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 /*
  19  * you can use these defines to enable debugging behavior for
  20  * apps compiled against libuci:
  21  *
  22  * #define UCI_DEBUG_TYPECAST:
  23  *   enable uci_element typecast checking at run time
  24  *
  25  */
  26
  27 #ifdef DEBUG_ALL
  28 #define UCI_DEBUG
  29 #define UCI_DEBUG_TYPECAST
  30 #endif
  31
  32 #include <stdbool.h>
  33 #include <setjmp.h>
  34 #include <stdio.h>
  35
  36 #define UCI_CONFDIR "/etc/config"
  37 #define UCI_SAVEDIR "/tmp/.uci"
  38 #define UCI_FILEMODE    0600
  39
  40 enum
  41 {
  42         UCI_OK = 0,
  43         UCI_ERR_MEM,
  44         UCI_ERR_INVAL,
  45         UCI_ERR_NOTFOUND,
  46         UCI_ERR_IO,
  47         UCI_ERR_PARSE,
  48         UCI_ERR_DUPLICATE,
  49         UCI_ERR_UNKNOWN,
  50         UCI_ERR_LAST
  51 };
  52
  53 struct uci_list;
  54 struct uci_list
  55 {
  56         struct uci_list *next;
  57         struct uci_list *prev;
  58 };
  59
  60 struct uci_element;
  61 struct uci_package;
  62 struct uci_section;
  63 struct uci_option;
  64 struct uci_history;
  65 struct uci_context;
  66 struct uci_backend;
  67 struct uci_parse_context;
  68
  69
  70 /**
  71  * uci_parse_tuple: Parse an uci tuple
  72  * @ctx: uci context
  73  * @str: input string
  74  * @package: output package pointer
  75  * @section: output section pointer
  76  * @option: output option pointer
  77  * @value: output value pointer
  78  *
  79  * format: <package>[.<section>[.<option>]][=<value>]
  80  */
  81 extern int uci_parse_tuple(struct uci_context *ctx, char *str, char **package, char **section, char **option, char **value);
  82
  83 /**
  84  * uci_alloc_context: Allocate a new uci context
  85  */
  86 extern struct uci_context *uci_alloc_context(void);
  87
  88 /**
  89  * uci_free_context: Free the uci context including all of its data
  90  */
  91 extern void uci_free_context(struct uci_context *ctx);
  92
  93 /**
  94  * uci_perror: Print the last uci error that occured
  95  * @ctx: uci context
  96  * @str: string to print before the error message
  97  */
  98 extern void uci_perror(struct uci_context *ctx, const char *str);
  99
 100 /**
 101  * uci_import: Import uci config data from a stream
 102  * @ctx: uci context
 103  * @stream: file stream to import from
 104  * @name: (optional) assume the config has the given name
 105  * @package: (optional) store the last parsed config package in this variable
 106  * @single: ignore the 'package' keyword and parse everything into a single package
 107  *
 108  * the name parameter is for config files that don't explicitly use the 'package <...>' keyword
 109  * if 'package' points to a non-null struct pointer, enable history tracking and merge
 110  */
 111 extern int uci_import(struct uci_context *ctx, FILE *stream, const char *name, struct uci_package **package, bool single);
 112
 113 /**
 114  * uci_export: Export one or all uci config packages
 115  * @ctx: uci context
 116  * @stream: output stream
 117  * @package: (optional) uci config package to export
 118  * @header: include the package header
 119  */
 120 extern int uci_export(struct uci_context *ctx, FILE *stream, struct uci_package *package, bool header);
 121
 122 /**
 123  * uci_load: Parse an uci config file and store it in the uci context
 124  *
 125  * @ctx: uci context
 126  * @name: name of the config file (relative to the config directory)
 127  * @package: store the loaded config package in this variable
 128  */
 129 extern int uci_load(struct uci_context *ctx, const char *name, struct uci_package **package);
 130
 131 /**
 132  * uci_unload: Unload a config file from the uci context
 133  *
 134  * @ctx: uci context
 135  * @package: pointer to the uci_package struct
 136  */
 137 extern int uci_unload(struct uci_context *ctx, struct uci_package *p);
 138
 139 /**
 140  * uci_lookup: Look up an uci element
 141  *
 142  * @ctx: uci context
 143  * @res: where to store the result
 144  * @package: uci_package struct
 145  * @section: config section (optional)
 146  * @option: option to search for (optional)
 147  *
 148  * If section is omitted, then a pointer to the config package is returned
 149  * If option is omitted, then a pointer to the config section is returned
 150  */
 151 extern int uci_lookup(struct uci_context *ctx, struct uci_element **res, struct uci_package *package, char *section, char *option);
 152
 153 /**
 154  * uci_add_section: Add an unnamed section
 155  * @ctx: uci context
 156  * @p: package to add the section to
 157  * @type: section type
 158  * @res: pointer to store a reference to the new section in
 159  */
 160 extern int uci_add_section(struct uci_context *ctx, struct uci_package *p, char *type, struct uci_section **res);
 161
 162 /**
 163  * uci_set_element_value: Replace an element's value with a new one
 164  * @ctx: uci context
 165  * @element: pointer to an uci_element struct pointer
 166  * @value: new value
 167  *
