924d965ba0
and Linux.
1886 lines
46 KiB
C
1886 lines
46 KiB
C
/*-
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* Copyright 1996, 1997, 1998, 1999, 2000 John D. Polstra.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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/*
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* Dynamic linker for ELF.
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*
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* John Polstra <jdp@polstra.com>.
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*/
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#ifndef __GNUC__
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#error "GCC is needed to compile this file"
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#endif
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#include <sys/param.h>
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#include <sys/mman.h>
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#include <sys/stat.h>
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#include <dlfcn.h>
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#include <err.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <stdarg.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include "debug.h"
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#include "rtld.h"
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#define END_SYM "_end"
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#define PATH_RTLD "/usr/libexec/ld-elf.so.1"
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/* Types. */
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typedef void (*func_ptr_type)();
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typedef struct Struct_LockInfo {
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void *context; /* Client context for creating locks */
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void *thelock; /* The one big lock */
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/* Methods */
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void (*rlock_acquire)(void *lock);
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void (*wlock_acquire)(void *lock);
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void (*lock_release)(void *lock);
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void (*lock_destroy)(void *lock);
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void (*context_destroy)(void *context);
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} LockInfo;
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/*
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* Function declarations.
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*/
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static const char *basename(const char *);
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static void die(void);
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static void digest_dynamic(Obj_Entry *);
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static Obj_Entry *digest_phdr(const Elf_Phdr *, int, caddr_t, const char *);
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static Obj_Entry *dlcheck(void *);
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static char *find_library(const char *, const Obj_Entry *);
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static void funclist_call(Funclist *);
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static void funclist_clear(Funclist *);
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static void funclist_init(Funclist *);
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static void funclist_push_head(Funclist *, InitFunc);
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static void funclist_push_tail(Funclist *, InitFunc);
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static const char *gethints(void);
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static void init_dag(Obj_Entry *);
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static void init_dag1(Obj_Entry *root, Obj_Entry *obj);
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static void init_rtld(caddr_t);
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static bool is_exported(const Elf_Sym *);
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static void linkmap_add(Obj_Entry *);
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static void linkmap_delete(Obj_Entry *);
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static int load_needed_objects(Obj_Entry *);
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static int load_preload_objects(void);
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static Obj_Entry *load_object(char *);
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static void lock_nop(void *);
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static Obj_Entry *obj_from_addr(const void *);
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static void objlist_add(Objlist *, Obj_Entry *);
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static Objlist_Entry *objlist_find(Objlist *, const Obj_Entry *);
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static void objlist_remove(Objlist *, Obj_Entry *);
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static int relocate_objects(Obj_Entry *, bool);
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static void rtld_exit(void);
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static char *search_library_path(const char *, const char *);
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static void set_program_var(const char *, const void *);
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static const Elf_Sym *symlook_list(const char *, unsigned long,
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Objlist *, const Obj_Entry **, bool in_plt);
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static void trace_loaded_objects(Obj_Entry *obj);
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static void unload_object(Obj_Entry *);
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static void unref_dag(Obj_Entry *);
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void r_debug_state(void);
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void xprintf(const char *, ...);
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/*
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* Data declarations.
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*/
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static char *error_message; /* Message for dlerror(), or NULL */
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struct r_debug r_debug; /* for GDB; */
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static bool trust; /* False for setuid and setgid programs */
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static char *ld_bind_now; /* Environment variable for immediate binding */
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static char *ld_debug; /* Environment variable for debugging */
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static char *ld_library_path; /* Environment variable for search path */
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static char *ld_preload; /* Environment variable for libraries to
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load first */
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static char *ld_tracing; /* Called from ldd to print libs */
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static Obj_Entry *obj_list; /* Head of linked list of shared objects */
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static Obj_Entry **obj_tail; /* Link field of last object in list */
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static Obj_Entry *obj_main; /* The main program shared object */
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static Obj_Entry obj_rtld; /* The dynamic linker shared object */
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static unsigned long curmark; /* Current mark value */
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static Objlist list_global = /* Objects dlopened with RTLD_GLOBAL */
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STAILQ_HEAD_INITIALIZER(list_global);
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static Objlist list_main = /* Objects loaded at program startup */
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STAILQ_HEAD_INITIALIZER(list_main);
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static LockInfo lockinfo;
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static Elf_Sym sym_zero; /* For resolving undefined weak refs. */
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#define GDB_STATE(s) r_debug.r_state = s; r_debug_state();
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extern Elf_Dyn _DYNAMIC;
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#pragma weak _DYNAMIC
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/*
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* These are the functions the dynamic linker exports to application
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* programs. They are the only symbols the dynamic linker is willing
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* to export from itself.
