src/shared/json.h

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 #pragma once
   3
   4 #include <stdbool.h>
   5 #include <stddef.h>
   6 #include <stdint.h>
   7
   8 #include "macro.h"
   9 #include "string-util.h"
  10 #include "util.h"
  11
  12 /*
  13   In case you wonder why we have our own JSON implementation, here are a couple of reasons why this implementation has
  14   benefits over various other implementatins:
  15
  16   - We need support for 64bit signed and unsigned integers, i.e. the full 64,5bit range of -9223372036854775808…18446744073709551615
  17   - All our variants are immutable after creation
  18   - Special values such as true, false, zero, null, empty strings, empty array, empty objects require zero dynamic memory
  19   - Progressive parsing
  20   - Our integer/real type implicitly converts, but only if that's safe and loss-lessly possible
  21   - There's a "builder" for putting together objects easily in varargs function calls
  22   - There's a "dispatcher" for mapping objects to C data structures
  23   - Every variant optionally carries parsing location information, which simplifies debugging and parse log error generation
  24   - Formatter has color, line, column support
  25
  26   Limitations:
  27   - Doesn't allow embedded NUL in strings
  28   - Can't store integers outside of the -9223372036854775808…18446744073709551615 range (it will use 'long double' for
  29     values outside this range, which is lossy)
  30   - Can't store negative zero (will be treated identical to positive zero, and not retained across serialization)
  31   - Can't store non-integer numbers that can't be stored in "long double" losslessly
  32   - Allows creation and parsing of objects with duplicate keys. The "dispatcher" will refuse them however. This means
  33     we can parse and pass around such objects, but will carefully refuse them when we convert them into our own data.
  34
  35   (These limitations should be pretty much in line with those of other JSON implementations, in fact might be less
  36   limiting in most cases even.)
  37 */
  38
  39 typedef struct JsonVariant JsonVariant;
  40
  41 typedef enum JsonVariantType {
  42         JSON_VARIANT_STRING,
  43         JSON_VARIANT_INTEGER,
  44         JSON_VARIANT_UNSIGNED,
  45         JSON_VARIANT_REAL,
  46         JSON_VARIANT_NUMBER, /* This a pseudo-type: we can never create variants of this type, but we use it as wildcard check for the above three types */
  47         JSON_VARIANT_BOOLEAN,
  48         JSON_VARIANT_ARRAY,
  49         JSON_VARIANT_OBJECT,
  50         JSON_VARIANT_NULL,
  51         _JSON_VARIANT_TYPE_MAX,
  52         _JSON_VARIANT_TYPE_INVALID = -1
  53 } JsonVariantType;
  54
  55 int json_variant_new_stringn(JsonVariant **ret, const char *s, size_t n);
  56 int json_variant_new_integer(JsonVariant **ret, intmax_t i);
  57 int json_variant_new_unsigned(JsonVariant **ret, uintmax_t u);
  58 int json_variant_new_real(JsonVariant **ret, long double d);
  59 int json_variant_new_boolean(JsonVariant **ret, bool b);
  60 int json_variant_new_array(JsonVariant **ret, JsonVariant **array, size_t n);
  61 int json_variant_new_array_bytes(JsonVariant **ret, const void *p, size_t n);
  62 int json_variant_new_array_strv(JsonVariant **ret, char **l);
  63 int json_variant_new_object(JsonVariant **ret, JsonVariant **array, size_t n);
  64 int json_variant_new_null(JsonVariant **ret);
  65
  66 static inline int json_variant_new_string(JsonVariant **ret, const char *s) {
  67         return json_variant_new_stringn(ret, s, strlen_ptr(s));
  68 }
  69
  70 JsonVariant *json_variant_ref(JsonVariant *v);
  71 JsonVariant *json_variant_unref(JsonVariant *v);
  72 void json_variant_unref_many(JsonVariant **array, size_t n);
