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_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_parse_context;
  63
  64
  65 /**
  66  * uci_alloc_context: Allocate a new uci context
  67  */
  68 extern struct uci_context *uci_alloc_context(void);
  69
  70 /**
  71  * uci_free_context: Free the uci context including all of its data
  72  */
  73 extern void uci_free_context(struct uci_context *ctx);
  74
  75 /**
  76  * uci_perror: Print the last uci error that occured
  77  * @ctx: uci context
  78  * @str: string to print before the error message
  79  */
  80 extern void uci_perror(struct uci_context *ctx, const char *str);
  81
  82 /**
  83  * uci_import: Import uci config data from a stream
  84  * @ctx: uci context
  85  * @stream: file stream to import from
  86  * @name: (optional) assume the config has the given name
  87  * @package: (optional) store the last parsed config package in this variable
  88  * @single: ignore the 'package' keyword and parse everything into a single package
  89  *
  90  * the name parameter is for config files that don't explicitly use the 'package <...>' keyword
  91  */
  92 extern int uci_import(struct uci_context *ctx, FILE *stream, const char *name, struct uci_package **package, bool single);
  93
  94 /**
  95  * uci_export: Export one or all uci config packages
  96  * @ctx: uci context
  97  * @stream: output stream
  98  * @package: (optional) uci config package to export
  99  * @header: include the package header
 100  */
 101 extern int uci_export(struct uci_context *ctx, FILE *stream, struct uci_package *package, bool header);
 102
 103 /**
 104  * uci_load: Parse an uci config file and store it in the uci context
 105  *
 106  * @ctx: uci context
 107  * @name: name of the config file (relative to the config directory)
 108  * @package: store the loaded config package in this variable
 109  */
 110 extern int uci_load(struct uci_context *ctx, const char *name, struct uci_package **package);
 111
 112 /**
 113  * uci_unload: Unload a config file from the uci context
 114  *
 115  * @ctx: uci context
 116  * @package: pointer to the uci_package struct
 117  */
 118 extern int uci_unload(struct uci_context *ctx, struct uci_package *p);
 119
 120 /**
 121  * uci_cleanup: Clean up after an error
 122  *
 123  * @ctx: uci context
 124  */
 125 extern int uci_cleanup(struct uci_context *ctx);
 126
 127 /**
 128  * uci_lookup: Look up an uci element
 129  *
 130  * @ctx: uci context
 131  * @res: where to store the result
 132  * @package: uci_package struct
 133  * @section: config section (optional)
 134  * @option: option to search for (optional)
 135  *
 136  * If section is omitted, then a pointer to the config package is returned
 137  * If option is omitted, then a pointer to the config section is returned
 138  */
 139 extern int uci_lookup(struct uci_context *ctx, struct uci_element **res, struct uci_package *package, char *section, char *option);
 140
 141 /**
 142  * uci_set_element_value: Replace an element's value with a new one
 143  * @ctx: uci context
 144  * @element: pointer to an uci_element struct pointer
 145  * @value: new value
 146  *
 147  * Only valid for uci_option and uci_section. Will replace the type string
 148  * when used with an uci_section
 149  */
 150 extern int uci_set_element_value(struct uci_context *ctx, struct uci_element **element, char *value);
 151
 152 /**
 153  * uci_set: Set an element's value; create the element if necessary
 154  * @ctx: uci context
 155  * @package: package name
 156  * @section: section name
 157  * @option: option name
 158  * @value: value (option) or type (section)
 159  */
 160 extern int uci_set(struct uci_context *ctx, char *package, char *section, char *option, char *value);
 161
 162 /**
 163  * uci_commit: commit changes to a package
 164  * @ctx: uci context
 165  * @p: uci_package struct
 166  */
 167 extern int uci_commit(struct uci_context *ctx, struct uci_package *p);
 168
 169 /**
 170  * uci_list_configs: List available uci config files
 171  *
 172  * @ctx: uci context
 173  */
 174 extern char **uci_list_configs(struct uci_context *ctx);
 175
 176 /* UCI data structures */
 177 enum uci_type {
 178         UCI_TYPE_PACKAGE = 0,
 179         UCI_TYPE_SECTION = 1,
 180         UCI_TYPE_OPTION = 2
 181 };
 182
 183 struct uci_element
 184 {
 185         struct uci_list list;
 186         enum uci_type type;
 187         char *name;
 188 };
 189
 190 struct uci_context
 191 {
 192         /* list of config packages */
 193         struct uci_list root;
 194
 195         /* parser context, use for error handling only */
 196         struct uci_parse_context *pctx;
 197
 198         /* private: */
 199         int errno;
 200         const char *func;
 201         jmp_buf trap;
 202         char *buf;
 203         int bufsz;
 204 };
 205
 206 struct uci_parse_context
 207 {
 208         /* error context */
 209         const char *reason;
 210         int line;
 211         int byte;
 212
 213         /* private: */
 214         struct uci_package *package;
 215         struct uci_section *section;
 216         FILE *file;
 217         const char *name;
 218         char *buf;
 219         int bufsz;
 220 };
 221
 222 struct uci_package
 223 {
 224         struct uci_element e;
 225         struct uci_list sections;
 226         struct uci_context *ctx;
 227         bool confdir;
 228         char *path;
 229
 230         /* private: */
 231         int n_section;
 232         struct uci_list history;
 233 };
 234
 235 struct uci_section
 236 {
 237         struct uci_element e;
 238         struct uci_list options;
 239         struct uci_package *package;
 240         char *type;
 241 };
 242
 243 struct uci_option
 244 {
 245         struct uci_element e;
 246         struct uci_section *section;
 247         char *value;
 248 };
 249
 250 enum uci_command {
 251         UCI_CMD_ADD,
 252         UCI_CMD_REMOVE,
 253         UCI_CMD_CHANGE
 254 };
 255
 256 struct uci_history
 257 {
 258         struct uci_list list;
 259         enum uci_command cmd;
 260         char *section;
 261         char *option;
 262         char *value;
 263 };
 264
 265 /* linked list handling */
 266 #ifndef offsetof
 267 #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
 268 #endif
 269
 270 /**
 271  * container_of - cast a member of a structure out to the containing structure
 272  * @ptr:    the pointer to the member.
