param: Introduce the notion of string parameters

Following the model of simple parameters, it is possible to find a home
for string parameters in params.h too. A new PARAM_STRING() macro deals
with the specificities of such parameters.

Since string parameters are typically not inherited by the cache process
they are guarded by a PARAM_ALL macro that defines whether a subset or
the whole list of parameters is processed when params.h is #include'd.

Refs #3250

bin/varnishd/mgt/mgt_param_tbl.c

@@ -39,33 +39,10 @@
 
 
 struct parspec mgt_parspec[] = {
+#define PARAM_ALL
 #define PARAM(ty, nm, ...) { #nm, __VA_ARGS__ },
 #include "tbl/params.h"
 
-	{ "cc_command", tweak_string, &mgt_cc_cmd,
-		NULL, NULL, VCC_CC,
-		NULL,
-		"Command used for compiling the C source code to a "
-		"dlopen(3) loadable object.  Any occurrence of %s in "
-		"the string will be replaced with the source file name, "
-		"and %o will be replaced with the output file name.",
-		MUST_RELOAD,
-		NULL, NULL, "defined when Varnish is built" },
-	{ "vcl_path", tweak_string, &mgt_vcl_path,
-		NULL, NULL, VARNISH_VCL_DIR,
-		NULL,
-		"Directory (or colon separated list of directories) "
-		"from which relative VCL filenames (vcl.load and "
-		"include) are to be found.  By default Varnish searches "
-		"VCL files in both the system configuration and shared "
-		"data directories to allow packages to drop their VCL "
-		"files in a standard location where relative includes "
-		"would work." },
-	{ "vmod_path", tweak_string, &mgt_vmod_path,
-		NULL, NULL, VARNISH_VMOD_DIR,
-		NULL,
-		"Directory (or colon separated list of directories) "
-		"where VMODs are to be found." },
 	{ "vcc_err_unref", tweak_bool, &mgt_vcc_err_unref,
 		NULL, NULL, "on",
 		"bool",

include/tbl/params.h

@@ -1260,6 +1260,57 @@ PARAM_SIMPLE(
 
 #undef MEMPOOL_TEXT
 
+#if defined(PARAM_ALL)
+
+/*--------------------------------------------------------------------
+ * String parameters
+ */
+
+#  define PARAM_STRING(nm, pv, def, ...) \
+	PARAM(, nm, tweak_string, pv, NULL, NULL, def, NULL, __VA_ARGS__)
+
+PARAM_STRING(
+	/* name */	cc_command,
+	/* priv */	&mgt_cc_cmd,
+	/* def */	VCC_CC,
+	/* descr */
+	"Command used for compiling the C source code to a "
+	"dlopen(3) loadable object.  Any occurrence of %s in "
+	"the string will be replaced with the source file name, "
+	"and %o will be replaced with the output file name.",
+	/* flags */	MUST_RELOAD
+)
+
+PARAM_STRING(
+	/* name */	vcl_path,
+	/* priv */	&mgt_vcl_path,
+	/* def */	VARNISH_VCL_DIR,
+	/* descr */
+	"Directory (or colon separated list of directories) "
+	"from which relative VCL filenames (vcl.load and "
+	"include) are to be found.  By default Varnish searches "
+	"VCL files in both the system configuration and shared "
+	"data directories to allow packages to drop their VCL "
+	"files in a standard location where relative includes "
+	"would work."
+)
+
+PARAM_STRING(
+	/* name */	vmod_path,
+	/* priv */	&mgt_vmod_path,
+	/* def */	VARNISH_VMOD_DIR,
+	/* descr */
+	"Directory (or colon separated list of directories) "
+	"where VMODs are to be found."
+)
+
+#  undef PARAM_ALL
+#  undef PARAM_STRING
+#endif /* defined(PARAM_ALL) */
+
+#undef PARAM_SIMPLE
+#undef PARAM
+
 #if 0 /* NOT ACTUALLY DEFINED HERE */
 /* actual location mgt_param_bits.c*/
 /* see tbl/debug_bits.h */
@@ -1637,7 +1688,4 @@ PARAM(
 )
 #endif /* NOT ACTUALLY DEFINED HERE */
 
-#undef PARAM_SIMPLE
-#undef PARAM
-
 /*lint -restore */