5353bfc3b4
_init() functions, initialize the global variables "__progname" and "environ". This makes it possible for the _init() functions to call things like getenv() and err().
1547 lines
38 KiB
C
1547 lines
38 KiB
C
/*-
|
|
* Copyright 1996-1998 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.
|
|
*
|
|
* $Id: rtld.c,v 1.21 1999/04/09 06:42:00 jdp Exp $
|
|
*/
|
|
|
|
/*
|
|
* Dynamic linker for ELF.
|
|
*
|
|
* John Polstra <jdp@polstra.com>.
|
|
*/
|
|
|
|
#ifndef __GNUC__
|
|
#error "GCC is needed to compile this file"
|
|
#endif
|
|
|
|
#include <sys/param.h>
|
|
#include <sys/mman.h>
|
|
|
|
#include <dlfcn.h>
|
|
#include <err.h>
|
|
#include <errno.h>
|
|
#include <fcntl.h>
|
|
#include <stdarg.h>
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include <unistd.h>
|
|
|
|
#include "debug.h"
|
|
#include "rtld.h"
|
|
|
|
/*
|
|
* Version number queried by dlversion(). The first 3 digits represent
|
|
* the base FreeBSD release. The last 3 digits are a serial number.
|
|
* Increase this when you fix a significant bug or add a significant
|
|
* feature.
|
|
*/
|
|
#define DL_VERSION 400001
|
|
|
|
/*
|
|
* Debugging support.
|
|
*/
|
|
|
|
#define assert(cond) ((cond) ? (void) 0 :\
|
|
(msg("oops: " __XSTRING(__LINE__) "\n"), abort()))
|
|
#define msg(s) (write(1, s, strlen(s)))
|
|
#define trace() msg("trace: " __XSTRING(__LINE__) "\n");
|
|
|
|
#define END_SYM "end"
|
|
|
|
/* Types. */
|
|
typedef void (*func_ptr_type)();
|
|
|
|
/*
|
|
* Function declarations.
|
|
*/
|
|
static const char *basename(const char *);
|
|
static void call_fini_functions(Obj_Entry *);
|
|
static void call_init_functions(Obj_Entry *);
|
|
static void die(void);
|
|
static void digest_dynamic(Obj_Entry *);
|
|
static Obj_Entry *digest_phdr(const Elf_Phdr *, int, caddr_t);
|
|
static Obj_Entry *dlcheck(void *);
|
|
static char *find_library(const char *, const Obj_Entry *);
|
|
static const char *gethints(void);
|
|
static void init_rtld(caddr_t);
|
|
static bool is_exported(const Elf_Sym *);
|
|
static void linkmap_add(Obj_Entry *);
|
|
static void linkmap_delete(Obj_Entry *);
|
|
static int load_needed_objects(Obj_Entry *);
|
|
static int load_preload_objects(void);
|
|
static Obj_Entry *load_object(char *);
|
|
static Obj_Entry *obj_from_addr(const void *);
|
|
static int relocate_objects(Obj_Entry *, bool);
|
|
static void rtld_exit(void);
|
|
static char *search_library_path(const char *, const char *);
|
|
static void set_program_var(const char *, const void *);
|
|
static void unref_object_dag(Obj_Entry *);
|
|
static void trace_loaded_objects(Obj_Entry *obj);
|
|
|
|
void r_debug_state(void);
|
|
void xprintf(const char *, ...);
|
|
|
|
/*
|
|
* Data declarations.
|
|
*/
|
|
static char *error_message; /* Message for dlerror(), or NULL */
|
|
struct r_debug r_debug; /* for GDB; */
|
|
static bool trust; /* False for setuid and setgid programs */
|
|
static char *ld_bind_now; /* Environment variable for immediate binding */
|
|
static char *ld_debug; /* Environment variable for debugging */
|
|
static char *ld_library_path; /* Environment variable for search path */
|
|
static char *ld_preload; /* Environment variable for libraries to
|
|
load first */
|
|
static char *ld_tracing; /* Called from ldd to print libs */
|
|
static Obj_Entry **main_tail; /* Value of obj_tail after loading main and
|
|
its needed shared libraries */
|
|
static Obj_Entry *obj_list; /* Head of linked list of shared objects */
|
|
static Obj_Entry **obj_tail; /* Link field of last object in list */
|
|
static Obj_Entry *obj_main; /* The main program shared object */
|
|
static Obj_Entry obj_rtld; /* The dynamic linker shared object */
|
|
|
|
static Elf_Sym sym_zero; /* For resolving undefined weak refs. */
|
|
|
|
#define GDB_STATE(s) r_debug.r_state = s; r_debug_state();
|
|
|
|
extern Elf_Dyn _DYNAMIC;
|
|
#pragma weak _DYNAMIC
|
|
|
|
/*
|
|
* These are the functions the dynamic linker exports to application
|
|
* programs. They are the only symbols the dynamic linker is willing
|
|
* to export from itself.
|
|
*/
|
|
static func_ptr_type exports[] = {
|
|
(func_ptr_type) &_rtld_error,
|
|
(func_ptr_type) &dlclose,
|
|
(func_ptr_type) &dlerror,
|
|
(func_ptr_type) &dlopen,
|
|
(func_ptr_type) &dlsym,
|
|
(func_ptr_type) &dladdr,
|
|
(func_ptr_type) &dlversion,
|
|
NULL
|
|
};
|
|
|
|
/*
|
|
* Global declarations normally provided by crt1. The dynamic linker is
|
|
* not build with crt1, so we have to provide them ourselves.
|
|
*/
|
|
char *__progname;
|
|
char **environ;
|
|
|
|
/*
|
|
* Main entry point for dynamic linking. The first argument is the
|
|
* stack pointer. The stack is expected to be laid out as described
|
|
* in the SVR4 ABI specification, Intel 386 Processor Supplement.
|
|
* Specifically, the stack pointer points to a word containing
|
|
* ARGC. Following that in the stack is a null-terminated sequence
|
|
* of pointers to argument strings. Then comes a null-terminated
|
|
* sequence of pointers to environment strings. Finally, there is a
|
|
* sequence of "auxiliary vector" entries.
|
|
*
|
|
* The second argument points to a place to store the dynamic linker's
|
|
* exit procedure pointer and the third to a place to store the main
|
|
* program's object.
|
|
*
|
|
* The return value is the main program's entry point.
|
|
*/
|
|
func_ptr_type
|
|
_rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp)
|
|
{
|
|
Elf_Auxinfo *aux_info[AT_COUNT];
|
|
int i;
|
|
int argc;
|
|
char **argv;
|
|
char **env;
|
|
Elf_Auxinfo *aux;
|
|
Elf_Auxinfo *auxp;
|
|
|
|
/*
|
|
* On entry, the dynamic linker itself has not been relocated yet.
