wrap-json: add packing tool for json

The functions wrap_json_pack and wrap_json_vpack
can be used to create json object. These functions
are likely to be compatible in the format with the
packing functions of the library jansson [1].

[1] http://jansson.readthedocs.io/en/2.10/apiref.html#building-values

Change-Id: I2e251bdb9b590ba55707c5a9ed60528cad927fb3
Signed-off-by: José Bollo <jose.bollo@iot.bzh>

2 files changed, 431 insertions, 0 deletions

diff --git a/src/wrap-json.c b/src/wrap-json.c
new file mode 100644
index 00000000..1b4b13ea
--- /dev/null
+++ b/src/wrap-json.c
@@ -0,0 +1,402 @@
+/*
+ Copyright (C) 2016, 2017 "IoT.bzh"
+
+ author: José Bollo <jose.bollo@iot.bzh>
+
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+*/
+
+#include <string.h>
+
+#include "wrap-json.h"
+
+#define STACKCOUNT 32
+#define STRCOUNT   8
+
+enum {
+	wrap_json_pack_error_none,
+	wrap_json_pack_error_null_object,
+	wrap_json_pack_error_truncated,
+	wrap_json_pack_error_internal_error,
+	wrap_json_pack_error_out_of_memory,
+	wrap_json_pack_error_invalid_character,
+	wrap_json_pack_error_too_long,
+	wrap_json_pack_error_too_deep,
+	wrap_json_pack_error_null_spec,
+	wrap_json_pack_error_null_key,
+	wrap_json_pack_error_null_string,
+	_wrap_json_pack_error_count_
+};
+
+static const char ignore_all[] = " \t\n\r,:";
+static const char accept_arr[] = "][{snbiIfoO";
+static const char accept_key[] = "s}";
+#define accept_any (&accept_arr[1])
+
+static const char *pack_errors[_wrap_json_pack_error_count_] =
+{
+	[wrap_json_pack_error_none] = "unknown error",
+	[wrap_json_pack_error_null_object] = "null object",
+	[wrap_json_pack_error_truncated] = "truncated",
+	[wrap_json_pack_error_internal_error] = "internal error",
+	[wrap_json_pack_error_out_of_memory] = "out of memory",
+	[wrap_json_pack_error_invalid_character] = "invalid character",
+	[wrap_json_pack_error_too_long] = "too long",
+	[wrap_json_pack_error_too_deep] = "too deep",
+	[wrap_json_pack_error_null_spec] = "spec is NULL",
+	[wrap_json_pack_error_null_key] = "key is NULL",
+	[wrap_json_pack_error_null_string] = "string is NULL"
+};
+
+int wrap_json_pack_error_position(int rc)
+{
+	if (rc < 0)
+		rc = -rc;
+	return (rc >> 4) + 1;
+}
+
+int wrap_json_pack_error_code(int rc)
+{
+	if (rc < 0)
+		rc = -rc;
+	return rc & 15;
+}
+
+const char *wrap_json_pack_error_string(int rc)
+{
+	rc = wrap_json_pack_error_code(rc);
+	if (rc >= sizeof pack_errors / sizeof *pack_errors)
+		rc = 0;
+	return pack_errors[rc];
+}
+
+
+
+static inline const char *skip(const char *d)
+{
+	while (*d && strchr(ignore_all, *d))
+		d++;
+	return d;
+}
+
+int wrap_json_vpack(struct json_object **result, const char *desc, va_list args)
+{
+	int nstr, notnull, nullable, rc;
+	size_t sz, dsz, ssz;
+	char *s;
+	char c;
+	const char *d;
+	char buffer[256];
+	struct { const char *str; size_t sz; } strs[STRCOUNT];
+	struct { struct json_object *cont, *key; const char *acc; char type; } stack[STACKCOUNT], *top;
+	struct json_object *obj;
+
+	ssz = sizeof buffer;
+	s = buffer;
+	top = stack;
+	top->key = NULL;
+	top->cont = NULL;
+	top->acc = accept_any;
+	top->type = 0;
+	if (!desc)
+		goto null_spec;
+	d = skip(desc);
+	for(;;) {
+		c = *d;
+		if (!c)
+			goto truncated;
+		if (!strchr(top->acc, c))
+			goto invalid_character;
+		d = skip(++d);
+		switch(c) {
+		case 's':
+			nullable = 0;
+			notnull = 0;
+			nstr = 0;
+			sz = 0;
+			for (;;) {