 168  * Only valid for uci_option and uci_section. Will replace the type string
 169  * when used with an uci_section
 170  */
 171 extern int uci_set_element_value(struct uci_context *ctx, struct uci_element **element, char *value);
 172
 173 /**
 174  * uci_set: Set an element's value; create the element if necessary
 175  * @ctx: uci context
 176  * @package: package name
 177  * @section: section name
 178  * @option: option name
 179  * @value: value (option) or type (section)
 180  * @result: store the updated element in this variable (optional)
 181  */
 182 extern int uci_set(struct uci_context *ctx, struct uci_package *p, char *section, char *option, char *value, struct uci_element **result);
 183
 184 /**
 185  * uci_rename: Rename an element
 186  * @ctx: uci context
 187  * @package: package name
 188  * @section: section name
 189  * @option: option name
 190  * @name: new name
 191  */
 192 extern int uci_rename(struct uci_context *ctx, struct uci_package *p, char *section, char *option, char *name);
 193
 194 /**
 195  * uci_delete_element: Delete a section or option
 196  * @ctx: uci context
 197  * @e: element (section or option)
 198  */
 199 extern int uci_delete_element(struct uci_context *ctx, struct uci_element *e);
 200
 201 /**
 202  * uci_delete: Delete a section or option
 203  * @ctx: uci context
 204  * @p: uci package
 205  * @section: section name
 206  * @option: option name (optional)
 207  */
 208 extern int uci_delete(struct uci_context *ctx, struct uci_package *p, char *section, char *option);
 209
 210 /**
 211  * uci_save: save change history 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 history
 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 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, char *section, 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 /* UCI data structures */
 277 enum uci_type {
 278         UCI_TYPE_HISTORY = 0,
 279         UCI_TYPE_PACKAGE = 1,
 280         UCI_TYPE_SECTION = 2,
 281         UCI_TYPE_OPTION = 3,
 282         UCI_TYPE_PATH = 4
 283 };
 284
 285 enum uci_flags {
 286         UCI_FLAG_STRICT =        (1 << 0), /* strict mode for the parser */
 287         UCI_FLAG_PERROR =        (1 << 1), /* print parser error messages */
 288         UCI_FLAG_EXPORT_NAME =   (1 << 2), /* when exporting, name unnamed sections */
 289         UCI_FLAG_SAVED_HISTORY = (1 << 3), /* store the saved history in memory as well */
 290 };
 291
 292 struct uci_element
 293 {
 294         struct uci_list list;
 295         enum uci_type type;
 296         char *name;
 297 };
 298
 299 struct uci_backend
 300 {
 301         const char *name;
 302         char **(*list_configs)(struct uci_context *ctx);
 303         struct uci_package *(*load)(struct uci_context *ctx, const char *name);
 304         void (*commit)(struct uci_context *ctx, struct uci_package **p, bool overwrite);
 305 };
 306
 307
 308 struct uci_context
 309 {
 310         /* list of config packages */
 311         struct uci_list root;
 312
 313         /* parser context, use for error handling only */
 314         struct uci_parse_context *pctx;
 315
 316         /* backend for import and export */
 317         struct uci_backend *backend;
 318
 319         /* uci runtime flags */
 320         enum uci_flags flags;
 321
 322         char *confdir;
 323         char *savedir;
 324
 325         /* search path for history files */
 326         struct uci_list history_path;
 327
 328         /* private: */
 329         int errno;
 330         const char *func;
 331         jmp_buf trap;
 332         bool internal;
 333         char *buf;
 334         int bufsz;
 335 };
 336
 337 struct uci_package
 338 {
 339         struct uci_element e;
 340         struct uci_list sections;
 341         struct uci_context *ctx;
 342         bool confdir;
 343         char *path;
 344
 345         /* private: */
 346         struct uci_backend *backend;
 347         int n_section;
 348         struct uci_list history;
 349         struct uci_list saved_history;
 350 };
 351
 352 struct uci_section
 353 {
 354         struct uci_element e;
 355         struct uci_list options;
 356         struct uci_package *package;
 357         bool anonymous;
 358         char *type;
 359 };
 360
 361 struct uci_option
 362 {
 363         struct uci_element e;
 364         struct uci_section *section;
 365         char *value;
 366 };
 367
 368 enum uci_command {
 369         UCI_CMD_ADD,
 370         UCI_CMD_REMOVE,
 371         UCI_CMD_CHANGE,
 372         UCI_CMD_RENAME
 373 };
 374
 375 struct uci_history
 376 {
 377         struct uci_element e;
 378         enum uci_command cmd;
 379         char *section;
 380         char *value;
 381 };
 382
 383 /* linked list handling */
 384 #ifndef offsetof
 385 #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
 386 #endif
 387
 388 /**
 389  * container_of - cast a member of a structure out to the containing structure
 390  * @ptr:    the pointer to the member.
