uci.h

   1 /*
   2  * libuci - Library for the Unified Configuration Interface
   3  * Copyright (C) 2008 Felix Fietkau <nbd@openwrt.org>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU Lesser General Public License version 2.1
   7  * as published by the Free Software Foundation
   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 Lesser General Public License for more details.
  13  */
  14
  15 #ifndef __LIBUCI_H
  16 #define __LIBUCI_H
  17
  18 #ifdef __cplusplus
  19 extern "C" {
  20 #endif
  21
  22 #include "uci_config.h"
  23
  24 /*
  25  * you can use these defines to enable debugging behavior for
  26  * apps compiled against libuci:
  27  *
  28  * #define UCI_DEBUG_TYPECAST:
  29  *   enable uci_element typecast checking at run time
  30  *
  31  */
  32
  33 #include <stdbool.h>
  34 #include <setjmp.h>
  35 #include <stdio.h>
  36 #include <stdint.h>
  37
  38 #define UCI_CONFDIR "/etc/config"
  39 #define UCI_SAVEDIR "/tmp/.uci"
  40 #define UCI_DIRMODE 0700
  41 #define UCI_FILEMODE 0600
  42
  43 enum
  44 {
  45         UCI_OK = 0,
  46         UCI_ERR_MEM,
  47         UCI_ERR_INVAL,
  48         UCI_ERR_NOTFOUND,
  49         UCI_ERR_IO,
  50         UCI_ERR_PARSE,
  51         UCI_ERR_DUPLICATE,
  52         UCI_ERR_UNKNOWN,
  53         UCI_ERR_LAST
  54 };
  55
  56 struct uci_list;
  57 struct uci_list
  58 {
  59         struct uci_list *next;
  60         struct uci_list *prev;
  61 };
  62
  63 struct uci_ptr;
  64 struct uci_plugin;
  65 struct uci_hook_ops;
  66 struct uci_element;
  67 struct uci_package;
  68 struct uci_section;
  69 struct uci_option;
  70 struct uci_delta;
  71 struct uci_context;
  72 struct uci_backend;
  73 struct uci_parse_option;
  74 struct uci_parse_context;
  75
  76
  77 /**
  78  * uci_alloc_context: Allocate a new uci context
  79  */
  80 extern struct uci_context *uci_alloc_context(void);
  81
  82 /**
  83  * uci_free_context: Free the uci context including all of its data
  84  */
  85 extern void uci_free_context(struct uci_context *ctx);
  86
  87 /**
  88  * uci_perror: Print the last uci error that occured
  89  * @ctx: uci context
  90  * @str: string to print before the error message
  91  */
  92 extern void uci_perror(struct uci_context *ctx, const char *str);
  93
  94 /**
  95  * uci_geterror: Get an error string for the last uci error
  96  * @ctx: uci context
  97  * @dest: target pointer for the string
  98  * @str: prefix for the error message
  99  *
 100  * Note: string must be freed by the caller
 101  */
 102 extern void uci_get_errorstr(struct uci_context *ctx, char **dest, const char *str);
 103
 104 /**
 105  * uci_import: Import uci config data from a stream
 106  * @ctx: uci context
 107  * @stream: file stream to import from
 108  * @name: (optional) assume the config has the given name
 109  * @package: (optional) store the last parsed config package in this variable
 110  * @single: ignore the 'package' keyword and parse everything into a single package
 111  *
 112  * the name parameter is for config files that don't explicitly use the 'package <...>' keyword
 113  * if 'package' points to a non-null struct pointer, enable delta tracking and merge
 114  */
 115 extern int uci_import(struct uci_context *ctx, FILE *stream, const char *name, struct uci_package **package, bool single);
 116
 117 /**
 118  * uci_export: Export one or all uci config packages
 119  * @ctx: uci context
 120  * @stream: output stream
 121  * @package: (optional) uci config package to export
 122  * @header: include the package header
 123  */
 124 extern int uci_export(struct uci_context *ctx, FILE *stream, struct uci_package *package, bool header);
 125
 126 /**
 127  * uci_load: Parse an uci config file and store it in the uci context
 128  *
 129  * @ctx: uci context
 130  * @name: name of the config file (relative to the config directory)
 131  * @package: store the loaded config package in this variable
 132  */
 133 extern int uci_load(struct uci_context *ctx, const char *name, struct uci_package **package);
 134
 135 /**
 136  * uci_unload: Unload a config file from the uci context
 137  *
 138  * @ctx: uci context
 139  * @package: pointer to the uci_package struct
 140  */
 141 extern int uci_unload(struct uci_context *ctx, struct uci_package *p);
 142
 143 /**
 144  * uci_lookup_ptr: Split an uci tuple string and look up an element tree
 145  * @ctx: uci context
 146  * @ptr: lookup result struct
 147  * @str: uci tuple string to look up
 148  * @extended: allow extended syntax lookup
 149  *
 150  * if extended is set to true, uci_lookup_ptr supports the following
 151  * extended syntax:
 152  *
 153  * Examples:
 154  *   network.@interface[0].ifname ('ifname' option of the first interface section)
 155  *   network.@interface[-1]       (last interface section)
 156  * Note: uci_lookup_ptr will automatically load a config package if necessary
 157  * @str must not be constant, as it will be modified and used for the strings inside @ptr,
 158  * thus it must also be available as long as @ptr is in use.
