rtld.h revision 63870 
1/*-
2 * Copyright 1996, 1997, 1998, 1999, 2000 John D. Polstra.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 *
25 * $FreeBSD: head/libexec/rtld-elf/rtld.h 63870 2000-07-26 04:24:40Z jdp $
26 */
27
28#ifndef RTLD_H /* { */
29#define RTLD_H 1
30
31#include <sys/types.h>
32#include <sys/queue.h>
33
34#include <link.h>
35#include <elf.h>
36#include <stddef.h>
37
38#include "rtld_machdep.h"
39
40#ifndef STANDARD_LIBRARY_PATH
41#define STANDARD_LIBRARY_PATH	"/usr/lib/elf:/usr/lib"
42#endif
43
44#define NEW(type)	((type *) xmalloc(sizeof(type)))
45#define CNEW(type)	((type *) xcalloc(sizeof(type)))
46
47/* We might as well do booleans like C++. */
48typedef unsigned char bool;
49#define false	0
50#define true	1
51
52struct stat;
53struct Struct_Obj_Entry;
54
55/* Lists of shared objects */
56typedef struct Struct_Objlist_Entry {
57    STAILQ_ENTRY(Struct_Objlist_Entry) link;
58    struct Struct_Obj_Entry *obj;
59} Objlist_Entry;
60
61typedef STAILQ_HEAD(Struct_Objlist, Struct_Objlist_Entry) Objlist;
62
63/* Types of init and fini functions */
64typedef void (*InitFunc)(void);
65
66/* Lists of shared object dependencies */
67typedef struct Struct_Needed_Entry {
68    struct Struct_Needed_Entry *next;
69    struct Struct_Obj_Entry *obj;
70    unsigned long name;		/* Offset of name in string table */
71} Needed_Entry;
72
73/* Lock object */
74typedef struct Struct_LockInfo {
75    void *context;		/* Client context for creating locks */
76    void *thelock;		/* The one big lock */
77    /* Debugging aids. */
78    volatile int rcount;	/* Number of readers holding lock */
79    volatile int wcount;	/* Number of writers holding lock */
80    /* Methods */
81    void *(*lock_create)(void *context);
82    void (*rlock_acquire)(void *lock);
83    void (*wlock_acquire)(void *lock);
84    void (*rlock_release)(void *lock);
85    void (*wlock_release)(void *lock);
86    void (*lock_destroy)(void *lock);
87    void (*context_destroy)(void *context);
88} LockInfo;
89
90/*
91 * Shared object descriptor.
92 *
93 * Items marked with "(%)" are dynamically allocated, and must be freed
94 * when the structure is destroyed.
95 *
96 * CAUTION: It appears that the JDK port peeks into these structures.
97 * It looks at "next" and "mapbase" at least.  Don't add new members
98 * near the front, until this can be straightened out.
99 */
100typedef struct Struct_Obj_Entry {
101    /*
102     * These two items have to be set right for compatibility with the
103     * original ElfKit crt1.o.
104     */
105    Elf_Word magic;		/* Magic number (sanity check) */
106    Elf_Word version;		/* Version number of struct format */
107
108    struct Struct_Obj_Entry *next;
109    char *path;			/* Pathname of underlying file (%) */
110    int refcount;
111    int dl_refcount;		/* Number of times loaded by dlopen */
112
113    /* These items are computed by map_object() or by digest_phdr(). */
114    caddr_t mapbase;		/* Base address of mapped region */
115    size_t mapsize;		/* Size of mapped region in bytes */
116    size_t textsize;		/* Size of text segment in bytes */
117    Elf_Addr vaddrbase;		/* Base address in shared object file */
118    caddr_t relocbase;		/* Relocation constant = mapbase - vaddrbase */
119    const Elf_Dyn *dynamic;	/* Dynamic section */
120    caddr_t entry;		/* Entry point */
121    const Elf_Phdr *phdr;	/* Program header if it is mapped, else NULL */
122    size_t phsize;		/* Size of program header in bytes */
123    const char *interp;		/* Pathname of the interpreter, if any */
124
125    /* Items from the dynamic section. */
126    Elf_Addr *pltgot;		/* PLT or GOT, depending on architecture */
127    const Elf_Rel *rel;		/* Relocation entries */
128    unsigned long relsize;	/* Size in bytes of relocation info */
129    const Elf_Rela *rela;	/* Relocation entries with addend */
130    unsigned long relasize;	/* Size in bytes of addend relocation info */
131    const Elf_Rel *pltrel;	/* PLT relocation entries */
132    unsigned long pltrelsize;	/* Size in bytes of PLT relocation info */
133    const Elf_Rela *pltrela;	/* PLT relocation entries with addend */
134    unsigned long pltrelasize;	/* Size in bytes of PLT addend reloc info */
135    const Elf_Sym *symtab;	/* Symbol table */
136    const char *strtab;		/* String table */
137    unsigned long strsize;	/* Size in bytes of string table */
138
139    const Elf_Addr *buckets;	/* Hash table buckets array */
140    unsigned long nbuckets;	/* Number of buckets */
141    const Elf_Addr *chains;	/* Hash table chain array */
142    unsigned long nchains;	/* Number of chains */
143
144    const char *rpath;		/* Search path specified in object */
145    Needed_Entry *needed;	/* Shared objects needed by this one (%) */
146
147    InitFunc init;		/* Initialization function to call */
148    InitFunc fini;		/* Termination function to call */
149
150    bool mainprog;		/* True if this is the main program */
151    bool rtld;			/* True if this is the dynamic linker */
152    bool textrel;		/* True if there are relocations to text seg */
153    bool symbolic;		/* True if generated with "-Bsymbolic" */
154    bool traced;		/* Already printed in ldd trace output */
155    bool jmpslots_done;		/* Already have relocated the jump slots */
156    bool init_done;		/* Already have added object to init list */
157
158    struct link_map linkmap;	/* for GDB */
159    Objlist dldags;		/* Object belongs to these dlopened DAGs (%) */
160    Objlist dagmembers;		/* DAG has these members (%) */
161    dev_t dev;			/* Object's filesystem's device */
162    ino_t ino;			/* Object's inode number */
163} Obj_Entry;
164
165#define RTLD_MAGIC	0xd550b87a
166#define RTLD_VERSION	1
167
168extern void _rtld_error(const char *, ...) __printflike(1, 2);
169extern Obj_Entry *map_object(int, const char *, const struct stat *);
170extern void *xcalloc(size_t);
171extern void *xmalloc(size_t);
172extern char *xstrdup(const char *);
173extern Elf_Addr _GLOBAL_OFFSET_TABLE_[];
174
175/*
176 * Function declarations.
177 */
178int do_copy_relocations(Obj_Entry *);
179unsigned long elf_hash(const char *);
180const Elf_Sym *find_symdef(unsigned long, Obj_Entry *, const Obj_Entry **,
181  bool);
182void init_pltgot(Obj_Entry *);
183void lockdflt_init(LockInfo *);
184void obj_free(Obj_Entry *);
185Obj_Entry *obj_new(void);
186int reloc_non_plt(Obj_Entry *, Obj_Entry *);
187int reloc_plt(Obj_Entry *);
188int reloc_jmpslots(Obj_Entry *);
189void _rtld_bind_start(void);
190const Elf_Sym *symlook_obj(const char *, unsigned long,
191  const Obj_Entry *, bool);
192
193#endif /* } */
194