xref: /openbmc/qemu/qobject/json-writer.c (revision 41192db3)
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 
json_writer_new(bool pretty)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 
json_writer_get(JSONWriter * writer)38 const char *json_writer_get(JSONWriter *writer)
39 {
40     g_assert(!writer->container_is_array->len);
41     return writer->contents->str;
42 }
43 
json_writer_get_and_free(JSONWriter * writer)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 
json_writer_free(JSONWriter * writer)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 
enter_container(JSONWriter * writer,bool is_array)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 
leave_container(JSONWriter * writer,bool is_array)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 
in_object(JSONWriter * writer)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 
pretty_newline(JSONWriter * writer)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 
pretty_newline_or_space(JSONWriter * writer)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 
quoted_str(JSONWriter * writer,const char * str)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 
maybe_comma_name(JSONWriter * writer,const char * name)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 
json_writer_start_object(JSONWriter * writer,const char * name)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 
json_writer_end_object(JSONWriter * writer)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 
json_writer_start_array(JSONWriter * writer,const char * name)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 
json_writer_end_array(JSONWriter * writer)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 
json_writer_bool(JSONWriter * writer,const char * name,bool val)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 
json_writer_null(JSONWriter * writer,const char * name)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 
json_writer_int64(JSONWriter * writer,const char * name,int64_t val)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 
json_writer_uint64(JSONWriter * writer,const char * name,uint64_t val)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 
json_writer_double(JSONWriter * writer,const char * name,double val)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 
json_writer_str(JSONWriter * writer,const char * name,const char * str)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