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*/
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static func_ptr_type exports[] = {
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(func_ptr_type) &_rtld_error,
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(func_ptr_type) &dlclose,
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(func_ptr_type) &dlerror,
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(func_ptr_type) &dlopen,
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(func_ptr_type) &dlsym,
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(func_ptr_type) &dladdr,
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(func_ptr_type) &dllockinit,
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NULL
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};
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/*
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* Global declarations normally provided by crt1. The dynamic linker is
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* not built with crt1, so we have to provide them ourselves.
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*/
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char *__progname;
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char **environ;
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static __inline void
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rlock_acquire(void)
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{
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lockinfo.rlock_acquire(lockinfo.thelock);
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}
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static __inline void
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wlock_acquire(void)
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{
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lockinfo.wlock_acquire(lockinfo.thelock);
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}
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static __inline void
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lock_release(void)
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{
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lockinfo.lock_release(lockinfo.thelock);
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}
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/*
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* Main entry point for dynamic linking. The first argument is the
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* stack pointer. The stack is expected to be laid out as described
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* in the SVR4 ABI specification, Intel 386 Processor Supplement.
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* Specifically, the stack pointer points to a word containing
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* ARGC. Following that in the stack is a null-terminated sequence
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* of pointers to argument strings. Then comes a null-terminated
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* sequence of pointers to environment strings. Finally, there is a
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* sequence of "auxiliary vector" entries.
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*
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* The second argument points to a place to store the dynamic linker's
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* exit procedure pointer and the third to a place to store the main
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* program's object.
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*
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* The return value is the main program's entry point.
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*/
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func_ptr_type
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_rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp)
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{
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Elf_Auxinfo *aux_info[AT_COUNT];
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int i;
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int argc;
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char **argv;
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char **env;
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Elf_Auxinfo *aux;
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Elf_Auxinfo *auxp;
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const char *argv0;
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Obj_Entry *obj;
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Funclist initlist;
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/*
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* On entry, the dynamic linker itself has not been relocated yet.
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* Be very careful not to reference any global data until after
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* init_rtld has returned. It is OK to reference file-scope statics
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* and string constants, and to call static and global functions.
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*/
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/* Find the auxiliary vector on the stack. */
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argc = *sp++;
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argv = (char **) sp;
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sp += argc + 1; /* Skip over arguments and NULL terminator */
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env = (char **) sp;
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while (*sp++ != 0) /* Skip over environment, and NULL terminator */
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;
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aux = (Elf_Auxinfo *) sp;
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/* Digest the auxiliary vector. */
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for (i = 0; i < AT_COUNT; i++)
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aux_info[i] = NULL;
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for (auxp = aux; auxp->a_type != AT_NULL; auxp++) {
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if (auxp->a_type < AT_COUNT)
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aux_info[auxp->a_type] = auxp;
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}
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/* Initialize and relocate ourselves. */
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assert(aux_info[AT_BASE] != NULL);
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init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr);
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__progname = obj_rtld.path;
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argv0 = argv[0] != NULL ? argv[0] : "(null)";
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environ = env;
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trust = geteuid() == getuid() && getegid() == getgid();
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ld_bind_now = getenv("LD_BIND_NOW");
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if (trust) {
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ld_debug = getenv("LD_DEBUG");
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ld_library_path = getenv("LD_LIBRARY_PATH");
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ld_preload = getenv("LD_PRELOAD");
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}
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ld_tracing = getenv("LD_TRACE_LOADED_OBJECTS");
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if (ld_debug != NULL && *ld_debug != '\0')
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debug = 1;
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dbg("%s is initialized, base address = %p", __progname,
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(caddr_t) aux_info[AT_BASE]->a_un.a_ptr);
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dbg("RTLD dynamic = %p", obj_rtld.dynamic);
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dbg("RTLD pltgot = %p", obj_rtld.pltgot);
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/*
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* Load the main program, or process its program header if it is
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* already loaded.