|
|
* Be very careful not to reference any global data until after
|
|
* init_rtld has returned. It is OK to reference file-scope statics
|
|
* and string constants, and to call static and global functions.
|
|
*/
|
|
|
|
/* Find the auxiliary vector on the stack. */
|
|
argc = *sp++;
|
|
argv = (char **) sp;
|
|
sp += argc + 1; /* Skip over arguments and NULL terminator */
|
|
env = (char **) sp;
|
|
while (*sp++ != 0) /* Skip over environment, and NULL terminator */
|
|
;
|
|
aux = (Elf_Auxinfo *) sp;
|
|
|
|
/* Digest the auxiliary vector. */
|
|
for (i = 0; i < AT_COUNT; i++)
|
|
aux_info[i] = NULL;
|
|
for (auxp = aux; auxp->a_type != AT_NULL; auxp++) {
|
|
if (auxp->a_type < AT_COUNT)
|
|
aux_info[auxp->a_type] = auxp;
|
|
}
|
|
|
|
/* Initialize and relocate ourselves. */
|
|
assert(aux_info[AT_BASE] != NULL);
|
|
init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr);
|
|
|
|
__progname = obj_rtld.path;
|
|
environ = env;
|
|
|
|
trust = geteuid() == getuid() && getegid() == getgid();
|
|
|
|
ld_bind_now = getenv("LD_BIND_NOW");
|
|
if (trust) {
|
|
ld_debug = getenv("LD_DEBUG");
|
|
ld_library_path = getenv("LD_LIBRARY_PATH");
|
|
ld_preload = getenv("LD_PRELOAD");
|
|
}
|
|
ld_tracing = getenv("LD_TRACE_LOADED_OBJECTS");
|
|
|
|
if (ld_debug != NULL && *ld_debug != '\0')
|
|
debug = 1;
|
|
dbg("%s is initialized, base address = %p", __progname,
|
|
(caddr_t) aux_info[AT_BASE]->a_un.a_ptr);
|
|
dbg("RTLD dynamic = %p", obj_rtld.dynamic);
|
|
dbg("RTLD pltgot = %p", obj_rtld.pltgot);
|
|
|
|
/*
|
|
* Load the main program, or process its program header if it is
|
|
* already loaded.
|
|
*/
|
|
if (aux_info[AT_EXECFD] != NULL) { /* Load the main program. */
|
|
int fd = aux_info[AT_EXECFD]->a_un.a_val;
|
|
dbg("loading main program");
|
|
obj_main = map_object(fd);
|
|
close(fd);
|
|
if (obj_main == NULL)
|
|
die();
|
|
} else { /* Main program already loaded. */
|
|
const Elf_Phdr *phdr;
|
|
int phnum;
|
|
caddr_t entry;
|
|
|
|
dbg("processing main program's program header");
|
|
assert(aux_info[AT_PHDR] != NULL);
|
|
phdr = (const Elf_Phdr *) aux_info[AT_PHDR]->a_un.a_ptr;
|
|
assert(aux_info[AT_PHNUM] != NULL);
|
|
phnum = aux_info[AT_PHNUM]->a_un.a_val;
|
|
assert(aux_info[AT_PHENT] != NULL);
|
|
assert(aux_info[AT_PHENT]->a_un.a_val == sizeof(Elf_Phdr));
|
|
assert(aux_info[AT_ENTRY] != NULL);
|
|
entry = (caddr_t) aux_info[AT_ENTRY]->a_un.a_ptr;
|
|
obj_main = digest_phdr(phdr, phnum, entry);
|
|
}
|
|
|
|
obj_main->path = xstrdup(argv[0] ? argv[0] : "(null)");
|
|
obj_main->mainprog = true;
|
|
digest_dynamic(obj_main);
|
|
|
|
linkmap_add(obj_main);
|
|
linkmap_add(&obj_rtld);
|
|
|
|
/* Link the main program into the list of objects. */
|
|
*obj_tail = obj_main;
|
|
obj_tail = &obj_main->next;
|
|
obj_main->refcount++;
|
|
|
|
/* Initialize a fake symbol for resolving undefined weak references. */
|
|
sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE);
|
|
sym_zero.st_shndx = SHN_ABS;
|
|
|
|
dbg("loading LD_PRELOAD libraries");
|
|
if (load_preload_objects() == -1)
|
|
die();
|
|
|
|
dbg("loading needed objects");
|
|
if (load_needed_objects(obj_main) == -1)
|
|
die();
|
|
main_tail = obj_tail;
|
|
|
|
if (ld_tracing) { /* We're done */
|
|
trace_loaded_objects(obj_main);
|
|
exit(0);
|
|
}
|
|
|
|
dbg("relocating objects");
|
|
if (relocate_objects(obj_main,
|
|
ld_bind_now != NULL && *ld_bind_now != '\0') == -1)
|
|
die();
|
|
|
|
dbg("doing copy relocations");
|
|
if (do_copy_relocations(obj_main) == -1)
|
|
die();
|
|
|
|
dbg("initializing key program variables");
|
|
set_program_var("__progname", argv[0] != NULL ? basename(argv[0]) : "");
|
|
set_program_var("environ", env);
|
|
|
|
dbg("calling _init functions");
|
|
call_init_functions(obj_main->next);
|
|
|
|
dbg("transferring control to program entry point = %p", obj_main->entry);
|
|
|
|
r_debug_state(); /* say hello to gdb! */
|
|
|
|
/* Return the exit procedure and the program entry point. */
|
|
*exit_proc = rtld_exit;
|
|
*objp = obj_main;
|
|
return (func_ptr_type) obj_main->entry;
|
|
}
|
|
|
|
caddr_t
|
|
_rtld_bind(const Obj_Entry *obj, Elf_Word reloff)
|
|
{
|
|
const Elf_Rel *rel;
|
|
const Elf_Sym *def;
|
|
const Obj_Entry *defobj;
|
|
Elf_Addr *where;
|
|
caddr_t target;
|
|
|
|
if (obj->pltrel)
|
|
rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff);
|
|
else
|
|
rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff);
|
|
|
|
where = (Elf_Addr *) (obj->relocbase + rel->r_offset);
|
|
def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true);
|
|
if (def == NULL)
|
|
die();
|
|
|
|
target = (caddr_t) (defobj->relocbase + def->st_value);
|
|
|
|
dbg("\"%s\" in \"%s\" ==> %p in \"%s\"",
|
|
defobj->strtab + def->st_name, basename(obj->path),
|
|
target, basename(defobj->path));
|
|
|
|
*where = (Elf_Addr) target;
|
|
return target;
|
|
}
|
|
|
|
/*
|
|
* Error reporting function. Use it like printf. If formats the message
|
|
* into a buffer, and sets things up so that the next call to dlerror()
|
|
* will return the message.