 159  */
 160 extern int uci_lookup_ptr(struct uci_context *ctx, struct uci_ptr *ptr, char *str, bool extended);
 161
 162 /**
 163  * uci_add_section: Add an unnamed section
 164  * @ctx: uci context
 165  * @p: package to add the section to
 166  * @type: section type
 167  * @res: pointer to store a reference to the new section in
 168  */
 169 extern int uci_add_section(struct uci_context *ctx, struct uci_package *p, const char *type, struct uci_section **res);
 170
 171 /**
 172  * uci_set: Set an element's value; create the element if necessary
 173  * @ctx: uci context
 174  * @ptr: uci pointer
 175  *
 176  * The updated/created element is stored in ptr->last
 177  */
 178 extern int uci_set(struct uci_context *ctx, struct uci_ptr *ptr);
 179
 180 /**
 181  * uci_add_list: Append a string to an element list
 182  * @ctx: uci context
 183  * @ptr: uci pointer (with value)
 184  *
 185  * Note: if the given option already contains a string value,
 186  * it will be converted to an 1-element-list before appending the next element
 187  */
 188 extern int uci_add_list(struct uci_context *ctx, struct uci_ptr *ptr);
 189
 190 /**
 191  * uci_del_list: Remove a string from an element list
 192  * @ctx: uci context
 193  * @ptr: uci pointer (with value)
 194  *
 195  */
 196 extern int uci_del_list(struct uci_context *ctx, struct uci_ptr *ptr);
 197
 198 /**
 199  * uci_reorder: Reposition a section
 200  * @ctx: uci context
 201  * @s: uci section to reposition
 202  * @pos: new position in the section list
 203  */
 204 extern int uci_reorder_section(struct uci_context *ctx, struct uci_section *s, int pos);
 205
 206 /**
 207  * uci_rename: Rename an element
 208  * @ctx: uci context
 209  * @ptr: uci pointer (with value)
 210  */
 211 extern int uci_rename(struct uci_context *ctx, struct uci_ptr *ptr);
 212
 213 /**
 214  * uci_delete: Delete a section or option
 215  * @ctx: uci context
 216  * @ptr: uci pointer
 217  */
 218 extern int uci_delete(struct uci_context *ctx, struct uci_ptr *ptr);
 219
 220 /**
 221  * uci_save: save change delta for a package
 222  * @ctx: uci context
 223  * @p: uci_package struct
 224  */
 225 extern int uci_save(struct uci_context *ctx, struct uci_package *p);
 226
 227 /**
 228  * uci_commit: commit changes to a package
 229  * @ctx: uci context
 230  * @p: uci_package struct pointer
 231  * @overwrite: overwrite existing config data and flush delta
 232  *
 233  * committing may reload the whole uci_package data,
 234  * the supplied pointer is updated accordingly
 235  */
 236 extern int uci_commit(struct uci_context *ctx, struct uci_package **p, bool overwrite);
 237
 238 /**
 239  * uci_list_configs: List available uci config files
 240  * @ctx: uci context
 241  *
 242  * caller is responsible for freeing the allocated memory behind list
 243  */
 244 extern int uci_list_configs(struct uci_context *ctx, char ***list);
 245
 246 /**
 247  * uci_set_savedir: override the default delta save directory
 248  * @ctx: uci context
 249  * @dir: directory name
 250  */
 251 extern int uci_set_savedir(struct uci_context *ctx, const char *dir);
 252
 253 /**
 254  * uci_set_savedir: override the default config storage directory
 255  * @ctx: uci context
 256  * @dir: directory name
 257  */
 258 extern int uci_set_confdir(struct uci_context *ctx, const char *dir);
 259
 260 /**
 261  * uci_add_delta_path: add a directory to the search path for change delta files
 262  * @ctx: uci context
 263  * @dir: directory name
 264  *
 265  * This function allows you to add directories, which contain 'overlays'
 266  * for the active config, that will never be committed.
