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