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