 267  */
 268 extern int uci_add_delta_path(struct uci_context *ctx, const char *dir);
 269
 270 /**
 271  * uci_revert: revert all changes to a config item
 272  * @ctx: uci context
 273  * @ptr: uci pointer
 274  */
 275 extern int uci_revert(struct uci_context *ctx, struct uci_ptr *ptr);
 276
 277 /**
 278  * uci_parse_argument: parse a shell-style argument, with an arbitrary quoting style
 279  * @ctx: uci context
 280  * @stream: input stream
 281  * @str: pointer to the current line (use NULL for parsing the next line)
 282  * @result: pointer for the result
 283  */
 284 extern int uci_parse_argument(struct uci_context *ctx, FILE *stream, char **str, char **result);
 285
 286 /**
 287  * uci_set_backend: change the default backend
 288  * @ctx: uci context
 289  * @name: name of the backend
 290  *
 291  * The default backend is "file", which uses /etc/config for config storage
 292  */
 293 extern int uci_set_backend(struct uci_context *ctx, const char *name);
 294
 295 /**
 296  * uci_validate_text: validate a value string for uci options
 297  * @str: value
 298  *
 299  * this function checks whether a given string is acceptable as value
 300  * for uci options
 301  */
 302 extern bool uci_validate_text(const char *str);
 303
 304
 305 /**
 306  * uci_add_hook: add a uci hook
 307  * @ctx: uci context
 308  * @ops: uci hook ops
 309  *
 310  * NB: allocated and freed by the caller
 311  */
 312 extern int uci_add_hook(struct uci_context *ctx, const struct uci_hook_ops *ops);
 313
 314 /**
 315  * uci_remove_hook: remove a uci hook
 316  * @ctx: uci context
 317  * @ops: uci hook ops
 318  */
 319 extern int uci_remove_hook(struct uci_context *ctx, const struct uci_hook_ops *ops);
 320
 321 /**
 322  * uci_load_plugin: load an uci plugin
 323  * @ctx: uci context
 324  * @filename: path to the uci plugin
 325  *
 326  * NB: plugin will be unloaded automatically when the context is freed
 327  */
 328 int uci_load_plugin(struct uci_context *ctx, const char *filename);
 329
 330 /**
 331  * uci_load_plugins: load all uci plugins from a directory
 332  * @ctx: uci context
 333  * @pattern: pattern of uci plugin files (optional)
 334  *
 335  * if pattern is NULL, then uci_load_plugins will call uci_load_plugin
 336  * for uci_*.so in <prefix>/lib/
 337  */
 338 int uci_load_plugins(struct uci_context *ctx, const char *pattern);
 339
 340 /**
 341  * uci_parse_ptr: parse a uci string into a uci_ptr
 342  * @ctx: uci context
 343  * @ptr: target data structure
 344  * @str: string to parse
 345  *
 346  * str is modified by this function
 347  */
 348 int uci_parse_ptr(struct uci_context *ctx, struct uci_ptr *ptr, char *str);
 349
 350 /**
 351  * uci_lookup_next: lookup a child element
 352  * @ctx: uci context
 353  * @e: target element pointer
 354  * @list: list of elements
 355  * @name: name of the child element
 356  *
 357  * if parent is NULL, the function looks up the package with the given name
 358  */
 359 int uci_lookup_next(struct uci_context *ctx, struct uci_element **e, struct uci_list *list, const char *name);
 360
 361 /**
 362  * uci_parse_section: look up a set of options
 363  * @s: uci section
 364  * @opts: list of options to look up
 365  * @n_opts: number of options to look up
 366  * @tb: array of pointers to found options
 367  */
 368 void uci_parse_section(struct uci_section *s, const struct uci_parse_option *opts,
 369                        int n_opts, struct uci_option **tb);
 370
 371 /**
 372  * uci_hash_options: build a hash over a list of options
 373  * @tb: list of option pointers
 374  * @n_opts: number of options
 375  */
 376 uint32_t uci_hash_options(struct uci_option **tb, int n_opts);
 377
 378
 379 /* UCI data structures */
 380 enum uci_type {
 381         UCI_TYPE_UNSPEC = 0,
 382         UCI_TYPE_DELTA = 1,
 383         UCI_TYPE_PACKAGE = 2,
