From 2e47141b8d44f235b74b843a6311e6136b9ce1bb Mon Sep 17 00:00:00 2001
From: Tom Hromatka <tom.hromatka@oracle.com>
Date: Wed, 15 Dec 2021 20:39:52 +0000
Subject: [PATCH] wrapper: Add function to remove name/value pair from a
 controller

Add a function to remove a name/value settings pair from
a cgroup_controller instance.  As part of this change, I did a small
refactor on cgroup_free_controllers() to make the code more reusable
throughout libcgroup.

Signed-off-by: Tom Hromatka <tom.hromatka@oracle.com>
Reviewed-by: Kamalesh Babulal <kamalesh.babulal@oracle.com>
---
 src/libcgroup-internal.h | 10 +++++++
 src/wrapper.c            | 63 +++++++++++++++++++++++++++++++++-------
 2 files changed, 62 insertions(+), 11 deletions(-)

diff --git a/src/libcgroup-internal.h b/src/libcgroup-internal.h
index 056085bc..a63244d1 100644
--- a/src/libcgroup-internal.h
+++ b/src/libcgroup-internal.h
@@ -378,6 +378,16 @@ int cgroup_test_subsys_mounted(const char *ctrl_name);
 int cgroup_copy_controller_values(struct cgroup_controller * const dst,
 				  const struct cgroup_controller * const src);
 
+/**
+ * Remove a name/value pair from a controller.
+ *
+ * @param controller
+ * @param name Name of the name/value pair to be removed
+ * @return 0 on success.  ECGROUPNOTEXIST if name does not exist.
+ */
+int cgroup_remove_value(struct cgroup_controller * const controller,
+			const char * const name);
+
 /**
  * Functions that are defined as STATIC can be placed within the UNIT_TEST
  * ifdef.  This will allow them to be included in the unit tests while
diff --git a/src/wrapper.c b/src/wrapper.c
index 150e6c4b..77467d35 100644
--- a/src/wrapper.c
+++ b/src/wrapper.c
@@ -159,24 +159,36 @@ end:
 	return ret;
 }
 
+static void cgroup_free_value(struct control_value *value)
+{
+	if (value->multiline_value)
+		free(value->multiline_value);
+	if (value->prev_name)
+		free(value->prev_name);
+
+	free(value);
+}
+
+static void cgroup_free_controller(struct cgroup_controller *ctrl)
+{
+	int i;
+
+	for (i = 0; i < ctrl->index; i++)
+		cgroup_free_value(ctrl->values[i]);
+	ctrl->index = 0;
+
+	free(ctrl);
+}
+
 void cgroup_free_controllers(struct cgroup *cgroup)
 {
-	int i, j;
+	int i;
 
 	if (!cgroup)
 		return;
 
 	for (i = 0; i < cgroup->index; i++) {
-		for (j = 0; j < cgroup->controller[i]->index; j++) {
-			if (cgroup->controller[i]->values[j]->multiline_value)
-				free(cgroup->controller[i]->values[j]->multiline_value);
-			if (cgroup->controller[i]->values[j]->prev_name)
-				free(cgroup->controller[i]->values[j]->prev_name);
-
-			free(cgroup->controller[i]->values[j]);
-		}
-		cgroup->controller[i]->index = 0;
-		free(cgroup->controller[i]);
+		cgroup_free_controller(cgroup->controller[i]);
 	}
 	cgroup->index = 0;
 }
@@ -297,6 +309,35 @@ int cgroup_add_value_bool(struct cgroup_controller *controller,
 	return ret;
 }
 
+int cgroup_remove_value(struct cgroup_controller * const controller,
+			const char * const name)
+{
+	int i;
+
+	for (i = 0; i < controller->index; i++) {
+		if (strcmp(controller->values[i]->name, name) == 0) {
+			cgroup_free_value(controller->values[i]);
+
+			if (i == (controller->index - 1)) {
+				/* This is the last entry in the table.
+				 * There's nothing to move
+				 */
+				controller->index--;
+			} else {
+				memmove(&controller->values[i],
+					&controller->values[i + 1],
+					sizeof(struct control_value *) *
+						(controller->index - i - 1));
+				controller->index--;
+			}
+
+			return 0;
+		}
+	}
+
+	return ECGROUPNOTEXIST;
+}
+
 int cgroup_compare_controllers(struct cgroup_controller *cgca,
 					struct cgroup_controller *cgcb)
 {
-- 
2.47.2