/*
- * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
- *
- * @APPLE_LICENSE_HEADER_START@
- *
* Copyright (c) 1999-2003 Apple Computer, Inc. All Rights Reserved.
*
+ * @APPLE_LICENSE_HEADER_START@
+ *
* 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 2.0 (the 'License'). You may not use this file except in
*
* @(#)nlist.h 8.2 (Berkeley) 1/21/94
*/
+#include <stdint.h>
/*
- * 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.
+ * Format of a symbol table entry of a Mach-O file for 32-bit architectures.
+ * 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 a larger
+ * number of sections not just the three sections (text, data and bss) in a BSD
+ * file.
*/
struct nlist {
union {
+#ifndef __LP64__
char *n_name; /* for use when in-core */
- long n_strx; /* index into the string table */
+#endif
+ uint32_t 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) */
+ uint8_t n_type; /* type flag, see below */
+ uint8_t n_sect; /* section number or NO_SECT */
+ int16_t n_desc; /* see <mach-o/stab.h> */
+ uint32_t n_value; /* value of this symbol (or stab offset) */
+};
+
+/*
+ * This is the symbol table entry structure for 64-bit architectures.
+ */
+struct nlist_64 {
+ union {
+ uint32_t n_strx; /* index into the string table */
+ } n_un;
+ uint8_t n_type; /* type flag, see below */
+ uint8_t n_sect; /* section number or NO_SECT */
+ uint16_t n_desc; /* see <mach-o/stab.h> */
+ uint64_t n_value; /* value of this symbol (or stab offset) */
};
/*
*/
/*
- * The n_type field really contains three fields:
+ * The n_type field really contains four fields:
* unsigned char N_STAB:3,
* N_PEXT:1,
* N_TYPE:3,
* 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 NO_SECT. The alignment of a common symbol may be set as a power of 2
+ * between 2^1 and 2^15 as part of the n_desc field using the macros below. If
+ * the alignment is not set (a value of zero) then natural alignment based on
+ * the size is used.
*/
+#define GET_COMM_ALIGN(n_desc) (((n_desc) >> 8) & 0x0f)
+#define SET_COMM_ALIGN(n_desc,align) \
+ (n_desc) = (((n_desc) & 0xf0ff) | (((align) & 0x0f) << 8))
/*
* To support the lazy binding of undefined symbols in the dynamic link-editor,
* REFERENCE_FLAG_DEFINED, is also used.
*/
/* Reference type bits of the n_desc field of undefined symbols */
-#define REFERENCE_TYPE 0xf
+#define REFERENCE_TYPE 0x7
/* types of references */
#define REFERENCE_FLAG_UNDEFINED_NON_LAZY 0
#define REFERENCE_FLAG_UNDEFINED_LAZY 1
#define REFERENCED_DYNAMICALLY 0x0010
/*
- * The non-reference type 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.
+ * 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,
+ * LC_LOAD_WEAK_DYLIB, LC_REEXPORT_DYLIB, LC_LOAD_UPWARD_DYLIB, and
+ * LC_LAZY_LOAD_DYLIB, etc. 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 refers to the executable
+ * image for references from plugins that refer to the executable that loads
+ * them.
+ *
+ * The DYNAMIC_LOOKUP_ORDINAL is for undefined symbols in a two-level namespace
+ * image that are looked up by the dynamic linker with flat namespace semantics.
+ * This ordinal was added as a feature in Mac OS X 10.3 by reducing the
+ * value of MAX_LIBRARY_ORDINAL by one. So it is legal for existing binaries
+ * or binaries built with older tools to have 0xfe (254) dynamic libraries. In
+ * this case the ordinal value 0xfe (254) must be treated as a library ordinal
+ * for compatibility.
*/
-#define N_DESC_DISCARDED 0x8000 /* symbol is discarded */
+#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 0xfd
+#define DYNAMIC_LOOKUP_ORDINAL 0xfe
+#define EXECUTABLE_ORDINAL 0xff
-#endif
+/*
+ * The bit 0x0020 of the n_desc field is used for two non-overlapping purposes
+ * and has two different symbolic names, N_NO_DEAD_STRIP and N_DESC_DISCARDED.
+ */
+
+/*
+ * The N_NO_DEAD_STRIP bit of the n_desc field only ever appears in a
+ * relocatable .o file (MH_OBJECT filetype). And is used to indicate to the
+ * static link editor it is never to dead strip the symbol.
+ */
+#define N_NO_DEAD_STRIP 0x0020 /* symbol is not to be dead stripped */
+
+/*
+ * The N_DESC_DISCARDED bit of the n_desc field never appears in linked image.
+ * But is used in very rare cases by the dynamic link editor to mark an in
+ * memory symbol as discared and longer used for linking.
+ */
+#define N_DESC_DISCARDED 0x0020 /* symbol is discarded */
+
+/*
+ * The N_WEAK_REF bit of the n_desc field indicates to the dynamic linker that
+ * the undefined symbol is allowed to be missing and is to have the address of
+ * zero when missing.
+ */
+#define N_WEAK_REF 0x0040 /* symbol is weak referenced */
+
+/*
+ * The N_WEAK_DEF bit of the n_desc field indicates to the static and dynamic
+ * linkers that the symbol definition is weak, allowing a non-weak symbol to
+ * also be used which causes the weak definition to be discared. Currently this
+ * is only supported for symbols in coalesed sections.
+ */
+#define N_WEAK_DEF 0x0080 /* coalesed symbol is a weak definition */
+
+/*
+ * The N_REF_TO_WEAK bit of the n_desc field indicates to the dynamic linker
+ * that the undefined symbol should be resolved using flat namespace searching.
+ */
+#define N_REF_TO_WEAK 0x0080 /* reference to a weak symbol */
+
+/*
+ * The N_ARM_THUMB_DEF bit of the n_desc field indicates that the symbol is
+ * a defintion of a Thumb function.
+ */
+#define N_ARM_THUMB_DEF 0x0008 /* symbol is a Thumb function (ARM) */
+
+/*
+ * The N_SYMBOL_RESOLVER bit of the n_desc field indicates that the
+ * that the function is actually a resolver function and should
+ * be called to get the address of the real function to use.
+ * This bit is only available in .o files (MH_OBJECT filetype)
+ */
+#define N_SYMBOL_RESOLVER 0x0100
+
+/*
+ * The N_ALT_ENTRY bit of the n_desc field indicates that the
+ * symbol is pinned to the previous content.
+ */
+#define N_ALT_ENTRY 0x0200
+
+#ifndef __STRICT_BSD__
+#ifdef __cplusplus
+extern "C" {
+#endif /* __cplusplus */
+/*
+ * The function nlist(3) from the C library.
+ */
+extern int nlist (const char *filename, struct nlist *list);
+#ifdef __cplusplus
+}
+#endif /* __cplusplus */
+#endif /* __STRICT_BSD__ */
+
+#endif /* _MACHO_LIST_H_ */
projects / apple / xnu.git / blobdiff