+				strs[nstr].str = va_arg(args, const char*);
+				if (strs[nstr].str)
+					notnull = 1;
+				if (*d == '?') {
+					d = skip(++d);
+					nullable = 1;
+				}
+				switch(*d) {
+				case '%': strs[nstr].sz = va_arg(args, size_t); d = skip(++d); break;
+				case '#': strs[nstr].sz = (size_t)va_arg(args, int); d = skip(++d); break;
+				default: strs[nstr].sz = strs[nstr].str ? strlen(strs[nstr].str) : 0; break;
+				}
+				sz += strs[nstr++].sz;
+				if (*d == '?') {
+					d = skip(++d);
+					nullable = 1;
+				}
+				if (*d != '+')
+					break;
+				if (nstr >= STRCOUNT)
+					goto too_long;
+				d = skip(++d);
+			}
+			if (*d == '*')
+				nullable = 1;
+			if (notnull) {
+				if (sz > ssz) {
+					ssz += ssz;
+					if (ssz < sz)
+						ssz = sz;
+					s = alloca(sz);
+				}
+				dsz = sz;
+				while (nstr) {
+					nstr--;
+					dsz -= strs[nstr].sz;
+					memcpy(&s[dsz], strs[nstr].str, strs[nstr].sz);
+				}
+				obj = json_object_new_string_len(s, sz);
+				if (!obj)
+					goto out_of_memory;
+			} else if (nullable)
+				obj = NULL;
+			else
+				goto null_string;
+			break;
+		case 'n':
+			obj = NULL;
+			break;
+		case 'b':
+			obj = json_object_new_boolean(va_arg(args, int));
+			if (!obj)
+				goto out_of_memory;
+			break;
+		case 'i':
+			obj = json_object_new_int(va_arg(args, int));
+			if (!obj)
+				goto out_of_memory;
+			break;
+		case 'I':
+			obj = json_object_new_int64(va_arg(args, int64_t));
+			if (!obj)
+				goto out_of_memory;
+			break;
+		case 'f':
+			obj = json_object_new_double(va_arg(args, double));
+			if (!obj)
+				goto out_of_memory;
+			break;
+		case 'o':
+		case 'O':
+			obj = va_arg(args, struct json_object*);
+			if (*d == '?')
+				d = skip(++d);
+			else if (*d != '*' && !obj)
+				goto null_object;
+			if (c == 'O')
+				json_object_get(obj);
+			break;
+		case '[':
+		case '{':
+			if (++top >= &stack[STACKCOUNT])
+				goto too_deep;
+			top->key = NULL;
+			if (c == '[') {
+				top->type = ']';
+				top->acc = accept_arr;
+				top->cont = json_object_new_array();
+			} else {
+				top->type = '}';
+				top->acc = accept_key;
+				top->cont = json_object_new_object();
+			}
+			if (!top->cont)
+				goto out_of_memory;
+			continue;
+		case '}':
+		case ']':
+			if (c != top->type || top <= stack)
+				goto invalid_character;
+			obj = (top--)->cont;
+			if (*d == '*' && !(c == '}' ? json_object_object_length(obj) : json_object_array_length(obj))) {
+				json_object_put(obj);
+				obj = NULL;
+			}
+			break;
+		default:
+			goto internal_error;
+		}
+		switch (top->type) {
+		case 0:
+			if (top != stack)
+				goto internal_error;
+			if (*d)
+				goto invalid_character;
+			*result = obj;
+			return 0;
+		case ']':
+			if (obj || *d != '*')
+				json_object_array_add(top->cont, obj);
+			if (*d == '*')
+				d = skip(++d);
+			break;
+		case '}':
+			if (!obj)
+				goto null_key;
+			top->key = obj;
+			top->acc = accept_any;
+			top->type = ':';
+			break;
+		case ':':
+			if (obj || *d != '*')
+				json_object_object_add(top->cont, json_object_get_string(top->key), obj);
+			if (*d == '*')
+				d = skip(++d);
+			json_object_put(top->key);
+			top->key = NULL;
+			top->acc = accept_key;
+			top->type = '}';
+			break;
+		}
+	}
+
+null_object:
+	rc = wrap_json_pack_error_null_object;
+	goto error;
+truncated:
+	rc = wrap_json_pack_error_truncated;
+	goto error;
+internal_error:
+	rc = wrap_json_pack_error_internal_error;
+	goto error;
