kernel/params.c

   1 /* Helpers for initial module or kernel cmdline parsing
   2    Copyright (C) 2001 Rusty Russell.
   3
   4     This program is free software; you can redistribute it and/or modify
   5     it under the terms of the GNU General Public License as published by
   6     the Free Software Foundation; either version 2 of the License, or
   7     (at your option) any later version.
   8
   9     This program is distributed in the hope that it will be useful,
  10     but WITHOUT ANY WARRANTY; without even the implied warranty of
  11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12     GNU General Public License for more details.
  13
  14     You should have received a copy of the GNU General Public License
  15     along with this program; if not, write to the Free Software
  16     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  17 */
  18 #include <linux/config.h>
  19 #include <linux/moduleparam.h>
  20 #include <linux/kernel.h>
  21 #include <linux/string.h>
  22 #include <linux/errno.h>
  23 #include <linux/module.h>
  24 #include <linux/device.h>
  25 #include <linux/err.h>
  26
  27 #if 0
  28 #define DEBUGP printk
  29 #else
  30 #define DEBUGP(fmt, a...)
  31 #endif
  32
  33 static inline int dash2underscore(char c)
  34 {
  35         if (c == '-')
  36                 return '_';
  37         return c;
  38 }
  39
  40 static inline int parameq(const char *input, const char *paramname)
  41 {
  42         unsigned int i;
  43         for (i = 0; dash2underscore(input[i]) == paramname[i]; i++)
  44                 if (input[i] == '\0')
  45                         return 1;
  46         return 0;
  47 }
  48
  49 static int parse_one(char *param,
  50                      char *val,
  51                      struct kernel_param *params,
  52                      unsigned num_params,
  53                      int (*handle_unknown)(char *param, char *val))
  54 {
  55         unsigned int i;
  56
  57         /* Find parameter */
  58         for (i = 0; i < num_params; i++) {
  59                 if (parameq(param, params[i].name)) {
  60                         DEBUGP("They are equal!  Calling %p\n",
  61                                params[i].set);
  62                         return params[i].set(val, &params[i]);
  63                 }
  64         }
  65
  66         if (handle_unknown) {
  67                 DEBUGP("Unknown argument: calling %p\n", handle_unknown);
  68                 return handle_unknown(param, val);
  69         }
  70
  71         DEBUGP("Unknown argument `%s'\n", param);
  72         return -ENOENT;
  73 }
  74
  75 /* You can use " around spaces, but can't escape ". */
  76 /* Hyphens and underscores equivalent in parameter names. */
  77 static char *next_arg(char *args, char **param, char **val)
  78 {
  79         unsigned int i, equals = 0;
  80         int in_quote = 0, quoted = 0;
  81         char *next;
  82
  83         /* Chew any extra spaces */
  84         while (*args == ' ') args++;
  85         if (*args == '"') {
  86                 args++;
  87                 in_quote = 1;
  88                 quoted = 1;
  89         }
  90
  91         for (i = 0; args[i]; i++) {
  92                 if (args[i] == ' ' && !in_quote)
  93                         break;
  94                 if (equals == 0) {
  95                         if (args[i] == '=')
  96                                 equals = i;
  97                 }
  98                 if (args[i] == '"')
  99                         in_quote = !in_quote;
 100         }
 101
 102         *param = args;
 103         if (!equals)
 104                 *val = NULL;
 105         else {
 106                 args[equals] = '\0';
 107                 *val = args + equals + 1;
 108
 109                 /* Don't include quotes in value. */
 110                 if (**val == '"') {
 111                         (*val)++;
 112                         if (args[i-1] == '"')
 113                                 args[i-1] = '\0';
 114                 }
 115                 if (quoted && args[i-1] == '"')
 116                         args[i-1] = '\0';
 117         }
 118
 119         if (args[i]) {
 120                 args[i] = '\0';
 121                 next = args + i + 1;
 122         } else
 123                 next = args + i;
 124         return next;
 125 }
 126
 127 /* Args looks like "foo=bar,bar2 baz=fuz wiz". */
 128 int parse_args(const char *name,
 129                char *args,
 130                struct kernel_param *params,
 131                unsigned num,
 132                int (*unknown)(char *param, char *val))
 133 {
 134         char *param, *val;
 135