 391  * @type:   the type of the container struct this is embedded in.
 392  * @member: the name of the member within the struct.
 393  */
 394 #define container_of(ptr, type, member) \
 395         ((type *) ((char *)ptr - offsetof(type,member)))
 396
 397
 398 /**
 399  * uci_list_entry: casts an uci_list pointer to the containing struct.
 400  * @_type: config, section or option
 401  * @_ptr: pointer to the uci_list struct
 402  */
 403 #define element_to(type, ptr) \
 404         container_of(ptr, struct uci_ ## type, e)
 405
 406 #define list_to_element(ptr) \
 407         container_of(ptr, struct uci_element, list)
 408
 409 /**
 410  * uci_foreach_entry: loop through a list of uci elements
 411  * @_list: pointer to the uci_list struct
 412  * @_ptr: iteration variable, struct uci_element
 413  *
 414  * use like a for loop, e.g:
 415  *   uci_foreach(&list, p) {
 416  *      ...
 417  *   }
 418  */
 419 #define uci_foreach_element(_list, _ptr)                \
 420         for(_ptr = list_to_element((_list)->next);      \
 421                 &_ptr->list != (_list);                 \
 422                 _ptr = list_to_element(_ptr->list.next))
 423
 424 /**
 425  * uci_foreach_entry_safe: like uci_foreach_safe, but safe for deletion
 426  * @_list: pointer to the uci_list struct
 427  * @_tmp: temporary variable, struct uci_element *
 428  * @_ptr: iteration variable, struct uci_element *
 429  *
 430  * use like a for loop, e.g:
 431  *   uci_foreach(&list, p) {
 432  *      ...
 433  *   }
 434  */
 435 #define uci_foreach_element_safe(_list, _tmp, _ptr)             \
 436         for(_ptr = list_to_element((_list)->next),              \
 437                 _tmp = list_to_element(_ptr->list.next);        \
 438                 &_ptr->list != (_list);                 \
 439                 _ptr = _tmp, _tmp = list_to_element(_ptr->list.next))
 440
 441 /**
 442  * uci_list_empty: returns true if a list is empty
 443  * @list: list head
 444  */
 445 #define uci_list_empty(list) ((list)->next == (list))
 446
 447 /* wrappers for dynamic type handling */
 448 #define uci_type_history UCI_TYPE_HISTORY
 449 #define uci_type_package UCI_TYPE_PACKAGE
 450 #define uci_type_section UCI_TYPE_SECTION
 451 #define uci_type_option UCI_TYPE_OPTION
 452
 453 /* element typecasting */
 454 #ifdef UCI_DEBUG_TYPECAST
 455 static const char *uci_typestr[] = {
 456         [uci_type_history] = "history",
 457         [uci_type_package] = "package",
 458         [uci_type_section] = "section",
 459         [uci_type_option] = "option",
 460 };
 461
 462 static void uci_typecast_error(int from, int to)
 463 {
 464         fprintf(stderr, "Invalid typecast from '%s' to '%s'\n", uci_typestr[from], uci_typestr[to]);
 465 }
 466
 467 #define BUILD_CAST(_type) \
 468         static inline struct uci_ ## _type *uci_to_ ## _type (struct uci_element *e) \
 469         { \
 470                 if (e->type != uci_type_ ## _type) { \
 471                         uci_typecast_error(e->type, uci_type_ ## _type); \
 472                 } \
 473                 return (struct uci_ ## _type *) e; \
 474         }
 475
 476 BUILD_CAST(history)
 477 BUILD_CAST(package)
 478 BUILD_CAST(section)
 479 BUILD_CAST(option)
 480
 481 #else
 482 #define uci_to_history(ptr) container_of(ptr, struct uci_history, e)
 483 #define uci_to_package(ptr) container_of(ptr, struct uci_package, e)
 484 #define uci_to_section(ptr) container_of(ptr, struct uci_section, e)
 485 #define uci_to_option(ptr)  container_of(ptr, struct uci_option, e)
 486 #endif
 487
 488 /**
 489  * uci_alloc_element: allocate a generic uci_element, reserve a buffer and typecast
 490  * @ctx: uci context
 491  * @type: {package,section,option}
 492  * @name: string containing the name of the element
 493  * @datasize: additional buffer size to reserve at the end of the struct
 494  */
 495 #define uci_alloc_element(ctx, type, name, datasize) \
 496         uci_to_ ## type (uci_alloc_generic(ctx, uci_type_ ## type, name, sizeof(struct uci_ ## type) + datasize))
 497
 498 #define uci_dataptr(ptr) \
 499         (((char *) ptr) + sizeof(*ptr))
 500
 501 #endif