rtld.h revision 55687 
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 55687 2000-01-09 21:13:48Z 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/* Lists of init or fini functions */
64typedef void (*InitFunc)(void);
65
66typedef struct Struct_Funclist_Entry {
67    STAILQ_ENTRY(Struct_Funclist_Entry) link;
68    InitFunc func;
69} Funclist_Entry;
70
71typedef STAILQ_HEAD(Struct_Funclist, Struct_Funclist_Entry) Funclist;
72
73/* Lists of shared object dependencies */
74typedef struct Struct_Needed_Entry {
75    struct Struct_Needed_Entry *next;
76    struct Struct_Obj_Entry *obj;
77    unsigned long name;		/* Offset of name in string table */
78} Needed_Entry;
79
80/*
81 * Shared object descriptor.
82 *
83 * Items marked with "(%)" are dynamically allocated, and must be freed
84 * when the structure is destroyed.
85 *
86 * CAUTION: It appears that the JDK port peeks into these structures.
87 * It looks at "next" and "mapbase" at least.  Don't add new members
88 * near the front, until this can be straightened out.
89 */
90typedef struct Struct_Obj_Entry {
91    /*
92     * These two items have to be set right for compatibility with the
93     * original ElfKit crt1.o.
94     */
95    Elf_Word magic;		/* Magic number (sanity check) */
96    Elf_Word version;		/* Version number of struct format */
97
98    struct Struct_Obj_Entry *next;
99    char *path;			/* Pathname of underlying file (%) */
100    int refcount;
101    int dl_refcount;		/* Number of times loaded by dlopen */
102
103    /* These items are computed by map_object() or by digest_phdr(). */
104    caddr_t mapbase;		/* Base address of mapped region */
105    size_t mapsize;		/* Size of mapped region in bytes */
106    size_t textsize;		/* Size of text segment in bytes */
107    Elf_Addr vaddrbase;		/* Base address in shared object file */
108    caddr_t relocbase;		/* Relocation constant = mapbase - vaddrbase */
109    const Elf_Dyn *dynamic;	/* Dynamic section */
110    caddr_t entry;		/* Entry point */
111    const Elf_Phdr *phdr;	/* Program header if it is mapped, else NULL */
112    size_t phsize;		/* Size of program header in bytes */
113    const char *interp;		/* Pathname of the interpreter, if any */
114
115    /* Items from the dynamic section. */
116    Elf_Addr *pltgot;		/* PLT or GOT, depending on architecture */
117    const Elf_Rel *rel;		/* Relocation entries */
118    unsigned long relsize;	/* Size in bytes of relocation info */
119    const Elf_Rela *rela;	/* Relocation entries with addend */
120    unsigned long relasize;	/* Size in bytes of addend relocation info */
121    const Elf_Rel *pltrel;	/* PLT relocation entries */
122    unsigned long pltrelsize;	/* Size in bytes of PLT relocation info */
123    const Elf_Rela *pltrela;	/* PLT relocation entries with addend */
124    unsigned long pltrelasize;	/* Size in bytes of PLT addend reloc info */
125    const Elf_Sym *symtab;	/* Symbol table */
126    const char *strtab;		/* String table */
127    unsigned long strsize;	/* Size in bytes of string table */
128
129    const Elf_Addr *buckets;	/* Hash table buckets array */
130    unsigned long nbuckets;	/* Number of buckets */
131    const Elf_Addr *chains;	/* Hash table chain array */
132    unsigned long nchains;	/* Number of chains */
133
134    const char *rpath;		/* Search path specified in object */
135    Needed_Entry *needed;	/* Shared objects needed by this one (%) */
136
137    InitFunc init;		/* Initialization function to call */
138    InitFunc fini;		/* Termination function to call */
139
140    bool mainprog;		/* True if this is the main program */
141    bool rtld;			/* True if this is the dynamic linker */
142    bool textrel;		/* True if there are relocations to text seg */
143    bool symbolic;		/* True if generated with "-Bsymbolic" */
144    bool traced;		/* Already printed in ldd trace output */
145
146    struct link_map linkmap;	/* for GDB */
147    Objlist dldags;		/* Object belongs to these dlopened DAGs (%) */
148    Objlist dagmembers;		/* DAG has these members (%) */
149    dev_t dev;			/* Object's filesystem's device */
150    ino_t ino;			/* Object's inode number */
151    unsigned long mark;		/* Set to "curmark" to avoid repeat visits */
152} Obj_Entry;
153
154#define RTLD_MAGIC	0xd550b87a
155#define RTLD_VERSION	1
156
157extern void _rtld_error(const char *, ...) __printflike(1, 2);
158extern Obj_Entry *map_object(int, const char *, const struct stat *);
159extern void *xcalloc(size_t);
160extern void *xmalloc(size_t);
161extern char *xstrdup(const char *);
162extern Elf_Addr _GLOBAL_OFFSET_TABLE_[];
163
164/*
165 * Function declarations.
166 */
167int do_copy_relocations(Obj_Entry *);
168unsigned long elf_hash(const char *);
169const Elf_Sym *find_symdef(unsigned long, Obj_Entry *, const Obj_Entry **,
170  bool);
171void init_pltgot(Obj_Entry *);
172void lockdflt_acquire(void *);
173void *lockdflt_create(void *);
174void lockdflt_destroy(void *);
175void lockdflt_release(void *);
176void obj_free(Obj_Entry *);
177Obj_Entry *obj_new(void);
178int reloc_non_plt(Obj_Entry *, Obj_Entry *);
179int reloc_plt(Obj_Entry *, bool);
180void _rtld_bind_start(void);
181const Elf_Sym *symlook_obj(const char *, unsigned long,
182  const Obj_Entry *, bool);
183
184#endif /* } */
185