uci: optimize update section in uci_set

Optimize for the case when there is no need to update the section and
the case there is no need to reallocate memory when updating a section
in uci_set.

Signed-off-by: Jan Venekamp <jan@venekamp.net>

list.c

@@ -727,14 +727,21 @@ int uci_set(struct uci_context *ctx, struct uci_ptr *ptr)
 			ptr->last = &ptr->o->e;
 		}
 	} else if (ptr->s && ptr->section) { /* update section */
-		struct uci_section *old = ptr->s;
-		ptr->s = uci_alloc_section(ptr->p, ptr->value, old->e.name, &old->e.list);
-		uci_section_transfer_options(ptr->s, old);
-		if (ptr->section == old->e.name)
-			ptr->section = ptr->s->e.name;
-		uci_free_section(old);
-		ptr->s->package->n_section--;
-		ptr->last = &ptr->s->e;
+		if (!strcmp(ptr->s->type, ptr->value))
+			return 0;
+
+		if (strlen(ptr->s->type) == strlen(ptr->value)) {
+			strcpy(ptr->s->type, ptr->value);
+		} else {
+			struct uci_section *old = ptr->s;
+			ptr->s = uci_alloc_section(ptr->p, ptr->value, old->e.name, &old->e.list);
+			uci_section_transfer_options(ptr->s, old);
+			if (ptr->section == old->e.name)
+				ptr->section = ptr->s->e.name;
+			uci_free_section(old);
+			ptr->s->package->n_section--;
+			ptr->last = &ptr->s->e;
+		}
 	} else {
 		UCI_THROW(ctx, UCI_ERR_INVAL);
 	}

tests/shunit2/tests.d/090_cli_options

@@ -11,8 +11,9 @@ test_add_delta() {
 	# save new changes in "$new_savedir"
 	mkdir -p "$new_savedir"
 	touch "$new_savedir/delta"
-	$UCI -P "$new_savedir" set delta.sec0=sectype
+	$UCI -P "$new_savedir" set delta.sec0=tmptype
 	$UCI -P "$new_savedir" add_list delta.sec0.li0=1
+	$UCI -P "$new_savedir" set delta.sec0=sectype
 
 	assertEquals "delta.sec0='sectype'
 delta.sec0.li0+='0'" "$($UCI changes)"
@@ -22,8 +23,9 @@ delta.sec0.li0+='0'" "$($UCI changes)"
 	assertTrue "$?"
 	assertEquals "delta.sec0='sectype'
 delta.sec0.li0+='0'
-delta.sec0='sectype'
-delta.sec0.li0+='1'" "$cmdoutput"
+delta.sec0='tmptype'
+delta.sec0.li0+='1'
+delta.sec0='sectype'" "$cmdoutput"
 
 	# check combined export.  Order matters here.
 	cmdoutput="$($UCI -P "$new_savedir" export)"