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
  39 enum
  40 {
  41         UCI_OK = 0,
  42         UCI_ERR_MEM,
  43         UCI_ERR_INVAL,
  44         UCI_ERR_NOTFOUND,
  45         UCI_ERR_IO,
  46         UCI_ERR_PARSE,
  47         UCI_ERR_DUPLICATE,
  48         UCI_ERR_UNKNOWN,
  49         UCI_ERR_LAST
  50 };
  51
  52 struct uci_list;
  53 struct uci_list
  54 {
  55         struct uci_list *next;
  56         struct uci_list *prev;
  57 };
  58
  59 struct uci_element;
  60 struct uci_package;
  61 struct uci_section;
  62 struct uci_option;
  63 struct uci_history;
  64 struct uci_context;
  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  */
 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_cleanup: Clean up after an error
 138  *
 139  * @ctx: uci context
 140  */
 141 extern int uci_cleanup(struct uci_context *ctx);
 142
 143 /**
 144  * uci_lookup: Look up an uci element
 145  *
 146  * @ctx: uci context
 147  * @res: where to store the result
 148  * @package: uci_package struct
 149  * @section: config section (optional)
 150  * @option: option to search for (optional)
 151  *
 152  * If section is omitted, then a pointer to the config package is returned
 153  * If option is omitted, then a pointer to the config section is returned
 154  */
 155 extern int uci_lookup(struct uci_context *ctx, struct uci_element **res, struct uci_package *package, char *section, char *option);
 156
 157 /**
 158  * uci_set_element_value: Replace an element's value with a new one
 159  * @ctx: uci context
 160  * @element: pointer to an uci_element struct pointer
 161  * @value: new value
 162  *
 163  * Only valid for uci_option and uci_section. Will replace the type string
 164  * when used with an uci_section
 165  */
 166 extern int uci_set_element_value(struct uci_context *ctx, struct uci_element **element, char *value);
 167
 168 /**
 169  * uci_set: Set an element's value; create the element if necessary
 170  * @ctx: uci context
 171  * @package: package name
 172  * @section: section name
 173  * @option: option name
 174  * @value: value (option) or type (section)
 175  */
 176 extern int uci_set(struct uci_context *ctx, char *package, char *section, char *option, char *value);
 177
 178 /**
 179  * uci_save: save change history for a package
 180  * @ctx: uci context
 181  * @p: uci_package struct
 182  */
 183 extern int uci_save(struct uci_context *ctx, struct uci_package *p);
 184
 185 /**
 186  * uci_commit: commit changes to a package
 187  * @ctx: uci context
 188  * @p: uci_package struct
 189  */
 190 extern int uci_commit(struct uci_context *ctx, struct uci_package *p);
 191
 192 /**
 193  * uci_list_configs: List available uci config files
 194  *
 195  * @ctx: uci context
 196  */
 197 extern char **uci_list_configs(struct uci_context *ctx);
 198
 199 /* UCI data structures */
 200 enum uci_type {
 201         UCI_TYPE_HISTORY = 0,
 202         UCI_TYPE_PACKAGE = 1,
 203         UCI_TYPE_SECTION = 2,
 204         UCI_TYPE_OPTION = 3
 205 };
 206
 207 struct uci_element
 208 {
 209         struct uci_list list;
 210         enum uci_type type;
 211         char *name;
 212 };
 213
 214 struct uci_context
 215 {
 216         /* list of config packages */
 217         struct uci_list root;
 218
 219         /* parser context, use for error handling only */
 220         struct uci_parse_context *pctx;
 221
 222         /* private: */
 223         int errno;
 224         const char *func;
 225         jmp_buf trap;
 226         bool internal;
 227         char *buf;
 228         int bufsz;
 229 };
 230
 231 struct uci_parse_context
 232 {
 233         /* error context */
 234         const char *reason;
 235         int line;
 236         int byte;
 237
 238         /* private: */
 239         struct uci_package *package;
 240         struct uci_section *section;
 241         FILE *file;
 242         const char *name;
 243         char *buf;
 244         int bufsz;
 245 };
 246
 247 struct uci_package
 248 {
 249         struct uci_element e;
 250         struct uci_list sections;
 251         struct uci_context *ctx;
 252         bool confdir;
 253         char *path;
 254
 255         /* private: */
 256         int n_section;
 257         struct uci_list history;
 258 };
 259
 260 struct uci_section
 261 {
 262         struct uci_element e;
 263         struct uci_list options;
 264         struct uci_package *package;
 265         char *type;
 266 };
 267
 268 struct uci_option
 269 {
 270         struct uci_element e;
 271         struct uci_section *section;
 272         char *value;
 273 };
 274
 275 enum uci_command {
 276         UCI_CMD_ADD,
 277         UCI_CMD_REMOVE,
 278         UCI_CMD_CHANGE
 279 };
 280
 281 struct uci_history
 282 {
 283         struct uci_element e;
 284         enum uci_command cmd;
 285         char *section;
 286         char *value;
 287 };
 288
 289 /* linked list handling */
 290 #ifndef offsetof
 291 #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
 292 #endif
 293
 294 /**
 295  * container_of - cast a member of a structure out to the containing structure
 296  * @ptr:    the pointer to the member.
