Export cgroup_find_parent and add testing code for it

This patch does not necessarily need to be accepted, it just provides testing
facility for new cgroup_find_parent.

Especially note the ugly dependence on ../src/tools/tools-common.c :)

Signed-off-by: Jan Safranek <jsafrane@redhat.com>

4 files changed, 96 insertions, 1 deletions

diff --git a/include/libcgroup.h b/include/libcgroup.h
index 3d5660c..0942161 100644
--- a/include/libcgroup.h
+++ b/include/libcgroup.h
@@ -364,6 +364,18 @@ int cgroup_get_controller_end(void **handle);
  */
 int cgroup_get_subsys_mount_point(char *controller, char **mount_point);
 
+/**
+ * Find the parent of the specified directory. It returns the parent (the
+ * parent is usually name/.. unless name is a mount point.
+ *
+ * @param cgroup The cgroup.
+ * @param parent Output, name of parent's group (if the group has parent) or
+ *	NULL, if the provided cgroup is the root group and has no parent.
+ *	Caller is responsible for freeing the returned string!
+ * @return 0 on success, >0 on error.
+ */
+int cgroup_find_parent(struct cgroup *cgroup, char **parent);
+
 /* The wrappers for filling libcg structures */
 
 struct cgroup *cgroup_new_cgroup(const char *name);
diff --git a/src/libcgroup.map b/src/libcgroup.map
index aa9d0d2..e66c332 100644
--- a/src/libcgroup.map
+++ b/src/libcgroup.map
@@ -73,4 +73,5 @@ global:
 	cgroup_get_procname_from_procfs;
 	cgroup_register_unchanged_process;
 	cgroup_change_cgroup_flags;
+	cgroup_find_parent;
 } CGROUP_0.33;
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 14bcdf3..0157a54 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -2,7 +2,7 @@ INCLUDES = -I$(top_srcdir)/include
 LDADD = $(top_srcdir)/src/.libs/libcgroup.la
 
 # compile the tests, but do not install them
-noinst_PROGRAMS = libcgrouptest01 libcg_ba setuid pathtest walk_test read_stats walk_task get_controller get_mount_point proctest
+noinst_PROGRAMS = libcgrouptest01 libcg_ba setuid pathtest walk_test read_stats walk_task get_controller get_mount_point proctest test_parent
 
 libcgrouptest01_SOURCES=libcgrouptest01.c test_functions.c libcgrouptest.h
 libcg_ba_SOURCES=libcg_ba.cpp
@@ -14,6 +14,7 @@ walk_task_SOURCES=walk_task.c
 get_controller_SOURCES=get_controller.c
 get_mount_point_SOURCES=get_mount_point.c
 proctest_SOURCES=proctest.c
+test_parent_SOURCES=test_parent.c ../src/tools/tools-common.c ../src/tools/tools-common.h
 
 EXTRA_DIST = pathtest.sh runlibcgrouptest.sh
 
diff --git a/tests/test_parent.c b/tests/test_parent.c
new file mode 100644
index 0000000..3b16439
--- /dev/null
+++ b/tests/test_parent.c
@@ -0,0 +1,81 @@
+#include <stdio.h>
+#include <libcgroup.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+
+/* Ugly, I know...  */
+#include "../src/tools/tools-common.h"
+
+struct cgroup_group_spec *cgroup_list[CG_HIER_MAX];
+
+int main(int argc, char **argv)
+{
+	int ret;
+	int i, j;
+	char *parent;
+	char controllers[PATH_MAX];
+	struct cgroup *cgroup;
+	struct cgroup_controller *cgc;
+
+	ret = cgroup_init();
+	if (ret) {
+		fprintf(stderr, "cgroup_init failed with %s\n",
+				cgroup_strerror(ret));
+		exit(1);
+	}
+
+	if (argc < 2) {
+		fprintf(stderr, "at least one argument is expected\n");
+		printf("Usage: %s <controllers>:<group> ... \n",
+				argv[0]);
+		exit(1);
+	}
+
+	for (i = 1; i < argc; i++) {
+		ret = parse_cgroup_spec(cgroup_list, argv[i]);
+		if (ret) {
+			fprintf(stderr, "cannot parse %s\n", argv[i]);
+			exit(1);
+		}
+	}
+
+	for (i = 0; i < CG_HIER_MAX; i++) {
+		if (!cgroup_list[i])
+			break;
+
+		cgroup = cgroup_new_cgroup(cgroup_list[i]->path);
+		if (cgroup == NULL) {
+			fprintf(stderr, "cannot create new cgroup for %s\n",
+					argv[i]);
+			exit(1);
+		}
+
+		memset(controllers, 0, sizeof(controllers));
+		for (j = 0; j < CG_CONTROLLER_MAX; j++) {
+			if (cgroup_list[i]->controllers[j] == NULL)
+				break;
+			strncat(controllers, cgroup_list[i]->controllers[j],
+					sizeof(controllers) -
+					strlen(controllers));
+			strncat(controllers, ",", sizeof(controllers) -
+					strlen(controllers));
+			cgc = cgroup_add_controller(cgroup,
+					cgroup_list[i]->controllers[j]);
+			if (cgc == NULL) {
+				fprintf(stderr, "cannot add %s to %s\n",
+						cgroup_list[i]->path,
+						cgroup_list[i]->controllers[j]);
+				exit(1);
+			}
+		}
+		ret = cgroup_find_parent(cgroup, &parent);
+		printf("Parent of %s:%s is: %s (%d)\n", controllers,
+				cgroup_list[i]->path, parent, ret);
+
+		free(parent);
+		cgroup_free_group_spec(cgroup_list[i]);
+		cgroup_free(&cgroup);
+	}
+	return 0;
+}