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_FILEMODE    0600
  36
  37 enum
  38 {
  39         UCI_OK = 0,
  40         UCI_ERR_MEM,
  41         UCI_ERR_INVAL,
  42         UCI_ERR_NOTFOUND,
  43         UCI_ERR_IO,
  44         UCI_ERR_PARSE,
  45         UCI_ERR_DUPLICATE,
  46         UCI_ERR_UNKNOWN,
  47         UCI_ERR_LAST
  48 };
  49
  50 struct uci_list;
  51 struct uci_list
  52 {
  53         struct uci_list *next;
  54         struct uci_list *prev;
  55 };
  56
  57 struct uci_element;
  58 struct uci_package;
  59 struct uci_section;
  60 struct uci_option;
  61 struct uci_history;
  62 struct uci_context;
  63 struct uci_backend;
  64 struct uci_parse_context;
  65
  66
  67 /**
  68  * uci_parse_tuple: Parse an uci tuple
  69  * @ctx: uci context
  70  * @str: input string
  71  * @package: output package pointer
  72  * @section: output section pointer
  73  * @option: output option pointer
  74  * @value: output value pointer
  75  *
  76  * format: <package>[.<section>[.<option>]][=<value>]
  77  */
  78 extern int uci_parse_tuple(struct uci_context *ctx, char *str, char **package, char **section, char **option, char **value);
  79
  80 /**
  81  * uci_alloc_context: Allocate a new uci context
  82  */
  83 extern struct uci_context *uci_alloc_context(void);
  84
  85 /**
  86  * uci_free_context: Free the uci context including all of its data
  87  */
  88 extern void uci_free_context(struct uci_context *ctx);
  89
  90 /**
  91  * uci_perror: Print the last uci error that occured
  92  * @ctx: uci context
  93  * @str: string to print before the error message
  94  */
  95 extern void uci_perror(struct uci_context *ctx, const char *str);
  96
  97 /**
  98  * uci_import: Import uci config data from a stream
  99  * @ctx: uci context
 100  * @stream: file stream to import from
 101  * @name: (optional) assume the config has the given name
 102  * @package: (optional) store the last parsed config package in this variable
 103  * @single: ignore the 'package' keyword and parse everything into a single package
 104  *
 105  * the name parameter is for config files that don't explicitly use the 'package <...>' keyword
 106  * if 'package' points to a non-null struct pointer, enable history tracking and merge
 107  */
 108 extern int uci_import(struct uci_context *ctx, FILE *stream, const char *name, struct uci_package **package, bool single);
 109
 110 /**
 111  * uci_export: Export one or all uci config packages
 112  * @ctx: uci context
 113  * @stream: output stream
 114  * @package: (optional) uci config package to export
 115  * @header: include the package header
 116  */
 117 extern int uci_export(struct uci_context *ctx, FILE *stream, struct uci_package *package, bool header);
 118
 119 /**
 120  * uci_load: Parse an uci config file and store it in the uci context
 121  *
 122  * @ctx: uci context
 123  * @name: name of the config file (relative to the config directory)
 124  * @package: store the loaded config package in this variable
 125  */
 126 extern int uci_load(struct uci_context *ctx, const char *name, struct uci_package **package);
 127
 128 /**
 129  * uci_unload: Unload a config file from the uci context
 130  *
 131  * @ctx: uci context
 132  * @package: pointer to the uci_package struct
 133  */
 134 extern int uci_unload(struct uci_context *ctx, struct uci_package *p);
 135
 136 /**
 137  * uci_lookup: Look up an uci element
 138  *
 139  * @ctx: uci context
 140  * @res: where to store the result
 141  * @package: uci_package struct
 142  * @section: config section (optional)
 143  * @option: option to search for (optional)
 144  *
 145  * If section is omitted, then a pointer to the config package is returned
 146  * If option is omitted, then a pointer to the config section is returned
 147  */
