Merge pull request #577 from deleriux/file_info_api

lxcfs: handle NULL path in lxcfs_releasedir/lxcfs_release

src/bindings.h

@@ -30,6 +30,8 @@
 /* Maximum number for 64 bit integer is a string with 21 digits: 2^64 - 1 = 21 */
 #define LXCFS_NUMSTRLEN64 21
 
+/* The definitions here are well-ordered. New values should go directly
+ * above LXC_TYPE_MAX only. */
 enum lxcfs_virt_t {
 	LXC_TYPE_CGDIR,
 	LXC_TYPE_CGFILE,
@@ -67,8 +69,15 @@ enum lxcfs_virt_t {
 
 	LXC_TYPE_SYS_DEVICES_SYSTEM_CPU_ONLINE,
 #define LXC_TYPE_SYS_DEVICES_SYSTEM_CPU_ONLINE_PATH "/sys/devices/system/cpu/online"
+	LXC_TYPE_MAX,
 };
 
+/* Macros below used to check the class from the file types above */
+#define LXCFS_TYPE_CGROUP(type) (type >= LXC_TYPE_CGDIR && type <= LXC_TYPE_CGFILE)
+#define LXCFS_TYPE_PROC(type) (type >= LXC_TYPE_PROC_MEMINFO && type <= LXC_TYPE_PROC_SLABINFO)
+#define LXCFS_TYPE_SYS(type) (type >= LXC_TYPE_SYS && type <= LXC_TYPE_SYS_DEVICES_SYSTEM_CPU_ONLINE)
+#define LXCFS_TYPE_OK(type) (type >= LXC_TYPE_CGDIR && type < LXC_TYPE_MAX)
+
 struct file_info {
 	char *controller;
 	char *cgroup;

src/lxcfs.c

@@ -8,6 +8,7 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <getopt.h>
+#include <inttypes.h>
 #include <libgen.h>
 #include <pthread.h>
 #include <sched.h>
@@ -65,6 +66,22 @@ static inline void users_unlock(void)
 	unlock_mutex(&user_count_mutex);
 }
 
+/* Returns file info type of custom type declaration carried
+ * in fuse_file_info */
+static inline enum lxcfs_virt_t file_info_type(struct fuse_file_info *fi)
+{
+	struct file_info *f;
+
+	f = INTTYPE_TO_PTR(fi->fh);
+	if (!f)
+		return -1;
+
+	if (!LXCFS_TYPE_OK(f->type))
+		return -1;
+
+	return f->type;
+}
+
 static pthread_t loadavg_pid = 0;
 
 /* Returns zero on success */
@@ -770,27 +787,34 @@ static int lxcfs_access(const char *path, int mode)
 static int lxcfs_releasedir(const char *path, struct fuse_file_info *fi)
 {
 	int ret;
+	enum lxcfs_virt_t type;
 
-	if (strcmp(path, "/") == 0)
-		return 0;
+	type = file_info_type(fi);
 
-	if (strncmp(path, "/cgroup", 7) == 0) {
+	if (LXCFS_TYPE_CGROUP(type)) {
 		up_users();
 		ret = do_cg_releasedir(path, fi);
 		down_users();
 		return ret;
 	}
 
-	if (strcmp(path, "/proc") == 0)
-		return 0;
-
-	if (strncmp(path, "/sys", 4) == 0) {
+	if (LXCFS_TYPE_SYS(type)) {
 		up_users();
 		ret = do_sys_releasedir(path, fi);
 		down_users();
 		return ret;
 	}
 
+	if (path) {
+		if (strcmp(path, "/") == 0)
+			return 0;
+		if (strcmp(path, "/proc") == 0)
+			return 0;
+	}
+
+	lxcfs_error("unknown file type: path=%s, type=%d, fi->fh=%" PRIu64,
+			path, type, fi->fh);
+
 	return -EINVAL;
 }
 
@@ -895,28 +919,34 @@ static int lxcfs_flush(const char *path, struct fuse_file_info *fi)
 static int lxcfs_release(const char *path, struct fuse_file_info *fi)
 {
 	int ret;
+	enum lxcfs_virt_t type;
 
-	if (strncmp(path, "/cgroup", 7) == 0) {
+	type = file_info_type(fi);
+
+	if (LXCFS_TYPE_CGROUP(type)) {
 		up_users();
 		ret = do_cg_release(path, fi);
 		down_users();
 		return ret;
 	}
 
-	if (strncmp(path, "/proc", 5) == 0) {
+	if (LXCFS_TYPE_PROC(type)) {
 		up_users();
 		ret = do_proc_release(path, fi);
 		down_users();
 		return ret;
 	}
 
-	if (strncmp(path, "/sys", 4) == 0) {
+	if (LXCFS_TYPE_SYS(type)) {
 		up_users();
 		ret = do_sys_release(path, fi);
 		down_users();
 		return ret;
 	}
 
+	lxcfs_error("unknown file type: path=%s, type=%d, fi->fh=%" PRIu64,
+			path, type, fi->fh);
+
 	return -EINVAL;
 }