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_element;
  59 struct uci_package;
  60 struct uci_section;
  61 struct uci_option;
  62 struct uci_history;
  63 struct uci_context;
  64 struct uci_backend;
  65 struct uci_parse_context;
  66
  67
  68 /**
  69  * uci_parse_tuple: Parse an uci tuple
  70  * @ctx: uci context
  71  * @str: input string
  72  * @package: output package pointer
  73  * @section: output section pointer
  74  * @option: output option pointer
  75  * @value: output value pointer
  76  *
  77  * format: <package>[.<section>[.<option>]][=<value>]
  78  */
  79 extern int uci_parse_tuple(struct uci_context *ctx, char *str, char **package, char **section, char **option, char **value);
  80
  81 /**
  82  * uci_alloc_context: Allocate a new uci context
  83  */
  84 extern struct uci_context *uci_alloc_context(void);
  85
  86 /**
  87  * uci_free_context: Free the uci context including all of its data
  88  */
  89 extern void uci_free_context(struct uci_context *ctx);
  90
  91 /**
  92  * uci_perror: Print the last uci error that occured
  93  * @ctx: uci context
  94  * @str: string to print before the error message
  95  */
  96 extern void uci_perror(struct uci_context *ctx, 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 history 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: Look up an uci element
 139  *
 140  * @ctx: uci context
 141  * @res: where to store the result
 142  * @package: uci_package struct
 143  * @section: config section (optional)
 144  * @option: option to search for (optional)
 145  *
 146  * If section is omitted, then a pointer to the config package is returned
 147  * If option is omitted, then a pointer to the config section is returned
 148  */
 149 extern int uci_lookup(struct uci_context *ctx, struct uci_element **res, struct uci_package *package, const char *section, const char *option);
 150
 151 /**
 152  * uci_add_section: Add an unnamed section
 153  * @ctx: uci context
 154  * @p: package to add the section to
 155  * @type: section type
 156  * @res: pointer to store a reference to the new section in
 157  */
 158 extern int uci_add_section(struct uci_context *ctx, struct uci_package *p, const char *type, struct uci_section **res);
 159
 160 /**
 161  * uci_set_element_value: Replace an element's value with a new one
 162  * @ctx: uci context
 163  * @element: pointer to an uci_element struct pointer
 164  * @value: new value
 165  *
 166  * Only valid for uci_option and uci_section. Will replace the type string
 167  * when used with an uci_section
 168  */
 169 extern int uci_set_element_value(struct uci_context *ctx, struct uci_element **element, const char *value);
 170
 171 /**
 172  * uci_set: Set an element's value; create the element if necessary
 173  * @ctx: uci context
 174  * @package: package name
 175  * @section: section name
 176  * @option: option name
 177  * @value: value (option) or type (section)
 178  * @result: store the updated element in this variable (optional)
 179  */
 180 extern int uci_set(struct uci_context *ctx, struct uci_package *p, const char *section, const char *option, const char *value, struct uci_element **result);
 181
 182 /**
 183  * uci_rename: Rename an element
 184  * @ctx: uci context
 185  * @package: package name
 186  * @section: section name
 187  * @option: option name
 188  * @name: new name
 189  */
 190 extern int uci_rename(struct uci_context *ctx, struct uci_package *p, char *section, char *option, char *name);
 191
 192 /**
 193  * uci_delete_element: Delete a section or option
 194  * @ctx: uci context
 195  * @e: element (section or option)
 196  */
 197 extern int uci_delete_element(struct uci_context *ctx, struct uci_element *e);
 198
 199 /**
 200  * uci_delete: Delete a section or option
 201  * @ctx: uci context
 202  * @p: uci package
 203  * @section: section name
 204  * @option: option name (optional)
 205  */
 206 extern int uci_delete(struct uci_context *ctx, struct uci_package *p, const char *section, const char *option);
 207
 208 /**
 209  * uci_save: save change history for a package
 210  * @ctx: uci context
 211  * @p: uci_package struct
 212  */
 213 extern int uci_save(struct uci_context *ctx, struct uci_package *p);
 214
 215 /**
 216  * uci_commit: commit changes to a package
 217  * @ctx: uci context
 218  * @p: uci_package struct pointer
 219  * @overwrite: overwrite existing config data and flush history
 220  *
 221  * committing may reload the whole uci_package data,
 222  * the supplied pointer is updated accordingly
 223  */
 224 extern int uci_commit(struct uci_context *ctx, struct uci_package **p, bool overwrite);
 225
 226 /**
 227  * uci_list_configs: List available uci config files
 228  * @ctx: uci context
 229  *
 230  * caller is responsible for freeing the allocated memory behind list
 231  */
 232 extern int uci_list_configs(struct uci_context *ctx, char ***list);
 233
 234 /**
 235  * uci_set_savedir: override the default history save directory
 236  * @ctx: uci context
 237  * @dir: directory name
 238  */
 239 extern int uci_set_savedir(struct uci_context *ctx, const char *dir);
 240
 241 /**
 242  * uci_set_savedir: override the default config storage directory
 243  * @ctx: uci context
 244  * @dir: directory name
 245  */
 246 extern int uci_set_confdir(struct uci_context *ctx, const char *dir);
 247
 248 /**
 249  * uci_add_history_path: add a directory to the search path for change history files
 250  * @ctx: uci context
 251  * @dir: directory name
 252  *
 253  * This function allows you to add directories, which contain 'overlays'
 254  * for the active config, that will never be committed.