 273  * @type:   the type of the container struct this is embedded in.
 274  * @member: the name of the member within the struct.
 275  */
 276 #define container_of(ptr, type, member) \
 277         ((type *) ((char *)ptr - offsetof(type,member)))
 278
 279
 280 /**
 281  * uci_list_entry: casts an uci_list pointer to the containing struct.
 282  * @_type: config, section or option
 283  * @_ptr: pointer to the uci_list struct
 284  */
 285 #define element_to(type, ptr) \
 286         container_of(ptr, struct uci_ ## type, e)
 287
 288 #define list_to_element(ptr) \
 289         container_of(ptr, struct uci_element, list)
 290
 291 /**
 292  * uci_foreach_entry: loop through a list of uci elements
 293  * @_list: pointer to the uci_list struct
 294  * @_ptr: iteration variable, struct uci_element
 295  *
 296  * use like a for loop, e.g:
 297  *   uci_foreach(&list, p) {
 298  *      ...
 299  *   }
 300  */
 301 #define uci_foreach_element(_list, _ptr)                \
 302         for(_ptr = list_to_element((_list)->next);      \
 303                 &_ptr->list != (_list);                 \
 304                 _ptr = list_to_element(_ptr->list.next))
 305
 306 /**
 307  * uci_foreach_entry_safe: like uci_foreach_safe, but safe for deletion
 308  * @_list: pointer to the uci_list struct
 309  * @_tmp: temporary variable, struct uci_element *
 310  * @_ptr: iteration variable, struct uci_element *
 311  *
 312  * use like a for loop, e.g:
 313  *   uci_foreach(&list, p) {
 314  *      ...
 315  *   }
 316  */
 317 #define uci_foreach_element_safe(_list, _tmp, _ptr)             \
 318         for(_ptr = list_to_element((_list)->next),              \
 319                 _tmp = list_to_element(_ptr->list.next);        \
 320                 &_ptr->list != (_list);                 \
 321                 _ptr = _tmp, _tmp = list_to_element(_ptr->list.next))
 322
 323 /**
 324  * uci_list_empty: returns true if a list is empty
 325  * @list: list head
 326  */
 327 #define uci_list_empty(list) ((list)->next == (list))
 328
 329 /* wrappers for dynamic type handling */
 330 #define uci_type_package UCI_TYPE_PACKAGE
 331 #define uci_type_section UCI_TYPE_SECTION
 332 #define uci_type_option UCI_TYPE_OPTION
 333
 334 /* element typecasting */
 335 #ifdef UCI_DEBUG_TYPECAST
 336 static const char *uci_typestr[] = {
 337         [uci_type_package] = "package",
 338         [uci_type_section] = "section",
 339         [uci_type_option] = "option"
 340 };
 341
 342 static void uci_typecast_error(int from, int to)
 343 {
 344         fprintf(stderr, "Invalid typecast from '%s' to '%s'\n", uci_typestr[from], uci_typestr[to]);
 345 }
 346
 347 #define BUILD_CAST(_type) \
 348         static inline struct uci_ ## _type *uci_to_ ## _type (struct uci_element *e) \
 349         { \
 350                 if (e->type != uci_type_ ## _type) { \
 351                         uci_typecast_error(e->type, uci_type_ ## _type); \
 352                 } \
 353                 return (struct uci_ ## _type *) e; \
 354         }
 355
 356 BUILD_CAST(package)
 357 BUILD_CAST(section)
 358 BUILD_CAST(option)
 359
 360 #else
 361 #define uci_to_package(ptr) container_of(ptr, struct uci_package, e)
 362 #define uci_to_section(ptr) container_of(ptr, struct uci_section, e)
 363 #define uci_to_option(ptr)  container_of(ptr, struct uci_option, e)
 364 #endif
 365
 366 /**
 367  * uci_alloc_element: allocate a generic uci_element, reserve a buffer and typecast
 368  * @ctx: uci context
 369  * @type: {package,section,option}
 370  * @name: string containing the name of the element
 371  * @datasize: additional buffer size to reserve at the end of the struct
 372  */
 373 #define uci_alloc_element(ctx, type, name, datasize) \
 374         uci_to_ ## type (uci_alloc_generic(ctx, uci_type_ ## type, name, sizeof(struct uci_ ## type) + datasize))
 375
 376 #define uci_dataptr(ptr) \
 377         (((char *) ptr) + sizeof(*ptr))
 378
 379 #endif