 136         DEBUGP("Parsing ARGS: %s\n", args);
 137
 138         while (*args) {
 139                 int ret;
 140
 141                 args = next_arg(args, &param, &val);
 142                 ret = parse_one(param, val, params, num, unknown);
 143                 switch (ret) {
 144                 case -ENOENT:
 145                         printk(KERN_ERR "%s: Unknown parameter `%s'\n",
 146                                name, param);
 147                         return ret;
 148                 case -ENOSPC:
 149                         printk(KERN_ERR
 150                                "%s: `%s' too large for parameter `%s'\n",
 151                                name, val ?: "", param);
 152                         return ret;
 153                 case 0:
 154                         break;
 155                 default:
 156                         printk(KERN_ERR
 157                                "%s: `%s' invalid for parameter `%s'\n",
 158                                name, val ?: "", param);
 159                         return ret;
 160                 }
 161         }
 162
 163         /* All parsed OK. */
 164         return 0;
 165 }
 166
 167 /* Lazy bastard, eh? */
 168 #define STANDARD_PARAM_DEF(name, type, format, tmptype, strtolfn)       \
 169         int param_set_##name(const char *val, struct kernel_param *kp)  \
 170         {                                                               \
 171                 char *endp;                                             \
 172                 tmptype l;                                              \
 173                                                                         \
 174                 if (!val) return -EINVAL;                               \
 175                 l = strtolfn(val, &endp, 0);                            \
 176                 if (endp == val || ((type)l != l))                      \
 177                         return -EINVAL;                                 \
 178                 *((type *)kp->arg) = l;                                 \
 179                 return 0;                                               \
 180         }                                                               \
 181         int param_get_##name(char *buffer, struct kernel_param *kp)     \
 182         {                                                               \
 183                 return sprintf(buffer, format, *((type *)kp->arg));     \
 184         }
 185
 186 STANDARD_PARAM_DEF(byte, unsigned char, "%c", unsigned long, simple_strtoul);
 187 STANDARD_PARAM_DEF(short, short, "%hi", long, simple_strtol);
 188 STANDARD_PARAM_DEF(ushort, unsigned short, "%hu", unsigned long, simple_strtoul);
 189 STANDARD_PARAM_DEF(int, int, "%i", long, simple_strtol);
 190 STANDARD_PARAM_DEF(uint, unsigned int, "%u", unsigned long, simple_strtoul);
 191 STANDARD_PARAM_DEF(long, long, "%li", long, simple_strtol);
 192 STANDARD_PARAM_DEF(ulong, unsigned long, "%lu", unsigned long, simple_strtoul);
 193
 194 int param_set_charp(const char *val, struct kernel_param *kp)
 195 {
 196         if (!val) {
 197                 printk(KERN_ERR "%s: string parameter expected\n",
 198                        kp->name);
 199                 return -EINVAL;
 200         }
 201
 202         if (strlen(val) > 1024) {
 203                 printk(KERN_ERR "%s: string parameter too long\n",
 204                        kp->name);
 205                 return -ENOSPC;
 206         }
 207
 208         *(char **)kp->arg = (char *)val;
 209         return 0;
 210 }
 211
 212 int param_get_charp(char *buffer, struct kernel_param *kp)
 213 {
 214         return sprintf(buffer, "%s", *((char **)kp->arg));
 215 }
 216
 217 int param_set_bool(const char *val, struct kernel_param *kp)
 218 {
 219         /* No equals means "set"... */
 220         if (!val) val = "1";
 221
 222         /* One of =[yYnN01] */
 223         switch (val[0]) {
 224         case 'y': case 'Y': case '1':
 225                 *(int *)kp->arg = 1;
 226                 return 0;
 227         case 'n': case 'N': case '0':
 228                 *(int *)kp->arg = 0;
 229                 return 0;
 230         }
 231         return -EINVAL;
 232 }
 233
 234 int param_get_bool(char *buffer, struct kernel_param *kp)
 235 {
 236         /* Y and N chosen as being relatively non-coder friendly */
 237         return sprintf(buffer, "%c", (*(int *)kp->arg) ? 'Y' : 'N');
 238 }
 239
 240 int param_set_invbool(const char *val, struct kernel_param *kp)
 241 {
 242         int boolval, ret;
 243         struct kernel_param dummy = { .arg = &boolval };
 244
 245         ret = param_set_bool(val, &dummy);
 246         if (ret == 0)
