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 <setjmp.h>
  33 #include <stdio.h>
  34
  35 #define UCI_CONFDIR "/etc/config"
  36
  37 enum
  38 {
  39         UCI_OK = 0,
  40         UCI_ERR_MEM,
  41         UCI_ERR_INVAL,
  42         UCI_ERR_NOTFOUND,
  43         UCI_ERR_IO,
  44         UCI_ERR_PARSE,
  45         UCI_ERR_UNKNOWN,
  46         UCI_ERR_LAST
  47 };
  48
  49 struct uci_list;
  50 struct uci_list
  51 {
  52         struct uci_list *next;
  53         struct uci_list *prev;
  54 };
  55
  56 struct uci_element;
  57 struct uci_package;
  58 struct uci_section;
  59 struct uci_option;
  60 struct uci_history;
  61 struct uci_parse_context;
  62
  63
  64 /**
  65  * uci_alloc_context: Allocate a new uci context
  66  */
  67 extern struct uci_context *uci_alloc_context(void);
  68
  69 /**
  70  * uci_free_context: Free the uci context including all of its data
  71  */
  72 extern void uci_free_context(struct uci_context *ctx);
  73
  74 /**
  75  * uci_perror: Print the last uci error that occured
  76  * @ctx: uci context
  77  * @str: string to print before the error message
  78  */
  79 extern void uci_perror(struct uci_context *ctx, const char *str);
  80
  81 /**
  82  * uci_import: Import uci config data from a stream
  83  * @ctx: uci context
  84  * @stream: file stream to import from
  85  * @name: (optional) assume the config has the given name
  86  * @package: (optional) store the last parsed config package in this variable
  87  *
  88  * the name parameter is for config files that don't explicitly use the 'package <...>' keyword
  89  */
  90 extern int uci_import(struct uci_context *ctx, FILE *stream, const char *name, struct uci_package **package);
  91
  92 /**
  93  * uci_export: Export one or all uci config packages
  94  * @ctx: uci context
  95  * @stream: output stream
  96  * @package: (optional) uci config package to export
  97  */
  98 extern int uci_export(struct uci_context *ctx, FILE *stream, struct uci_package *package);
  99
 100 /**
 101  * uci_load: Parse an uci config file and store it in the uci context
 102  *
 103  * @ctx: uci context
 104  * @name: name of the config file (relative to the config directory)
 105  * @package: store the loaded config package in this variable
 106  */
 107 extern int uci_load(struct uci_context *ctx, const char *name, struct uci_package **package);
 108
 109 /**
 110  * uci_unload: Unload a config file from the uci context
 111  *
 112  * @ctx: uci context
 113  * @name: name of the config file
 114  */
 115 extern int uci_unload(struct uci_context *ctx, const char *name);
 116
 117 /**
 118  * uci_cleanup: Clean up after an error
 119  *
 120  * @ctx: uci context
 121  */
 122 extern int uci_cleanup(struct uci_context *ctx);
 123
 124 /**
 125  * uci_lookup: Look up an uci element
 126  *
 127  * @ctx: uci context
 128  * @res: where to store the result
 129  * @package: config package
 130  * @section: config section (optional)
 131  * @option: option to search for (optional)
 132  *
 133  * If section is omitted, then a pointer to the config package is returned
 134  * If option is omitted, then a pointer to the config section is returned
 135  */
 136 extern int uci_lookup(struct uci_context *ctx, struct uci_element **res, char *package, char *section, char *option);
 137
 138 /**
 139  * uci_set_element_value: Replace an element's value with a new one
 140  * @ctx: uci context
 141  * @element: pointer to an uci_element struct pointer
 142  * @value: new value
 143  *
 144  * Only valid for uci_option and uci_section. Will replace the type string
 145  * when used with an uci_section
 146  */
 147 extern int uci_set_element_value(struct uci_context *ctx, struct uci_element **element, char *value);
 148
 149 /**
 150  * uci_set: Set an element's value; create the element if necessary
 151  * @ctx: uci context
 152  * @package: package name
 153  * @section: section name
 154  * @option: option name
 155  * @value: value (option) or type (section)
 156  */
 157 extern int uci_set(struct uci_context *ctx, char *package, char *section, char *option, char *value);
 158
 159 /**
 160  * uci_list_configs: List available uci config files
 161  *
 162  * @ctx: uci context
 163  */
 164 extern char **uci_list_configs(struct uci_context *ctx);
 165
 166 /* UCI data structures */
 167 enum uci_type {
 168         UCI_TYPE_PACKAGE = 0,
 169         UCI_TYPE_SECTION = 1,
 170         UCI_TYPE_OPTION = 2
 171 };
 172
 173 struct uci_element
 174 {
 175         struct uci_list list;
 176         enum uci_type type;
 177         char *name;
 178 };
 179
 180 struct uci_context
 181 {
 182         /* list of config packages */
 183         struct uci_list root;
 184
 185         /* parser context, use for error handling only */
 186         struct uci_parse_context *pctx;
 187
 188         /* private: */
 189         int errno;
 190         const char *func;
 191         jmp_buf trap;
 192         char *buf;
 193         int bufsz;
 194 };
 195
 196 struct uci_parse_context
 197 {
 198         /* error context */
 199         const char *reason;
 200         int line;
 201         int byte;
 202
 203         /* private: */
 204         struct uci_package *package;
 205         struct uci_section *section;
 206         FILE *file;
 207         const char *name;
 208         char *buf;
 209         int bufsz;
 210 };
 211
 212 struct uci_package
 213 {
 214         struct uci_element e;
 215         struct uci_list sections;
 216         struct uci_context *ctx;
 217         /* private: */
 218         int n_section;
 219         struct uci_list history;
 220 };
 221
 222 struct uci_section
 223 {
 224         struct uci_element e;
 225         struct uci_list options;
 226         struct uci_package *package;
 227         char *type;
 228 };
 229
 230 struct uci_option
 231 {
 232         struct uci_element e;
 233         struct uci_section *section;
 234         char *value;
 235 };
 236
 237 enum uci_command {
 238         UCI_CMD_ADD,
 239         UCI_CMD_REMOVE,
 240         UCI_CMD_CHANGE
 241 };
 242
 243 struct uci_history
 244 {
 245         struct uci_list list;
 246         enum uci_command cmd;
 247         char *section;
 248         char *option;
 249         char *value;
 250 };
 251
 252 /* linked list handling */
 253 #ifndef offsetof
 254 #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
 255 #endif
 256
 257 /**
 258  * container_of - cast a member of a structure out to the containing structure
 259  * @ptr:    the pointer to the member.
