freebsd-skq/libexec/rtld-elf/rtld.h
John Polstra 44a028c369 Revamp the code that calls shared libraries' init and fini functions.
Formerly the init functions were called in the opposite of the
order in which libraries were loaded, and libraries were loaded
according to a breadth-first traversal of the dependency graph.
That ordering came from SVR4.0, and it was easy to implement but
not always sensible.

Now we do a depth-first walk over the dependency graph and call
the init functions in an order such that each shared object's needed
objects are initialized before the shared object itself.  At the
same time we build a list of finalization (fini) functions in the
opposite order, to guarantee correct C++ destructor ordering whenever
possible.  (It may not be possible if dlopen and dlclose are used
in strange ways, but we come as close as one can come.)

The need for this renovation has become apparent as more programs
have started using multithreading.  The multithreaded C library
libc_r requires initialization, whereas the standard libc does not.
Since virtually every other object depends on the C library, it is
important that it get initialized first.
2000-07-26 04:24:40 +00:00

194 lines
7.2 KiB
C

/*-
* Copyright 1996, 1997, 1998, 1999, 2000 John D. Polstra.
* All rights reserved.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
*
* $FreeBSD$
*/
#ifndef RTLD_H /* { */
#define RTLD_H 1
#include <sys/types.h>
#include <sys/queue.h>
#include <link.h>
#include <elf.h>
#include <stddef.h>
#include "rtld_machdep.h"
#ifndef STANDARD_LIBRARY_PATH
#define STANDARD_LIBRARY_PATH "/usr/lib/elf:/usr/lib"
#endif
#define NEW(type) ((type *) xmalloc(sizeof(type)))
#define CNEW(type) ((type *) xcalloc(sizeof(type)))
/* We might as well do booleans like C++. */
typedef unsigned char bool;
#define false 0
#define true 1
struct stat;
struct Struct_Obj_Entry;
/* Lists of shared objects */
typedef struct Struct_Objlist_Entry {
STAILQ_ENTRY(Struct_Objlist_Entry) link;
struct Struct_Obj_Entry *obj;
} Objlist_Entry;
typedef STAILQ_HEAD(Struct_Objlist, Struct_Objlist_Entry) Objlist;
/* Types of init and fini functions */
typedef void (*InitFunc)(void);
/* Lists of shared object dependencies */
typedef struct Struct_Needed_Entry {
struct Struct_Needed_Entry *next;
struct Struct_Obj_Entry *obj;
unsigned long name; /* Offset of name in string table */
} Needed_Entry;
/* Lock object */
typedef struct Struct_LockInfo {
void *context; /* Client context for creating locks */
void *thelock; /* The one big lock */
/* Debugging aids. */
volatile int rcount; /* Number of readers holding lock */
volatile int wcount; /* Number of writers holding lock */
/* Methods */
void *(*lock_create)(void *context);
void (*rlock_acquire)(void *lock);
void (*wlock_acquire)(void *lock);
void (*rlock_release)(void *lock);
void (*wlock_release)(void *lock);
void (*lock_destroy)(void *lock);
void (*context_destroy)(void *context);
} LockInfo;
/*
* Shared object descriptor.
*
* Items marked with "(%)" are dynamically allocated, and must be freed
* when the structure is destroyed.
*
* CAUTION: It appears that the JDK port peeks into these structures.
* It looks at "next" and "mapbase" at least. Don't add new members
* near the front, until this can be straightened out.
*/
typedef struct Struct_Obj_Entry {
/*
* These two items have to be set right for compatibility with the
* original ElfKit crt1.o.
*/
Elf_Word magic; /* Magic number (sanity check) */
Elf_Word version; /* Version number of struct format */
struct Struct_Obj_Entry *next;
char *path; /* Pathname of underlying file (%) */
int refcount;
int dl_refcount; /* Number of times loaded by dlopen */
/* These items are computed by map_object() or by digest_phdr(). */
caddr_t mapbase; /* Base address of mapped region */
size_t mapsize; /* Size of mapped region in bytes */
size_t textsize; /* Size of text segment in bytes */
Elf_Addr vaddrbase; /* Base address in shared object file */
caddr_t relocbase; /* Relocation constant = mapbase - vaddrbase */
const Elf_Dyn *dynamic; /* Dynamic section */
caddr_t entry; /* Entry point */
const Elf_Phdr *phdr; /* Program header if it is mapped, else NULL */
size_t phsize; /* Size of program header in bytes */
const char *interp; /* Pathname of the interpreter, if any */
/* Items from the dynamic section. */
Elf_Addr *pltgot; /* PLT or GOT, depending on architecture */
const Elf_Rel *rel; /* Relocation entries */
unsigned long relsize; /* Size in bytes of relocation info */
const Elf_Rela *rela; /* Relocation entries with addend */
unsigned long relasize; /* Size in bytes of addend relocation info */
const Elf_Rel *pltrel; /* PLT relocation entries */
unsigned long pltrelsize; /* Size in bytes of PLT relocation info */
const Elf_Rela *pltrela; /* PLT relocation entries with addend */
unsigned long pltrelasize; /* Size in bytes of PLT addend reloc info */
const Elf_Sym *symtab; /* Symbol table */
const char *strtab; /* String table */
unsigned long strsize; /* Size in bytes of string table */
const Elf_Addr *buckets; /* Hash table buckets array */
unsigned long nbuckets; /* Number of buckets */
const Elf_Addr *chains; /* Hash table chain array */
unsigned long nchains; /* Number of chains */
const char *rpath; /* Search path specified in object */
Needed_Entry *needed; /* Shared objects needed by this one (%) */
InitFunc init; /* Initialization function to call */
InitFunc fini; /* Termination function to call */
bool mainprog; /* True if this is the main program */
bool rtld; /* True if this is the dynamic linker */
bool textrel; /* True if there are relocations to text seg */
bool symbolic; /* True if generated with "-Bsymbolic" */
bool traced; /* Already printed in ldd trace output */
bool jmpslots_done; /* Already have relocated the jump slots */
bool init_done; /* Already have added object to init list */
struct link_map linkmap; /* for GDB */
Objlist dldags; /* Object belongs to these dlopened DAGs (%) */
Objlist dagmembers; /* DAG has these members (%) */
dev_t dev; /* Object's filesystem's device */
ino_t ino; /* Object's inode number */
} Obj_Entry;
#define RTLD_MAGIC 0xd550b87a
#define RTLD_VERSION 1
extern void _rtld_error(const char *, ...) __printflike(1, 2);
extern Obj_Entry *map_object(int, const char *, const struct stat *);
extern void *xcalloc(size_t);
extern void *xmalloc(size_t);
extern char *xstrdup(const char *);
extern Elf_Addr _GLOBAL_OFFSET_TABLE_[];
/*
* Function declarations.
*/
int do_copy_relocations(Obj_Entry *);
unsigned long elf_hash(const char *);
const Elf_Sym *find_symdef(unsigned long, Obj_Entry *, const Obj_Entry **,
bool);
void init_pltgot(Obj_Entry *);
void lockdflt_init(LockInfo *);
void obj_free(Obj_Entry *);
Obj_Entry *obj_new(void);
int reloc_non_plt(Obj_Entry *, Obj_Entry *);
int reloc_plt(Obj_Entry *);
int reloc_jmpslots(Obj_Entry *);
void _rtld_bind_start(void);
const Elf_Sym *symlook_obj(const char *, unsigned long,
const Obj_Entry *, bool);
#endif /* } */