|
|
*/
|
|
void
|
|
_rtld_error(const char *fmt, ...)
|
|
{
|
|
static char buf[512];
|
|
va_list ap;
|
|
|
|
va_start(ap, fmt);
|
|
vsnprintf(buf, sizeof buf, fmt, ap);
|
|
error_message = buf;
|
|
va_end(ap);
|
|
}
|
|
|
|
static const char *
|
|
basename(const char *name)
|
|
{
|
|
const char *p = strrchr(name, '/');
|
|
return p != NULL ? p + 1 : name;
|
|
}
|
|
|
|
static void
|
|
call_fini_functions(Obj_Entry *first)
|
|
{
|
|
Obj_Entry *obj;
|
|
|
|
for (obj = first; obj != NULL; obj = obj->next)
|
|
if (obj->fini != NULL)
|
|
(*obj->fini)();
|
|
}
|
|
|
|
static void
|
|
call_init_functions(Obj_Entry *first)
|
|
{
|
|
if (first != NULL) {
|
|
call_init_functions(first->next);
|
|
if (first->init != NULL)
|
|
(*first->init)();
|
|
}
|
|
}
|
|
|
|
static void
|
|
die(void)
|
|
{
|
|
const char *msg = dlerror();
|
|
|
|
if (msg == NULL)
|
|
msg = "Fatal error";
|
|
errx(1, "%s", msg);
|
|
}
|
|
|
|
/*
|
|
* Process a shared object's DYNAMIC section, and save the important
|
|
* information in its Obj_Entry structure.
|
|
*/
|
|
static void
|
|
digest_dynamic(Obj_Entry *obj)
|
|
{
|
|
const Elf_Dyn *dynp;
|
|
Needed_Entry **needed_tail = &obj->needed;
|
|
const Elf_Dyn *dyn_rpath = NULL;
|
|
int plttype = DT_REL;
|
|
|
|
for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) {
|
|
switch (dynp->d_tag) {
|
|
|
|
case DT_REL:
|
|
obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr);
|
|
break;
|
|
|
|
case DT_RELSZ:
|
|
obj->relsize = dynp->d_un.d_val;
|
|
break;
|
|
|
|
case DT_RELENT:
|
|
assert(dynp->d_un.d_val == sizeof(Elf_Rel));
|
|
break;
|
|
|
|
case DT_JMPREL:
|
|
obj->pltrel = (const Elf_Rel *)
|
|
(obj->relocbase + dynp->d_un.d_ptr);
|
|
break;
|
|
|
|
case DT_PLTRELSZ:
|
|
obj->pltrelsize = dynp->d_un.d_val;
|
|
break;
|
|
|
|
case DT_RELA:
|
|
obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr);
|
|
break;
|
|
|
|
case DT_RELASZ:
|
|
obj->relasize = dynp->d_un.d_val;
|
|
break;
|
|
|
|
case DT_RELAENT:
|
|
assert(dynp->d_un.d_val == sizeof(Elf_Rela));
|
|
break;
|
|
|
|
case DT_PLTREL:
|
|
plttype = dynp->d_un.d_val;
|
|
assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA);
|
|
break;
|
|
|
|
case DT_SYMTAB:
|
|
obj->symtab = (const Elf_Sym *)
|
|
(obj->relocbase + dynp->d_un.d_ptr);
|
|
break;
|
|
|
|
case DT_SYMENT:
|
|
assert(dynp->d_un.d_val == sizeof(Elf_Sym));
|
|
break;
|
|
|
|
case DT_STRTAB:
|
|
obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr);
|
|
break;
|
|
|
|
case DT_STRSZ:
|
|
obj->strsize = dynp->d_un.d_val;
|
|
break;
|
|
|
|
case DT_HASH:
|
|
{
|
|
const Elf_Addr *hashtab = (const Elf_Addr *)
|
|
(obj->relocbase + dynp->d_un.d_ptr);
|
|
obj->nbuckets = hashtab[0];
|
|
obj->nchains = hashtab[1];
|
|
obj->buckets = hashtab + 2;
|
|
obj->chains = obj->buckets + obj->nbuckets;
|
|
}
|
|
break;
|
|
|
|
case DT_NEEDED:
|
|
if (!obj->rtld) {
|
|
Needed_Entry *nep = NEW(Needed_Entry);
|
|
nep->name = dynp->d_un.d_val;
|
|
nep->obj = NULL;
|
|
nep->next = NULL;
|
|
|
|
*needed_tail = nep;
|
|
needed_tail = &nep->next;
|
|
}
|
|
break;
|
|
|
|
case DT_PLTGOT:
|
|
obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr);
|
|
break;
|
|
|
|
case DT_TEXTREL:
|
|
obj->textrel = true;
|
|
break;
|
|
|
|
case DT_SYMBOLIC:
|
|
obj->symbolic = true;
|
|
break;
|
|
|
|
case DT_RPATH:
|
|
/*
|
|
* We have to wait until later to process this, because we
|
|
* might not have gotten the address of the string table yet.
|
|
*/
|
|
dyn_rpath = dynp;
|
|
break;
|
|
|
|
case DT_SONAME:
|
|
/* Not used by the dynamic linker. */
|
|
break;
|
|
|
|
case DT_INIT:
|
|
obj->init = (void (*)(void)) (obj->relocbase + dynp->d_un.d_ptr);
|
|
break;
|
|
|
|
case DT_FINI:
|
|
obj->fini = (void (*)(void)) (obj->relocbase + dynp->d_un.d_ptr);
|
|
break;
|
|
|
|
case DT_DEBUG:
|
|
/* XXX - not implemented yet */
|
|
dbg("Filling in DT_DEBUG entry");
|
|
((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug;
|
|
break;
|
|
|
|
default:
|
|
xprintf("Ignored d_tag %d\n",dynp->d_tag);
|
|
break;
|
|
}
|
|
}
|
|
|
|
obj->traced = false;
|
|
|
|
if (plttype == DT_RELA) {
|
|
obj->pltrela = (const Elf_Rela *) obj->pltrel;
|
|
obj->pltrel = NULL;
|
|
obj->pltrelasize = obj->pltrelsize;
|
|
obj->pltrelsize = 0;
|
|
}
|
|
|
|
if (dyn_rpath != NULL)
|
|
obj->rpath = obj->strtab + dyn_rpath->d_un.d_val;
|
|
}
|
|
|
|
/*
|
|
* Process a shared object's program header. This is used only for the
|
|
* main program, when the kernel has already loaded the main program
|
|
* into memory before calling the dynamic linker. It creates and
|
|
* returns an Obj_Entry structure.
