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