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*/
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if (aux_info[AT_EXECFD] != NULL) { /* Load the main program. */
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int fd = aux_info[AT_EXECFD]->a_un.a_val;
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dbg("loading main program");
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obj_main = map_object(fd, argv0, NULL);
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close(fd);
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if (obj_main == NULL)
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die();
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} else { /* Main program already loaded. */
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const Elf_Phdr *phdr;
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int phnum;
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caddr_t entry;
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dbg("processing main program's program header");
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assert(aux_info[AT_PHDR] != NULL);
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phdr = (const Elf_Phdr *) aux_info[AT_PHDR]->a_un.a_ptr;
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assert(aux_info[AT_PHNUM] != NULL);
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phnum = aux_info[AT_PHNUM]->a_un.a_val;
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assert(aux_info[AT_PHENT] != NULL);
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assert(aux_info[AT_PHENT]->a_un.a_val == sizeof(Elf_Phdr));
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assert(aux_info[AT_ENTRY] != NULL);
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entry = (caddr_t) aux_info[AT_ENTRY]->a_un.a_ptr;
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if ((obj_main = digest_phdr(phdr, phnum, entry, argv0)) == NULL)
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die();
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}
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obj_main->path = xstrdup(argv0);
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obj_main->mainprog = true;
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/*
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* Get the actual dynamic linker pathname from the executable if
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* possible. (It should always be possible.) That ensures that
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* gdb will find the right dynamic linker even if a non-standard
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* one is being used.
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*/
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if (obj_main->interp != NULL &&
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strcmp(obj_main->interp, obj_rtld.path) != 0) {
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free(obj_rtld.path);
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obj_rtld.path = xstrdup(obj_main->interp);
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}
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digest_dynamic(obj_main);
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linkmap_add(obj_main);
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linkmap_add(&obj_rtld);
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/* Link the main program into the list of objects. */
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*obj_tail = obj_main;
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obj_tail = &obj_main->next;
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obj_main->refcount++;
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/* Initialize a fake symbol for resolving undefined weak references. */
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sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE);
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sym_zero.st_shndx = SHN_ABS;
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dbg("loading LD_PRELOAD libraries");
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if (load_preload_objects() == -1)
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die();
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dbg("loading needed objects");
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if (load_needed_objects(obj_main) == -1)
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die();
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/*
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* Make a list of all objects loaded at startup. Also construct
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* the list of init functions to call, in reverse order.
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*/
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funclist_init(&initlist);
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for (obj = obj_list; obj != NULL; obj = obj->next) {
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objlist_add(&list_main, obj);
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if (obj->init != NULL && !obj->mainprog)
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funclist_push_head(&initlist, obj->init);
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}
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if (ld_tracing) { /* We're done */
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trace_loaded_objects(obj_main);
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exit(0);
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}
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if (relocate_objects(obj_main,
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ld_bind_now != NULL && *ld_bind_now != '\0') == -1)
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die();
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dbg("doing copy relocations");
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if (do_copy_relocations(obj_main) == -1)
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die();
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dbg("initializing key program variables");
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set_program_var("__progname", argv[0] != NULL ? basename(argv[0]) : "");
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set_program_var("environ", env);
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dbg("initializing default locks");
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dllockinit(NULL, NULL, NULL, NULL, NULL, NULL, NULL);
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r_debug_state(); /* say hello to gdb! */
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funclist_call(&initlist);
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wlock_acquire();
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funclist_clear(&initlist);
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lock_release();
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dbg("transferring control to program entry point = %p", obj_main->entry);
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/* Return the exit procedure and the program entry point. */
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*exit_proc = rtld_exit;
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*objp = obj_main;
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return (func_ptr_type) obj_main->entry;
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}
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Elf_Addr
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_rtld_bind(Obj_Entry *obj, Elf_Word reloff)
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{
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const Elf_Rel *rel;
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const Elf_Sym *def;
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const Obj_Entry *defobj;
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Elf_Addr *where;
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Elf_Addr target;
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wlock_acquire();
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if (obj->pltrel)
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rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff);
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else
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rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff);
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where = (Elf_Addr *) (obj->relocbase + rel->r_offset);
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def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true);
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if (def == NULL)
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die();
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target = (Elf_Addr)(defobj->relocbase + def->st_value);
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dbg("\"%s\" in \"%s\" ==> %p in \"%s\"",
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defobj->strtab + def->st_name, basename(obj->path),
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(void *)target, basename(defobj->path));
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reloc_jmpslot(where, target);
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lock_release();
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return target;
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}
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/*
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* Error reporting function. Use it like printf. If formats the message
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* into a buffer, and sets things up so that the next call to dlerror()
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* will return the message.
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*/
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void
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_rtld_error(const char *fmt, ...)
