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