Check for trailing garbage (comma) at the end of objects and arrays, before closing bracket

.github/workflows/main.yml

@@ -55,7 +55,7 @@ jobs:
 
       - name: Build and run tests
         run: |
-          c89 -ansi -Wall -Wpedantic -Werror -pedantic -pedantic-errors -D_ANSI_SOURCE -DJSON_TRACK_SOURCE -I. json.c tests/test.c -lm -o json-test
+          c89 -ansi -Wall -Wpedantic -Werror -pedantic -pedantic-errors -D_ANSI_SOURCE -DJSON_TRACK_SOURCE -DJSON_LINTING=1 -I. json.c tests/test.c -lm -o json-test
           cd tests
           ../json-test
 
@@ -103,7 +103,7 @@ jobs:
         run: cl /permissive- /Zc:preprocessor /Zc:throwingNew /volatile:iso /utf-8 /std:c++latest /Zc:__cplusplus /Wall /DJSON_TRACK_SOURCE /LD /Tp json.c
 
       - name: Build test executable
-        run: cl /permissive- /Zc:preprocessor /Zc:throwingNew /volatile:iso /utf-8 /std:c++latest /Zc:__cplusplus /Wall /DJSON_TRACK_SOURCE /I . /MT /Tp json.c /Tp tests\test.c /Fetests\json-test.exe
+        run: cl /permissive- /Zc:preprocessor /Zc:throwingNew /volatile:iso /utf-8 /std:c++latest /Zc:__cplusplus /Wall /DJSON_TRACK_SOURCE /DJSON_LINTING=1 /I . /MT /Tp json.c /Tp tests\test.c /Fetests\json-test.exe
 
       - name: Run tests
         if: matrix.arch != 'amd64_arm' && matrix.arch != 'amd64_arm64'

README.md

@@ -61,6 +61,16 @@ Example usage:
 * `"-Djson_int_t=long long"`
 * `-Djson_int_t=__int128`
 
+### `JSON_LINTING`
+Loads code branches used for strict ECMA-404 JSON parsing.
+
+Setting JSON_LINTING to 1 additionally requires the use of the runtime option (json_enable_comments) to perform linting.
+Setting JSON_LINTING to 2 performs linting without requiring the runtime option.
+
+Example usage:
+* `-DJSON_LINTING=1`
+* `-DJSON_LINTING=2`
+
 