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{
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static char buf[512];
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va_list ap;
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va_start(ap, fmt);
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vsnprintf(buf, sizeof buf, fmt, ap);
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error_message = buf;
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va_end(ap);
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}
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static const char *
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basename(const char *name)
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{
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const char *p = strrchr(name, '/');
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return p != NULL ? p + 1 : name;
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}
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static void
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die(void)
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{
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const char *msg = dlerror();
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if (msg == NULL)
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msg = "Fatal error";
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errx(1, "%s", msg);
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}
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/*
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* Process a shared object's DYNAMIC section, and save the important
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* information in its Obj_Entry structure.
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*/
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static void
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digest_dynamic(Obj_Entry *obj)
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{
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const Elf_Dyn *dynp;
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Needed_Entry **needed_tail = &obj->needed;
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const Elf_Dyn *dyn_rpath = NULL;
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int plttype = DT_REL;
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for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) {
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switch (dynp->d_tag) {
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case DT_REL:
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obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr);
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break;
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case DT_RELSZ:
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obj->relsize = dynp->d_un.d_val;
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break;
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case DT_RELENT:
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assert(dynp->d_un.d_val == sizeof(Elf_Rel));
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break;
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case DT_JMPREL:
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obj->pltrel = (const Elf_Rel *)
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(obj->relocbase + dynp->d_un.d_ptr);
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break;
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case DT_PLTRELSZ:
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obj->pltrelsize = dynp->d_un.d_val;
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break;
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case DT_RELA:
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obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr);
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break;
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case DT_RELASZ:
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obj->relasize = dynp->d_un.d_val;
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break;
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case DT_RELAENT:
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assert(dynp->d_un.d_val == sizeof(Elf_Rela));
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break;
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case DT_PLTREL:
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plttype = dynp->d_un.d_val;
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assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA);
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break;
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case DT_SYMTAB:
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obj->symtab = (const Elf_Sym *)
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(obj->relocbase + dynp->d_un.d_ptr);
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break;
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|
|
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 = (InitFunc) (obj->relocbase + dynp->d_un.d_ptr);
|
|
break;
|
|
|
|
case DT_FINI:
|
|
obj->fini = (InitFunc) (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:
|
|
dbg("Ignoring d_tag %d = %#x", dynp->d_tag, 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, const char *path)
|
|
{
|
|
Obj_Entry *obj;
|
|
const Elf_Phdr *phlimit = phdr + phnum;
|
|
const Elf_Phdr *ph;
|
|
int nsegs = 0;
|
|
|
|
obj = obj_new();
|
|
for (ph = phdr; ph < phlimit; ph++) {
|
|
switch (ph->p_type) {
|
|
|
|
case PT_PHDR:
|
|
if ((const Elf_Phdr *)ph->p_vaddr != phdr) {
|
|
_rtld_error("%s: invalid PT_PHDR", path);
|
|
return NULL;
|
|
}
|
|
obj->phdr = (const Elf_Phdr *) ph->p_vaddr;
|
|
obj->phsize = ph->p_memsz;
|
|
break;
|
|
|
|
case PT_INTERP:
|
|
obj->interp = (const char *) ph->p_vaddr;
|
|
break;
|
|
|
|
case PT_LOAD:
|
|
if (nsegs >= 2) {
|
|
_rtld_error("%s: too many PT_LOAD segments", path);
|
|
return NULL;
|
|
}
|
|
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;
|
|
}
|
|
}
|
|
if (nsegs < 2) {
|
|
_rtld_error("%s: too few PT_LOAD segments", path);
|
|
return NULL;
|
|
}
|
|
|
|
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:
|
|
* rpath in the referencing file
|
|
* LD_LIBRARY_PATH
|
|
* ldconfig hints
|
|
* /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, Obj_Entry *refobj,
|
|
const Obj_Entry **defobj_out, bool in_plt)
|
|
{
|
|
const Elf_Sym *ref;
|
|
const Elf_Sym *def;
|
|
const Elf_Sym *symp;
|
|
const Obj_Entry *obj;
|
|
const Obj_Entry *defobj;
|
|
const Objlist_Entry *elm;
|
|
const char *name;
|
|
unsigned long hash;
|
|
|
|
ref = refobj->symtab + symnum;
|
|
name = refobj->strtab + ref->st_name;
|
|
hash = elf_hash(name);
|
|
def = NULL;
|
|
defobj = NULL;
|
|
curmark++;
|
|
|
|
if (refobj->symbolic) { /* Look first in the referencing object */
|
|
symp = symlook_obj(name, hash, refobj, in_plt);
|
|
refobj->mark = curmark;
|
|
if (symp != NULL) {
|
|
def = symp;
|
|
defobj = refobj;
|
|
}
|
|
}
|
|
|
|
/* Search all objects loaded at program start up. */
|
|
if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
|
|
symp = symlook_list(name, hash, &list_main, &obj, in_plt);
|
|
if (symp != NULL &&
|
|
(def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) {
|
|
def = symp;
|
|
defobj = obj;
|
|
}
|
|
}
|
|
|
|
/* Search all dlopened DAGs containing the referencing object. */
|
|
STAILQ_FOREACH(elm, &refobj->dldags, link) {
|
|
if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK)
|
|
break;
|
|
symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt);
|
|
if (symp != NULL &&
|
|
(def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) {
|
|
def = symp;
|
|
defobj = obj;
|
|
}
|
|
}
|
|
|
|
/* Search all RTLD_GLOBAL objects. */
|
|
if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
|
|
symp = symlook_list(name, hash, &list_global, &obj, in_plt);
|
|
if (symp != NULL &&
|
|
(def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) {
|
|
def = symp;
|
|
defobj = obj;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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 (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
|
|
symp = symlook_obj(name, hash, &obj_rtld, in_plt);
|
|
if (symp != NULL && is_exported(symp)) {
|
|
def = symp;
|
|
defobj = &obj_rtld;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* If we found no definition and the reference is weak, treat the
|
|
* symbol as having the value zero.
