Replace json-c library with minimal replacement

FWTS uses a subset of json-c functionality, so replace it with
our own implementation that supports this subset. This also
removes the dependency of two flavours of json libraries that
fwts has been using and also allows us to perform deeper memory
allocation and leaking tracking with static analysis tools.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Alex Hung <alex.hung@canonical.com>
Acked-by: Ivan Hu <ivan.hu@canonical.com>

configure.ac

@@ -9,8 +9,6 @@
 	  AC_PROG_LIBTOOL
 	  AC_C_INLINE
 	  AM_PROG_CC_C_O
-	  AC_SEARCH_LIBS([json_object_from_file], [json json-c], [], [ AC_MSG_ERROR([no available json library]) ])
-	  AC_SEARCH_LIBS([json_object_object_get_ex], [json json-c], [ AC_DEFINE([JSON_HAS_GET_EX], [1], [Define if we have json_object_object_get_ex])], [])
   	  AC_CHECK_FUNCS([localtime_r])
 	  AC_CHECK_FUNCS([dup2])
 	  AC_CHECK_FUNCS([getcwd])
@@ -61,7 +59,6 @@
 	  AC_CHECK_HEADERS([time.h])
 	  AC_CHECK_HEADERS([sys/ioctl.h])
 	  AC_CHECK_HEADERS([sys/time.h])
-	  AC_CHECK_HEADERS([json/json.h])
 	  AC_CHECK_HEADERS([glib.h])
 	  AC_CHECK_HEADERS([gio/gio.h])
 	  AC_CHECK_HEADERS([asm/opal-prd.h])

src/lib/include/fwts.h

@@ -153,6 +153,8 @@
 
 #define FWTS_JSON_DATA_PATH	DATAROOTDIR "/fwts"
 
+#include <inttypes.h>
+
 #include "fwts_version.h"
 #include "fwts_backtrace.h"
 #include "fwts_types.h"

src/lib/include/fwts_json.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2012-2020 Canonical
+ * Copyright (C) 2010-2020 Canonical
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
@@ -16,26 +16,15 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  *
  */
-
 #ifndef __FWTS_JSON_H__
 #define __FWTS_JSON_H__
 
-#include <json.h>
-
-#define __FWTS_JSON_ERR_PTR__ ((json_object*) -1)
 /*
- *  Older versions of json-c may return an error in an
- *  object as a ((json_object*)-1), where as newer
- *  versions return NULL, so check for these. Sigh.
+ *  Minimal subset of json for fwts
  */
-#define FWTS_JSON_ERROR(ptr) \
-	( (ptr == NULL) || ((const json_object *)ptr == __FWTS_JSON_ERR_PTR__) )
 
-/*
- * json-c 0.13.99 does not define TRUE/FALSE anymore
- * the json-c maintainers replaced them with pure 1/0
- * https://github.com/json-c/json-c/commit/0992aac61f8b
- */
+#define FWTS_JSON_ERROR(ptr) 	(!ptr)
+
 #ifndef FALSE
 #define FALSE 0
 #endif
@@ -44,4 +33,46 @@
 #define TRUE  1
 #endif
 
+/*
+ *  json types supported
+ */
+typedef enum {
+	type_null,
+	type_int,
+	type_string,
+	type_object,
+	type_array,
+} json_type;
+
+/*
+ *  json object information
+ */
+typedef struct json_object {
+	char *key;		/* Null if undefined */
+	int length;		/* Length of a collection of objects */
+	json_type type;		/* Object type */
+        union {
+                void *ptr;	/* string or object array pointer */
+                int  intval;	/* integer value */
+        } u;
+} json_object;
+
+/*
+ *  minimal json c library functions as required by fwts
+ */
+json_object *json_object_from_file(const char *filename);
+json_object *json_object_object_get(json_object *obj, const char *key);
+int json_object_array_length(json_object *obj);
+json_object *json_object_array_get_idx(json_object *obj, int index);
+const char *json_object_get_string(json_object *obj);
+json_object *json_object_new_int(int);
+void json_object_object_add(json_object *obj, const char *key, json_object *value);
+
+json_object *json_object_new_object(void);
+json_object *json_object_new_array(void);
+char *json_object_to_json_string(json_object *obj);
+void json_object_put(json_object *obj);
+json_object *json_object_new_string(const char *str);
+int json_object_array_add(json_object *obj, json_object *item);
+
 #endif

src/lib/src/Makefile.am

@@ -82,6 +82,7 @@ libfwts_la_SOURCES = 		\
 	fwts_interactive.c 	\
 	fwts_ioport.c		\
 	fwts_ipmi.c		\
+	fwts_json.c		\
 	fwts_keymap.c 		\
 	fwts_klog.c 		\
 	fwts_olog.c		\