 Runtime Options
 ---------------
@@ -69,6 +79,10 @@ settings |= json_enable_comments;
 ```
 Enables C-style `// line` and `/* block */` comments.
 ```c
+settings |= json_enable_linting;
+```
+Enables strict ECMA-404 JSON parsing
+```c
 size_t value_extra
 ```
 The amount of space (if any) to allocate at the end of each `json_value`, in

configure.ac

@@ -29,6 +29,16 @@ if test "x$enable_value_pos" = xyes; then
 	CFLAGS="$CFLAGS -DJSON_TRACK_SOURCE"
 fi
 
+AC_ARG_ENABLE([enable-linting],
+	[AS_HELP_STRING([--enable-linting],
+		 [ Enables strict ECMA-404 JSON parsing. @<:@default=disabled@:>@])],
+	[enable_linting="$enableval"],
+	[enable_linting=no]
+)
+if test "x$enable_linting" = xyes; then
+	CFLAGS="$CFLAGS -DJSON_LINTING=1"
+fi
+
 AC_SUBST(VERSION_MAJOR, $VERSION_MAJOR)
 
 AC_CONFIG_FILES([

examples/test_json.c

@@ -168,6 +168,14 @@ int main(int argc, char** argv)
 
         value = json_parse(json,file_size);
 
+        /*
+         * Use json_parse_ex to enable runtime options
+         */
+        /* json_settings settings = { 0 }; */
+        /* settings.settings |= json_enable_comments; */
+        /* settings.settings |= json_enable_linting; */
+        /* value = json_parse_ex(&settings, json, file_size, 0); */
+
         if (value == NULL) {
                 fprintf(stderr, "Unable to parse data\n");
                 free(file_contents);

json.c

@@ -69,6 +69,18 @@ typedef unsigned int json_uchar;
 
 const struct _json_value json_value_none;
 
+#if defined JSON_LINTING && JSON_LINTING == 1
+int compile_option_linting = 0;
+#elif defined JSON_LINTING && JSON_LINTING == 2
+int compile_option_linting = 1;
+#endif
+
+/*
+ * Called when parsing closing brackets of objects and arrays
+ * Decrements json_char ptr, ignoring whitespace, allowing digits and { } [ ] " true false null
+ */
+static int trailing_garbage (const json_char * ptr);
+
 static unsigned char hex_value (json_char c)
 {
    if (isdigit((unsigned char)c))
@@ -550,9 +562,23 @@ json_value * json_parse_ex (json_settings * settings,
                case ']':
 
                   if (top && top->type == json_array)
+                  {
+                     #if defined JSON_LINTING && (JSON_LINTING == 1 || JSON_LINTING == 2)
+                     if (state.settings.settings & json_enable_linting || compile_option_linting == 1)
+                     {
+                        if (trailing_garbage(state.ptr))
+                        {
+                           sprintf (error, "Trailing garbage before %d:%d",
+                                    state.cur_line, state.cur_col);
+                           goto e_failed;
+                        }
+                     }
+                     #endif
                      flags = (flags & ~ (flag_need_comma | flag_seek_value)) | flag_next;
+                  }
                   else
-                  {  sprintf (error, "%u:%u: Unexpected `]`", line_and_col);
+                  {  
+                     sprintf (error, "%u:%u: Unexpected `]`", line_and_col);
                      goto e_failed;
                   }
 
@@ -742,6 +768,18 @@ json_value * json_parse_ex (json_settings * settings,
 
                   case '}':
 
+                     #if defined JSON_LINTING && (JSON_LINTING == 1 || JSON_LINTING == 2)
+                     if (state.settings.settings & json_enable_linting || compile_option_linting == 1)
+                     {
+                        if (trailing_garbage(state.ptr))
+                        {
+                           sprintf (error, "Trailing garbage before %d:%d",
+                             state.cur_line, state.cur_col);
+                           goto e_failed;
+                        }
+                     }
+                     #endif
+
                      flags = (flags & ~ flag_need_comma) | flag_next;
                      break;
 
@@ -1055,3 +1093,56 @@ void json_value_free (json_value * value)
    settings.mem_free = default_free;
    json_value_free_ex (&settings, value);
 }
+
+int trailing_garbage (const json_char * ptr)
+{
+   json_char * marker = (char *)ptr;
+   do
+   {
+      marker--;
+   }
+   while (isspace(*marker));
+
+   switch (*marker)
+   {
+      case '}':
+      case '{':
+      case ']':
+      case '[':
+      case '"':
+        return 0;
+
+      case 'e':
+         /* Allow true */
+         if (strncmp(marker-3, "true", 4) == 0)
+         {
+            return 0;
+         }
+
+         /* Allow false */
+         if (strncmp(marker-4, "false", 5) == 0)
+         {
+            return 0;
+         }
+         return 1;
+
+      case 'l':
+         /* Allow null */
+         if (strncmp(marker-3, "null", 4) == 0)
+         {
+            return 0;
+         }
+         return 1;
+
+      default:
+         /* Allow digits */
+         if (isdigit(*marker))
+         {
+            return 0;
+         }
+         else
+         {
+            return 1;
+         }
+   }
+}

json.h

@@ -80,6 +80,7 @@ typedef struct
 } json_settings;
 
 #define json_enable_comments  0x01
+#define json_enable_linting   0x02
 
 typedef enum
 {

tests/invalid-0011.json

@@ -0,0 +1,3 @@
+{
+    "a": "b",
+}

tests/invalid-0012.json

@@ -0,0 +1,3 @@
+[
+    "foo",
+]

tests/test.c

@@ -136,7 +136,8 @@ static int json_verify(const char * filename_format, unsigned highest_file_num,
 
    if(extensions == 1)
    {
-      settings.settings = json_enable_comments;
+      settings.settings |= json_enable_comments;
+      settings.settings |= json_enable_linting;
    }
 
    for(test_num = 0; ; ++test_num)
@@ -227,7 +228,7 @@ int main(void)
    JSON_COMPARE_STRING(1, "\\ud841\\udf31", "𠜱"); /* TODO: this should actually succeed after PR #58 is merged */
 
    if(0 != json_verify(      "valid-%04u.json", 13, 0, 0)){ exit_code = EXIT_FAILURE; }
-   if(0 != json_verify(    "invalid-%04u.json", 10, 0, 1)){ exit_code = EXIT_FAILURE; }
+   if(0 != json_verify(    "invalid-%04u.json", 12, 0, 1)){ exit_code = EXIT_FAILURE; }
    if(0 != json_verify(  "ext-valid-%04u.json",  3, 1, 0)){ exit_code = EXIT_FAILURE; }
    if(0 != json_verify("ext-invalid-%04u.json",  2, 1, 1)){ exit_code = EXIT_FAILURE; }