|
|
*/
|
|
static Obj_Entry *
|
|
digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry)
|
|
{
|
|
Obj_Entry *obj = CNEW(Obj_Entry);
|
|
const Elf_Phdr *phlimit = phdr + phnum;
|
|
const Elf_Phdr *ph;
|
|
int nsegs = 0;
|
|
|
|
for (ph = phdr; ph < phlimit; ph++) {
|
|
switch (ph->p_type) {
|
|
|
|
case PT_PHDR:
|
|
assert((const Elf_Phdr *) ph->p_vaddr == phdr);
|
|
obj->phdr = (const Elf_Phdr *) ph->p_vaddr;
|
|
obj->phsize = ph->p_memsz;
|
|
break;
|
|
|
|
case PT_LOAD:
|
|
assert(nsegs < 2);
|
|
if (nsegs == 0) { /* First load segment */
|
|
obj->vaddrbase = trunc_page(ph->p_vaddr);
|
|
obj->mapbase = (caddr_t) obj->vaddrbase;
|
|
obj->relocbase = obj->mapbase - obj->vaddrbase;
|
|
obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) -
|
|
obj->vaddrbase;
|
|
} else { /* Last load segment */
|
|
obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) -
|
|
obj->vaddrbase;
|
|
}
|
|
nsegs++;
|
|
break;
|
|
|
|
case PT_DYNAMIC:
|
|
obj->dynamic = (const Elf_Dyn *) ph->p_vaddr;
|
|
break;
|
|
}
|
|
}
|
|
assert(nsegs == 2);
|
|
|
|
obj->entry = entry;
|
|
return obj;
|
|
}
|
|
|
|
static Obj_Entry *
|
|
dlcheck(void *handle)
|
|
{
|
|
Obj_Entry *obj;
|
|
|
|
for (obj = obj_list; obj != NULL; obj = obj->next)
|
|
if (obj == (Obj_Entry *) handle)
|
|
break;
|
|
|
|
if (obj == NULL || obj->dl_refcount == 0) {
|
|
_rtld_error("Invalid shared object handle %p", handle);
|
|
return NULL;
|
|
}
|
|
return obj;
|
|
}
|
|
|
|
/*
|
|
* Hash function for symbol table lookup. Don't even think about changing
|
|
* this. It is specified by the System V ABI.
|
|
*/
|
|
unsigned long
|
|
elf_hash(const char *name)
|
|
{
|
|
const unsigned char *p = (const unsigned char *) name;
|
|
unsigned long h = 0;
|
|
unsigned long g;
|
|
|
|
while (*p != '\0') {
|
|
h = (h << 4) + *p++;
|
|
if ((g = h & 0xf0000000) != 0)
|
|
h ^= g >> 24;
|
|
h &= ~g;
|
|
}
|
|
return h;
|
|
}
|
|
|
|
/*
|
|
* Find the library with the given name, and return its full pathname.
|
|
* The returned string is dynamically allocated. Generates an error
|
|
* message and returns NULL if the library cannot be found.
|
|
*
|
|
* If the second argument is non-NULL, then it refers to an already-
|
|
* loaded shared object, whose library search path will be searched.
|
|
*
|
|
* The search order is:
|
|
* LD_LIBRARY_PATH
|
|
* ldconfig hints
|
|
* rpath in the referencing file
|
|
* /usr/lib
|
|
*/
|
|
static char *
|
|
find_library(const char *name, const Obj_Entry *refobj)
|
|
{
|
|
char *pathname;
|
|
|
|
if (strchr(name, '/') != NULL) { /* Hard coded pathname */
|
|
if (name[0] != '/' && !trust) {
|
|
_rtld_error("Absolute pathname required for shared object \"%s\"",
|
|
name);
|
|
return NULL;
|
|
}
|
|
return xstrdup(name);
|
|
}
|
|
|
|
dbg(" Searching for \"%s\"", name);
|
|
|
|
if ((refobj != NULL &&
|
|
(pathname = search_library_path(name, refobj->rpath)) != NULL) ||
|
|
(pathname = search_library_path(name, ld_library_path)) != NULL ||
|
|
(pathname = search_library_path(name, gethints())) != NULL ||
|
|
(pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL)
|
|
return pathname;
|
|
|
|
_rtld_error("Shared object \"%s\" not found", name);
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Given a symbol number in a referencing object, find the corresponding
|
|
* definition of the symbol. Returns a pointer to the symbol, or NULL if
|
|
* no definition was found. Returns a pointer to the Obj_Entry of the
|
|
* defining object via the reference parameter DEFOBJ_OUT.
|
|
*/
|
|
const Elf_Sym *
|
|
find_symdef(unsigned long symnum, const Obj_Entry *refobj,
|
|
const Obj_Entry **defobj_out, bool in_plt)
|
|
{
|
|
const Elf_Sym *ref;
|
|
const Elf_Sym *strongdef;
|
|
const Elf_Sym *weakdef;
|
|
const Obj_Entry *obj;
|
|
const Obj_Entry *strongobj;
|
|
const Obj_Entry *weakobj;
|
|
const char *name;
|
|
unsigned long hash;
|
|
|
|
ref = refobj->symtab + symnum;
|
|
name = refobj->strtab + ref->st_name;
|
|
hash = elf_hash(name);
|
|
|
|
if (refobj->symbolic) { /* Look first in the referencing object */
|
|
const Elf_Sym *def = symlook_obj(name, hash, refobj, in_plt);
|
|
if (def != NULL) {
|
|
*defobj_out = refobj;
|
|
return def;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Look in all loaded objects. Skip the referencing object, if
|
|
* we have already searched it. We keep track of the first weak
|
|
* definition and the first strong definition we encounter. If
|
|
* we find a strong definition we stop searching, because there
|
|
* won't be anything better than that.
|
|
*/
|
|
strongdef = weakdef = NULL;
|
|
strongobj = weakobj = NULL;
|
|
for (obj = obj_list; obj != NULL; obj = obj->next) {
|
|
if (obj != refobj || !refobj->symbolic) {
|
|
const Elf_Sym *def = symlook_obj(name, hash, obj, in_plt);
|
|
if (def != NULL) {
|
|
if (ELF_ST_BIND(def->st_info) == STB_WEAK) {
|
|
if (weakdef == NULL) {
|
|
weakdef = def;
|
|
weakobj = obj;
|
|
}
|
|
} else {
|
|
strongdef = def;
|
|
strongobj = obj;
|
|
break; /* We are done. */
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* If we still don't have a strong definition, search the dynamic
|
|
* linker itself, and possibly resolve the symbol from there.
|
|
* This is how the application links to dynamic linker services
|
|
* such as dlopen. Only the values listed in the "exports" array
|
|
* can be resolved from the dynamic linker.
