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