H4CK3R 4/hacker04/04_HACK04.ISO/darwin/darwinx86.iso/usr/include/mach-o/nlist.h

C/C++ Source or Header | 2001-09-14 | 10.2 KB | 229 lines

/*
 * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 *
 * Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
 * Reserved.  This file contains Original Code and/or Modifications of
 * Original Code as defined in and that are subject to the Apple Public
 * Source License Version 1.1 (the "License").  You may not use this file
 * except in compliance with the License.  Please obtain a copy of the
 * License at http://www.apple.com/publicsource and read it before using
 * this file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON- INFRINGEMENT.  Please see the
 * License for the specific language governing rights and limitations
 * under the License.
 *
 * @APPLE_LICENSE_HEADER_END@
 */
#ifndef _MACHO_NLIST_H_
#define _MACHO_NLIST_H_
/*    $NetBSD: nlist.h,v 1.5 1994/10/26 00:56:11 cgd Exp $    */

/*-
 * Copyright (c) 1991, 1993
 *    The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    This product includes software developed by the University of
 *    California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *    @(#)nlist.h    8.2 (Berkeley) 1/21/94
 */

/*
 * Format of a symbol table entry of a Mach-O file.  Modified from the BSD
 * format.  The modifications from the original format were changing n_other
 * (an unused field) to n_sect and the addition of the N_SECT type.  These
 * modifications are required to support symbols in an arbitrary number of
 * sections not just the three sections (text, data and bss) in a BSD file.
 */
struct nlist {
    union {
        char *n_name;    /* for use when in-core */
        long  n_strx;    /* index into the string table */
    } n_un;
    unsigned char n_type;    /* type flag, see below */
    unsigned char n_sect;    /* section number or NO_SECT */
    short          n_desc;    /* see <mach-o/stab.h> */
    unsigned long n_value;    /* value of this symbol (or stab offset) */
};

/*
 * Symbols with a index into the string table of zero (n_un.n_strx == 0) are
 * defined to have a null, "", name.  Therefore all string indexes to non null
 * names must not have a zero string index.  This is bit historical information
 * that has never been well documented.
 */

/*
 * The n_type field really contains three fields:
 *    unsigned char N_STAB:3,
 *              N_PEXT:1,
 *              N_TYPE:3,
 *              N_EXT:1;
 * which are used via the following masks.
 */
#define    N_STAB    0xe0  /* if any of these bits set, a symbolic debugging entry */
#define    N_PEXT    0x10  /* private external symbol bit */
#define    N_TYPE    0x0e  /* mask for the type bits */
#define    N_EXT    0x01  /* external symbol bit, set for external symbols */

/*
 * Only symbolic debugging entries have some of the N_STAB bits set and if any
 * of these bits are set then it is a symbolic debugging entry (a stab).  In
 * which case then the values of the n_type field (the entire field) are given
 * in <mach-o/stab.h>
 */

/*
 * Values for N_TYPE bits of the n_type field.
 */
#define    N_UNDF    0x0        /* undefined, n_sect == NO_SECT */
#define    N_ABS    0x2        /* absolute, n_sect == NO_SECT */
#define    N_SECT    0xe        /* defined in section number n_sect */
#define    N_PBUD    0xc        /* prebound undefined (defined in a dylib) */
#define N_INDR    0xa        /* indirect */

/*
 * If the type is N_INDR then the symbol is defined to be the same as another
 * symbol.  In this case the n_value field is an index into the string table
 * of the other symbol's name.  When the other symbol is defined then they both
 * take on the defined type and value.
 */

/*
 * If the type is N_SECT then the n_sect field contains an ordinal of the
 * section the symbol is defined in.  The sections are numbered from 1 and
 * refer to sections in order they appear in the load commands for the file
 * they are in.  This means the same ordinal may very well refer to different
 * sections in different files.
 *
 * The n_value field for all symbol table entries (including N_STAB's) gets
 * updated by the link editor based on the value of it's n_sect field and where
 * the section n_sect references gets relocated.  If the value of the n_sect
 * field is NO_SECT then it's n_value field is not changed by the link editor.
 */
#define    NO_SECT        0    /* symbol is not in any section */
#define MAX_SECT    255    /* 1 thru 255 inclusive */

