[master] 4ba159323 cli: Make param.set -j output the updated parameter

[Dridi Boukelmoune]

commit 4ba159323447a469e5717085572681bc6f588465
Author: Dridi Boukelmoune <dridi.boukelmoune at gmail.com>
Date:   Wed Jan 5 23:26:42 2022 +0100

    cli: Make param.set -j output the updated parameter
    
    Closes #3756

diff --git a/bin/varnishd/mgt/mgt_param.c b/bin/varnishd/mgt/mgt_param.c
index fd77e2942..1ea94da54 100644
--- a/bin/varnishd/mgt/mgt_param.c
+++ b/bin/varnishd/mgt/mgt_param.c
@@ -580,6 +580,16 @@ mcf_param_set(struct cli *cli, const char * const *av, void *priv)
 	MCF_ParamSet(cli, av[2], av[3]);
 }
 
+static void v_matchproto_(cli_func_t)
+mcf_param_set_json(struct cli *cli, const char * const *av, void *priv)
+{
+	const char *const avs[] = { av[0], av[1], av[2], av[3], NULL };
+
+	MCF_ParamSet(cli, av[3], av[4]);
+	if (cli->result == CLIS_OK)
+		mcf_param_show_json(cli, avs, priv);
+}
+
 /*--------------------------------------------------------------------*/
 
 static void v_matchproto_(cli_func_t)
@@ -683,10 +693,9 @@ mcf_wash_param(struct cli *cli, struct parspec *pp, enum mcf_which_e which,
 /*--------------------------------------------------------------------*/
 
 static struct cli_proto cli_params[] = {
-	{ CLICMD_PARAM_SHOW,		"", mcf_param_show,
-	  mcf_param_show_json },
-	{ CLICMD_PARAM_SET,		"", mcf_param_set },
-	{ CLICMD_PARAM_RESET,		"", mcf_param_reset },
+	{ CLICMD_PARAM_SHOW,	"", mcf_param_show, mcf_param_show_json },
+	{ CLICMD_PARAM_SET,	"", mcf_param_set, mcf_param_set_json },
+	{ CLICMD_PARAM_RESET,	"", mcf_param_reset },
 	{ NULL }
 };
 
diff --git a/bin/varnishtest/tests/b00042.vtc b/bin/varnishtest/tests/b00042.vtc
index 7f580ef24..037469ec7 100644
--- a/bin/varnishtest/tests/b00042.vtc
+++ b/bin/varnishtest/tests/b00042.vtc
@@ -38,6 +38,7 @@ varnish v1 -clijson	"param.show -j pool_req"
 varnish v1 -clijson	"param.show -j pool_sess"
 varnish v1 -clijson	"param.show -j changed"
 varnish v1 -clijson	"param.show -j"
+varnish v1 -clijson	"param.set -j default_ttl 0"
 varnish v1 -clierr 106	"param.show -j -l"
 varnish v1 -clierr 106	"param.show -j fofofofo"
 varnish v1 -clierr 105	"param.show debug debug"
diff --git a/include/tbl/cli_cmds.h b/include/tbl/cli_cmds.h
index d4466e4c7..27443bc70 100644
--- a/include/tbl/cli_cmds.h
+++ b/include/tbl/cli_cmds.h
@@ -195,9 +195,14 @@ CLI_CMD(PARAM_SHOW,
 
 CLI_CMD(PARAM_SET,
 	"param.set",
-	"param.set <param> <value>",
+	"param.set [-j] <param> <value>",
 	"Set parameter value.",
-	"",
+	"  The JSON output is the same as ``param.show -j <param>`` and"
+	" contains the updated value as it would be represented by a"
+	" subsequent execution of ``param.show``.\n\n"
+	"  This can be useful to later verify that a parameter value didn't"
+	" change and to use the value from the JSON output to reset the"
+	" parameter to the desired value.",
 	2,2
 )