 384         UCI_TYPE_SECTION = 3,
 385         UCI_TYPE_OPTION = 4,
 386         UCI_TYPE_PATH = 5,
 387         UCI_TYPE_BACKEND = 6,
 388         UCI_TYPE_ITEM = 7,
 389         UCI_TYPE_HOOK = 8,
 390         UCI_TYPE_PLUGIN = 9,
 391 };
 392
 393 enum uci_option_type {
 394         UCI_TYPE_STRING = 0,
 395         UCI_TYPE_LIST = 1,
 396 };
 397
 398 enum uci_flags {
 399         UCI_FLAG_STRICT =        (1 << 0), /* strict mode for the parser */
 400         UCI_FLAG_PERROR =        (1 << 1), /* print parser error messages */
 401         UCI_FLAG_EXPORT_NAME =   (1 << 2), /* when exporting, name unnamed sections */
 402         UCI_FLAG_SAVED_DELTA = (1 << 3), /* store the saved delta in memory as well */
 403 };
 404
 405 struct uci_element
 406 {
 407         struct uci_list list;
 408         enum uci_type type;
 409         char *name;
 410 };
 411
 412 struct uci_backend
 413 {
 414         struct uci_element e;
 415         char **(*list_configs)(struct uci_context *ctx);
 416         struct uci_package *(*load)(struct uci_context *ctx, const char *name);
 417         void (*commit)(struct uci_context *ctx, struct uci_package **p, bool overwrite);
 418
 419         /* private: */
 420         const void *ptr;
 421         void *priv;
 422 };
 423
 424 struct uci_context
 425 {
 426         /* list of config packages */
 427         struct uci_list root;
 428
 429         /* parser context, use for error handling only */
 430         struct uci_parse_context *pctx;
 431
 432         /* backend for import and export */
 433         struct uci_backend *backend;
 434         struct uci_list backends;
 435
 436         /* uci runtime flags */
 437         enum uci_flags flags;
 438
 439         char *confdir;
 440         char *savedir;
 441
 442         /* search path for delta files */
 443         struct uci_list delta_path;
 444
 445         /* private: */
 446         int err;
 447         const char *func;
 448         jmp_buf trap;
 449         bool internal, nested;
 450         char *buf;
 451         int bufsz;
 452
 453         struct uci_list hooks;
 454         struct uci_list plugins;
 455 };
 456
 457 struct uci_package
 458 {
 459         struct uci_element e;
 460         struct uci_list sections;
 461         struct uci_context *ctx;
 462         bool has_delta;
 463         char *path;
 464
 465         /* private: */
 466         struct uci_backend *backend;
 467         void *priv;
 468         int n_section;
 469         struct uci_list delta;
 470         struct uci_list saved_delta;
 471 };
 472
 473 struct uci_section
 474 {
 475         struct uci_element e;
 476         struct uci_list options;
 477         struct uci_package *package;
 478         bool anonymous;
 479         char *type;
 480 };
 481
 482 struct uci_option
 483 {
 484         struct uci_element e;
 485         struct uci_section *section;
 486         enum uci_option_type type;
 487         union {
 488                 struct uci_list list;
 489                 char *string;
 490         } v;
 491 };
 492
 493 enum uci_command {
 494         UCI_CMD_ADD,
 495         UCI_CMD_REMOVE,
 496         UCI_CMD_CHANGE,
 497         UCI_CMD_RENAME,
 498         UCI_CMD_REORDER,
 499         UCI_CMD_LIST_ADD,
 500         UCI_CMD_LIST_DEL,
 501 };
 502
 503 struct uci_delta
 504 {
 505         struct uci_element e;
 506         enum uci_command cmd;
 507         char *section;
 508         char *value;
 509 };
 510
 511 struct uci_ptr
 512 {
 513         enum uci_type target;
 514         enum {
 515                 UCI_LOOKUP_DONE =     (1 << 0),
 516                 UCI_LOOKUP_COMPLETE = (1 << 1),
 517                 UCI_LOOKUP_EXTENDED = (1 << 2),
 518         } flags;
 519
 520         struct uci_package *p;
 521         struct uci_section *s;
 522         struct uci_option *o;
 523         struct uci_element *last;
 524