  73
  74 DEFINE_TRIVIAL_CLEANUP_FUNC(JsonVariant *, json_variant_unref);
  75
  76 const char *json_variant_string(JsonVariant *v);
  77 intmax_t json_variant_integer(JsonVariant *v);
  78 uintmax_t json_variant_unsigned(JsonVariant *v);
  79 long double json_variant_real(JsonVariant *v);
  80 bool json_variant_boolean(JsonVariant *v);
  81
  82 JsonVariantType json_variant_type(JsonVariant *v);
  83 bool json_variant_has_type(JsonVariant *v, JsonVariantType type);
  84
  85 static inline bool json_variant_is_string(JsonVariant *v) {
  86         return json_variant_has_type(v, JSON_VARIANT_STRING);
  87 }
  88
  89 static inline bool json_variant_is_integer(JsonVariant *v) {
  90         return json_variant_has_type(v, JSON_VARIANT_INTEGER);
  91 }
  92
  93 static inline bool json_variant_is_unsigned(JsonVariant *v) {
  94         return json_variant_has_type(v, JSON_VARIANT_UNSIGNED);
  95 }
  96
  97 static inline bool json_variant_is_real(JsonVariant *v) {
  98         return json_variant_has_type(v, JSON_VARIANT_REAL);
  99 }
 100
 101 static inline bool json_variant_is_number(JsonVariant *v) {
 102         return json_variant_has_type(v, JSON_VARIANT_NUMBER);
 103 }
 104
 105 static inline bool json_variant_is_boolean(JsonVariant *v) {
 106         return json_variant_has_type(v, JSON_VARIANT_BOOLEAN);
 107 }
 108
 109 static inline bool json_variant_is_array(JsonVariant *v) {
 110         return json_variant_has_type(v, JSON_VARIANT_ARRAY);
 111 }
 112
 113 static inline bool json_variant_is_object(JsonVariant *v) {
 114         return json_variant_has_type(v, JSON_VARIANT_OBJECT);
 115 }
 116
 117 static inline bool json_variant_is_null(JsonVariant *v) {
 118         return json_variant_has_type(v, JSON_VARIANT_NULL);
 119 }
 120
 121 bool json_variant_is_negative(JsonVariant *v);
 122
 123 size_t json_variant_elements(JsonVariant *v);
 124 JsonVariant *json_variant_by_index(JsonVariant *v, size_t index);
 125 JsonVariant *json_variant_by_key(JsonVariant *v, const char *key);
 126 JsonVariant *json_variant_by_key_full(JsonVariant *v, const char *key, JsonVariant **ret_key);
 127
 128 bool json_variant_equal(JsonVariant *a, JsonVariant *b);
 129
 130 struct json_variant_foreach_state {
 131         JsonVariant *variant;
 132         size_t idx;
 133 };
 134
 135 #define JSON_VARIANT_ARRAY_FOREACH(i, v)                                \
 136         for (struct json_variant_foreach_state _state = { (v), 0 };     \
 137              _state.idx < json_variant_elements(_state.variant) &&      \
 138                      ({ i = json_variant_by_index(_state.variant, _state.idx); \
 139                              true; });                                  \
 140              _state.idx++)
 141
 142 #define JSON_VARIANT_OBJECT_FOREACH(k, e, v)                            \
 143         for (struct json_variant_foreach_state _state = { (v), 0 };     \
 144              _state.idx < json_variant_elements(_state.variant) &&      \
 145                      ({ k = json_variant_by_index(_state.variant, _state.idx); \
 146                              e = json_variant_by_index(_state.variant, _state.idx + 1); \
 147                              true; });                                  \
 148              _state.idx += 2)
 149
 150 int json_variant_get_source(JsonVariant *v, const char **ret_source, unsigned *ret_line, unsigned *ret_column);
 151
 152 typedef enum JsonFormatFlags {
 153         JSON_FORMAT_NEWLINE    = 1 << 0, /* suffix with newline */
 154         JSON_FORMAT_PRETTY     = 1 << 1, /* add internal whitespace to appeal to human readers */
 155         JSON_FORMAT_COLOR      = 1 << 2, /* insert ANSI color sequences */
 156         JSON_FORMAT_COLOR_AUTO = 1 << 3, /* insert ANSI color sequences if colors_enabled() says so */
