target: remove events that are set to empty string

Current code allows replacing the body of an existing event, but
it doesn't provides a way to remove it.
Replacing the event with an empty string makes the event still
present and visible through
	$target_name eventlist

The presence of empty events makes more complex checking for the
event not set or set to empty.

Remove the event when set to empty string.

While there, add 'Jim_Length' to the list of allowed CamelCase
symbols, avoiding the associated checkpatch error.

Change-Id: I1ec2e1a71d298a0eba0b6863902645bcc6c4cb09
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/8814
Tested-by: jenkins

Author: borneoa

src/target/target.c

@@ -4968,6 +4968,17 @@ static int target_configure(struct jim_getopt_info *goi, struct target *target)
 						LOG_INFO("DEPRECATED target event %s; use TPIU events {pre,post}-{enable,disable}", n->name);
 					/* END_DEPRECATED_TPIU */
 
+					jim_getopt_obj(goi, &o);
+					if (Jim_Length(o) == 0) {
+						/* empty action, drop existing one */
+						if (teap) {
+							list_del(&teap->list);
+							Jim_DecrRefCount(teap->interp, teap->body);
+							free(teap);
+						}
+						break;
+					}
+
 					bool replace = true;
 					if (!teap) {
 						/* create new */
@@ -4976,7 +4987,6 @@ static int target_configure(struct jim_getopt_info *goi, struct target *target)
 					}
 					teap->event = n->value;
 					teap->interp = goi->interp;
-					jim_getopt_obj(goi, &o);
 					if (teap->body)
 						Jim_DecrRefCount(teap->interp, teap->body);
 					teap->body  = Jim_DuplicateObj(goi->interp, o);

tools/scripts/camelcase.txt

@@ -122,6 +122,7 @@ Jim_GetWide
 Jim_IncrRefCount
 Jim_InitStaticExtensions
 Jim_Interp
+Jim_Length
 Jim_ListAppendElement
 Jim_ListGetIndex
 Jim_ListLength