|
|
*/
|
|
if (def == NULL && ELF_ST_BIND(ref->st_info) == STB_WEAK) {
|
|
def = &sym_zero;
|
|
defobj = obj_main;
|
|
}
|
|
|
|
if (def != NULL)
|
|
*defobj_out = defobj;
|
|
else
|
|
_rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name);
|
|
return def;
|
|
}
|
|
|
|
static void
|
|
funclist_call(Funclist *list)
|
|
{
|
|
Funclist_Entry *elm;
|
|
|
|
STAILQ_FOREACH(elm, list, link) {
|
|
dbg("calling init/fini function at %p", elm->func);
|
|
(*elm->func)();
|
|
}
|
|
}
|
|
|
|
static void
|
|
funclist_clear(Funclist *list)
|
|
{
|
|
Funclist_Entry *elm;
|
|
|
|
while (!STAILQ_EMPTY(list)) {
|
|
elm = STAILQ_FIRST(list);
|
|
STAILQ_REMOVE_HEAD(list, link);
|
|
free(elm);
|
|
}
|
|
}
|
|
|
|
static void
|
|
funclist_init(Funclist *list)
|
|
{
|
|
STAILQ_INIT(list);
|
|
}
|
|
|
|
static void
|
|
funclist_push_head(Funclist *list, InitFunc func)
|
|
{
|
|
Funclist_Entry *elm;
|
|
|
|
elm = NEW(Funclist_Entry);
|
|
elm->func = func;
|
|
STAILQ_INSERT_HEAD(list, elm, link);
|
|
}
|
|
|
|
static void
|
|
funclist_push_tail(Funclist *list, InitFunc func)
|
|
{
|
|
Funclist_Entry *elm;
|
|
|
|
elm = NEW(Funclist_Entry);
|
|
elm->func = func;
|
|
STAILQ_INSERT_TAIL(list, elm, link);
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
}
|
|
|
|
static void
|
|
init_dag(Obj_Entry *root)
|
|
{
|
|
curmark++;
|
|
init_dag1(root, root);
|
|
}
|
|
|
|
static void
|
|
init_dag1(Obj_Entry *root, Obj_Entry *obj)
|
|
{
|
|
const Needed_Entry *needed;
|
|
|
|
if (obj->mark == curmark)
|
|
return;
|
|
obj->mark = curmark;
|
|
objlist_add(&obj->dldags, root);
|
|
objlist_add(&root->dagmembers, obj);
|
|
for (needed = obj->needed; needed != NULL; needed = needed->next)
|
|
if (needed->obj != NULL)
|
|
init_dag1(root, needed->obj);
|
|
}
|
|
|
|
/*
|
|
* 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 = PATH_RTLD;
|
|
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;
|
|
static const char delim[] = " \t:;";
|
|
|
|
if (p == NULL)
|
|
return NULL;
|
|
|
|
p += strspn(p, delim);
|
|
while (*p != '\0') {
|
|
size_t len = strcspn(p, delim);
|
|
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, delim);
|
|
}
|
|
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;
|
|
int fd = -1;
|
|
struct stat sb;
|
|
|
|
for (obj = obj_list->next; obj != NULL; obj = obj->next)
|
|
if (strcmp(obj->path, path) == 0)
|
|
break;
|
|
|
|
/*
|
|
* If we didn't find a match by pathname, open the file and check
|
|
* again by device and inode. This avoids false mismatches caused
|
|
* by multiple links or ".." in pathnames.
