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_list_configs: List available uci config files
 140  *
 141  * @ctx: uci context
 142  */
 143 extern char **uci_list_configs(struct uci_context *ctx);
 144
 145 /* UCI data structures */
 146 enum uci_type {
 147         uci_type_package = 0,
 148         uci_type_section = 1,
 149         uci_type_option = 2
 150 };
 151
 152 struct uci_element
 153 {
 154         struct uci_list list;
 155         enum uci_type type;
 156         char *name;
 157 };
 158
 159 struct uci_context
 160 {
 161         /* list of config packages */
 162         struct uci_list root;
 163
 164         /* parser context, use for error handling only */
 165         struct uci_parse_context *pctx;
 166
 167         /* private: */
 168         int errno;
 169         jmp_buf trap;
 170         char *buf;
 171         int bufsz;
 172 };
 173
 174 struct uci_parse_context
 175 {
 176         /* error context */
 177         const char *reason;
 178         int line;
 179         int byte;
 180
 181         /* private: */
 182         struct uci_package *package;
 183         struct uci_section *section;
 184         FILE *file;
 185         const char *name;
 186         char *buf;
 187         int bufsz;
 188 };
 189
 190 struct uci_package
 191 {
 192         struct uci_element e;
 193         struct uci_list sections;
 194         struct uci_context *ctx;
 195         /* private: */
 196         int n_section;
 197 };
 198
 199 struct uci_section
 200 {
 201         struct uci_element e;
 202         struct uci_list options;
 203         struct uci_package *package;
 204         char *type;
 205 };
 206
 207 struct uci_option
 208 {
 209         struct uci_element e;
 210         struct uci_section *section;
 211         char *value;
 212 };
 213
 214 enum uci_command {
 215         UCI_CMD_ADD,
 216         UCI_CMD_REMOVE,
 217         UCI_CMD_CHANGE
 218 };
 219
 220 struct uci_history
 221 {
 222         struct uci_list list;
 223         enum uci_command cmd;
 224         union {
 225                 struct uci_element element;
 226                 struct uci_package package;
 227                 struct uci_section section;
 228                 struct uci_option option;
 229         } data;
 230 };
 231
 232 /* linked list handling */
 233 #ifndef offsetof
 234 #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
 235 #endif
 236
 237 /**
 238  * container_of - cast a member of a structure out to the containing structure
 239  * @ptr:    the pointer to the member.
 240  * @type:   the type of the container struct this is embedded in.
 241  * @member: the name of the member within the struct.
 242  */
 243 #define container_of(ptr, type, member) \
 244         ((type *) ((char *)ptr - offsetof(type,member)))
 245
 246
 247 /**
 248  * uci_list_entry: casts an uci_list pointer to the containing struct.
 249  * @_type: config, section or option
 250  * @_ptr: pointer to the uci_list struct
 251  */
 252 #define element_to(type, ptr) \
 253         container_of(ptr, struct uci_ ## type, e)
 254
 255 #define list_to_element(ptr) \
 256         container_of(ptr, struct uci_element, list)
 257
 258 /**
 259  * uci_foreach_entry: loop through a list of uci elements
 260  * @_list: pointer to the uci_list struct
 261  * @_ptr: iteration variable, struct uci_element
 262  *
 263  * use like a for loop, e.g:
 264  *   uci_foreach(&list, p) {
 265  *      ...
 266  *   }
 267  */
 268 #define uci_foreach_element(_list, _ptr)                \
 269         for(_ptr = list_to_element((_list)->next);      \
 270                 &_ptr->list != (_list);                 \
 271                 _ptr = list_to_element(_ptr->list.next))
 272
 273 /**
 274  * uci_foreach_entry_safe: like uci_foreach_safe, but safe for deletion
 275  * @_list: pointer to the uci_list struct
 276  * @_tmp: temporary variable, struct uci_element *
 277  * @_ptr: iteration variable, struct uci_element *
 278  *
 279  * use like a for loop, e.g:
 280  *   uci_foreach(&list, p) {
 281  *      ...
 282  *   }
 283  */
 284 #define uci_foreach_element_safe(_list, _tmp, _ptr)             \
 285         for(_ptr = list_to_element((_list)->next),              \
 286                 _tmp = list_to_element(_ptr->list.next);        \
 287                 &_ptr->list != (_list);                 \
 288                 _ptr = _tmp, _tmp = list_to_element(_ptr->list.next))
 289
 290 /* returns true if a list is empty */
 291 #define uci_list_empty(list) ((list)->next == (list))
 292
 293 /* element typecasting */
 294 #ifdef UCI_DEBUG_TYPECAST
 295 static const char *uci_typestr[] = {
 296         [uci_type_package] = "package",
 297         [uci_type_section] = "section",
 298         [uci_type_option] = "option"
 299 };
 300
 301 static void uci_typecast_error(int from, int to)
 302 {
 303         fprintf(stderr, "Invalid typecast from '%s' to '%s'\n", uci_typestr[from], uci_typestr[to]);
 304 }
 305
 306 #define BUILD_CAST(_type) \
 307         static inline struct uci_ ## _type *uci_to_ ## _type (struct uci_element *e) \
 308         { \
 309                 if (e->type != uci_type_ ## _type) { \
 310                         uci_typecast_error(e->type, uci_type_ ## _type); \
 311                 } \
 312                 return (struct uci_ ## _type *) e; \
 313         }
 314
 315 BUILD_CAST(package)
 316 BUILD_CAST(section)
 317 BUILD_CAST(option)
 318
 319 #else
 320 #define uci_to_package(ptr) container_of(ptr, struct uci_package, e)
 321 #define uci_to_section(ptr) container_of(ptr, struct uci_section, e)
 322 #define uci_to_option(ptr)  container_of(ptr, struct uci_option, e)
 323 #endif
 324
 325 /**
 326  * uci_alloc_element: allocate a generic uci_element, reserve a buffer and typecast
 327  * @ctx: uci context
 328  * @type: {package,section,option}
 329  * @name: string containing the name of the element
 330  * @datasize: additional buffer size to reserve at the end of the struct
 331  */
 332 #define uci_alloc_element(ctx, type, name, datasize) \
 333         uci_to_ ## type (uci_alloc_generic(ctx, uci_type_ ## type, name, sizeof(struct uci_ ## type) + datasize))
 334
 335 #define uci_dataptr(ptr) \
 336         (((char *) ptr) + sizeof(*ptr))
 337
 338 #endif