/*
 * Common symbols are represented by undefined (N_UNDF) external (N_EXT) types
 * who's values (n_value) are non-zero.  In which case the value of the n_value
 * field is the size (in bytes) of the common symbol.  The n_sect field is set
 * to NO_SECT.
 */

/*
 * To support the lazy binding of undefined symbols in the dynamic link-editor,
 * the undefined symbols in the symbol table (the nlist structures) are marked
 * with the indication if the undefined reference is a lazy reference or
 * non-lazy reference.  If both a non-lazy reference and a lazy reference is
 * made to the same symbol the non-lazy reference takes precedence.  A reference
 * is lazy only when all references to that symbol are made through a symbol
 * pointer in a lazy symbol pointer section.
 *
 * The implementation of marking nlist structures in the symbol table for
 * undefined symbols will be to use some of the bits of the n_desc field as a
 * reference type.  The mask REFERENCE_TYPE will be applied to the n_desc field
 * of an nlist structure for an undefined symbol to determine the type of
 * undefined reference (lazy or non-lazy).
 *
 * The constants for the REFERENCE FLAGS are propagated to the reference table
 * in a shared library file.  In that case the constant for a defined symbol,
 * REFERENCE_FLAG_DEFINED, is also used.
 */
/* Reference type bits of the n_desc field of undefined symbols */
#define REFERENCE_TYPE                0xf
/* types of references */
#define REFERENCE_FLAG_UNDEFINED_NON_LAZY        0
#define REFERENCE_FLAG_UNDEFINED_LAZY            1
#define REFERENCE_FLAG_DEFINED                2
#define REFERENCE_FLAG_PRIVATE_DEFINED            3
#define REFERENCE_FLAG_PRIVATE_UNDEFINED_NON_LAZY    4
#define REFERENCE_FLAG_PRIVATE_UNDEFINED_LAZY        5

/*
 * To simplify stripping of objects that use are used with the dynamic link
 * editor, the static link editor marks the symbols defined an object that are
 * referenced by a dynamicly bound object (dynamic shared libraries, bundles).
 * With this marking strip knows not to strip these symbols.
 */
#define REFERENCED_DYNAMICALLY    0x0010

/*
 * For images created by the static link editor with the -twolevel_namespace
 * option in effect the flags field of the mach header is marked with
 * MH_TWOLEVEL.  And the binding of the undefined references of the image are
 * determined by the static link editor.  Which library an undefined symbol is
 * bound to is recorded by the static linker in the high 8 bits of the n_desc
 * field using the SET_LIBRARY_ORDINAL macro below.  The ordinal recorded
 * references the libraries listed in the Mach-O's LC_LOAD_DYLIB load commands
 * in the order they appear in the headers.   The library ordinals start from 1.
 * For a dynamic library that is built as a two-level namespace image the
 * undefined references from module defined in another use the same nlist struct
 * an in that case SELF_LIBRARY_ORDINAL is used as the library ordinal.  For
 * defined symbols in all images they also must have the library ordinal set to
 * SELF_LIBRARY_ORDINAL.  The EXECUTABLE_ORDINAL is refers to the executable
 * image for references from plugins that refer to the executable that loads
 * them.
 */
#define GET_LIBRARY_ORDINAL(n_desc) (((n_desc) >> 8) & 0xff)
#define SET_LIBRARY_ORDINAL(n_desc,ordinal) \
    (n_desc) = (((n_desc) & 0x00ff) | (((ordinal) & 0xff) << 8))
#define SELF_LIBRARY_ORDINAL 0x0
#define MAX_LIBRARY_ORDINAL 0xfe
#define EXECUTABLE_ORDINAL 0xff

/*
 * The non-reference type bits and the non-library ordinal bits of the n_desc
 * field for global symbols are reserved for the dynamic link editor.  All of
 * these bits must start out zero in the object file.  The N_DESC_DISCARDED
 * bit never appears in an object file but is used in very rare cases by the
 * dynamic link editor.
 */
#define N_DESC_DISCARDED 0x0020    /* symbol is discarded */

#ifndef __STRICT_BSD__
/*
 * The function nlist(3) from the C library.
 */
extern int nlist (const char *filename, struct nlist *list);
#endif __STRICT_BSD__

#endif _MACHO_LIST_H_