 247                 *(int *)kp->arg = !boolval;
 248         return ret;
 249 }
 250
 251 int param_get_invbool(char *buffer, struct kernel_param *kp)
 252 {
 253         int val;
 254         struct kernel_param dummy = { .arg = &val };
 255
 256         val = !*(int *)kp->arg;
 257         return param_get_bool(buffer, &dummy);
 258 }
 259
 260 /* We cheat here and temporarily mangle the string. */
 261 int param_array(const char *name,
 262                 const char *val,
 263                 unsigned int min, unsigned int max,
 264                 void *elem, int elemsize,
 265                 int (*set)(const char *, struct kernel_param *kp),
 266                 int *num)
 267 {
 268         int ret;
 269         struct kernel_param kp;
 270         char save;
 271
 272         /* Get the name right for errors. */
 273         kp.name = name;
 274         kp.arg = elem;
 275
 276         /* No equals sign? */
 277         if (!val) {
 278                 printk(KERN_ERR "%s: expects arguments\n", name);
 279                 return -EINVAL;
 280         }
 281
 282         *num = 0;
 283         /* We expect a comma-separated list of values. */
 284         do {
 285                 int len;
 286
 287                 if (*num == max) {
 288                         printk(KERN_ERR "%s: can only take %i arguments\n",
 289                                name, max);
 290                         return -EINVAL;
 291                 }
 292                 len = strcspn(val, ",");
 293
 294                 /* nul-terminate and parse */
 295                 save = val[len];
 296                 ((char *)val)[len] = '\0';
 297                 ret = set(val, &kp);
 298
 299                 if (ret != 0)
 300                         return ret;
 301                 kp.arg += elemsize;
 302                 val += len+1;
 303                 (*num)++;
 304         } while (save == ',');
 305
 306         if (*num < min) {
 307                 printk(KERN_ERR "%s: needs at least %i arguments\n",
 308                        name, min);
 309                 return -EINVAL;
 310         }
 311         return 0;
 312 }
 313
 314 int param_array_set(const char *val, struct kernel_param *kp)
 315 {
 316         struct kparam_array *arr = kp->arg;
 317         unsigned int temp_num;
 318
 319         return param_array(kp->name, val, 1, arr->max, arr->elem,
 320                            arr->elemsize, arr->set, arr->num ?: &temp_num);
 321 }
 322
 323 int param_array_get(char *buffer, struct kernel_param *kp)
 324 {
 325         int i, off, ret;
 326         struct kparam_array *arr = kp->arg;
 327         struct kernel_param p;
 328
 329         p = *kp;
 330         for (i = off = 0; i < (arr->num ? *arr->num : arr->max); i++) {
 331                 if (i)
 332                         buffer[off++] = ',';
 333                 p.arg = arr->elem + arr->elemsize * i;
 334                 ret = arr->get(buffer + off, &p);
 335                 if (ret < 0)
 336                         return ret;
 337                 off += ret;
 338         }
 339         buffer[off] = '\0';
 340         return off;
 341 }
 342
 343 int param_set_copystring(const char *val, struct kernel_param *kp)
 344 {
 345         struct kparam_string *kps = kp->arg;
 346
 347         if (strlen(val)+1 > kps->maxlen) {
 348                 printk(KERN_ERR "%s: string doesn't fit in %u chars.\n",
 349                        kp->name, kps->maxlen-1);
 350                 return -ENOSPC;
 351         }
 352         strcpy(kps->string, val);
 353         return 0;
 354 }
 355
 356 int param_get_string(char *buffer, struct kernel_param *kp)
 357 {
 358         struct kparam_string *kps = kp->arg;
 359         return strlcpy(buffer, kps->string, kps->maxlen);
 360 }
 361
 362 /* sysfs output in /sys/modules/XYZ/parameters/ */
 363
 364 extern struct kernel_param __start___param[], __stop___param[];
 365
 366 #define MAX_KBUILD_MODNAME KOBJ_NAME_LEN
 367
 368 struct param_attribute
 369 {
 370         struct module_attribute mattr;
 371         struct kernel_param *param;
 372 };
 373
 374 struct module_param_attrs
 375 {
 376         struct attribute_group grp;
 377         struct param_attribute attrs[0];
 378 };
 379
 380 #define to_param_attr(n) container_of(n, struct param_attribute, mattr);
 381
 382 static ssize_t param_attr_show(struct module_attribute *mattr,
 383                                struct module *mod, char *buf)
 384 {
 385         int count;
 386         struct param_attribute *attribute = to_param_attr(mattr);
 387
 388         if (!attribute->param->get)
 389                 return -EPERM;
 390
 391         count = attribute->param->get(buf, attribute->param);