 255  */
 256 extern int uci_add_history_path(struct uci_context *ctx, const char *dir);
 257
 258 /**
 259  * uci_revert: revert all changes to a config item
 260  * @ctx: uci context
 261  * @p: pointer to a uci_package struct ptr (will be replaced by the revert)
 262  * @section: section name (optional)
 263  * @option option name (optional)
 264  */
 265 extern int uci_revert(struct uci_context *ctx, struct uci_package **p, const char *section, const char *option);
 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 /* UCI data structures */
 286 enum uci_type {
 287         UCI_TYPE_HISTORY = 0,
 288         UCI_TYPE_PACKAGE = 1,
 289         UCI_TYPE_SECTION = 2,
 290         UCI_TYPE_OPTION = 3,
 291         UCI_TYPE_PATH = 4,
 292         UCI_TYPE_BACKEND = 5,
 293 };
 294
 295 enum uci_flags {
 296         UCI_FLAG_STRICT =        (1 << 0), /* strict mode for the parser */
 297         UCI_FLAG_PERROR =        (1 << 1), /* print parser error messages */
 298         UCI_FLAG_EXPORT_NAME =   (1 << 2), /* when exporting, name unnamed sections */
 299         UCI_FLAG_SAVED_HISTORY = (1 << 3), /* store the saved history in memory as well */
 300 };
 301
 302 struct uci_element
 303 {
 304         struct uci_list list;
 305         enum uci_type type;
 306         char *name;
 307 };
 308
 309 struct uci_backend
 310 {
 311         struct uci_element e;
 312         char **(*list_configs)(struct uci_context *ctx);
 313         struct uci_package *(*load)(struct uci_context *ctx, const char *name);
 314         void (*commit)(struct uci_context *ctx, struct uci_package **p, bool overwrite);
 315
 316         /* private: */
 317         const void *ptr;
 318         void *priv;
 319 };
 320
 321 struct uci_context
 322 {
 323         /* list of config packages */
 324         struct uci_list root;
 325
 326         /* parser context, use for error handling only */
 327         struct uci_parse_context *pctx;
 328
 329         /* backend for import and export */
 330         struct uci_backend *backend;
 331         struct uci_list backends;
 332
 333         /* uci runtime flags */
 334         enum uci_flags flags;
 335
 336         char *confdir;
 337         char *savedir;
 338
 339         /* search path for history files */
 340         struct uci_list history_path;
 341
 342         /* private: */
 343         int err;
 344         const char *func;
 345         jmp_buf trap;
 346         bool internal;
 347         char *buf;
 348         int bufsz;
 349 };
 350
 351 struct uci_package
 352 {
 353         struct uci_element e;
 354         struct uci_list sections;
 355         struct uci_context *ctx;
 356         bool has_history;
 357         char *path;
 358
 359         /* private: */
 360         struct uci_backend *backend;
 361         void *priv;
 362         int n_section;
 363         struct uci_list history;
 364         struct uci_list saved_history;
 365 };
 366
 367 struct uci_section
 368 {
 369         struct uci_element e;
 370         struct uci_list options;
 371         struct uci_package *package;
 372         bool anonymous;
 373         char *type;
 374 };
 375
 376 struct uci_option
 377 {
 378         struct uci_element e;
 379         struct uci_section *section;
 380         char *value;
 381 };
 382
 383 enum uci_command {
 384         UCI_CMD_ADD,
 385         UCI_CMD_REMOVE,
 386         UCI_CMD_CHANGE,
 387         UCI_CMD_RENAME
 388 };
 389
 390 struct uci_history
 391 {
 392         struct uci_element e;
 393         enum uci_command cmd;
 394         char *section;
 395         char *value;
 396 };
 397
 398
 399 /* linked list handling */
 400 #ifndef offsetof
 401 #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
 402 #endif
 403
 404 /**
 405  * container_of - cast a member of a structure out to the containing structure
 406  * @ptr:    the pointer to the member.
 407  * @type:   the type of the container struct this is embedded in.
