elf.c

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    lockstate = rlock_acquire(rtld_bind_lock);

    if (handle == NULL || handle == RTLD_SELF) {
	void *retaddr;

	retaddr = __builtin_return_address(0);	/* __GNUC__ only */
	if ((obj = obj_from_addr(retaddr)) == NULL)
	    _rtld_error("Cannot determine caller's shared object");
    } else
	obj = dlcheck(handle);

    if (obj == NULL) {
	rlock_release(rtld_bind_lock, lockstate);
	return (-1);
    }

    error = 0;
    switch (request) {
    case RTLD_DI_LINKMAP:
	*((struct link_map const **)p) = &obj->linkmap;
	break;
    case RTLD_DI_ORIGIN:
	error = rtld_dirname(obj->path, p);
	break;

    case RTLD_DI_SERINFOSIZE:
    case RTLD_DI_SERINFO:
	error = do_search_info(obj, request, (struct dl_serinfo *)p);
	break;

    default:
	_rtld_error("Invalid request %d passed to dlinfo()", request);
	error = -1;
    }

    rlock_release(rtld_bind_lock, lockstate);

    return (error);
}

struct fill_search_info_args {
    int		 request;
    unsigned int flags;
    Dl_serinfo  *serinfo;
    Dl_serpath  *serpath;
    char	*strspace;
};

static void *
fill_search_info(const char *dir, size_t dirlen, void *param)
{
    struct fill_search_info_args *arg;

    arg = param;

    if (arg->request == RTLD_DI_SERINFOSIZE) {
	arg->serinfo->dls_cnt ++;
	arg->serinfo->dls_size += dirlen + 1;
    } else {
	struct dl_serpath *s_entry;

	s_entry = arg->serpath;
	s_entry->dls_name  = arg->strspace;
	s_entry->dls_flags = arg->flags;

	strncpy(arg->strspace, dir, dirlen);
	arg->strspace[dirlen] = '\0';

	arg->strspace += dirlen + 1;
	arg->serpath++;
    }

    return (NULL);
}

static int
do_search_info(const Obj_Entry *obj, int request, struct dl_serinfo *info)
{
    struct dl_serinfo _info;
    struct fill_search_info_args args;

    args.request = RTLD_DI_SERINFOSIZE;
    args.serinfo = &_info;

    _info.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
    _info.dls_cnt  = 0;

    path_enumerate(ld_library_path, fill_search_info, &args);
    path_enumerate(obj->rpath, fill_search_info, &args);
    path_enumerate(gethints(), fill_search_info, &args);
    path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args);


    if (request == RTLD_DI_SERINFOSIZE) {
	info->dls_size = _info.dls_size;
	info->dls_cnt = _info.dls_cnt;
	return (0);
    }

    if (info->dls_cnt != _info.dls_cnt || info->dls_size != _info.dls_size) {
	_rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()");
	return (-1);
    }

    args.request  = RTLD_DI_SERINFO;
    args.serinfo  = info;
    args.serpath  = &info->dls_serpath[0];
    args.strspace = (char *)&info->dls_serpath[_info.dls_cnt];

    args.flags = LA_SER_LIBPATH;
    if (path_enumerate(ld_library_path, fill_search_info, &args) != NULL)
	return (-1);

    args.flags = LA_SER_RUNPATH;
    if (path_enumerate(obj->rpath, fill_search_info, &args) != NULL)
	return (-1);

    args.flags = LA_SER_CONFIG;
    if (path_enumerate(gethints(), fill_search_info, &args) != NULL)
	return (-1);

    args.flags = LA_SER_DEFAULT;
    if (path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args) != NULL)
	return (-1);
    return (0);
}

static int
rtld_dirname(const char *path, char *bname)
{
    const char *endp;

    /* Empty or NULL string gets treated as "." */
    if (path == NULL || *path == '\0') {
	bname[0] = '.';
	bname[1] = '\0';
	return (0);
    }

    /* Strip trailing slashes */
    endp = path + strlen(path) - 1;
    while (endp > path && *endp == '/')
	endp--;

    /* Find the start of the dir */
    while (endp > path && *endp != '/')
	endp--;

    /* Either the dir is "/" or there are no slashes */
    if (endp == path) {
	bname[0] = *endp == '/' ? '/' : '.';
	bname[1] = '\0';
	return (0);
    } else {
	do {
	    endp--;
	} while (endp > path && *endp == '/');
    }

    if (endp - path + 2 > PATH_MAX)
    {
	_rtld_error("Filename is too long: %s", path);
	return(-1);
    }

    strncpy(bname, path, endp - path + 1);
    bname[endp - path + 1] = '\0';
    return (0);
}

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.
 *
 * The two parameters allow the debugger to easily find and determine
 * what the runtime loader is doing and to whom it is doing it.
 *
 * When the loadhook trap is hit (r_debug_state, set at program
 * initialization), the arguments can be found on the stack:
 *
 *  +8   struct link_map *m
 *  +4   struct r_debug  *rd
 *  +0   RetAddr
 */
void
r_debug_state(struct r_debug* rd, struct link_map *m)
{
}

/*
 * Get address of the pointer variable in the main program.
 */
static const void **
get_program_var_addr(const char *name)
{
    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);
	    return addr;
	}
    }
    return NULL;
}

/*
 * 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 void **addr;

    if ((addr = get_program_var_addr(name)) != NULL) {
	dbg("\"%s\": *%p <-- %p", name, addr, value);
	*addr = value;
    }
}

/*
 * Given a symbol name 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.
 */
static const Elf_Sym *
symlook_default(const char *name, unsigned long hash,
    const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt)
{
    DoneList donelist;
    const Elf_Sym *def;
    const Elf_Sym *symp;
    const Obj_Entry *obj;
    const Obj_Entry *defobj;
    const Objlist_Entry *elm;
    def = NULL;
    defobj = NULL;
    donelist_init(&donelist);

    /* Look first in the referencing object if linked symbolically. */
    if (refobj->symbolic && !donelist_check(&donelist, refobj)) {
	symp = symlook_obj(name, hash, refobj, in_plt);
	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, &donelist);
	if (symp != NULL &&
	  (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) {
	    def = symp;
	    defobj = obj;
	}
    }

    /* Search all DAGs whose roots are RTLD_GLOBAL objects. */
    STAILQ_FOREACH(elm, &list_global, link) {
       if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK)
           break;
       symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt,
         &donelist);
	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,
	  &donelist);
	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 (def != NULL)
	*defobj_out = defobj;
    return def;
}

static const Elf_Sym *
symlook_list(const char *name, unsigned long hash, Objlist *objlist,
  const Obj_Entry **defobj_out, bool in_plt, DoneList *dlp)
{
    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 (donelist_check(dlp, elm->obj))
	    continue;
	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;
}

#endif /* 0 */

/*
 * 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 (name[0] == strp[0] && 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;
}

#if 0

static void
trace_loaded_objects(Obj_Entry *obj)
{
    char	*fmt1, *fmt2, *fmt, *main_local, *list_containers;
    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";

    list_containers = getenv(LD_ "TRACE_LOADED_OBJECTS_ALL");

    for (; obj; obj = obj->next) {
	Needed_Entry		*needed;
	char			*name, *path;
	bool			is_lib;

	if (list_containers && obj->needed != NULL)
	    printf("%s:\n", obj->path);
	for (needed = obj->needed; needed; needed = needed->next) {
	    if (needed->obj != NULL) {
		if (needed->obj->traced && !list_containers)
		    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');