 392         if (count > 0) {
 393                 strcat(buf, "\n");
 394                 ++count;
 395         }
 396         return count;
 397 }
 398
 399 /* sysfs always hands a nul-terminated string in buf.  We rely on that. */
 400 static ssize_t param_attr_store(struct module_attribute *mattr,
 401                                 struct module *owner,
 402                                 const char *buf, size_t len)
 403 {
 404         int err;
 405         struct param_attribute *attribute = to_param_attr(mattr);
 406
 407         if (!attribute->param->set)
 408                 return -EPERM;
 409
 410         err = attribute->param->set(buf, attribute->param);
 411         if (!err)
 412                 return len;
 413         return err;
 414 }
 415
 416 #ifdef CONFIG_MODULES
 417 #define __modinit
 418 #else
 419 #define __modinit __init
 420 #endif
 421
 422 /*
 423  * param_sysfs_setup - setup sysfs support for one module or KBUILD_MODNAME
 424  * @mk: struct module_kobject (contains parent kobject)
 425  * @kparam: array of struct kernel_param, the actual parameter definitions
 426  * @num_params: number of entries in array
 427  * @name_skip: offset where the parameter name start in kparam[].name. Needed for built-in "modules"
 428  *
 429  * Create a kobject for a (per-module) group of parameters, and create files
 430  * in sysfs. A pointer to the param_kobject is returned on success,
 431  * NULL if there's no parameter to export, or other ERR_PTR(err).
 432  */
 433 static __modinit struct module_param_attrs *
 434 param_sysfs_setup(struct module_kobject *mk,
 435                   struct kernel_param *kparam,
 436                   unsigned int num_params,
 437                   unsigned int name_skip)
 438 {
 439         struct module_param_attrs *mp;
 440         unsigned int valid_attrs = 0;
 441         unsigned int i, size[2];
 442         struct param_attribute *pattr;
 443         struct attribute **gattr;
 444         int err;
 445
 446         for (i=0; i<num_params; i++) {
 447                 if (kparam[i].perm)
 448                         valid_attrs++;
 449         }
 450
 451         if (!valid_attrs)
 452                 return NULL;
 453
 454         size[0] = ALIGN(sizeof(*mp) +
 455                         valid_attrs * sizeof(mp->attrs[0]),
 456                         sizeof(mp->grp.attrs[0]));
 457         size[1] = (valid_attrs + 1) * sizeof(mp->grp.attrs[0]);
 458
 459         mp = kmalloc(size[0] + size[1], GFP_KERNEL);
 460         if (!mp)
 461                 return ERR_PTR(-ENOMEM);
 462
 463         mp->grp.name = "parameters";
 464         mp->grp.attrs = (void *)mp + size[0];
 465
 466         pattr = &mp->attrs[0];
 467         gattr = &mp->grp.attrs[0];
 468         for (i = 0; i < num_params; i++) {
 469                 struct kernel_param *kp = &kparam[i];
 470                 if (kp->perm) {
 471                         pattr->param = kp;
 472                         pattr->mattr.show = param_attr_show;
 473                         pattr->mattr.store = param_attr_store;
 474                         pattr->mattr.attr.name = (char *)&kp->name[name_skip];
 475                         pattr->mattr.attr.owner = mk->mod;
 476                         pattr->mattr.attr.mode = kp->perm;
 477                         *(gattr++) = &(pattr++)->mattr.attr;
 478                 }
 479         }
 480         *gattr = NULL;
 481
 482         if ((err = sysfs_create_group(&mk->kobj, &mp->grp))) {
 483                 kfree(mp);
 484                 return ERR_PTR(err);
 485         }
 486         return mp;
 487 }
 488
 489
 490 #ifdef CONFIG_MODULES
 491
 492 /*
 493  * module_param_sysfs_setup - setup sysfs support for one module
 494  * @mod: module
 495  * @kparam: module parameters (array)
 496  * @num_params: number of module parameters
 497  *
 498  * Adds sysfs entries for module parameters, and creates a link from
 499  * /sys/module/[mod->name]/parameters to /sys/parameters/[mod->name]/
 500  */
 501 int module_param_sysfs_setup(struct module *mod,
 502                              struct kernel_param *kparam,
 503                              unsigned int num_params)
 504 {
 505         struct module_param_attrs *mp;
 506
 507         mp = param_sysfs_setup(&mod->mkobj, kparam, num_params, 0);
 508         if (IS_ERR(mp))
 509                 return PTR_ERR(mp);
 510
 511         mod->param_attrs = mp;
 512         return 0;
 513 }
 514
 515 /*
 516  * module_param_sysfs_remove - remove sysfs support for one module
 517  * @mod: module
 518  *
 519  * Remove sysfs entries for module parameters and the corresponding
 520  * kobject.