 408  * @member: the name of the member within the struct.
 409  */
 410 #define container_of(ptr, type, member) \
 411         ((type *) ((char *)ptr - offsetof(type,member)))
 412
 413
 414 /**
 415  * uci_list_entry: casts an uci_list pointer to the containing struct.
 416  * @_type: config, section or option
 417  * @_ptr: pointer to the uci_list struct
 418  */
 419 #define list_to_element(ptr) \
 420         container_of(ptr, struct uci_element, list)
 421
 422 /**
 423  * uci_foreach_entry: loop through a list of uci elements
 424  * @_list: pointer to the uci_list struct
 425  * @_ptr: iteration variable, struct uci_element
 426  *
 427  * use like a for loop, e.g:
 428  *   uci_foreach(&list, p) {
 429  *      ...
 430  *   }
 431  */
 432 #define uci_foreach_element(_list, _ptr)                \
 433         for(_ptr = list_to_element((_list)->next);      \
 434                 &_ptr->list != (_list);                 \
 435                 _ptr = list_to_element(_ptr->list.next))
 436
 437 /**
 438  * uci_foreach_entry_safe: like uci_foreach_safe, but safe for deletion
 439  * @_list: pointer to the uci_list struct
 440  * @_tmp: temporary variable, struct uci_element *
 441  * @_ptr: iteration variable, struct uci_element *
 442  *
 443  * use like a for loop, e.g:
 444  *   uci_foreach(&list, p) {
 445  *      ...
 446  *   }
 447  */
 448 #define uci_foreach_element_safe(_list, _tmp, _ptr)             \
 449         for(_ptr = list_to_element((_list)->next),              \
 450                 _tmp = list_to_element(_ptr->list.next);        \
 451                 &_ptr->list != (_list);                 \
 452                 _ptr = _tmp, _tmp = list_to_element(_ptr->list.next))
 453
 454 /**
 455  * uci_list_empty: returns true if a list is empty
 456  * @list: list head
 457  */
 458 #define uci_list_empty(list) ((list)->next == (list))
 459
 460 /* wrappers for dynamic type handling */
 461 #define uci_type_backend UCI_TYPE_BACKEND
 462 #define uci_type_history UCI_TYPE_HISTORY
 463 #define uci_type_package UCI_TYPE_PACKAGE
 464 #define uci_type_section UCI_TYPE_SECTION
 465 #define uci_type_option UCI_TYPE_OPTION
 466
 467 /* element typecasting */
 468 #ifdef UCI_DEBUG_TYPECAST
 469 static const char *uci_typestr[] = {
 470         [uci_type_backend] = "backend",
 471         [uci_type_history] = "history",
 472         [uci_type_package] = "package",
 473         [uci_type_section] = "section",
 474         [uci_type_option] = "option",
 475 };
 476
 477 static void uci_typecast_error(int from, int to)
 478 {
 479         fprintf(stderr, "Invalid typecast from '%s' to '%s'\n", uci_typestr[from], uci_typestr[to]);
 480 }
 481
 482 #define BUILD_CAST(_type) \
 483         static inline struct uci_ ## _type *uci_to_ ## _type (struct uci_element *e) \
 484         { \
 485                 if (e->type != uci_type_ ## _type) { \
 486                         uci_typecast_error(e->type, uci_type_ ## _type); \
 487                 } \
 488                 return (struct uci_ ## _type *) e; \
 489         }
 490
 491 BUILD_CAST(backend)
 492 BUILD_CAST(history)
 493 BUILD_CAST(package)
 494 BUILD_CAST(section)
 495 BUILD_CAST(option)
 496
 497 #else
 498 #define uci_to_backend(ptr) container_of(ptr, struct uci_backend, e)
 499 #define uci_to_history(ptr) container_of(ptr, struct uci_history, e)
 500 #define uci_to_package(ptr) container_of(ptr, struct uci_package, e)
 501 #define uci_to_section(ptr) container_of(ptr, struct uci_section, e)
 502 #define uci_to_option(ptr)  container_of(ptr, struct uci_option, e)
 503 #endif
 504
 505 /**
 506  * uci_alloc_element: allocate a generic uci_element, reserve a buffer and typecast
 507  * @ctx: uci context
 508  * @type: {package,section,option}
 509  * @name: string containing the name of the element
 510  * @datasize: additional buffer size to reserve at the end of the struct
 511  */
 512 #define uci_alloc_element(ctx, type, name, datasize) \
 513         uci_to_ ## type (uci_alloc_generic(ctx, uci_type_ ## type, name, sizeof(struct uci_ ## type) + datasize))
 514
 515 #define uci_dataptr(ptr) \
 516         (((char *) ptr) + sizeof(*ptr))
 517
 518 #endif