 525         const char *package;
 526         const char *section;
 527         const char *option;
 528         const char *value;
 529 };
 530
 531 struct uci_hook_ops
 532 {
 533         void (*load)(const struct uci_hook_ops *ops, struct uci_package *p);
 534         void (*set)(const struct uci_hook_ops *ops, struct uci_package *p, struct uci_delta *e);
 535 };
 536
 537 struct uci_hook
 538 {
 539         struct uci_element e;
 540         const struct uci_hook_ops *ops;
 541 };
 542
 543 struct uci_plugin_ops
 544 {
 545         int (*attach)(struct uci_context *ctx);
 546         void (*detach)(struct uci_context *ctx);
 547 };
 548
 549 struct uci_plugin
 550 {
 551         struct uci_element e;
 552         const struct uci_plugin_ops *ops;
 553         void *dlh;
 554 };
 555
 556 struct uci_parse_option {
 557         const char *name;
 558         enum uci_option_type type;
 559 };
 560
 561
 562 /* linked list handling */
 563 #ifndef offsetof
 564 #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
 565 #endif
 566
 567 /**
 568  * container_of - cast a member of a structure out to the containing structure
 569  * @ptr:    the pointer to the member.
 570  * @type:   the type of the container struct this is embedded in.
 571  * @member: the name of the member within the struct.
 572  */
 573 #ifndef container_of
 574 #define container_of(ptr, type, member) \
 575         ((type *) ((char *)ptr - offsetof(type,member)))
 576 #endif
 577
 578
 579 /**
 580  * uci_list_entry: casts an uci_list pointer to the containing struct.
 581  * @_type: config, section or option
 582  * @_ptr: pointer to the uci_list struct
 583  */
 584 #define list_to_element(ptr) \
 585         container_of(ptr, struct uci_element, list)
 586
 587 /**
 588  * uci_foreach_entry: loop through a list of uci elements
 589  * @_list: pointer to the uci_list struct
 590  * @_ptr: iteration variable, struct uci_element
 591  *
 592  * use like a for loop, e.g:
 593  *   uci_foreach(&list, p) {
 594  *      ...
 595  *   }
 596  */
 597 #define uci_foreach_element(_list, _ptr)                \
 598         for(_ptr = list_to_element((_list)->next);      \
 599                 &_ptr->list != (_list);                 \
 600                 _ptr = list_to_element(_ptr->list.next))
 601
 602 /**
 603  * uci_foreach_entry_safe: like uci_foreach_safe, but safe for deletion
 604  * @_list: pointer to the uci_list struct
 605  * @_tmp: temporary variable, struct uci_element *
 606  * @_ptr: iteration variable, struct uci_element *
 607  *
 608  * use like a for loop, e.g:
 609  *   uci_foreach(&list, p) {
 610  *      ...
 611  *   }
 612  */
 613 #define uci_foreach_element_safe(_list, _tmp, _ptr)             \
 614         for(_ptr = list_to_element((_list)->next),              \
 615                 _tmp = list_to_element(_ptr->list.next);        \
 616                 &_ptr->list != (_list);                 \
 617                 _ptr = _tmp, _tmp = list_to_element(_ptr->list.next))
 618
 619 /**
 620  * uci_list_empty: returns true if a list is empty
 621  * @list: list head
 622  */
 623 #define uci_list_empty(list) ((list)->next == (list))
 624
 625 /* wrappers for dynamic type handling */
 626 #define uci_type_backend UCI_TYPE_BACKEND
 627 #define uci_type_delta UCI_TYPE_DELTA
 628 #define uci_type_package UCI_TYPE_PACKAGE
 629 #define uci_type_section UCI_TYPE_SECTION
 630 #define uci_type_option UCI_TYPE_OPTION
 631 #define uci_type_hook UCI_TYPE_HOOK
 632 #define uci_type_plugin UCI_TYPE_PLUGIN
 633
 634 /* element typecasting */
 635 #ifdef UCI_DEBUG_TYPECAST
 636 static const char *uci_typestr[] = {
 637         [uci_type_backend] = "backend",
 638         [uci_type_delta] = "delta",
 639         [uci_type_package] = "package",
 640         [uci_type_section] = "section",
 641         [uci_type_option] = "option",