 148 extern int uci_lookup(struct uci_context *ctx, struct uci_element **res, struct uci_package *package, char *section, char *option);
 149
 150 /**
 151  * uci_add_section: Add an unnamed section
 152  * @ctx: uci context
 153  * @p: package to add the section to
 154  * @type: section type
 155  * @res: pointer to store a reference to the new section in
 156  */
 157 extern int uci_add_section(struct uci_context *ctx, struct uci_package *p, char *type, struct uci_section **res);
 158
 159 /**
 160  * uci_set_element_value: Replace an element's value with a new one
 161  * @ctx: uci context
 162  * @element: pointer to an uci_element struct pointer
 163  * @value: new value
 164  *
 165  * Only valid for uci_option and uci_section. Will replace the type string
 166  * when used with an uci_section
 167  */
 168 extern int uci_set_element_value(struct uci_context *ctx, struct uci_element **element, char *value);
 169
 170 /**
 171  * uci_set: Set an element's value; create the element if necessary
 172  * @ctx: uci context
 173  * @package: package name
 174  * @section: section name
 175  * @option: option name
 176  * @value: value (option) or type (section)
 177  * @result: store the updated element in this variable (optional)
 178  */
 179 extern int uci_set(struct uci_context *ctx, struct uci_package *p, char *section, char *option, char *value, struct uci_element **result);
 180
 181 /**
 182  * uci_rename: Rename an element
 183  * @ctx: uci context
 184  * @package: package name
 185  * @section: section name
 186  * @option: option name
 187  * @name: new name
 188  */
 189 extern int uci_rename(struct uci_context *ctx, struct uci_package *p, char *section, char *option, char *name);
 190
 191 /**
 192  * uci_delete_element: Delete a section or option
 193  * @ctx: uci context
 194  * @e: element (section or option)
 195  */
 196 extern int uci_delete_element(struct uci_context *ctx, struct uci_element *e);
 197
 198 /**
 199  * uci_delete: Delete a section or option
 200  * @ctx: uci context
 201  * @p: uci package
 202  * @section: section name
 203  * @option: option name (optional)
 204  */
 205 extern int uci_delete(struct uci_context *ctx, struct uci_package *p, char *section, char *option);
 206
 207 /**
 208  * uci_save: save change history for a package
 209  * @ctx: uci context
 210  * @p: uci_package struct
 211  */
 212 extern int uci_save(struct uci_context *ctx, struct uci_package *p);
 213
 214 /**
 215  * uci_commit: commit changes to a package
 216  * @ctx: uci context
 217  * @p: uci_package struct pointer
 218  * @overwrite: overwrite existing config data and flush history
 219  *
 220  * committing may reload the whole uci_package data,
 221  * the supplied pointer is updated accordingly
 222  */
 223 extern int uci_commit(struct uci_context *ctx, struct uci_package **p, bool overwrite);
 224
 225 /**
 226  * uci_list_configs: List available uci config files
 227  * @ctx: uci context
 228  *
 229  * caller is responsible for freeing the allocated memory behind list
 230  */
 231 extern int uci_list_configs(struct uci_context *ctx, char ***list);
 232
 233 /**
 234  * uci_set_savedir: override the default history save directory
 235  * @ctx: uci context
 236  * @dir: directory name
 237  */
 238 extern int uci_set_savedir(struct uci_context *ctx, const char *dir);
 239
 240 /**
 241  * uci_set_savedir: override the default config storage directory
 242  * @ctx: uci context
 243  * @dir: directory name
 244  */
 245 extern int uci_set_confdir(struct uci_context *ctx, const char *dir);
 246
 247 /**
 248  * uci_add_history_path: add a directory to the search path for change history files
 249  * @ctx: uci context
 250  * @dir: directory name
 251  *
 252  * This function allows you to add directories, which contain 'overlays'
 253  * for the active config, that will never be committed.
