
+
+/* The purpose of this program is very simple. It dynamically loads
+ * libEGL.so.1 and then prints out the filename of the file which was
+ * loaded.
+ *
+ * We use this in Glaze in order to determine the libEGL.so.1 library
+ * that would be loaded if it weren't for us messing around with
+ * LD_LIBRARY_PATH causing Glaze's libEGL.so.1 to be loaded instead.
+ *
+ * Using a program like this allows us to directly inspect what the
+ * dynamic loader actually does. This is much more reliable than
+ * trying to recreate its search-path logic which would requrie at
+ * least:
+ *
+ *     * Parsing LD_LIBRARY_PATH
+ *
+ *     * Correctly interpreting $LIB within LD_LIBRARY_PATH
+ *
+ *     * Knowing the canonical name for the current architecture for
+ *        *$LIB
+ *
+ *     * Parsing /etc/ld.so.conf entries
+ *
+ *     * etc. etc.
+ */
+int
+main (void)
+{
+       Dl_info info;
+       void *handle;
+       void *function;
+
+       handle = dlopen ("libEGL.so.1", RTLD_NOW);
+       if (handle == NULL) {
+               fprintf (stderr, "glaze-find-libegl: Failed to dlopen libEGL.so.1\n");
+               return 1;
+       }
+
+       function = dlsym (handle, "eglSwapBuffers");
+       if (function == NULL) {
+               fprintf (stderr, "glaze-find-libegl: Failed to dlsym eglSwapBuffers\n");
+               return 1;
+       }
+
+       if (dladdr (function, &info) == 0) {
+               fprintf (stderr, "glaze-find-libegl: Failed to dladdr eglSwapBuffers\n");
+               return 1;
+       }
+
+       printf ("%s\n", info.dli_fname);
+
+       return 0;
+}