|
|
*/
|
|
if (strongdef == NULL) {
|
|
const Elf_Sym *def = symlook_obj(name, hash, &obj_rtld, in_plt);
|
|
if (def != NULL && is_exported(def)) {
|
|
if (ELF_ST_BIND(def->st_info) == STB_WEAK) {
|
|
if (weakdef == NULL) {
|
|
weakdef = def;
|
|
weakobj = &obj_rtld;
|
|
}
|
|
} else {
|
|
strongdef = def;
|
|
strongobj = &obj_rtld;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (strongdef != NULL) {
|
|
*defobj_out = strongobj;
|
|
return strongdef;
|
|
}
|
|
if (weakdef != NULL) {
|
|
*defobj_out = weakobj;
|
|
return weakdef;
|
|
}
|
|
|
|
if (ELF_ST_BIND(ref->st_info) == STB_WEAK) {
|
|
*defobj_out = obj_main;
|
|
return &sym_zero;
|
|
}
|
|
|
|
_rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name);
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Return the search path from the ldconfig hints file, reading it if
|
|
* necessary. Returns NULL if there are problems with the hints file,
|
|
* or if the search path there is empty.
|
|
*/
|
|
static const char *
|
|
gethints(void)
|
|
{
|
|
static char *hints;
|
|
|
|
if (hints == NULL) {
|
|
int fd;
|
|
struct elfhints_hdr hdr;
|
|
char *p;
|
|
|
|
/* Keep from trying again in case the hints file is bad. */
|
|
hints = "";
|
|
|
|
if ((fd = open(_PATH_ELF_HINTS, O_RDONLY)) == -1)
|
|
return NULL;
|
|
if (read(fd, &hdr, sizeof hdr) != sizeof hdr ||
|
|
hdr.magic != ELFHINTS_MAGIC ||
|
|
hdr.version != 1) {
|
|
close(fd);
|
|
return NULL;
|
|
}
|
|
p = xmalloc(hdr.dirlistlen + 1);
|
|
if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 ||
|
|
read(fd, p, hdr.dirlistlen + 1) != hdr.dirlistlen + 1) {
|
|
free(p);
|
|
close(fd);
|
|
return NULL;
|
|
}
|
|
hints = p;
|
|
close(fd);
|
|
}
|
|
return hints[0] != '\0' ? hints : NULL;
|
|
}
|
|
|
|
/*
|
|
* Initialize the dynamic linker. The argument is the address at which
|
|
* the dynamic linker has been mapped into memory. The primary task of
|
|
* this function is to relocate the dynamic linker.
|
|
*/
|
|
static void
|
|
init_rtld(caddr_t mapbase)
|
|
{
|
|
/*
|
|
* Conjure up an Obj_Entry structure for the dynamic linker.
|
|
*
|
|
* The "path" member is supposed to be dynamically-allocated, but we
|
|
* aren't yet initialized sufficiently to do that. Below we will
|
|
* replace the static version with a dynamically-allocated copy.
|
|
*/
|
|
obj_rtld.path = "/usr/libexec/ld-elf.so.1";
|
|
obj_rtld.rtld = true;
|
|
obj_rtld.mapbase = mapbase;
|
|
#ifdef PIC
|
|
obj_rtld.relocbase = mapbase;
|
|
#endif
|
|
if (&_DYNAMIC != 0) {
|
|
obj_rtld.dynamic = rtld_dynamic(&obj_rtld);
|
|
digest_dynamic(&obj_rtld);
|
|
assert(obj_rtld.needed == NULL);
|
|
assert(!obj_rtld.textrel);
|
|
|
|
/*
|
|
* Temporarily put the dynamic linker entry into the object list, so
|
|
* that symbols can be found.
|
|
*/
|
|
obj_list = &obj_rtld;
|
|
obj_tail = &obj_rtld.next;
|
|
|
|
relocate_objects(&obj_rtld, true);
|
|
}
|
|
|
|
/* Make the object list empty again. */
|
|
obj_list = NULL;
|
|
obj_tail = &obj_list;
|
|
|
|
/* Replace the path with a dynamically allocated copy. */
|
|
obj_rtld.path = xstrdup(obj_rtld.path);
|
|
|
|
r_debug.r_brk = r_debug_state;
|
|
r_debug.r_state = RT_CONSISTENT;
|
|
}
|
|
|
|
static bool
|
|
is_exported(const Elf_Sym *def)
|
|
{
|
|
func_ptr_type value;
|
|
const func_ptr_type *p;
|
|
|
|
value = (func_ptr_type)(obj_rtld.relocbase + def->st_value);
|
|
for (p = exports; *p != NULL; p++)
|
|
if (*p == value)
|
|
return true;
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* Given a shared object, traverse its list of needed objects, and load
|
|
* each of them. Returns 0 on success. Generates an error message and
|
|
* returns -1 on failure.
|
|
*/
|
|
static int
|
|
load_needed_objects(Obj_Entry *first)
|
|
{
|
|
Obj_Entry *obj;
|
|
|
|
for (obj = first; obj != NULL; obj = obj->next) {
|
|
Needed_Entry *needed;
|
|
|
|
for (needed = obj->needed; needed != NULL; needed = needed->next) {
|
|
const char *name = obj->strtab + needed->name;
|
|
char *path = find_library(name, obj);
|
|
|
|
needed->obj = NULL;
|
|
if (path == NULL && !ld_tracing)
|
|
return -1;
|
|
|
|
if (path) {
|
|
needed->obj = load_object(path);
|
|
if (needed->obj == NULL && !ld_tracing)
|
|
return -1; /* XXX - cleanup */
|
|
}
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int
|
|
load_preload_objects(void)
|
|
{
|
|
char *p = ld_preload;
|
|
|
|
if (p == NULL)
|
|
return NULL;
|
|
|
|
p += strspn(p, ":;");
|
|
while (*p != '\0') {
|
|
size_t len = strcspn(p, ":;");
|
|
char *path;
|
|
char savech;
|
|
|
|
savech = p[len];
|
|
p[len] = '\0';
|
|
if ((path = find_library(p, NULL)) == NULL)
|
|
return -1;
|
|
if (load_object(path) == NULL)
|
|
return -1; /* XXX - cleanup */
|
|
p[len] = savech;
|
|
p += len;
|
|
p += strspn(p, ":;");
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Load a shared object into memory, if it is not already loaded. The
|
|
* argument must be a string allocated on the heap. This function assumes
|
|
* responsibility for freeing it when necessary.
|
|
*
|
|
* Returns a pointer to the Obj_Entry for the object. Returns NULL
|
|
* on failure.