 254  */
 255 extern int uci_add_history_path(struct uci_context *ctx, const char *dir);
 256
 257 /**
 258  * uci_revert: revert all changes to a config item
 259  * @ctx: uci context
 260  * @p: pointer to a uci_package struct ptr (will be replaced by the revert)
 261  * @section: section name (optional)
 262  * @option option name (optional)
 263  */
 264 extern int uci_revert(struct uci_context *ctx, struct uci_package **p, char *section, char *option);
 265
 266 /**
 267  * uci_parse_argument: parse a shell-style argument, with an arbitrary quoting style
 268  * @ctx: uci context
 269  * @stream: input stream
 270  * @str: pointer to the current line (use NULL for parsing the next line)
 271  * @result: pointer for the result
 272  */
 273 extern int uci_parse_argument(struct uci_context *ctx, FILE *stream, char **str, char **result);
 274
 275 /**
 276  * uci_set_backend: change the default backend
 277  * @ctx: uci context
 278  * @name: name of the backend
 279  *
 280  * The default backend is "file", which uses /etc/config for config storage
 281  */
 282 extern int uci_set_backend(struct uci_context *ctx, const char *name);
 283
 284 /* UCI data structures */
 285 enum uci_type {
 286         UCI_TYPE_HISTORY = 0,
 287         UCI_TYPE_PACKAGE = 1,
 288         UCI_TYPE_SECTION = 2,
 289         UCI_TYPE_OPTION = 3,
 290         UCI_TYPE_PATH = 4,
 291         UCI_TYPE_BACKEND = 5,
 292 };
 293
 294 enum uci_flags {
 295         UCI_FLAG_STRICT =        (1 << 0), /* strict mode for the parser */
 296         UCI_FLAG_PERROR =        (1 << 1), /* print parser error messages */
 297         UCI_FLAG_EXPORT_NAME =   (1 << 2), /* when exporting, name unnamed sections */
 298         UCI_FLAG_SAVED_HISTORY = (1 << 3), /* store the saved history in memory as well */
 299 };
 300
 301 struct uci_element
 302 {
 303         struct uci_list list;
 304         enum uci_type type;
 305         char *name;
 306 };
 307
 308 struct uci_backend
 309 {
 310         struct uci_element e;
 311         char **(*list_configs)(struct uci_context *ctx);
 312         struct uci_package *(*load)(struct uci_context *ctx, const char *name);
 313         void (*commit)(struct uci_context *ctx, struct uci_package **p, bool overwrite);
 314 };
 315
 316 struct uci_context
 317 {
 318         /* list of config packages */
 319         struct uci_list root;
 320
 321         /* parser context, use for error handling only */
 322         struct uci_parse_context *pctx;
 323
 324         /* backend for import and export */
 325         struct uci_backend *backend;
 326         struct uci_list backends;
 327
 328         /* uci runtime flags */
 329         enum uci_flags flags;
 330
 331         char *confdir;
 332         char *savedir;
 333
 334         /* search path for history files */
 335         struct uci_list history_path;
 336
 337         /* private: */
 338         int errno;
 339         const char *func;
 340         jmp_buf trap;
 341         bool internal;
 342         char *buf;
 343         int bufsz;
 344 };
 345
 346 struct uci_package
 347 {
 348         struct uci_element e;
 349         struct uci_list sections;
 350         struct uci_context *ctx;
 351         bool has_history;
 352         char *path;
 353
 354         /* private: */
 355         struct uci_backend *backend;
 356         void *priv;
 357         int n_section;
 358         struct uci_list history;
 359         struct uci_list saved_history;
 360 };
 361
 362 struct uci_section
 363 {
 364         struct uci_element e;
 365         struct uci_list options;
 366         struct uci_package *package;
 367         bool anonymous;
 368         char *type;
 369 };
 370
 371 struct uci_option
 372 {
 373         struct uci_element e;
 374         struct uci_section *section;
 375         char *value;
 376 };
 377
 378 enum uci_command {
 379         UCI_CMD_ADD,
 380         UCI_CMD_REMOVE,
 381         UCI_CMD_CHANGE,
 382         UCI_CMD_RENAME
 383 };
 384
 385 struct uci_history
 386 {
 387         struct uci_element e;
 388         enum uci_command cmd;
 389         char *section;
 390         char *value;
 391 };
 392
 393 #define UCI_BACKEND(_var, _name, ...)   \
 394 struct uci_backend _var = {             \
 395         .e.list = {                     \
 396                 .next = &_var.e.list,   \
 397                 .prev = &_var.e.list,   \
 398         },                              \
 399         .e.name = _name,                \
 400         .e.type = UCI_TYPE_BACKEND,     \
 401         __VA_ARGS__                     \
 402 }
 403
 404
 405 /* linked list handling */
 406 #ifndef offsetof
 407 #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
 408 #endif
 409
 410 /**
 411  * container_of - cast a member of a structure out to the containing structure
 412  * @ptr:    the pointer to the member.
 413  * @type:   the type of the container struct this is embedded in.
 414  * @member: the name of the member within the struct.
 415  */
 416 #define container_of(ptr, type, member) \
 417         ((type *) ((char *)ptr - offsetof(type,member)))
 418
 419
 420 /**
 421  * uci_list_entry: casts an uci_list pointer to the containing struct.