|
|
*
|
|
* To avoid a race, we open the file and use fstat() rather than
|
|
* using stat().
|
|
*/
|
|
if (obj == NULL) {
|
|
if ((fd = open(path, O_RDONLY)) == -1) {
|
|
_rtld_error("Cannot open \"%s\"", path);
|
|
return NULL;
|
|
}
|
|
if (fstat(fd, &sb) == -1) {
|
|
_rtld_error("Cannot fstat \"%s\"", path);
|
|
close(fd);
|
|
return NULL;
|
|
}
|
|
for (obj = obj_list->next; obj != NULL; obj = obj->next) {
|
|
if (obj->ino == sb.st_ino && obj->dev == sb.st_dev) {
|
|
close(fd);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (obj == NULL) { /* First use of this object, so we must map it in */
|
|
dbg("loading \"%s\"", path);
|
|
obj = map_object(fd, path, &sb);
|
|
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 void
|
|
lock_nop(void *lock)
|
|
{
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
static void
|
|
objlist_add(Objlist *list, Obj_Entry *obj)
|
|
{
|
|
Objlist_Entry *elm;
|
|
|
|
elm = NEW(Objlist_Entry);
|
|
elm->obj = obj;
|
|
STAILQ_INSERT_TAIL(list, elm, link);
|
|
}
|
|
|
|
static Objlist_Entry *
|
|
objlist_find(Objlist *list, const Obj_Entry *obj)
|
|
{
|
|
Objlist_Entry *elm;
|
|
|
|
STAILQ_FOREACH(elm, list, link)
|
|
if (elm->obj == obj)
|
|
return elm;
|
|
return NULL;
|
|
}
|
|
|
|
static void
|
|
objlist_remove(Objlist *list, Obj_Entry *obj)
|
|
{
|
|
Objlist_Entry *elm;
|
|
|
|
if ((elm = objlist_find(list, obj)) != NULL) {
|
|
STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link);
|
|
free(elm);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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)
|
|
{
|
|
Obj_Entry *obj;
|
|
|
|
dbg("rtld_exit()");
|
|
for (obj = obj_list->next; obj != NULL; obj = obj->next)
|
|
if (obj->fini != NULL)
|
|
(*obj->fini)();
|
|
}
|
|
|
|
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;
|
|
Obj_Entry *obj;
|
|
Funclist finilist;
|
|
|
|
wlock_acquire();
|
|
root = dlcheck(handle);
|
|
if (root == NULL) {
|
|
lock_release();
|
|
return -1;
|
|
}
|
|
|
|
/* Unreference the object and its dependencies. */
|
|
root->dl_refcount--;
|
|
unref_dag(root);
|
|
|
|
if (root->refcount == 0) {
|
|
/*
|
|
* The object is no longer referenced, so we must unload it.
|
|
* First, make a list of the fini functions and then call them
|
|
* with no locks held.
|
|
*/
|
|
funclist_init(&finilist);
|
|
for (obj = obj_list->next; obj != NULL; obj = obj->next)
|
|
if (obj->refcount == 0 && obj->fini != NULL)
|
|
funclist_push_tail(&finilist, obj->fini);
|
|
|
|
lock_release();
|
|
funclist_call(&finilist);
|
|
wlock_acquire();
|
|
funclist_clear(&finilist);
|
|
|
|
/* Finish cleaning up the newly-unreferenced objects. */
|
|
GDB_STATE(RT_DELETE);
|
|
unload_object(root);
|
|
GDB_STATE(RT_CONSISTENT);
|
|
}
|
|
lock_release();
|
|
return 0;
|
|
}
|
|
|
|
const char *
|
|
dlerror(void)
|
|
{
|
|
char *msg = error_message;
|
|
error_message = NULL;
|
|
return msg;
|
|
}
|
|
|
|
void
|
|
dllockinit(void *context,
|
|
void *(*lock_create)(void *context),
|
|
void (*rlock_acquire)(void *lock),
|
|
void (*wlock_acquire)(void *lock),
|
|
void (*lock_release)(void *lock),
|
|
void (*lock_destroy)(void *lock),
|
|
void (*context_destroy)(void *context))
|
|
{
|
|
/* NULL arguments mean reset to the built-in locks. */
|
|
if (lock_create == NULL) {
|
|
context = NULL;
|
|
lock_create = lockdflt_create;
|
|
rlock_acquire = wlock_acquire = lockdflt_acquire;
|
|
lock_release = lockdflt_release;
|
|
lock_destroy = lockdflt_destroy;
|
|
context_destroy = NULL;
|
|
}
|
|
|
|
/* Temporarily set locking methods to no-ops. */
|
|
lockinfo.rlock_acquire = lock_nop;
|
|
lockinfo.wlock_acquire = lock_nop;
|
|
lockinfo.lock_release = lock_nop;
|
|
|
|
/* Release any existing locks and context. */
|
|
if (lockinfo.lock_destroy != NULL)
|
|
lockinfo.lock_destroy(lockinfo.thelock);
|
|
if (lockinfo.context_destroy != NULL)
|
|
lockinfo.context_destroy(lockinfo.context);
|
|
|
|
/*
|
|
* Allocate the locks we will need and call all the new locking
|
|
* methods, to accomplish any needed lazy binding for the methods
|
|
* themselves.
