1 /* 2 * JSON Writer 3 * 4 * Copyright IBM, Corp. 2009 5 * Copyright (c) 2010-2020 Red Hat Inc. 6 * 7 * Authors: 8 * Anthony Liguori <aliguori@us.ibm.com> 9 * Markus Armbruster <armbru@redhat.com> 10 * 11 * This work is licensed under the terms of the GNU LGPL, version 2.1 or later. 12 * See the COPYING.LIB file in the top-level directory. 13 * 14 */ 15 16 #include "qemu/osdep.h" 17 #include "qapi/qmp/json-writer.h" 18 #include "qemu/unicode.h" 19 20 struct JSONWriter { 21 bool pretty; 22 bool need_comma; 23 GString *contents; 24 GByteArray *container_is_array; 25 }; 26 27 JSONWriter *json_writer_new(bool pretty) 28 { 29 JSONWriter *writer = g_new(JSONWriter, 1); 30 31 writer->pretty = pretty; 32 writer->need_comma = false; 33 writer->contents = g_string_new(NULL); 34 writer->container_is_array = g_byte_array_new(); 35 return writer; 36 } 37 38 const char *json_writer_get(JSONWriter *writer) 39 { 40 g_assert(!writer->container_is_array->len); 41 return writer->contents->str; 42 } 43 44 GString *json_writer_get_and_free(JSONWriter *writer) 45 { 46 GString *contents = writer->contents; 47 48 writer->contents = NULL; 49 g_byte_array_free(writer->container_is_array, true); 50 g_free(writer); 51 return contents; 52 } 53 54 void json_writer_free(JSONWriter *writer) 55 { 56 if (writer) { 57 g_string_free(json_writer_get_and_free(writer), true); 58 } 59 } 60 61 static void enter_container(JSONWriter *writer, bool is_array) 62 { 63 unsigned depth = writer->container_is_array->len; 64 65 g_byte_array_set_size(writer->container_is_array, depth + 1); 66 writer->container_is_array->data[depth] = is_array; 67 writer->need_comma = false; 68 } 69 70 static void leave_container(JSONWriter *writer, bool is_array) 71 { 72 unsigned depth = writer->container_is_array->len; 73 74 assert(depth); 75 assert(writer->container_is_array->data[depth - 1] == is_array); 76 g_byte_array_set_size(writer->container_is_array, depth - 1); 77 writer->need_comma = true; 78 } 79 80 static bool in_object(JSONWriter *writer) 81 { 82 unsigned depth = writer->container_is_array->len; 83 84 return depth && !writer->container_is_array->data[depth - 1]; 85 } 86 87 static void pretty_newline(JSONWriter *writer) 88 { 89 if (writer->pretty) { 90 g_string_append_printf(writer->contents, "\n%*s", 91 writer->container_is_array->len * 4, ""); 92 } 93 } 94 95 static void pretty_newline_or_space(JSONWriter *writer) 96 { 97 if (writer->pretty) { 98 g_string_append_printf(writer->contents, "\n%*s", 99 writer->container_is_array->len * 4, ""); 100 } else { 101 g_string_append_c(writer->contents, ' '); 102 } 103 } 104 105 static void quoted_str(JSONWriter *writer, const char *str) 106 { 107 const char *ptr; 108 char *end; 109 int cp; 110 111 g_string_append_c(writer->contents, '"'); 112 113 for (ptr = str; *ptr; ptr = end) { 114 cp = mod_utf8_codepoint(ptr, 6, &end); 115 switch (cp) { 116 case '\"': 117 g_string_append(writer->contents, "\\\""); 118 break; 119 case '\\': 120 g_string_append(writer->contents, "\\\\"); 121 break; 122 case '\b': 123 g_string_append(writer->contents, "\\b"); 124 break; 125 case '\f': 126 g_string_append(writer->contents, "\\f"); 127 break; 128 case '\n': 129 g_string_append(writer->contents, "\\n"); 130 break; 131 case '\r': 132 g_string_append(writer->contents, "\\r"); 133 break; 134 case '\t': 135 g_string_append(writer->contents, "\\t"); 136 break; 137 default: 138 if (cp < 0) { 139 cp = 0xFFFD; /* replacement character */ 140 } 141 if (cp > 0xFFFF) { 142 /* beyond BMP; need a surrogate pair */ 143 g_string_append_printf(writer->contents, "\\u%04X\\u%04X", 144 0xD800 + ((cp - 0x10000) >> 10), 145 0xDC00 + ((cp - 0x10000) & 0x3FF)); 146 } else if (cp < 0x20 || cp >= 0x7F) { 147 g_string_append_printf(writer->contents, "\\u%04X", cp); 148 } else { 149 g_string_append_c(writer->contents, cp); 150 } 151 } 152 }; 153 154 g_string_append_c(writer->contents, '"'); 155 } 156 157 static void maybe_comma_name(JSONWriter *writer, const char *name) 158 { 159 if (writer->need_comma) { 160 g_string_append_c(writer->contents, ','); 161 pretty_newline_or_space(writer); 162 } else { 163 if (writer->contents->len) { 164 pretty_newline(writer); 165 } 166 writer->need_comma = true; 167 } 168 169 if (in_object(writer)) { 170 quoted_str(writer, name); 171 g_string_append(writer->contents, ": "); 172 } 173 } 174 175 void json_writer_start_object(JSONWriter *writer, const char *name) 176 { 177 maybe_comma_name(writer, name); 178 g_string_append_c(writer->contents, '{'); 179 enter_container(writer, false); 180 } 181 182 void json_writer_end_object(JSONWriter *writer) 183 { 184 leave_container(writer, false); 185 pretty_newline(writer); 186 g_string_append_c(writer->contents, '}'); 187 } 188 189 void json_writer_start_array(JSONWriter *writer, const char *name) 190 { 191 maybe_comma_name(writer, name); 192 g_string_append_c(writer->contents, '['); 193 enter_container(writer, true); 194 } 195 196 void json_writer_end_array(JSONWriter *writer) 197 { 198 leave_container(writer, true); 199 pretty_newline(writer); 200 g_string_append_c(writer->contents, ']'); 201 } 202 203 void json_writer_bool(JSONWriter *writer, const char *name, bool val) 204 { 205 maybe_comma_name(writer, name); 206 g_string_append(writer->contents, val ? "true" : "false"); 207 } 208 209 void json_writer_null(JSONWriter *writer, const char *name) 210 { 211 maybe_comma_name(writer, name); 212 g_string_append(writer->contents, "null"); 213 } 214 215 void json_writer_int64(JSONWriter *writer, const char *name, int64_t val) 216 { 217 maybe_comma_name(writer, name); 218 g_string_append_printf(writer->contents, "%" PRId64, val); 219 } 220 221 void json_writer_uint64(JSONWriter *writer, const char *name, uint64_t val) 222 { 223 maybe_comma_name(writer, name); 224 g_string_append_printf(writer->contents, "%" PRIu64, val); 225 } 226 227 void json_writer_double(JSONWriter *writer, const char *name, double val) 228 { 229 maybe_comma_name(writer, name); 230 231 /* 232 * FIXME: g_string_append_printf() is locale dependent; but JSON 233 * requires numbers to be formatted as if in the C locale. 234 * Dependence on C locale is a pervasive issue in QEMU. 235 */ 236 /* 237 * FIXME: This risks printing Inf or NaN, which are not valid 238 * JSON values. 239 */ 240 g_string_append_printf(writer->contents, "%.17g", val); 241 } 242 243 void json_writer_str(JSONWriter *writer, const char *name, const char *str) 244 { 245 maybe_comma_name(writer, name); 246 quoted_str(writer, str); 247 } 248