 642         [uci_type_hook] = "hook",
 643         [uci_type_plugin] = "plugin",
 644 };
 645
 646 static void uci_typecast_error(int from, int to)
 647 {
 648         fprintf(stderr, "Invalid typecast from '%s' to '%s'\n", uci_typestr[from], uci_typestr[to]);
 649 }
 650
 651 #define BUILD_CAST(_type) \
 652         static inline struct uci_ ## _type *uci_to_ ## _type (struct uci_element *e) \
 653         { \
 654                 if (e->type != uci_type_ ## _type) { \
 655                         uci_typecast_error(e->type, uci_type_ ## _type); \
 656                 } \
 657                 return (struct uci_ ## _type *) e; \
 658         }
 659
 660 BUILD_CAST(backend)
 661 BUILD_CAST(delta)
 662 BUILD_CAST(package)
 663 BUILD_CAST(section)
 664 BUILD_CAST(option)
 665 BUILD_CAST(hook)
 666 BUILD_CAST(plugin)
 667
 668 #else
 669 #define uci_to_backend(ptr) container_of(ptr, struct uci_backend, e)
 670 #define uci_to_delta(ptr) container_of(ptr, struct uci_delta, e)
 671 #define uci_to_package(ptr) container_of(ptr, struct uci_package, e)
 672 #define uci_to_section(ptr) container_of(ptr, struct uci_section, e)
 673 #define uci_to_option(ptr)  container_of(ptr, struct uci_option, e)
 674 #define uci_to_hook(ptr)    container_of(ptr, struct uci_hook, e)
 675 #define uci_to_plugin(ptr)  container_of(ptr, struct uci_plugin, e)
 676 #endif
 677
 678 /**
 679  * uci_alloc_element: allocate a generic uci_element, reserve a buffer and typecast
 680  * @ctx: uci context
 681  * @type: {package,section,option}
 682  * @name: string containing the name of the element
 683  * @datasize: additional buffer size to reserve at the end of the struct
 684  */
 685 #define uci_alloc_element(ctx, type, name, datasize) \
 686         uci_to_ ## type (uci_alloc_generic(ctx, uci_type_ ## type, name, sizeof(struct uci_ ## type) + datasize))
 687
 688 #define uci_dataptr(ptr) \
 689         (((char *) ptr) + sizeof(*ptr))
 690
 691 /**
 692  * uci_lookup_package: look up a package
 693  * @ctx: uci context
 694  * @name: name of the package
 695  */
 696 static inline struct uci_package *
 697 uci_lookup_package(struct uci_context *ctx, const char *name)
 698 {
 699         struct uci_element *e = NULL;
 700         if (uci_lookup_next(ctx, &e, &ctx->root, name) == 0)
 701                 return uci_to_package(e);
 702         else
 703                 return NULL;
 704 }
 705
 706 /**
 707  * uci_lookup_section: look up a section
 708  * @ctx: uci context
 709  * @p: package that the section belongs to
 710  * @name: name of the section
 711  */
 712 static inline struct uci_section *
 713 uci_lookup_section(struct uci_context *ctx, struct uci_package *p, const char *name)
 714 {
 715         struct uci_element *e = NULL;
 716         if (uci_lookup_next(ctx, &e, &p->sections, name) == 0)
 717                 return uci_to_section(e);
 718         else
 719                 return NULL;
 720 }
 721
 722 /**
 723  * uci_lookup_option: look up an option
 724  * @ctx: uci context
 725  * @section: section that the option belongs to
 726  * @name: name of the option
 727  */
 728 static inline struct uci_option *
 729 uci_lookup_option(struct uci_context *ctx, struct uci_section *s, const char *name)
 730 {
 731         struct uci_element *e = NULL;
 732         if (uci_lookup_next(ctx, &e, &s->options, name) == 0)
 733                 return uci_to_option(e);
 734         else
 735                 return NULL;
 736 }
 737
 738 static inline const char *
 739 uci_lookup_option_string(struct uci_context *ctx, struct uci_section *s, const char *name)
 740 {
 741         struct uci_option *o;
 742
 743         o = uci_lookup_option(ctx, s, name);
 744         if (!o || o->type != UCI_TYPE_STRING)
 745                 return NULL;
 746
 747         return o->v.string;
 748 }
 749
 750 #ifdef __cplusplus
 751 }
 752 #endif
 753
 754 #endif