|
|
*/
|
|
static Obj_Entry *
|
|
load_object(char *path)
|
|
{
|
|
Obj_Entry *obj;
|
|
|
|
for (obj = obj_list->next; obj != NULL; obj = obj->next)
|
|
if (strcmp(obj->path, path) == 0)
|
|
break;
|
|
|
|
if (obj == NULL) { /* First use of this object, so we must map it in */
|
|
int fd;
|
|
|
|
if ((fd = open(path, O_RDONLY)) == -1) {
|
|
_rtld_error("Cannot open \"%s\"", path);
|
|
return NULL;
|
|
}
|
|
obj = map_object(fd);
|
|
close(fd);
|
|
if (obj == NULL) {
|
|
free(path);
|
|
return NULL;
|
|
}
|
|
|
|
obj->path = path;
|
|
digest_dynamic(obj);
|
|
|
|
*obj_tail = obj;
|
|
obj_tail = &obj->next;
|
|
linkmap_add(obj); /* for GDB */
|
|
|
|
dbg(" %p .. %p: %s", obj->mapbase,
|
|
obj->mapbase + obj->mapsize - 1, obj->path);
|
|
if (obj->textrel)
|
|
dbg(" WARNING: %s has impure text", obj->path);
|
|
} else
|
|
free(path);
|
|
|
|
obj->refcount++;
|
|
return obj;
|
|
}
|
|
|
|
static Obj_Entry *
|
|
obj_from_addr(const void *addr)
|
|
{
|
|
unsigned long endhash;
|
|
Obj_Entry *obj;
|
|
|
|
endhash = elf_hash(END_SYM);
|
|
for (obj = obj_list; obj != NULL; obj = obj->next) {
|
|
const Elf_Sym *endsym;
|
|
|
|
if (addr < (void *) obj->mapbase)
|
|
continue;
|
|
if ((endsym = symlook_obj(END_SYM, endhash, obj, true)) == NULL)
|
|
continue; /* No "end" symbol?! */
|
|
if (addr < (void *) (obj->relocbase + endsym->st_value))
|
|
return obj;
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Relocate newly-loaded shared objects. The argument is a pointer to
|
|
* the Obj_Entry for the first such object. All objects from the first
|
|
* to the end of the list of objects are relocated. Returns 0 on success,
|
|
* or -1 on failure.
|
|
*/
|
|
static int
|
|
relocate_objects(Obj_Entry *first, bool bind_now)
|
|
{
|
|
Obj_Entry *obj;
|
|
|
|
for (obj = first; obj != NULL; obj = obj->next) {
|
|
if (obj != &obj_rtld)
|
|
dbg("relocating \"%s\"", obj->path);
|
|
if (obj->nbuckets == 0 || obj->nchains == 0 || obj->buckets == NULL ||
|
|
obj->symtab == NULL || obj->strtab == NULL) {
|
|
_rtld_error("%s: Shared object has no run-time symbol table",
|
|
obj->path);
|
|
return -1;
|
|
}
|
|
|
|
if (obj->textrel) {
|
|
/* There are relocations to the write-protected text segment. */
|
|
if (mprotect(obj->mapbase, obj->textsize,
|
|
PROT_READ|PROT_WRITE|PROT_EXEC) == -1) {
|
|
_rtld_error("%s: Cannot write-enable text segment: %s",
|
|
obj->path, strerror(errno));
|
|
return -1;
|
|
}
|
|
}
|
|
|
|
/* Process the non-PLT relocations. */
|
|
if (reloc_non_plt(obj, &obj_rtld))
|
|
return -1;
|
|
|
|
if (obj->textrel) { /* Re-protected the text segment. */
|
|
if (mprotect(obj->mapbase, obj->textsize,
|
|
PROT_READ|PROT_EXEC) == -1) {
|
|
_rtld_error("%s: Cannot write-protect text segment: %s",
|
|
obj->path, strerror(errno));
|
|
return -1;
|
|
}
|
|
}
|
|
|
|
/* Process the PLT relocations. */
|
|
if (reloc_plt(obj, bind_now))
|
|
return -1;
|
|
|
|
/*
|
|
* Set up the magic number and version in the Obj_Entry. These
|
|
* were checked in the crt1.o from the original ElfKit, so we
|
|
* set them for backward compatibility.
|
|
*/
|
|
obj->magic = RTLD_MAGIC;
|
|
obj->version = RTLD_VERSION;
|
|
|
|
/* Set the special PLT or GOT entries. */
|
|
init_pltgot(obj);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Cleanup procedure. It will be called (by the atexit mechanism) just
|
|
* before the process exits.
|
|
*/
|
|
static void
|
|
rtld_exit(void)
|
|
{
|
|
dbg("rtld_exit()");
|
|
call_fini_functions(obj_list->next);
|
|
}
|
|
|
|
static char *
|
|
search_library_path(const char *name, const char *path)
|
|
{
|
|
size_t namelen = strlen(name);
|
|
const char *p = path;
|
|
|
|
if (p == NULL)
|
|
return NULL;
|
|
|
|
p += strspn(p, ":;");
|
|
while (*p != '\0') {
|
|
size_t len = strcspn(p, ":;");
|
|
|
|
if (*p == '/' || trust) {
|
|
char *pathname;
|
|
const char *dir = p;
|
|
size_t dirlen = len;
|
|
|
|
pathname = xmalloc(dirlen + 1 + namelen + 1);
|
|
strncpy(pathname, dir, dirlen);
|
|
pathname[dirlen] = '/';
|
|
strcpy(pathname + dirlen + 1, name);
|
|
|
|
dbg(" Trying \"%s\"", pathname);
|
|
if (access(pathname, F_OK) == 0) /* We found it */
|
|
return pathname;
|
|
|
|
free(pathname);
|
|
}
|
|
p += len;
|
|
p += strspn(p, ":;");
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
int
|
|
dlclose(void *handle)
|
|
{
|
|
Obj_Entry *root = dlcheck(handle);
|
|
|
|
if (root == NULL)
|
|
return -1;
|
|
|
|
GDB_STATE(RT_DELETE);
|
|
|
|
root->dl_refcount--;
|
|
unref_object_dag(root);
|
|
if (root->refcount == 0) { /* We are finished with some objects. */
|
|
Obj_Entry *obj;
|
|
Obj_Entry **linkp;
|
|
|
|
/* Finalize objects that are about to be unmapped. */
|
|
for (obj = obj_list->next; obj != NULL; obj = obj->next)
|
|
if (obj->refcount == 0 && obj->fini != NULL)
|
|
(*obj->fini)();
|
|
|
|
/* Unmap all objects that are no longer referenced. */