 157         JSON_FORMAT_SOURCE     = 1 << 4, /* prefix with source filename/line/column */
 158         JSON_FORMAT_SSE        = 1 << 5, /* prefix/suffix with W3C server-sent events */
 159         JSON_FORMAT_SEQ        = 1 << 6, /* prefix/suffix with RFC 7464 application/json-seq */
 160 } JsonFormatFlags;
 161
 162 int json_variant_format(JsonVariant *v, JsonFormatFlags flags, char **ret);
 163 void json_variant_dump(JsonVariant *v, JsonFormatFlags flags, FILE *f, const char *prefix);
 164
 165 int json_parse(const char *string, JsonVariant **ret, unsigned *ret_line, unsigned *ret_column);
 166 int json_parse_continue(const char **p, JsonVariant **ret, unsigned *ret_line, unsigned *ret_column);
 167 int json_parse_file(FILE *f, const char *path, JsonVariant **ret, unsigned *ret_line, unsigned *ret_column);
 168
 169 enum {
 170         _JSON_BUILD_STRING,
 171         _JSON_BUILD_INTEGER,
 172         _JSON_BUILD_UNSIGNED,
 173         _JSON_BUILD_REAL,
 174         _JSON_BUILD_BOOLEAN,
 175         _JSON_BUILD_ARRAY_BEGIN,
 176         _JSON_BUILD_ARRAY_END,
 177         _JSON_BUILD_OBJECT_BEGIN,
 178         _JSON_BUILD_OBJECT_END,
 179         _JSON_BUILD_PAIR,
 180         _JSON_BUILD_PAIR_CONDITION,
 181         _JSON_BUILD_NULL,
 182         _JSON_BUILD_VARIANT,
 183         _JSON_BUILD_LITERAL,
 184         _JSON_BUILD_STRV,
 185         _JSON_BUILD_MAX,
 186 };
 187
 188 #define JSON_BUILD_STRING(s) _JSON_BUILD_STRING, ({ const char *_x = s; _x; })
 189 #define JSON_BUILD_INTEGER(i) _JSON_BUILD_INTEGER, ({ intmax_t _x = i; _x; })
 190 #define JSON_BUILD_UNSIGNED(u) _JSON_BUILD_UNSIGNED, ({ uintmax_t _x = u; _x; })
 191 #define JSON_BUILD_REAL(d) _JSON_BUILD_REAL, ({ long double _x = d; _x; })
 192 #define JSON_BUILD_BOOLEAN(b) _JSON_BUILD_BOOLEAN, ({ bool _x = b; _x; })
 193 #define JSON_BUILD_ARRAY(...) _JSON_BUILD_ARRAY_BEGIN, __VA_ARGS__, _JSON_BUILD_ARRAY_END
 194 #define JSON_BUILD_OBJECT(...) _JSON_BUILD_OBJECT_BEGIN, __VA_ARGS__, _JSON_BUILD_OBJECT_END
 195 #define JSON_BUILD_PAIR(n, ...) _JSON_BUILD_PAIR, ({ const char *_x = n; _x; }), __VA_ARGS__
 196 #define JSON_BUILD_PAIR_CONDITION(c, n, ...) _JSON_BUILD_PAIR_CONDITION, ({ bool _x = c; _x; }), ({ const char *_x = n; _x; }), __VA_ARGS__
 197 #define JSON_BUILD_NULL _JSON_BUILD_NULL
 198 #define JSON_BUILD_VARIANT(v) _JSON_BUILD_VARIANT, ({ JsonVariant *_x = v; _x; })
 199 #define JSON_BUILD_LITERAL(l) _JSON_BUILD_LITERAL, ({ const char *_x = l; _x; })
 200 #define JSON_BUILD_STRV(l) _JSON_BUILD_STRV, ({ char **_x = l; _x; })
 201
 202 int json_build(JsonVariant **ret, ...);
 203 int json_buildv(JsonVariant **ret, va_list ap);
 204
 205 /* A bitmask of flags used by the dispatch logic. Note that this is a combined bit mask, that is generated from the bit
 206  * mask originally passed into json_dispatch(), the individual bitmask associated with the static JsonDispatch callout
 207  * entry, as well the bitmask specified for json_log() calls */
 208 typedef enum JsonDispatchFlags {
 209         /* The following three may be set in JsonDispatch's .flags field or the json_dispatch() flags parameter  */
 210         JSON_PERMISSIVE = 1 << 0, /* Shall parsing errors be considered fatal for this property? */
 211         JSON_MANDATORY  = 1 << 1, /* Should existance of this property be mandatory? */
 212         JSON_LOG        = 1 << 2, /* Should the parser log about errors? */
 213
 214         /* The following two may be passed into log_json() in addition to the three above */
 215         JSON_DEBUG      = 1 << 3, /* Indicates that this log message is a debug message */
 216         JSON_WARNING    = 1 << 4, /* Indicates that this log message is a warning message */
 217 } JsonDispatchFlags;
 218
