[LTP] [PATCH v3 2/3] tst_cgroup: Add safe_cg_open and safe_cg_fchown functions

[Yang Xu]

safe_cg_open is used to open the sub control's file ie cgroup.procs
and returns the opened fd number. The opened fd array is stored in
fds argument.

safe_cg_fchown is used to use fchownat to change file's uid and gid.

Signed-off-by: Yang Xu <xuyang2018.jy@fujitsu.com>
---
 include/tst_cgroup.h | 44 +++++++++++++++++++++++++++++
 lib/tst_cgroup.c     | 66 +++++++++++++++++++++++++++-----------------
 2 files changed, 85 insertions(+), 25 deletions(-)

diff --git a/include/tst_cgroup.h b/include/tst_cgroup.h
index d06847cc6..70c5b3fd4 100644
--- a/include/tst_cgroup.h
+++ b/include/tst_cgroup.h
@@ -89,6 +89,32 @@ enum tst_cg_ver {
 	TST_CG_V2 = 2,
 };
 
+/* Controller sub-systems */
+enum cgroup_ctrl_indx {
+	CTRL_MEMORY = 1,
+	CTRL_CPU,
+	CTRL_CPUSET,
+	CTRL_IO,
+	CTRL_PIDS,
+	CTRL_HUGETLB,
+	CTRL_CPUACCT,
+	CTRL_DEVICES,
+	CTRL_FREEZER,
+	CTRL_NETCLS,
+	CTRL_NETPRIO,
+	CTRL_BLKIO,
+	CTRL_MISC,
+	CTRL_PERFEVENT,
+	CTRL_DEBUG
+};
+
+#define CTRLS_MAX CTRL_DEBUG
+
+/* At most we can have one cgroup V1 tree for each controller and one
+ * (empty) v2 tree.
+ */
+#define ROOTS_MAX (CTRLS_MAX + 1)
+
 /* Used to specify CGroup hierarchy configuration options, allowing a
  * test to request a particular CGroup structure.
  */
@@ -201,6 +227,24 @@ void safe_cg_printf(const char *const file, const int lineno,
 			const char *const fmt, ...)
 			__attribute__ ((format (printf, 5, 6), nonnull));
 
+#define SAFE_CG_OPEN(cg, file_name, flags, fds)			\
+	safe_cg_open(__FILE__, __LINE__, (cg), (file_name), (flags), (fds))
+
+int safe_cg_open(const char *const file, const int lineno,
+			const struct tst_cg_group *const cg,
+			const char *const file_name,
+			int flags, int *fds)
+			__attribute__ ((nonnull));
+
+#define SAFE_CG_FCHOWN(cg, file_name, owner, group)		\
+	safe_cg_fchown(__FILE__, __LINE__, (cg), (file_name), (owner), (group))
+
+void safe_cg_fchown(const char *const file, const int lineno,
+			const struct tst_cg_group *const cg,
+			const char *const file_name,
+			uid_t owner, gid_t group)
+			__attribute__ ((nonnull));
+
 #define SAFE_CG_SCANF(cg, file_name, fmt, ...)			\
 	safe_cg_scanf(__FILE__, __LINE__,				\
 			  (cg), (file_name), (fmt), __VA_ARGS__)
diff --git a/lib/tst_cgroup.c b/lib/tst_cgroup.c
index 1cfd79243..3d9568efe 100644
--- a/lib/tst_cgroup.c
+++ b/lib/tst_cgroup.c
@@ -77,31 +77,6 @@ struct cgroup_root {
 	int no_cpuset_prefix:1;
 };
 
-/* Controller sub-systems */
-enum cgroup_ctrl_indx {
-	CTRL_MEMORY = 1,
-	CTRL_CPU,
-	CTRL_CPUSET,
-	CTRL_IO,
-	CTRL_PIDS,
-	CTRL_HUGETLB,
-	CTRL_CPUACCT,
-	CTRL_DEVICES,
-	CTRL_FREEZER,
-	CTRL_NETCLS,
-	CTRL_NETPRIO,
-	CTRL_BLKIO,
-	CTRL_MISC,
-	CTRL_PERFEVENT,
-	CTRL_DEBUG
-};
-#define CTRLS_MAX CTRL_DEBUG
-
-/* At most we can have one cgroup V1 tree for each controller and one
- * (empty) v2 tree.
- */
-#define ROOTS_MAX (CTRLS_MAX + 1)
-
 /* Describes a controller file or knob
  *
  * The primary purpose of this is to map V2 names to V1
@@ -1320,6 +1295,47 @@ void safe_cg_printf(const char *const file, const int lineno,
 	}
 }
 
+int safe_cg_open(const char *const file, const int lineno,
+		      const struct tst_cg_group *cg,
+		      const char *const file_name, int flags, int *fds)
+{
+	const struct cgroup_file *const cfile =
+		cgroup_file_find(file, lineno, file_name);
+	struct cgroup_dir *const *dir;
+	const char *alias;
+	int i = 0;
+
+	for_each_dir(cg, cfile->ctrl_indx, dir) {
+		alias = cgroup_file_alias(cfile, *dir);
+		if (!alias)
+			continue;
+
+		fds[i++] = safe_openat(file, lineno, (*dir)->dir_fd, alias, flags);
+	}
+
+	return i;
+}
+
+void safe_cg_fchown(const char *const file, const int lineno,
+			const struct tst_cg_group *cg,
+			const char *const file_name,
+			uid_t owner, gid_t group)
+{
+	const struct cgroup_file *const cfile =
+		cgroup_file_find(file, lineno, file_name);
+	struct cgroup_dir *const *dir;
+	const char *alias;
+
+	for_each_dir(cg, cfile->ctrl_indx, dir) {
+		alias = cgroup_file_alias(cfile, *dir);
+		if (!alias)
+			continue;
+
+		safe_fchownat(file, lineno, (*dir)->dir_fd, alias, owner, group, 0);
+	}
+}
+
+
 void safe_cg_scanf(const char *const file, const int lineno,
 		       const struct tst_cg_group *const cg,
 		       const char *const file_name,
-- 
2.27.0