|
|
*/
|
|
lockinfo.thelock = lock_create(lockinfo.context);
|
|
rlock_acquire(lockinfo.thelock);
|
|
lock_release(lockinfo.thelock);
|
|
wlock_acquire(lockinfo.thelock);
|
|
lock_release(lockinfo.thelock);
|
|
|
|
/* Record the new method information. */
|
|
lockinfo.context = context;
|
|
lockinfo.rlock_acquire = rlock_acquire;
|
|
lockinfo.wlock_acquire = wlock_acquire;
|
|
lockinfo.lock_release = lock_release;
|
|
lockinfo.lock_destroy = lock_destroy;
|
|
lockinfo.context_destroy = context_destroy;
|
|
}
|
|
|
|
void *
|
|
dlopen(const char *name, int mode)
|
|
{
|
|
Obj_Entry **old_obj_tail;
|
|
Obj_Entry *obj;
|
|
Obj_Entry *initobj;
|
|
Funclist initlist;
|
|
|
|
funclist_init(&initlist);
|
|
|
|
wlock_acquire();
|
|
GDB_STATE(RT_ADD);
|
|
|
|
old_obj_tail = obj_tail;
|
|
obj = NULL;
|
|
if (name == NULL) {
|
|
obj = obj_main;
|
|
obj->refcount++;
|
|
} else {
|
|
char *path = find_library(name, obj_main);
|
|
if (path != NULL)
|
|
obj = load_object(path);
|
|
}
|
|
|
|
if (obj) {
|
|
obj->dl_refcount++;
|
|
if (mode & RTLD_GLOBAL && objlist_find(&list_global, obj) == NULL)
|
|
objlist_add(&list_global, obj);
|
|
mode &= RTLD_MODEMASK;
|
|
if (*old_obj_tail != NULL) { /* We loaded something new. */
|
|
assert(*old_obj_tail == obj);
|
|
|
|
if (load_needed_objects(obj) == -1 ||
|
|
(init_dag(obj), relocate_objects(obj, mode == RTLD_NOW)) == -1) {
|
|
obj->dl_refcount--;
|
|
unref_dag(obj);
|
|
if (obj->refcount == 0)
|
|
unload_object(obj);
|
|
obj = NULL;
|
|
} else {
|
|
/* Make list of init functions to call, in reverse order */
|
|
for (initobj = obj; initobj != NULL; initobj = initobj->next)
|
|
if (initobj->init != NULL)
|
|
funclist_push_head(&initlist, initobj->init);
|
|
}
|
|
}
|
|
}
|
|
|
|
GDB_STATE(RT_CONSISTENT);
|
|
|
|
/* Call the init functions with no locks held. */
|
|
lock_release();
|
|
funclist_call(&initlist);
|
|
wlock_acquire();
|
|
funclist_clear(&initlist);
|
|
lock_release();
|
|
return obj;
|
|
}
|
|
|
|
void *
|
|
dlsym(void *handle, const char *name)
|
|
{
|
|
const Obj_Entry *obj;
|
|
unsigned long hash;
|
|
const Elf_Sym *def;
|
|
const Obj_Entry *defobj;
|
|
|
|
hash = elf_hash(name);
|
|
def = NULL;
|
|
defobj = NULL;
|
|
|
|
wlock_acquire();
|
|
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");
|
|
lock_release();
|
|
return NULL;
|
|
}
|
|
if (handle == NULL) { /* Just the caller's shared object. */
|
|
def = symlook_obj(name, hash, obj, true);
|
|
defobj = obj;
|
|
} else { /* All the shared objects after the caller's */
|
|
while ((obj = obj->next) != NULL) {
|
|
if ((def = symlook_obj(name, hash, obj, true)) != NULL) {
|
|
defobj = obj;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
} else {
|
|
if ((obj = dlcheck(handle)) == NULL) {
|
|
lock_release();
|
|
return NULL;
|
|
}
|
|
|
|
if (obj->mainprog) {
|
|
/* Search main program and all libraries loaded by it. */
|
|
curmark++;
|
|
def = symlook_list(name, hash, &list_main, &defobj, true);
|
|
} 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);
|
|
defobj = obj;
|
|
}
|
|
}
|
|
|
|