 297  * @type:   the type of the container struct this is embedded in.
 298  * @member: the name of the member within the struct.
 299  */
 300 #define container_of(ptr, type, member) \
 301         ((type *) ((char *)ptr - offsetof(type,member)))
 302
 303
 304 /**
 305  * uci_list_entry: casts an uci_list pointer to the containing struct.
 306  * @_type: config, section or option
 307  * @_ptr: pointer to the uci_list struct
 308  */
 309 #define element_to(type, ptr) \
 310         container_of(ptr, struct uci_ ## type, e)
 311
 312 #define list_to_element(ptr) \
 313         container_of(ptr, struct uci_element, list)
 314
 315 /**
 316  * uci_foreach_entry: loop through a list of uci elements
 317  * @_list: pointer to the uci_list struct
 318  * @_ptr: iteration variable, struct uci_element
 319  *
 320  * use like a for loop, e.g:
 321  *   uci_foreach(&list, p) {
 322  *      ...
 323  *   }
 324  */
 325 #define uci_foreach_element(_list, _ptr)                \
 326         for(_ptr = list_to_element((_list)->next);      \
 327                 &_ptr->list != (_list);                 \
 328                 _ptr = list_to_element(_ptr->list.next))
 329
 330 /**
 331  * uci_foreach_entry_safe: like uci_foreach_safe, but safe for deletion
 332  * @_list: pointer to the uci_list struct
 333  * @_tmp: temporary variable, struct uci_element *
 334  * @_ptr: iteration variable, struct uci_element *
 335  *
 336  * use like a for loop, e.g:
 337  *   uci_foreach(&list, p) {
 338  *      ...
 339  *   }
 340  */
 341 #define uci_foreach_element_safe(_list, _tmp, _ptr)             \
 342         for(_ptr = list_to_element((_list)->next),              \
 343                 _tmp = list_to_element(_ptr->list.next);        \
 344                 &_ptr->list != (_list);                 \
 345                 _ptr = _tmp, _tmp = list_to_element(_ptr->list.next))
 346
 347 /**
 348  * uci_list_empty: returns true if a list is empty
 349  * @list: list head
 350  */
 351 #define uci_list_empty(list) ((list)->next == (list))
 352
 353 /* wrappers for dynamic type handling */
 354 #define uci_type_history UCI_TYPE_HISTORY
 355 #define uci_type_package UCI_TYPE_PACKAGE
 356 #define uci_type_section UCI_TYPE_SECTION
 357 #define uci_type_option UCI_TYPE_OPTION
 358
 359 /* element typecasting */
 360 #ifdef UCI_DEBUG_TYPECAST
 361 static const char *uci_typestr[] = {
 362         [uci_type_history] = "history",
 363         [uci_type_package] = "package",
 364         [uci_type_section] = "section",
 365         [uci_type_option] = "option",
 366 };
 367
 368 static void uci_typecast_error(int from, int to)
 369 {
 370         fprintf(stderr, "Invalid typecast from '%s' to '%s'\n", uci_typestr[from], uci_typestr[to]);
 371 }
 372
 373 #define BUILD_CAST(_type) \
 374         static inline struct uci_ ## _type *uci_to_ ## _type (struct uci_element *e) \
 375         { \
 376                 if (e->type != uci_type_ ## _type) { \
 377                         uci_typecast_error(e->type, uci_type_ ## _type); \
 378                 } \
 379                 return (struct uci_ ## _type *) e; \
 380         }
 381
 382 BUILD_CAST(history)
 383 BUILD_CAST(package)
 384 BUILD_CAST(section)
 385 BUILD_CAST(option)
 386
 387 #else
 388 #define uci_to_history(ptr) container_of(ptr, struct uci_history, e)
 389 #define uci_to_package(ptr) container_of(ptr, struct uci_package, e)
 390 #define uci_to_section(ptr) container_of(ptr, struct uci_section, e)
 391 #define uci_to_option(ptr)  container_of(ptr, struct uci_option, e)
 392 #endif
 393
 394 /**
 395  * uci_alloc_element: allocate a generic uci_element, reserve a buffer and typecast
 396  * @ctx: uci context
 397  * @type: {package,section,option}
 398  * @name: string containing the name of the element
 399  * @datasize: additional buffer size to reserve at the end of the struct
 400  */
 401 #define uci_alloc_element(ctx, type, name, datasize) \
 402         uci_to_ ## type (uci_alloc_generic(ctx, uci_type_ ## type, name, sizeof(struct uci_ ## type) + datasize))
 403
 404 #define uci_dataptr(ptr) \
 405         (((char *) ptr) + sizeof(*ptr))
 406
 407 #endif