Function to format a message before printing

There is the need to print info about swupd operations in a parsable
JSON format.

This function provides a wrapper function to format the messages to
comply with the JSON format if the --json-output flag is used.

Signed-off-by: Castulo Martinez <castulo.martinez@intel.com>

src/globals.c

@@ -59,7 +59,6 @@ bool keepcache = false;
 timelist *global_times = NULL;
 int max_retries = 3;
 int retry_delay = 10;
-bool json_output = false;
 
 /* NOTE: Today the content and version server urls are the same in
  * all cases.  It is highly likely these will eventually differ, eg:

src/lib/log.c

@@ -19,19 +19,94 @@
 
 #define _GNU_SOURCE
 
+#include <ctype.h>
 #include <stdarg.h>
+#include <stdlib.h>
+#include <string.h>
 #include <time.h>
 
 #include "log.h"
 #define DEBUG_HEADER_SIZE 50
 
 static int cur_log_level = LOG_INFO;
+static int json_format = 0;
 
 void set_log_level(int log_level)
 {
 	cur_log_level = log_level;
 }
 
+void set_json_format(void)
+{
+	json_format = 1;
+}
+
+void json_start(const char *op)
+{
+	if (json_format) {
+		fprintf(stderr, "[\n");
+		fflush(stderr);
+		fprintf(stderr, "{ \"%s\" : \"start\" },\n", op);
+		fflush(stderr);
+	}
+}
+
+void json_end(const char *op)
+{
+	if (json_format) {
+		fprintf(stderr, "{ \"%s\" : \"end\" }\n", op);
+		fflush(stderr);
+		fprintf(stderr, "]\n");
+		fflush(stderr);
+	}
+}
+
+void format_to_json(const char *type, const char *msg, va_list args_list)
+{
+	const int MAX_TYPE_LENGTH = 8;
+	char *full_msg;
+	char ltype[MAX_TYPE_LENGTH];
+
+	/* make sure the type is all lower case */
+	if (type) {
+		for (int i = 0; type[i]; i++) {
+			ltype[i] = tolower(type[i]);
+		}
+		ltype[strlen(type)] = '\0';
+	} else {
+		/* if no type was provided we default to info */
+		strcpy(ltype, "info");
+	}
+
+	/* build the full message based on all the arguments */
+	if (vasprintf(&full_msg, msg, args_list) < 0) {
+		abort();
+	}
+
+	if (strcmp(full_msg, "") != 0) {
+		int j = 0;
+		for (unsigned int i = 0; i <= strlen(full_msg); i++) {
+			/* if the message has double quotes replace them with single quotes
+			* since double quotes are not supported in JSON */
+			if (full_msg[i] == '"') {
+				full_msg[i] = '\'';
+			}
+			/* remove all '\n' from the message */
+			if (full_msg[i] != '\n') {
+				full_msg[j] = full_msg[i];
+				j++;
+			}
+		}
+		full_msg[j] = '\0';
+
+		/* add the JSON format and print immediately */
+		fprintf(stderr, "{ \"type\" : \"%s\", \"msg\" : \"%s\" },\n", ltype, full_msg);
+		fflush(stderr);
+	}
+
+	free(full_msg);
+}
+
 void log_full(int log_level, FILE *out, const char *file, int line, const char *label, const char *format, ...)
 {
 	if (cur_log_level < log_level) {
@@ -44,7 +119,7 @@ void log_full(int log_level, FILE *out, const char *file, int line, const char *
 	int printed;
 
 	// In debug mode, print more information
-	if (cur_log_level == LOG_DEBUG) {
+	if (cur_log_level == LOG_DEBUG && !json_format) {
 		time_t currtime;
 		time(&currtime);
 		timeinfo = localtime(&currtime);
@@ -56,11 +131,18 @@ void log_full(int log_level, FILE *out, const char *file, int line, const char *
 		}
 	}
 
-	if (label) {
-		fprintf(out, "%s: ", label);
+	/* initialize the arguments list */
+	va_start(ap, format);
+
+	if (json_format) {
+		format_to_json(label, format, ap);
+	} else {
+		if (label) {
+			fprintf(out, "%s: ", label);
+		}
+		vfprintf(out, format, ap);
 	}
 
-	va_start(ap, format);
-	vfprintf(out, format, ap);
+	/* clean memory assigned to arguments list */
 	va_end(ap);
 }

src/lib/log.h

@@ -2,7 +2,6 @@
 #define __SWUPD_LOG__
 
 #include <stdio.h>
-#include <stdlib.h>
 
 #ifdef __cplusplus
 extern "C" {
@@ -34,6 +33,26 @@ void log_full(int log_level, FILE *out, const char *file, int line, const char *
 #define info(_fmt, ...) log_full(LOG_INFO, stdout, __FILE__, __LINE__, NULL, _fmt, ##__VA_ARGS__);
 #define debug(_fmt, ...) log_full(LOG_DEBUG, stdout, __FILE__, __LINE__, "Debug", _fmt, ##__VA_ARGS__);
 
+/*
+ * Enables the JSON formatter
+ */
+void set_json_format(void);
+
+/*
+ * Converts the provided message to a JSON formatted stream
+ */
+void format_to_json(const char *, const char *, va_list);
+
+/*
+ * Generates the initial message of a JSON stream
+ */
+void json_start(const char *);
+
+/*
+ * Generates the final message of a JSON stream
+ */
+void json_end(const char *);
+
 #ifdef __cplusplus
 }
 #endif

src/swupd.h

@@ -188,7 +188,6 @@ extern int skip_diskspace_check;
 extern timelist *global_times;
 extern int max_retries;
 extern int retry_delay;
-extern bool json_output;
 
 extern char *version_url;
 extern char *content_url;