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