+out_of_memory:
+	rc = wrap_json_pack_error_out_of_memory;
+	goto error;
+invalid_character:
+	rc = wrap_json_pack_error_invalid_character;
+	goto error;
+too_long:
+	rc = wrap_json_pack_error_too_long;
+	goto error;
+too_deep:
+	rc = wrap_json_pack_error_too_deep;
+	goto error;
+null_spec:
+	rc = wrap_json_pack_error_null_spec;
+	goto error;
+null_key:
+	rc = wrap_json_pack_error_null_key;
+	goto error;
+null_string:
+	rc = wrap_json_pack_error_null_string;
+	goto error;
+error:
+	do {
+		json_object_put(top->key);
+		json_object_put(top->cont);
+	} while (--top >= stack);
+	*result = NULL;
+	rc = rc | (int)((d - desc) << 4);
+	return -rc;
+}
+
+int wrap_json_pack(struct json_object **result, const char *desc, ...)
+{
+	int rc;
+	va_list args;
+
+	va_start(args, desc);
+	rc = wrap_json_vpack(result, desc, args);
+	va_end(args);
+	return rc;
+}
+
+#if 1
+#include <stdio.h>
+
+void T(const char *desc, ...)
+{
+	int rc;
+	va_list args;
+	struct json_object *result;
+
+	va_start(args, desc);
+	rc = wrap_json_vpack(&result, desc, args);
+	va_end(args);
+	if (!rc) 
+		printf("  SUCCESS %s\n\n", json_object_to_json_string(result));
+	else
+		printf("  ERROR[char %d err %d] %s\n\n", wrap_json_pack_error_position(rc), wrap_json_pack_error_code(rc), wrap_json_pack_error_string(rc));
+	json_object_put(result);
+}
+
+#define t(...) printf("testing(%s)\n",#__VA_ARGS__); T(__VA_ARGS__);
+
+int main()
+{
+	char buffer[4] = {'t', 'e', 's', 't'};
+
+	t("n");
+	t("b", 1);
+	t("b", 0);
+	t("i", 1);
+	t("I", (uint64_t)0x123456789abcdef);
+	t("f", 3.14);
+	t("s", "test");
+	t("s?", "test");
+	t("s?", NULL);
+	t("s#", "test asdf", 4);
+	t("s%", "test asdf", (size_t)4);
+	t("s#", buffer, 4);
+	t("s%", buffer, (size_t)4);
+	t("s++", "te", "st", "ing");
+	t("s#+#+", "test", 1, "test", 2, "test");
+	t("s%+%+", "test", (size_t)1, "test", (size_t)2, "test");
+	t("{}", 1.0);
+	t("[]", 1.0);
+	t("o", json_object_new_int(1));
+	t("o?", json_object_new_int(1));
+	t("o?", NULL);
+	t("O", json_object_new_int(1));
+	t("O?", json_object_new_int(1));
+	t("O?", NULL);
+	t("{s:[]}", "foo");
+	t("{s+#+: []}", "foo", "barbar", 3, "baz");
+	t("{s:s,s:o,s:O}", "a", NULL, "b", NULL, "c", NULL);
+	t("{s:**}", "a", NULL);
+	t("{s:s*,s:o*,s:O*}", "a", NULL, "b", NULL, "c", NULL);
+	t("[i,i,i]", 0, 1, 2);
+	t("[s,o,O]", NULL, NULL, NULL);
+	t("[**]", NULL);
+	t("[s*,o*,O*]", NULL, NULL, NULL);
+	t(" s ", "test");
+	t("[ ]");
+	t("[ i , i,  i ] ", 1, 2, 3);
+	t("{\n\n1");
+	t("[}");
+	t("{]");
+	t("[");
+	t("{");
+	t("[i]a", 42);
+	t("ia", 42);
+	t("s", NULL);
+	t("+", NULL);
+	t(NULL);
+	t("{s:i}", NULL, 1);
+	t("{ {}: s }", "foo");
+	t("{ s: {},  s:[ii{} }", "foo", "bar", 12, 13);
+	t("[[[[[   [[[[[  [[[[ }]]]] ]]]] ]]]]]");
+	return 0;
+}
+
+#endif
+
+
diff --git a/src/wrap-json.h b/src/wrap-json.h
new file mode 100644
index 00000000..1e95dcf2
--- /dev/null
+++ b/src/wrap-json.h
@@ -0,0 +1,29 @@
+/*
+ Copyright (C) 2016, 2017 "IoT.bzh"
+
+ author: José Bollo <jose.bollo@iot.bzh>
+
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+*/
+
+#pragma once
+
+#include <stdarg.h>
+#include <json-c/json.h>
+
+extern int wrap_json_pack_error_position(int rc);
+extern int wrap_json_pack_error_code(int rc);
+extern const char *wrap_json_pack_error_string(int rc);
+extern int wrap_json_vpack(struct json_object **result, const char *desc, va_list args);
+extern int wrap_json_pack(struct json_object **result, const char *desc, ...);
+