dispatch/dlopen.hpp

/**************************************************************************
 *
 * Copyright 2011 Jose Fonseca
 * All Rights Reserved.
 *
 * 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.
 *
 **************************************************************************/

/*
 * Provides access to real dlopen, as tracing libraries interpose it.
 */

#ifndef _DLOPEN_HPP_
#define _DLOPEN_HPP_

#include <dlfcn.h>

#include "os.hpp"


/*
 * Invoke the true dlopen() function.
 */
static void *_dlopen(const char *filename, int flag)
{
    typedef void * (*PFN_DLOPEN)(const char *, int);
    static PFN_DLOPEN dlopen_ptr = NULL;

    if (!dlopen_ptr) {
#ifdef ANDROID
        /* Android does not have dlopen in libdl.so; instead, the
         * implementation is available in the dynamic linker itself.
         * Oddly enough, we still can interpose it, but need to use
         * RTLD_DEFAULT to get pointer to the original function.  */
        dlopen_ptr = (PFN_DLOPEN)dlsym(RTLD_DEFAULT, "dlopen");
#else
        dlopen_ptr = (PFN_DLOPEN)dlsym(RTLD_NEXT, "dlopen");
#endif
        if (!dlopen_ptr) {
            os::log("apitrace: error: failed to look up real dlopen\n");
            return NULL;
        }
    }

    return dlopen_ptr(filename, flag);
}

#endif /* _DLOPEN_HPP_ */