[PATCH] libubox: jshn: append_json using jshn.sh

[Jaymin Patel]

Whenever json_load or json_load_file is called, it calls
json_init and due to that, it cleans up existing json data.
With the addition of a new argument -a in jshn, It skips the step
of json_init and appends new json into existing json. It helps in
cases when there is a need to merge multiple json.

A sample script with the usage of json_append and json_append_file

cat /tmp/sample.sh

. /usr/share/libubox/jshn.sh

json_init
json_add_string json1 json1
json_dump
j1=$(json_dump)

json_init
json_add_string json2 json2
json_append "$j1"
json_dump
json_dump > /tmp/test.json

json_init
json_add_string json2 json2
json_append "$j1"
json_add_object old_json
json_append_file /tmp/test.json
json_dump

Output:
{ "json1": "json1" }
{ "json2": "json2", "json1": "json1" }
{ "json2": "json2", "json1": "json1", "old_json": { "json2": "json2", "json1": "json1" } }

Signed-off-by: Jaymin Patel <jem.patel at gmail.com>
---
 jshn.c     | 22 ++++++++++++++--------
 sh/jshn.sh |  8 ++++++++
 2 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/jshn.c b/jshn.c
index 1b685e5..971246f 100644
--- a/jshn.c
+++ b/jshn.c
@@ -172,7 +172,7 @@ static int add_json_element(const char *key, json_object *obj)
 	return 0;
 }
 
-static int jshn_parse(const char *str)
+static int jshn_parse(const char *str, bool append)
 {
 	json_object *obj;
 
@@ -183,7 +183,9 @@ static int jshn_parse(const char *str)
 		fprintf(stderr, "Failed to parse message data\n");
 		return 1;
 	}
-	fprintf(stdout, "json_init;\n");
+	if (!append) {
+		fprintf(stdout, "json_init;\n");
+	}
 	add_json_object(obj);
 	fflush(stdout);
 	json_object_put(obj);
@@ -313,7 +315,7 @@ out:
 
 static int usage(const char *progname)
 {
-	fprintf(stderr, "Usage: %s [-n] [-i] -r <message>|-R <file>|-o <file>|-p <prefix>|-w\n", progname);
+	fprintf(stderr, "Usage: %s [-n] [-i] [-a] -r <message>|-R <file>|-o <file>|-p <prefix>|-w\n", progname);
 	return 2;
 }
 
@@ -338,7 +340,7 @@ static int avl_strcmp_var(const void *k1, const void *k2, void *ptr)
 	return c1 - c2;
 }
 
-static int jshn_parse_file(const char *path)
+static int jshn_parse_file(const char *path, bool append)
 {
 	struct stat sb;
 	int ret = 0;
@@ -369,7 +371,7 @@ static int jshn_parse_file(const char *path)
 		return 3;
 	}
 
-	ret = jshn_parse(fbuf);
+	ret = jshn_parse(fbuf, append);
 	free(fbuf);
 	close(fd);
 
@@ -397,6 +399,7 @@ int main(int argc, char **argv)
 {
 	extern char **environ;
 	bool no_newline = false;
+	bool append_object = false;
 	bool indent = false;
 	struct env_var *vars;
 	int i;
@@ -423,17 +426,17 @@ int main(int argc, char **argv)
 		avl_insert(&env_vars, &vars[i].avl);
 	}
 
-	while ((ch = getopt(argc, argv, "p:nir:R:o:w")) != -1) {
+	while ((ch = getopt(argc, argv, "p:anir:R:o:w")) != -1) {
 		switch(ch) {
 		case 'p':
 			var_prefix = optarg;
 			var_prefix_len = strlen(var_prefix);
 			break;
 		case 'r':
-			ret = jshn_parse(optarg);
+			ret = jshn_parse(optarg, append_object);
 			goto exit;
 		case 'R':
-			ret = jshn_parse_file(optarg);
+			ret = jshn_parse_file(optarg, append_object);
 			goto exit;
 		case 'w':
 			ret = jshn_format(no_newline, indent, stdout);
@@ -441,6 +444,9 @@ int main(int argc, char **argv)
 		case 'o':
 			ret = jshn_format_file(optarg, no_newline, indent);
 			goto exit;
+		case 'a':
+			append_object = true;
+			break;
 		case 'n':
 			no_newline = true;
 			break;
diff --git a/sh/jshn.sh b/sh/jshn.sh
index 7b0155d..ba3f1f3 100644
--- a/sh/jshn.sh
+++ b/sh/jshn.sh
@@ -180,6 +180,14 @@ json_load() {
 	eval "`jshn -r "$1"`"
 }
 
+json_append() {
+	eval "`jshn -a -r "$1"`"
+}
+
+json_append_file() {
+	eval "`jshn -a -R "$1"`"
+}
+
 json_load_file() {
 	eval "`jshn -R "$1"`"
 }
-- 
2.25.1