initial work on a wifi/http configuration module

components/wifi-manager/json.c

@@ -0,0 +1,144 @@
+/*
+@file json.c
+@brief handles very basic JSON with a minimal footprint on the system
+
+This code is a lightly modified version of cJSON 1.4.7. cJSON is licensed under the MIT license:
+Copyright (c) 2009 Dave Gamble
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+of the Software, and to permit persons to whom the Software is furnished to do
+so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT
+OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+OTHER DEALINGS IN THE SOFTWARE.
+
+@see https://github.com/DaveGamble/cJSON
+*/
+
+#include "json.h"
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdbool.h>
+
+
+bool json_print_string(const unsigned char *input, unsigned char *output_buffer)
+{
+	const unsigned char *input_pointer = NULL;
+	unsigned char *output = NULL;
+	unsigned char *output_pointer = NULL;
+	size_t output_length = 0;
+	/* numbers of additional characters needed for escaping */
+	size_t escape_characters = 0;
+
+	if (output_buffer == NULL)
+	{
+		return false;
+	}
+
+	/* empty string */
+	if (input == NULL)
+	{
+		//output = ensure(output_buffer, sizeof("\"\""), hooks);
+		if (output == NULL)
+		{
+			return false;
+		}
+		strcpy((char*)output, "\"\"");
+
+		return true;
+	}
+
+	/* set "flag" to 1 if something needs to be escaped */
+	for (input_pointer = input; *input_pointer; input_pointer++)
+	{
+		if (strchr("\"\\\b\f\n\r\t", *input_pointer))
+		{
+			/* one character escape sequence */
+			escape_characters++;
+		}
+		else if (*input_pointer < 32)
+		{
+			/* UTF-16 escape sequence uXXXX */
+			escape_characters += 5;
+		}
+	}
+	output_length = (size_t)(input_pointer - input) + escape_characters;
+
+	/* in the original cJSON it is possible to realloc here in case output buffer is too small.
+	 * This is overkill for an embedded system. */
+	output = output_buffer;
+
+	/* no characters have to be escaped */
+	if (escape_characters == 0)
+	{
+		output[0] = '\"';
+		memcpy(output + 1, input, output_length);
+		output[output_length + 1] = '\"';
+		output[output_length + 2] = '\0';
+
+		return true;
+	}
+
+	output[0] = '\"';
+	output_pointer = output + 1;
+	/* copy the string */
+	for (input_pointer = input; *input_pointer != '\0'; (void)input_pointer++, output_pointer++)
+	{
+		if ((*input_pointer > 31) && (*input_pointer != '\"') && (*input_pointer != '\\'))
+		{
+			/* normal character, copy */
+			*output_pointer = *input_pointer;
+		}
+		else
+		{
+			/* character needs to be escaped */
+			*output_pointer++ = '\\';
+			switch (*input_pointer)
+			{
+			case '\\':
+				*output_pointer = '\\';
+				break;
+			case '\"':
+				*output_pointer = '\"';
+				break;
+			case '\b':
+				*output_pointer = 'b';
+				break;
+			case '\f':
+				*output_pointer = 'f';
+				break;
+			case '\n':
+				*output_pointer = 'n';
+				break;
+			case '\r':
+				*output_pointer = 'r';
+				break;
+			case '\t':
+				*output_pointer = 't';
+				break;
+			default:
+				/* escape and print as unicode codepoint */
+				sprintf((char*)output_pointer, "u%04x", *input_pointer);
+				output_pointer += 4;
+				break;
+			}
+		}
+	}
+	output[output_length + 1] = '\"';
+	output[output_length + 2] = '\0';
+
+	return true;
+}
+