 521  */
 522 void module_param_sysfs_remove(struct module *mod)
 523 {
 524         if (mod->param_attrs) {
 525                 sysfs_remove_group(&mod->mkobj.kobj,
 526                                    &mod->param_attrs->grp);
 527                 /* We are positive that no one is using any param
 528                  * attrs at this point.  Deallocate immediately. */
 529                 kfree(mod->param_attrs);
 530                 mod->param_attrs = NULL;
 531         }
 532 }
 533 #endif
 534
 535 /*
 536  * kernel_param_sysfs_setup - wrapper for built-in params support
 537  */
 538 static void __init kernel_param_sysfs_setup(const char *name,
 539                                             struct kernel_param *kparam,
 540                                             unsigned int num_params,
 541                                             unsigned int name_skip)
 542 {
 543         struct module_kobject *mk;
 544
 545         mk = kmalloc(sizeof(struct module_kobject), GFP_KERNEL);
 546         memset(mk, 0, sizeof(struct module_kobject));
 547
 548         mk->mod = THIS_MODULE;
 549         kobj_set_kset_s(mk, module_subsys);
 550         kobject_set_name(&mk->kobj, name);
 551         kobject_register(&mk->kobj);
 552
 553         /* no need to keep the kobject if no parameter is exported */
 554         if (!param_sysfs_setup(mk, kparam, num_params, name_skip)) {
 555                 kobject_unregister(&mk->kobj);
 556                 kfree(mk);
 557         }
 558 }
 559
 560 /*
 561  * param_sysfs_builtin - add contents in /sys/parameters for built-in modules
 562  *
 563  * Add module_parameters to sysfs for "modules" built into the kernel.
 564  *
 565  * The "module" name (KBUILD_MODNAME) is stored before a dot, the
 566  * "parameter" name is stored behind a dot in kernel_param->name. So,
 567  * extract the "module" name for all built-in kernel_param-eters,
 568  * and for all who have the same, call kernel_param_sysfs_setup.