|
|
linkp = &obj_list->next;
|
|
while ((obj = *linkp) != NULL) {
|
|
if (obj->refcount == 0) {
|
|
munmap(obj->mapbase, obj->mapsize);
|
|
free(obj->path);
|
|
while (obj->needed != NULL) {
|
|
Needed_Entry *needed = obj->needed;
|
|
obj->needed = needed->next;
|
|
free(needed);
|
|
}
|
|
linkmap_delete(obj);
|
|
*linkp = obj->next;
|
|
free(obj);
|
|
} else
|
|
linkp = &obj->next;
|
|
}
|
|
obj_tail = linkp;
|
|
}
|
|
|
|
GDB_STATE(RT_CONSISTENT);
|
|
|
|
return 0;
|
|
}
|
|
|
|
const char *
|
|
dlerror(void)
|
|
{
|
|
char *msg = error_message;
|
|
error_message = NULL;
|
|
return msg;
|
|
}
|
|
|
|
void *
|
|
dlopen(const char *name, int mode)
|
|
{
|
|
Obj_Entry **old_obj_tail = obj_tail;
|
|
Obj_Entry *obj = NULL;
|
|
|
|
GDB_STATE(RT_ADD);
|
|
|
|
if (name == NULL)
|
|
obj = obj_main;
|
|
else {
|
|
char *path = find_library(name, obj_main);
|
|
if (path != NULL)
|
|
obj = load_object(path);
|
|
}
|
|
|
|
if (obj) {
|
|
obj->dl_refcount++;
|
|
if (*old_obj_tail != NULL) { /* We loaded something new. */
|
|
assert(*old_obj_tail == obj);
|
|
|
|
/* XXX - Clean up properly after an error. */
|
|
if (load_needed_objects(obj) == -1) {
|
|
obj->dl_refcount--;
|
|
obj = NULL;
|
|
} else if (relocate_objects(obj, mode == RTLD_NOW) == -1) {
|
|
obj->dl_refcount--;
|
|
obj = NULL;
|
|
} else
|
|
call_init_functions(obj);
|
|
}
|
|
}
|
|
|
|
GDB_STATE(RT_CONSISTENT);
|
|
|
|
return obj;
|
|
}
|
|
|
|
void *
|
|
dlsym(void *handle, const char *name)
|
|
{
|
|
const Obj_Entry *obj;
|
|
unsigned long hash;
|
|
const Elf_Sym *def;
|
|
|
|
hash = elf_hash(name);
|
|
def = NULL;
|
|
|
|
if (handle == NULL || handle == RTLD_NEXT) {
|
|
void *retaddr;
|
|
|
|
retaddr = __builtin_return_address(0); /* __GNUC__ only */
|
|
if ((obj = obj_from_addr(retaddr)) == NULL) {
|
|
_rtld_error("Cannot determine caller's shared object");
|
|
return NULL;
|
|
}
|
|
if (handle == NULL) /* Just the caller's shared object. */
|
|
def = symlook_obj(name, hash, obj, true);
|
|
else { /* All the shared objects after the caller's */
|
|
while ((obj = obj->next) != NULL)
|
|
if ((def = symlook_obj(name, hash, obj, true)) != NULL)
|
|
break;
|
|
}
|
|
} else {
|
|
if ((obj = dlcheck(handle)) == NULL)
|
|
return NULL;
|
|
|
|
if (obj->mainprog) {
|
|
/* Search main program and all libraries loaded by it. */
|
|
for ( ; obj != *main_tail; obj = obj->next)
|
|
if ((def = symlook_obj(name, hash, obj, true)) != NULL)
|
|
break;
|
|
} else {
|
|
/*
|
|
* XXX - This isn't correct. The search should include the whole
|
|
* DAG rooted at the given object.
|
|
*/
|
|
def = symlook_obj(name, hash, obj, true);
|
|
}
|
|
}
|
|
|
|
if (def != NULL)
|
|
return obj->relocbase + def->st_value;
|
|
|
|
_rtld_error("Undefined symbol \"%s\"", name);
|
|
return NULL;
|
|
}
|
|
|
|
int
|
|
dlversion(void)
|
|
{
|
|
return DL_VERSION;
|
|
}
|
|
|
|
int
|
|
dladdr(const void *addr, Dl_info *info)
|
|
{
|
|
const Obj_Entry *obj;
|
|
const Elf_Sym *def;
|
|
void *symbol_addr;
|
|
unsigned long symoffset;
|
|
|
|
obj = obj_from_addr(addr);
|
|
if (obj == NULL) {
|
|
_rtld_error("No shared object contains address");
|
|
return 0;
|
|
}
|
|
info->dli_fname = obj->path;
|
|
info->dli_fbase = obj->mapbase;
|
|
info->dli_saddr = (void *)0;
|
|
info->dli_sname = NULL;
|
|
|
|
/*
|
|
* Walk the symbol list looking for the symbol whose address is
|
|
* closest to the address sent in.
|
|
*/
|
|
for (symoffset = 0; symoffset < obj->nchains; symoffset++) {
|
|
def = obj->symtab + symoffset;
|
|
|
|
/*
|
|
* For skip the symbol if st_shndx is either SHN_UNDEF or
|
|
* SHN_COMMON.
|
|
*/
|
|
if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON)
|
|
continue;
|
|
|
|
/*
|
|
* If the symbol is greater than the specified address, or if it
|
|
* is further away from addr than the current nearest symbol,
|
|
* then reject it.
|
|
*/
|
|
symbol_addr = obj->relocbase + def->st_value;
|
|
if (symbol_addr > addr || symbol_addr < info->dli_saddr)
|
|
continue;
|
|
|
|
/* Update our idea of the nearest symbol. */
|
|
info->dli_sname = obj->strtab + def->st_name;
|
|
info->dli_saddr = symbol_addr;
|
|
|
|
/* Exact match? */
|
|
if (info->dli_saddr == addr)
|
|
break;
|
|
}
|
|
return 1;
|
|
}
|
|
|
|
static void
|
|
linkmap_add(Obj_Entry *obj)
|
|
{
|
|
struct link_map *l = &obj->linkmap;
|
|
struct link_map *prev;
|
|
|
|
obj->linkmap.l_name = obj->path;
|
|
obj->linkmap.l_addr = obj->mapbase;
|
|
obj->linkmap.l_ld = obj->dynamic;
|
|
#ifdef __mips__
|
|
/* GDB needs load offset on MIPS to use the symbols */
|
|
obj->linkmap.l_offs = obj->relocbase;
|
|
#endif
|
|
|
|
if (r_debug.r_map == NULL) {
|
|
r_debug.r_map = l;
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Scan to the end of the list, but not past the entry for the
|
|
* dynamic linker, which we want to keep at the very end.