 422  * @_type: config, section or option
 423  * @_ptr: pointer to the uci_list struct
 424  */
 425 #define list_to_element(ptr) \
 426         container_of(ptr, struct uci_element, list)
 427
 428 /**
 429  * uci_foreach_entry: loop through a list of uci elements
 430  * @_list: pointer to the uci_list struct
 431  * @_ptr: iteration variable, struct uci_element
 432  *
 433  * use like a for loop, e.g:
 434  *   uci_foreach(&list, p) {
 435  *      ...
 436  *   }
 437  */
 438 #define uci_foreach_element(_list, _ptr)                \
 439         for(_ptr = list_to_element((_list)->next);      \
 440                 &_ptr->list != (_list);                 \
 441                 _ptr = list_to_element(_ptr->list.next))
 442
 443 /**
 444  * uci_foreach_entry_safe: like uci_foreach_safe, but safe for deletion
 445  * @_list: pointer to the uci_list struct
 446  * @_tmp: temporary variable, struct uci_element *
 447  * @_ptr: iteration variable, struct uci_element *
 448  *
 449  * use like a for loop, e.g:
 450  *   uci_foreach(&list, p) {
 451  *      ...
 452  *   }
 453  */
 454 #define uci_foreach_element_safe(_list, _tmp, _ptr)             \
 455         for(_ptr = list_to_element((_list)->next),              \
 456                 _tmp = list_to_element(_ptr->list.next);        \
 457                 &_ptr->list != (_list);                 \
 458                 _ptr = _tmp, _tmp = list_to_element(_ptr->list.next))
 459
 460 /**
 461  * uci_list_empty: returns true if a list is empty
 462  * @list: list head
 463  */
 464 #define uci_list_empty(list) ((list)->next == (list))
 465
 466 /* wrappers for dynamic type handling */
 467 #define uci_type_backend UCI_TYPE_BACKEND
 468 #define uci_type_history UCI_TYPE_HISTORY
 469 #define uci_type_package UCI_TYPE_PACKAGE
 470 #define uci_type_section UCI_TYPE_SECTION
 471 #define uci_type_option UCI_TYPE_OPTION
 472
 473 /* element typecasting */
 474 #ifdef UCI_DEBUG_TYPECAST
 475 static const char *uci_typestr[] = {
 476         [uci_type_backend] = "backend",
 477         [uci_type_history] = "history",
 478         [uci_type_package] = "package",
 479         [uci_type_section] = "section",
 480         [uci_type_option] = "option",
 481 };
 482
 483 static void uci_typecast_error(int from, int to)
 484 {
 485         fprintf(stderr, "Invalid typecast from '%s' to '%s'\n", uci_typestr[from], uci_typestr[to]);
 486 }
 487
 488 #define BUILD_CAST(_type) \
 489         static inline struct uci_ ## _type *uci_to_ ## _type (struct uci_element *e) \
 490         { \
 491                 if (e->type != uci_type_ ## _type) { \
 492                         uci_typecast_error(e->type, uci_type_ ## _type); \
 493                 } \
 494                 return (struct uci_ ## _type *) e; \
 495         }
 496
 497 BUILD_CAST(backend)
 498 BUILD_CAST(history)
 499 BUILD_CAST(package)
 500 BUILD_CAST(section)
 501 BUILD_CAST(option)
 502
 503 #else
 504 #define uci_to_backend(ptr) container_of(ptr, struct uci_backend, e)
 505 #define uci_to_history(ptr) container_of(ptr, struct uci_history, e)
 506 #define uci_to_package(ptr) container_of(ptr, struct uci_package, e)
 507 #define uci_to_section(ptr) container_of(ptr, struct uci_section, e)
 508 #define uci_to_option(ptr)  container_of(ptr, struct uci_option, e)
 509 #endif
 510
 511 /**
 512  * uci_alloc_element: allocate a generic uci_element, reserve a buffer and typecast
 513  * @ctx: uci context
 514  * @type: {package,section,option}
 515  * @name: string containing the name of the element
 516  * @datasize: additional buffer size to reserve at the end of the struct
 517  */
 518 #define uci_alloc_element(ctx, type, name, datasize) \
 519         uci_to_ ## type (uci_alloc_generic(ctx, uci_type_ ## type, name, sizeof(struct uci_ ## type) + datasize))
 520
 521 #define uci_dataptr(ptr) \
 522         (((char *) ptr) + sizeof(*ptr))
 523
 524 #endif