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
  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_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  */
 107 extern int uci_import(struct uci_context *ctx, FILE *stream, const char *name, struct uci_package **package, bool single);
 108
 109 /**
 110  * uci_export: Export one or all uci config packages
 111  * @ctx: uci context
 112  * @stream: output stream
 113  * @package: (optional) uci config package to export
 114  * @header: include the package header
 115  */
 116 extern int uci_export(struct uci_context *ctx, FILE *stream, struct uci_package *package, bool header);
 117
 118 /**
 119  * uci_load: Parse an uci config file and store it in the uci context
 120  *
 121  * @ctx: uci context
 122  * @name: name of the config file (relative to the config directory)
 123  * @package: store the loaded config package in this variable
 124  */
 125 extern int uci_load(struct uci_context *ctx, const char *name, struct uci_package **package);
 126
 127 /**
 128  * uci_unload: Unload a config file from the uci context
 129  *
 130  * @ctx: uci context
 131  * @package: pointer to the uci_package struct
 132  */
 133 extern int uci_unload(struct uci_context *ctx, struct uci_package *p);
 134
 135 /**
 136  * uci_cleanup: Clean up after an error
 137  *
 138  * @ctx: uci context
 139  */
 140 extern int uci_cleanup(struct uci_context *ctx);
 141
 142 /**
 143  * uci_lookup: Look up an uci element
 144  *
 145  * @ctx: uci context
 146  * @res: where to store the result
 147  * @package: uci_package struct
 148  * @section: config section (optional)
 149  * @option: option to search for (optional)
 150  *
 151  * If section is omitted, then a pointer to the config package is returned
 152  * If option is omitted, then a pointer to the config section is returned
 153  */
 154 extern int uci_lookup(struct uci_context *ctx, struct uci_element **res, struct uci_package *package, char *section, char *option);
 155
 156 /**
 157  * uci_set_element_value: Replace an element's value with a new one
 158  * @ctx: uci context
 159  * @element: pointer to an uci_element struct pointer
 160  * @value: new value
 161  *
 162  * Only valid for uci_option and uci_section. Will replace the type string
 163  * when used with an uci_section
 164  */
 165 extern int uci_set_element_value(struct uci_context *ctx, struct uci_element **element, char *value);
 166
 167 /**
 168  * uci_set: Set an element's value; create the element if necessary
 169  * @ctx: uci context
 170  * @package: package name
 171  * @section: section name
 172  * @option: option name
 173  * @value: value (option) or type (section)
 174  */
 175 extern int uci_set(struct uci_context *ctx, char *package, char *section, char *option, char *value);
 176
 177 /**
 178  * uci_commit: commit changes to a package
 179  * @ctx: uci context
 180  * @p: uci_package struct
 181  */
 182 extern int uci_commit(struct uci_context *ctx, struct uci_package *p);
 183
 184 /**
 185  * uci_list_configs: List available uci config files
 186  *
 187  * @ctx: uci context
 188  */
 189 extern char **uci_list_configs(struct uci_context *ctx);
 190
 191 /* UCI data structures */
 192 enum uci_type {
 193         UCI_TYPE_PACKAGE = 0,
 194         UCI_TYPE_SECTION = 1,
 195         UCI_TYPE_OPTION = 2
 196 };
 197
 198 struct uci_element
 199 {
 200         struct uci_list list;
 201         enum uci_type type;
 202         char *name;
 203 };
 204
 205 struct uci_context
 206 {
 207         /* list of config packages */
 208         struct uci_list root;
 209
 210         /* parser context, use for error handling only */
 211         struct uci_parse_context *pctx;
 212
 213         /* private: */
 214         int errno;
 215         const char *func;
 216         jmp_buf trap;
 217         char *buf;
 218         int bufsz;
 219 };
 220
 221 struct uci_parse_context
 222 {
 223         /* error context */
 224         const char *reason;
 225         int line;
 226         int byte;
 227
 228         /* private: */
 229         struct uci_package *package;
 230         struct uci_section *section;
 231         FILE *file;
 232         const char *name;
 233         char *buf;
 234         int bufsz;
 235 };
 236
 237 struct uci_package
 238 {
 239         struct uci_element e;
 240         struct uci_list sections;
 241         struct uci_context *ctx;
 242         bool confdir;
 243         char *path;
 244
 245         /* private: */
 246         int n_section;
 247         struct uci_list history;
 248 };
 249
 250 struct uci_section
 251 {
 252         struct uci_element e;
 253         struct uci_list options;
 254         struct uci_package *package;
 255         char *type;
 256 };
 257
 258 struct uci_option
 259 {
 260         struct uci_element e;
 261         struct uci_section *section;
 262         char *value;
 263 };
 264
 265 enum uci_command {
 266         UCI_CMD_ADD,
 267         UCI_CMD_REMOVE,
 268         UCI_CMD_CHANGE
 269 };
 270
 271 struct uci_history
 272 {
 273         struct uci_list list;
 274         enum uci_command cmd;
 275         char *section;
 276         char *option;
 277         char *value;
 278 };
 279
 280 /* linked list handling */
 281 #ifndef offsetof
 282 #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
 283 #endif
 284
 285 /**
 286  * container_of - cast a member of a structure out to the containing structure
 287  * @ptr:    the pointer to the member.