if (def != NULL) {
|
|
lock_release();
|
|
return defobj->relocbase + def->st_value;
|
|
}
|
|
|
|
_rtld_error("Undefined symbol \"%s\"", name);
|
|
lock_release();
|
|
return NULL;
|
|
}
|
|
|
|
int
|
|
dladdr(const void *addr, Dl_info *info)
|
|
{
|
|
const Obj_Entry *obj;
|
|
const Elf_Sym *def;
|
|
void *symbol_addr;
|
|
unsigned long symoffset;
|
|
|
|
wlock_acquire();
|
|
obj = obj_from_addr(addr);
|
|
if (obj == NULL) {
|
|
_rtld_error("No shared object contains address");
|
|
lock_release();
|
|
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;
|
|
}
|
|
lock_release();
|
|
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;
|
|
}
|
|
}
|
|
}
|
|
|
|
static const Elf_Sym *
|
|
symlook_list(const char *name, unsigned long hash, Objlist *objlist,
|
|
const Obj_Entry **defobj_out, bool in_plt)
|
|
{
|
|
const Elf_Sym *symp;
|
|
const Elf_Sym *def;
|
|
const Obj_Entry *defobj;
|
|
const Objlist_Entry *elm;
|
|
|
|
def = NULL;
|
|
defobj = NULL;
|
|
STAILQ_FOREACH(elm, objlist, link) {
|
|
if (elm->obj->mark == curmark)
|
|
continue;
|
|
elm->obj->mark = curmark;
|
|
if ((symp = symlook_obj(name, hash, elm->obj, in_plt)) != NULL) {
|
|
if (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK) {
|
|
def = symp;
|
|
defobj = elm->obj;
|
|
if (ELF_ST_BIND(def->st_info) != STB_WEAK)
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
if (def != NULL)
|
|
*defobj_out = defobj;
|
|
return def;
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
|
|
if (symnum >= obj->nchains)
|
|
return NULL; /* Bad object */
|
|
symp = obj->symtab + symnum;
|
|
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;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Unload a dlopened object and its dependencies from memory and from
|
|
* our data structures. It is assumed that the DAG rooted in the
|
|
* object has already been unreferenced, and that the object has a
|
|
* reference count of 0.
|
|
*/
|
|
static void
|
|
unload_object(Obj_Entry *root)
|
|
{
|
|
Obj_Entry *obj;
|
|
Obj_Entry **linkp;
|
|
Objlist_Entry *elm;
|
|
|
|
assert(root->refcount == 0);
|
|
|
|
/* Remove the DAG from all objects' DAG lists. */
|
|
STAILQ_FOREACH(elm, &root->dagmembers , link)
|
|
objlist_remove(&elm->obj->dldags, root);
|
|
|
|
/* Remove the DAG from the RTLD_GLOBAL list. */
|
|
objlist_remove(&list_global, root);
|
|
|
|
/* Unmap all objects that are no longer referenced. */
|
|
linkp = &obj_list->next;
|
|
while ((obj = *linkp) != NULL) {
|
|
if (obj->refcount == 0) {
|
|
dbg("unloading \"%s\"", obj->path);
|
|
munmap(obj->mapbase, obj->mapsize);
|
|
linkmap_delete(obj);
|
|
*linkp = obj->next;
|
|
obj_free(obj);
|
|
} else
|
|
linkp = &obj->next;
|
|
}
|
|
obj_tail = linkp;
|
|
}
|
|
|
|
static void
|
|
unref_dag(Obj_Entry *root)
|
|
{
|
|
const Needed_Entry *needed;
|
|
|
|
assert(root->refcount != 0);
|
|
root->refcount--;
|
|
if (root->refcount == 0)
|
|
for (needed = root->needed; needed != NULL; needed = needed->next)
|
|
if (needed->obj != NULL)
|
|
unref_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);
|
|
}
|