 260  * @type:   the type of the container struct this is embedded in.
 261  * @member: the name of the member within the struct.
 262  */
 263 #define container_of(ptr, type, member) \
 264         ((type *) ((char *)ptr - offsetof(type,member)))
 265
 266
 267 /**
 268  * uci_list_entry: casts an uci_list pointer to the containing struct.
 269  * @_type: config, section or option
 270  * @_ptr: pointer to the uci_list struct
 271  */
 272 #define element_to(type, ptr) \
 273         container_of(ptr, struct uci_ ## type, e)
 274
 275 #define list_to_element(ptr) \
 276         container_of(ptr, struct uci_element, list)
 277
 278 /**
 279  * uci_foreach_entry: loop through a list of uci elements
 280  * @_list: pointer to the uci_list struct
 281  * @_ptr: iteration variable, struct uci_element
 282  *
 283  * use like a for loop, e.g:
 284  *   uci_foreach(&list, p) {
 285  *      ...
 286  *   }
 287  */
 288 #define uci_foreach_element(_list, _ptr)                \
 289         for(_ptr = list_to_element((_list)->next);      \
 290                 &_ptr->list != (_list);                 \
 291                 _ptr = list_to_element(_ptr->list.next))
 292
 293 /**
 294  * uci_foreach_entry_safe: like uci_foreach_safe, but safe for deletion
 295  * @_list: pointer to the uci_list struct
 296  * @_tmp: temporary variable, struct uci_element *
 297  * @_ptr: iteration variable, struct uci_element *
 298  *
 299  * use like a for loop, e.g:
 300  *   uci_foreach(&list, p) {
 301  *      ...
 302  *   }
 303  */
 304 #define uci_foreach_element_safe(_list, _tmp, _ptr)             \
 305         for(_ptr = list_to_element((_list)->next),              \
 306                 _tmp = list_to_element(_ptr->list.next);        \
 307                 &_ptr->list != (_list);                 \
 308                 _ptr = _tmp, _tmp = list_to_element(_ptr->list.next))
 309
 310 /* returns true if a list is empty */
 311 #define uci_list_empty(list) ((list)->next == (list))
 312
 313 /* wrappers for dynamic type handling */
 314 #define uci_type_package UCI_TYPE_PACKAGE
 315 #define uci_type_section UCI_TYPE_SECTION
 316 #define uci_type_option UCI_TYPE_OPTION
 317
 318 /* element typecasting */
 319 #ifdef UCI_DEBUG_TYPECAST
 320 static const char *uci_typestr[] = {
 321         [uci_type_package] = "package",
 322         [uci_type_section] = "section",
 323         [uci_type_option] = "option"
 324 };
 325
 326 static void uci_typecast_error(int from, int to)
 327 {
 328         fprintf(stderr, "Invalid typecast from '%s' to '%s'\n", uci_typestr[from], uci_typestr[to]);
 329 }
 330
 331 #define BUILD_CAST(_type) \
 332         static inline struct uci_ ## _type *uci_to_ ## _type (struct uci_element *e) \
 333         { \
 334                 if (e->type != uci_type_ ## _type) { \
 335                         uci_typecast_error(e->type, uci_type_ ## _type); \
 336                 } \
 337                 return (struct uci_ ## _type *) e; \
 338         }
 339
 340 BUILD_CAST(package)
 341 BUILD_CAST(section)
 342 BUILD_CAST(option)
 343
 344 #else
 345 #define uci_to_package(ptr) container_of(ptr, struct uci_package, e)
 346 #define uci_to_section(ptr) container_of(ptr, struct uci_section, e)
 347 #define uci_to_option(ptr)  container_of(ptr, struct uci_option, e)
 348 #endif
 349
 350 /**
 351  * uci_alloc_element: allocate a generic uci_element, reserve a buffer and typecast
 352  * @ctx: uci context
 353  * @type: {package,section,option}
 354  * @name: string containing the name of the element
 355  * @datasize: additional buffer size to reserve at the end of the struct
 356  */
 357 #define uci_alloc_element(ctx, type, name, datasize) \
 358         uci_to_ ## type (uci_alloc_generic(ctx, uci_type_ ## type, name, sizeof(struct uci_ ## type) + datasize))
 359
 360 #define uci_dataptr(ptr) \
 361         (((char *) ptr) + sizeof(*ptr))
 362
 363 #endif