 288  * @type:   the type of the container struct this is embedded in.
 289  * @member: the name of the member within the struct.
 290  */
 291 #define container_of(ptr, type, member) \
 292         ((type *) ((char *)ptr - offsetof(type,member)))
 293
 294
 295 /**
 296  * uci_list_entry: casts an uci_list pointer to the containing struct.
 297  * @_type: config, section or option
 298  * @_ptr: pointer to the uci_list struct
 299  */
 300 #define element_to(type, ptr) \
 301         container_of(ptr, struct uci_ ## type, e)
 302
 303 #define list_to_element(ptr) \
 304         container_of(ptr, struct uci_element, list)
 305
 306 /**
 307  * uci_foreach_entry: loop through a list of uci elements
 308  * @_list: pointer to the uci_list struct
 309  * @_ptr: iteration variable, struct uci_element
 310  *
 311  * use like a for loop, e.g:
 312  *   uci_foreach(&list, p) {
 313  *      ...
 314  *   }
 315  */
 316 #define uci_foreach_element(_list, _ptr)                \
 317         for(_ptr = list_to_element((_list)->next);      \
 318                 &_ptr->list != (_list);                 \
 319                 _ptr = list_to_element(_ptr->list.next))
 320
 321 /**
 322  * uci_foreach_entry_safe: like uci_foreach_safe, but safe for deletion
 323  * @_list: pointer to the uci_list struct
 324  * @_tmp: temporary variable, struct uci_element *
 325  * @_ptr: iteration variable, struct uci_element *
 326  *
 327  * use like a for loop, e.g:
 328  *   uci_foreach(&list, p) {
 329  *      ...
 330  *   }
 331  */
 332 #define uci_foreach_element_safe(_list, _tmp, _ptr)             \
 333         for(_ptr = list_to_element((_list)->next),              \
 334                 _tmp = list_to_element(_ptr->list.next);        \
 335                 &_ptr->list != (_list);                 \
 336                 _ptr = _tmp, _tmp = list_to_element(_ptr->list.next))
 337
 338 /**
 339  * uci_list_empty: returns true if a list is empty
 340  * @list: list head
 341  */
 342 #define uci_list_empty(list) ((list)->next == (list))
 343
 344 /* wrappers for dynamic type handling */
 345 #define uci_type_package UCI_TYPE_PACKAGE
 346 #define uci_type_section UCI_TYPE_SECTION
 347 #define uci_type_option UCI_TYPE_OPTION
 348
 349 /* element typecasting */
 350 #ifdef UCI_DEBUG_TYPECAST
 351 static const char *uci_typestr[] = {
 352         [uci_type_package] = "package",
 353         [uci_type_section] = "section",
 354         [uci_type_option] = "option"
 355 };
 356
 357 static void uci_typecast_error(int from, int to)
 358 {
 359         fprintf(stderr, "Invalid typecast from '%s' to '%s'\n", uci_typestr[from], uci_typestr[to]);
 360 }
 361
 362 #define BUILD_CAST(_type) \
 363         static inline struct uci_ ## _type *uci_to_ ## _type (struct uci_element *e) \
 364         { \
 365                 if (e->type != uci_type_ ## _type) { \
 366                         uci_typecast_error(e->type, uci_type_ ## _type); \
 367                 } \
 368                 return (struct uci_ ## _type *) e; \
 369         }
 370
 371 BUILD_CAST(package)
 372 BUILD_CAST(section)
 373 BUILD_CAST(option)
 374
 375 #else
 376 #define uci_to_package(ptr) container_of(ptr, struct uci_package, e)
 377 #define uci_to_section(ptr) container_of(ptr, struct uci_section, e)
 378 #define uci_to_option(ptr)  container_of(ptr, struct uci_option, e)
 379 #endif
 380
 381 /**
 382  * uci_alloc_element: allocate a generic uci_element, reserve a buffer and typecast
 383  * @ctx: uci context
 384  * @type: {package,section,option}
 385  * @name: string containing the name of the element
 386  * @datasize: additional buffer size to reserve at the end of the struct
 387  */
 388 #define uci_alloc_element(ctx, type, name, datasize) \
 389         uci_to_ ## type (uci_alloc_generic(ctx, uci_type_ ## type, name, sizeof(struct uci_ ## type) + datasize))
 390
 391 #define uci_dataptr(ptr) \
 392         (((char *) ptr) + sizeof(*ptr))
 393
 394 #endif