Kernel: Fix directory permissions

We did not care about X bit in directories and instead used only the
R bit for search/read.

libc/dirent.cpp

@@ -58,7 +58,7 @@ DIR* fdopendir(int fd)
 
 DIR* opendir(const char* dirname)
 {
-	int fd = open(dirname, O_SEARCH);
+	int fd = open(dirname, O_RDONLY);
 	if (fd == -1)
 		return nullptr;
 	return fdopendir(fd);

libc/include/sys/syscall.h

@@ -52,6 +52,8 @@ __BEGIN_DECLS
 #define SYS_SET_PGID 45
 #define SYS_FCNTL 46
 #define SYS_NANOSLEEP 47
+#define SYS_FSTATAT 48
+#define SYS_STAT 49 // stat/lstat
 
 __END_DECLS
 

libc/sys/stat.cpp

@@ -11,38 +11,15 @@ int fstat(int fildes, struct stat* buf)
 
 int fstatat(int fd, const char* __restrict path, struct stat* __restrict buf, int flag)
 {
-	if (flag == AT_SYMLINK_NOFOLLOW)
-		flag = O_NOFOLLOW;
-	else if (flag)
-	{
-		errno = EINVAL;
-		return -1;
-	}
-
-	int target = openat(fd, path, O_SEARCH | flag);
-	if (target == -1)
-		return -1;
-	int ret = fstat(target, buf);
-	close(target);
-	return ret;
+	return syscall(SYS_FSTATAT, fd, path, buf, flag);
 }
 
 int lstat(const char* __restrict path, struct stat* __restrict buf)
 {
-	int fd = open(path, O_SEARCH | O_NOFOLLOW);
-	if (fd == -1)
-		return -1;
-	int ret = fstat(fd, buf);
-	close(fd);
-	return ret;
+	return syscall(SYS_STAT, path, buf, AT_SYMLINK_NOFOLLOW);
 }
 
 int stat(const char* __restrict path, struct stat* __restrict buf)
 {
-	int fd = open(path, O_SEARCH);
-	if (fd == -1)
-		return -1;
-	int ret = fstat(fd, buf);
-	close(fd);
-	return ret;
+	return syscall(SYS_STAT, path, buf, 0);
 }