/*
 * Macros to hook functions.
 *
 * Copyright (C) 2013  Simon Ruderich
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef MACROS_H
#define MACROS_H 1

/* Hook the function by creating a function with the same name. With
 * LD_PRELOAD our function will be preferred. The original function is stored
 * in a static variable (real_*). */

#define _HOOK_PRE(type, name) \
        int handle; \
        int saved_errno = errno; \
        DLSYM_FUNCTION(real_ ## name, #name);
#define _HOOK_PRE_FD(type, name, fd) \
        type result; \
        _HOOK_PRE_FD_(type, name, fd)
#define _HOOK_PRE_FD_(type, name, fd) \
        _HOOK_PRE(type, name) \
        handle = check_handle_fd(fd); \
        if (handle) { \
            handle_fd_pre(fd, handle); \
        } \
        errno = saved_errno;
#define _HOOK_PRE_FILE(type, name, file) \
        type result; \
        _HOOK_PRE(type, name) \
        handle = check_handle_fd(fileno(file)); \
        if (handle) { \
            handle_file_pre(file, handle); \
        } \
        errno = saved_errno;
/* Save and restore the errno to make sure we return the errno of the original
 * function call. */
#define _HOOK_POST_FD_(fd) \
        if (handle) { \
            saved_errno = errno; \
            handle_fd_post(fd, handle); \
            errno = saved_errno; \
        }
#define _HOOK_POST_FD(fd) \
        _HOOK_POST_FD_(fd) \
        return result;
#define _HOOK_POST_FILE(file) \
        if (handle) { \
            saved_errno = errno; \
            handle_file_post(file, handle); \
            errno = saved_errno; \
        } \
        return result;


#define HOOK_VOID1(type, name, fd, type1, arg1) \
    static type (*real_ ## name)(type1); \
    type name(type1 arg1) { \
        _HOOK_PRE_FD_(type, name, fd) \
        real_ ## name(arg1); \
        _HOOK_POST_FD_(fd) \
    }

#define HOOK_FD3(type, name, fd, type1, arg1, type2, arg2, type3, arg3) \
    static type (*real_ ## name)(type1, type2, type3); \
    type name(type1 arg1, type2 arg2, type3 arg3) { \
        _HOOK_PRE_FD(type, name, fd) \
        result = real_ ## name(arg1, arg2, arg3); \
        _HOOK_POST_FD(fd) \
    }

#define HOOK_FILE1(type, name, file, type1, arg1) \
    static type (*real_ ## name)(type1); \
    type name(type1 arg1) { \
        _HOOK_PRE_FILE(type, name, file) \
        result = real_ ## name(arg1); \
        _HOOK_POST_FILE(file) \
    }
#define HOOK_FILE2(type, name, file, type1, arg1, type2, arg2) \
    static type (*real_ ## name)(type1, type2); \
    type name(type1 arg1, type2 arg2) { \
        _HOOK_PRE_FILE(type, name, file) \
        result = real_ ## name(arg1, arg2); \
        _HOOK_POST_FILE(file) \
    }
#define HOOK_FILE3(type, name, file, type1, arg1, type2, arg2, type3, arg3) \
    static type (*real_ ## name)(type1, type2, type3); \
    type name(type1 arg1, type2 arg2, type3 arg3) { \
        _HOOK_PRE_FILE(type, name, file) \
        result = real_ ## name(arg1, arg2, arg3); \
        _HOOK_POST_FILE(file) \
    }
#define HOOK_FILE4(type, name, file, type1, arg1, type2, arg2, type3, arg3, type4, arg4) \
    static type (*real_ ## name)(type1, type2, type3, type4); \
    type name(type1 arg1, type2 arg2, type3 arg3, type4 arg4) { \
        _HOOK_PRE_FILE(type, name, file) \
        result = real_ ## name(arg1, arg2, arg3, arg4); \
        _HOOK_POST_FILE(file) \
    }

#define HOOK_VAR_FILE1(type, name, file, func, type1, arg1) \
    static type (*real_ ## func)(type1, va_list); \
    type name(type1 arg1, ...) { \
        va_list ap; \
        _HOOK_PRE_FILE(type, func, file) \
        va_start(ap, arg1); \
        result = real_ ## func(arg1, ap); \
        va_end(ap); \
        _HOOK_POST_FILE(file) \
    }
#define HOOK_VAR_FILE2(type, name, file, func, type1, arg1, type2, arg2) \
    static type (*real_ ## func)(type1, type2, va_list); \
    type name(type1 arg1, type2 arg2, ...) { \
        va_list ap; \
        _HOOK_PRE_FILE(type, func, file) \
        va_start(ap, arg2); \
        result = real_ ## func(arg1, arg2, ap); \
        va_end(ap); \
        _HOOK_POST_FILE(file) \
    }
#define HOOK_VAR_FILE3(type, name, file, func, type1, arg1, type2, arg2, type3, arg3) \
    static type (*real_ ## func)(type1, type2, type3, va_list); \
    type name(type1 arg1, type2 arg2, type3 arg3, ...) \
    { \
        va_list ap; \
        _HOOK_PRE_FILE(type, func, file) \
        va_start(ap, arg3); \
        result = real_ ## func(arg1, arg2, arg3, ap); \
        va_end(ap); \
        _HOOK_POST_FILE(file) \
    }

#endif