 569  */
 570 static void __init param_sysfs_builtin(void)
 571 {
 572         struct kernel_param *kp, *kp_begin = NULL;
 573         unsigned int i, name_len, count = 0;
 574         char modname[MAX_KBUILD_MODNAME + 1] = "";
 575
 576         for (i=0; i < __stop___param - __start___param; i++) {
 577                 char *dot;
 578
 579                 kp = &__start___param[i];
 580
 581                 /* We do not handle args without periods. */
 582                 dot = memchr(kp->name, '.', MAX_KBUILD_MODNAME);
 583                 if (!dot) {
 584                         DEBUGP("couldn't find period in %s\n", kp->name);
 585                         continue;
 586                 }
 587                 name_len = dot - kp->name;
 588
 589                 /* new kbuild_modname? */
 590                 if (strlen(modname) != name_len
 591                     || strncmp(modname, kp->name, name_len) != 0) {
 592                         /* add a new kobject for previous kernel_params. */
 593                         if (count)
 594                                 kernel_param_sysfs_setup(modname,
 595                                                          kp_begin,
 596                                                          count,
 597                                                          strlen(modname)+1);
 598
 599                         strncpy(modname, kp->name, name_len);
 600                         modname[name_len] = '\0';
 601                         count = 0;
 602                         kp_begin = kp;
 603                 }
 604                 count++;
 605         }
 606
 607         /* last kernel_params need to be registered as well */
 608         if (count)
 609                 kernel_param_sysfs_setup(modname, kp_begin, count,
 610                                          strlen(modname)+1);
 611 }
 612
 613
 614 /* module-related sysfs stuff */
 615 #ifdef CONFIG_MODULES
 616
 617 #define to_module_attr(n) container_of(n, struct module_attribute, attr);
 618 #define to_module_kobject(n) container_of(n, struct module_kobject, kobj);
 619
 620 static ssize_t module_attr_show(struct kobject *kobj,
 621                                 struct attribute *attr,
 622                                 char *buf)
 623 {
 624         struct module_attribute *attribute;
 625         struct module_kobject *mk;
 626         int ret;
 627
 628         attribute = to_module_attr(attr);
 629         mk = to_module_kobject(kobj);
 630
 631         if (!attribute->show)
 632                 return -EIO;
 633
 634         if (!try_module_get(mk->mod))
 635                 return -ENODEV;
 636
 637         ret = attribute->show(attribute, mk->mod, buf);
 638
 639         module_put(mk->mod);
 640
 641         return ret;
 642 }
 643
 644 static ssize_t module_attr_store(struct kobject *kobj,
 645                                 struct attribute *attr,
 646                                 const char *buf, size_t len)
 647 {
 648         struct module_attribute *attribute;
 649         struct module_kobject *mk;
 650         int ret;
 651
 652         attribute = to_module_attr(attr);
 653         mk = to_module_kobject(kobj);
 654
 655         if (!attribute->store)
 656                 return -EIO;
 657
 658         if (!try_module_get(mk->mod))
 659                 return -ENODEV;
 660
 661         ret = attribute->store(attribute, mk->mod, buf, len);
 662
 663         module_put(mk->mod);
 664
 665         return ret;
 666 }
 667
 668 static struct sysfs_ops module_sysfs_ops = {
 669         .show = module_attr_show,
 670         .store = module_attr_store,
 671 };
 672
 673 #else
 674 static struct sysfs_ops module_sysfs_ops = {
 675         .show = NULL,
 676         .store = NULL,
 677 };
 678 #endif
 679
 680 static struct kobj_type module_ktype = {
 681         .sysfs_ops =    &module_sysfs_ops,
 682 };
 683
 684 decl_subsys(module, &module_ktype, NULL);
 685
 686 /*
 687  * param_sysfs_init - wrapper for built-in params support
 688  */
 689 static int __init param_sysfs_init(void)
 690 {
 691         subsystem_register(&module_subsys);
 692
 693         param_sysfs_builtin();
 694
 695         return 0;
 696 }
 697 __initcall(param_sysfs_init);
 698
 699 EXPORT_SYMBOL(param_set_byte);
 700 EXPORT_SYMBOL(param_get_byte);
 701 EXPORT_SYMBOL(param_set_short);
 702 EXPORT_SYMBOL(param_get_short);
 703 EXPORT_SYMBOL(param_set_ushort);
 704 EXPORT_SYMBOL(param_get_ushort);
 705 EXPORT_SYMBOL(param_set_int);
 706 EXPORT_SYMBOL(param_get_int);
 707 EXPORT_SYMBOL(param_set_uint);
 708 EXPORT_SYMBOL(param_get_uint);
 709 EXPORT_SYMBOL(param_set_long);
 710 EXPORT_SYMBOL(param_get_long);
 711 EXPORT_SYMBOL(param_set_ulong);
 712 EXPORT_SYMBOL(param_get_ulong);
 713 EXPORT_SYMBOL(param_set_charp);
 714 EXPORT_SYMBOL(param_get_charp);
 715 EXPORT_SYMBOL(param_set_bool);
 716 EXPORT_SYMBOL(param_get_bool);
 717 EXPORT_SYMBOL(param_set_invbool);
 718 EXPORT_SYMBOL(param_get_invbool);
 719 EXPORT_SYMBOL(param_array_set);
 720 EXPORT_SYMBOL(param_array_get);
 721 EXPORT_SYMBOL(param_set_copystring);
 722 EXPORT_SYMBOL(param_get_string);