MINOR: sample: list registered sample converter functions

Similar to the sample fetch keywords, let's also list the converter
keywords. They're much simpler since there's no compatibility matrix.
Instead the input and output types are listed. This is called by
dump_registered_keywords() for the "cnv" keywords class.
diff --git a/include/haproxy/sample.h b/include/haproxy/sample.h
index f6ce3c0..9ec4df1 100644
--- a/include/haproxy/sample.h
+++ b/include/haproxy/sample.h
@@ -50,6 +50,7 @@
 const char *sample_ckp_names(unsigned int use);
 struct sample_fetch *find_sample_fetch(const char *kw, int len);
 void smp_dump_fetch_kw(void);
+void smp_dump_conv_kw(void);
 struct sample_fetch *sample_fetch_getnext(struct sample_fetch *current, int *idx);
 struct sample_conv *sample_conv_getnext(struct sample_conv *current, int *idx);
 int smp_resolve_args(struct proxy *p, char **err);
diff --git a/src/haproxy.c b/src/haproxy.c
index a17692c..adb9a7a 100644
--- a/src/haproxy.c
+++ b/src/haproxy.c
@@ -1828,6 +1828,7 @@
 			printf("acl: ACL keywords\n");
 			printf("cfg: configuration keywords\n");
 			printf("cli: CLI keywords\n");
+			printf("cnv: sample converter keywords\n");
 			printf("flt: filter names\n");
 			printf("smp: sample fetch functions\n");
 			printf("svc: service names\n");
@@ -1852,6 +1853,11 @@
 			cli_list_keywords();
 		}
 
+		if (all || strcmp(kwd_dump, "cnv") == 0) {
+			printf("# List of registered sample converter functions:\n");
+			smp_dump_conv_kw();
+		}
+
 		if (all || strcmp(kwd_dump, "flt") == 0) {
 			printf("# List of registered filter names:\n");
 			flt_dump_kws(NULL);
diff --git a/src/sample.c b/src/sample.c
index c4b7da9..e4d254b 100644
--- a/src/sample.c
+++ b/src/sample.c
@@ -495,6 +495,45 @@
 	}
 }
 
+/* dump list of registered sample converter keywords on stdout */
+void smp_dump_conv_kw(void)
+{
+	struct sample_conv_kw_list *kwl;
+	struct sample_conv *kw;
+	uint64_t mask;
+	int index;
+	int arg;
+
+	list_for_each_entry(kwl, &sample_convs.list, list) {
+		for (index = 0; kwl->kw[index].kw != NULL; index++) {
+			kw = &kwl->kw[index];
+			printf("%s", kw->kw);
+			if (kw->arg_mask) {
+				mask = kw->arg_mask >> ARGM_BITS;
+				printf("(");
+				for (arg = 0;
+				     arg < ARGM_NBARGS && ((mask >> (arg * ARGT_BITS)) & ARGT_MASK);
+				     arg++) {
+					if (arg == (kw->arg_mask & ARGM_MASK)) {
+						/* now dumping extra args */
+						printf("[");
+					}
+					if (arg)
+						printf(",");
+					printf("%s", arg_type_names[(mask >> (arg * ARGT_BITS)) & ARGT_MASK]);
+				}
+				if (arg > (kw->arg_mask & ARGM_MASK)) {
+					/* extra args were dumped */
+					printf("]");
+				}
+				printf(")");
+			}
+			printf(": %s => %s", smp_to_type[kw->out_type], smp_to_type[kw->in_type]);
+			printf("\n");
+		}
+	}
+}
+
 /* This function browses the list of available sample fetches. <current> is
  * the last used sample fetch. If it is the first call, it must set to NULL.
  * <idx> is the index of the next sample fetch entry. It is used as private