|
|
*/
|
|
for (prev = r_debug.r_map;
|
|
prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap;
|
|
prev = prev->l_next)
|
|
;
|
|
|
|
/* Link in the new entry. */
|
|
l->l_prev = prev;
|
|
l->l_next = prev->l_next;
|
|
if (l->l_next != NULL)
|
|
l->l_next->l_prev = l;
|
|
prev->l_next = l;
|
|
}
|
|
|
|
static void
|
|
linkmap_delete(Obj_Entry *obj)
|
|
{
|
|
struct link_map *l = &obj->linkmap;
|
|
|
|
if (l->l_prev == NULL) {
|
|
if ((r_debug.r_map = l->l_next) != NULL)
|
|
l->l_next->l_prev = NULL;
|
|
return;
|
|
}
|
|
|
|
if ((l->l_prev->l_next = l->l_next) != NULL)
|
|
l->l_next->l_prev = l->l_prev;
|
|
}
|
|
|
|
/*
|
|
* Function for the debugger to set a breakpoint on to gain control.
|
|
*/
|
|
void
|
|
r_debug_state(void)
|
|
{
|
|
}
|
|
|
|
/*
|
|
* Set a pointer variable in the main program to the given value. This
|
|
* is used to set key variables such as "environ" before any of the
|
|
* init functions are called.
|
|
*/
|
|
static void
|
|
set_program_var(const char *name, const void *value)
|
|
{
|
|
const Obj_Entry *obj;
|
|
unsigned long hash;
|
|
|
|
hash = elf_hash(name);
|
|
for (obj = obj_main; obj != NULL; obj = obj->next) {
|
|
const Elf_Sym *def;
|
|
|
|
if ((def = symlook_obj(name, hash, obj, false)) != NULL) {
|
|
const void **addr;
|
|
|
|
addr = (const void **)(obj->relocbase + def->st_value);
|
|
dbg("\"%s\": *%p <-- %p", name, addr, value);
|
|
*addr = value;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Search the symbol table of a single shared object for a symbol of
|
|
* the given name. Returns a pointer to the symbol, or NULL if no
|
|
* definition was found.
|
|
*
|
|
* The symbol's hash value is passed in for efficiency reasons; that
|
|
* eliminates many recomputations of the hash value.
|
|
*/
|
|
const Elf_Sym *
|
|
symlook_obj(const char *name, unsigned long hash, const Obj_Entry *obj,
|
|
bool in_plt)
|
|
{
|
|
if (obj->buckets != NULL) {
|
|
unsigned long symnum = obj->buckets[hash % obj->nbuckets];
|
|
|
|
while (symnum != STN_UNDEF) {
|
|
const Elf_Sym *symp;
|
|
const char *strp;
|
|
|
|
assert(symnum < obj->nchains);
|
|
symp = obj->symtab + symnum;
|
|
assert(symp->st_name != 0);
|
|
strp = obj->strtab + symp->st_name;
|
|
|
|
if (strcmp(name, strp) == 0)
|
|
return symp->st_shndx != SHN_UNDEF ||
|
|
(!in_plt && symp->st_value != 0 &&
|
|
ELF_ST_TYPE(symp->st_info) == STT_FUNC) ? symp : NULL;
|
|
|
|
symnum = obj->chains[symnum];
|
|
}
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
static void
|
|
trace_loaded_objects(Obj_Entry *obj)
|
|
{
|
|
char *fmt1, *fmt2, *fmt, *main_local;
|
|
int c;
|
|
|
|
if ((main_local = getenv("LD_TRACE_LOADED_OBJECTS_PROGNAME")) == NULL)
|
|
main_local = "";
|
|
|
|
if ((fmt1 = getenv("LD_TRACE_LOADED_OBJECTS_FMT1")) == NULL)
|
|
fmt1 = "\t%o => %p (%x)\n";
|
|
|
|
if ((fmt2 = getenv("LD_TRACE_LOADED_OBJECTS_FMT2")) == NULL)
|
|
fmt2 = "\t%o (%x)\n";
|
|
|
|
for (; obj; obj = obj->next) {
|
|
Needed_Entry *needed;
|
|
char *name, *path;
|
|
bool is_lib;
|
|
|
|
for (needed = obj->needed; needed; needed = needed->next) {
|
|
if (needed->obj != NULL) {
|
|
if (needed->obj->traced)
|
|
continue;
|
|
needed->obj->traced = true;
|
|
path = needed->obj->path;
|
|
} else
|
|
path = "not found";
|
|
|
|
name = (char *)obj->strtab + needed->name;
|
|
is_lib = strncmp(name, "lib", 3) == 0; /* XXX - bogus */
|
|
|
|
fmt = is_lib ? fmt1 : fmt2;
|
|
while ((c = *fmt++) != '\0') {
|
|
switch (c) {
|
|
default:
|
|
putchar(c);
|
|
continue;
|
|
case '\\':
|
|
switch (c = *fmt) {
|
|
case '\0':
|
|
continue;
|
|
case 'n':
|
|
putchar('\n');
|
|
break;
|
|
case 't':
|
|
putchar('\t');
|
|
break;
|
|
}
|
|
break;
|
|
case '%':
|
|
switch (c = *fmt) {
|
|
case '\0':
|
|
continue;
|
|
case '%':
|
|
default:
|
|
putchar(c);
|
|
break;
|
|
case 'A':
|
|
printf("%s", main_local);
|
|
break;
|
|
case 'a':
|
|
printf("%s", obj_main->path);
|
|
break;
|
|
case 'o':
|
|
printf("%s", name);
|
|
break;
|
|
#if 0
|
|
case 'm':
|
|
printf("%d", sodp->sod_major);
|
|
break;
|
|
case 'n':
|
|
printf("%d", sodp->sod_minor);
|
|
break;
|
|
#endif
|
|
case 'p':
|
|
printf("%s", path);
|
|
break;
|
|
case 'x':
|
|
printf("%p", needed->obj ? needed->obj->mapbase : 0);
|
|
break;
|
|
}
|
|
break;
|
|
}
|
|
++fmt;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
static void
|
|
unref_object_dag(Obj_Entry *root)
|
|
{
|
|
assert(root->refcount != 0);
|
|
root->refcount--;
|
|
if (root->refcount == 0) {
|
|
const Needed_Entry *needed;
|
|
|
|
for (needed = root->needed; needed != NULL; needed = needed->next)
|
|
unref_object_dag(needed->obj);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Non-mallocing printf, for use by malloc itself.
|
|
* XXX - This doesn't belong in this module.
|
|
*/
|
|
void
|
|
xprintf(const char *fmt, ...)
|
|
{
|
|
char buf[256];
|
|
va_list ap;
|
|
|
|
va_start(ap, fmt);
|
|
vsprintf(buf, fmt, ap);
|
|
(void)write(1, buf, strlen(buf));
|
|
va_end(ap);
|
|
}
|