 219 typedef int (*JsonDispatchCallback)(const char *name, JsonVariant *variant, JsonDispatchFlags flags, void *userdata);
 220
 221 typedef struct JsonDispatch {
 222         const char *name;
 223         JsonVariantType type;
 224         JsonDispatchCallback callback;
 225         size_t offset;
 226         JsonDispatchFlags flags;
 227 } JsonDispatch;
 228
 229 int json_dispatch(JsonVariant *v, const JsonDispatch table[], JsonDispatchCallback bad, JsonDispatchFlags flags, void *userdata);
 230
 231 int json_dispatch_string(const char *name, JsonVariant *variant, JsonDispatchFlags flags, void *userdata);
 232 int json_dispatch_strv(const char *name, JsonVariant *variant, JsonDispatchFlags flags, void *userdata);
 233 int json_dispatch_boolean(const char *name, JsonVariant *variant, JsonDispatchFlags flags, void *userdata);
 234 int json_dispatch_tristate(const char *name, JsonVariant *variant, JsonDispatchFlags flags, void *userdata);
 235 int json_dispatch_variant(const char *name, JsonVariant *variant, JsonDispatchFlags flags, void *userdata);
 236 int json_dispatch_integer(const char *name, JsonVariant *variant, JsonDispatchFlags flags, void *userdata);
 237 int json_dispatch_unsigned(const char *name, JsonVariant *variant, JsonDispatchFlags flags, void *userdata);
 238 int json_dispatch_uint32(const char *name, JsonVariant *variant, JsonDispatchFlags flags, void *userdata);
 239 int json_dispatch_int32(const char *name, JsonVariant *variant, JsonDispatchFlags flags, void *userdata);
 240
 241 assert_cc(sizeof(uintmax_t) == sizeof(uint64_t))
 242 #define json_dispatch_uint64 json_dispatch_unsigned
 243
 244 assert_cc(sizeof(intmax_t) == sizeof(int64_t))
 245 #define json_dispatch_int64 json_dispatch_integer
 246
 247 static inline int json_dispatch_level(JsonDispatchFlags flags) {
 248
 249         /* Did the user request no logging? If so, then never log higher than LOG_DEBUG. Also, if this is marked as
 250          * debug message, then also log at debug level. */
 251
 252         if (!(flags & JSON_LOG) ||
 253             (flags & JSON_DEBUG))
 254                 return LOG_DEBUG;
 255
 256         /* Are we invoked in permissive mode, or is this explicitly marked as warning message? Then this should be
 257          * printed at LOG_WARNING */
 258         if (flags & (JSON_PERMISSIVE|JSON_WARNING))
 259                 return LOG_WARNING;
 260
 261         /* Otherwise it's an error. */
 262         return LOG_ERR;
 263 }
 264
 265 int json_log_internal(JsonVariant *variant, int level, int error, const char *file, int line, const char *func, const char *format, ...)  _printf_(7, 8);
 266
 267 #define json_log(variant, flags, error, ...)                       \
 268         ({                                                              \
 269                 int _level = json_dispatch_level(flags), _e = (error);    \
 270                 (log_get_max_level() >= LOG_PRI(_level))                \
 271                         ? json_log_internal(variant, _level, _e, __FILE__, __LINE__, __func__, __VA_ARGS__) \
 272                         : -abs(_e);                                     \
 273         })
 274
 275 #define JSON_VARIANT_STRING_CONST(x) _JSON_VARIANT_STRING_CONST(UNIQ, (x))
 276
 277 #define _JSON_VARIANT_STRING_CONST(xq, x)                               \
 278         ({                                                              \
 279                 _align_(2) static const char UNIQ_T(json_string_const, xq)[] = (x); \
 280                 assert((((uintptr_t) UNIQ_T(json_string_const, xq)) & 1) == 0); \
 281                 (JsonVariant*) ((uintptr_t) UNIQ_T(json_string_const, xq) + 1); \
 282         })
 283
 284 const char *json_variant_type_to_string(JsonVariantType t);
 285 JsonVariantType json_variant_type_from_string(const char *s);