Fixed MTP to work with TWRP

fs/utimes.c

@@ -0,0 +1,235 @@
+#include <linux/compiler.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/linkage.h>
+#include <linux/mount.h>
+#include <linux/namei.h>
+#include <linux/sched.h>
+#include <linux/stat.h>
+#include <linux/utime.h>
+#include <linux/syscalls.h>
+#include <asm/uaccess.h>
+#include <asm/unistd.h>
+
+#ifdef __ARCH_WANT_SYS_UTIME
+
+/*
+ * sys_utime() can be implemented in user-level using sys_utimes().
+ * Is this for backwards compatibility?  If so, why not move it
+ * into the appropriate arch directory (for those architectures that
+ * need it).
+ */
+
+/* If times==NULL, set access and modification to current time,
+ * must be owner or have write permission.
+ * Else, update from *times, must be owner or super user.
+ */
+SYSCALL_DEFINE2(utime, char __user *, filename, struct utimbuf __user *, times)
+{
+	struct timespec tv[2];
+
+	if (times) {
+		if (get_user(tv[0].tv_sec, &times->actime) ||
+		    get_user(tv[1].tv_sec, &times->modtime))
+			return -EFAULT;
+		tv[0].tv_nsec = 0;
+		tv[1].tv_nsec = 0;
+	}
+	return do_utimes(AT_FDCWD, filename, times ? tv : NULL, 0);
+}
+
+#endif
+
+static bool nsec_valid(long nsec)
+{
+	if (nsec == UTIME_OMIT || nsec == UTIME_NOW)
+		return true;
+
+	return nsec >= 0 && nsec <= 999999999;
+}
+
+static int utimes_common(struct path *path, struct timespec *times)
+{
+	int error;
+	struct iattr newattrs;
+	struct inode *inode = path->dentry->d_inode;
+	struct inode *delegated_inode = NULL;
+
+	error = mnt_want_write(path->mnt);
+	if (error)
+		goto out;
+
+	if (times && times[0].tv_nsec == UTIME_NOW &&
+		     times[1].tv_nsec == UTIME_NOW)
+		times = NULL;
+
+	newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
+	if (times) {
+		if (times[0].tv_nsec == UTIME_OMIT)
+			newattrs.ia_valid &= ~ATTR_ATIME;
+		else if (times[0].tv_nsec != UTIME_NOW) {
+			newattrs.ia_atime.tv_sec = times[0].tv_sec;
+			newattrs.ia_atime.tv_nsec = times[0].tv_nsec;
+			newattrs.ia_valid |= ATTR_ATIME_SET;
+		}
+
+		if (times[1].tv_nsec == UTIME_OMIT)
+			newattrs.ia_valid &= ~ATTR_MTIME;
+		else if (times[1].tv_nsec != UTIME_NOW) {
+			newattrs.ia_mtime.tv_sec = times[1].tv_sec;
+			newattrs.ia_mtime.tv_nsec = times[1].tv_nsec;
+			newattrs.ia_valid |= ATTR_MTIME_SET;
+		}
+		/*
+		 * Tell inode_change_ok(), that this is an explicit time
+		 * update, even if neither ATTR_ATIME_SET nor ATTR_MTIME_SET
+		 * were used.
+		 */
+		newattrs.ia_valid |= ATTR_TIMES_SET;
+	} else {
+		/*
+		 * If times is NULL (or both times are UTIME_NOW),
+		 * then we need to check permissions, because
+		 * inode_change_ok() won't do it.
+		 */
+		error = -EACCES;
+                if (IS_IMMUTABLE(inode))
+			goto mnt_drop_write_and_out;
+
+		if (!inode_owner_or_capable(inode)) {
+			error = inode_permission(inode, MAY_WRITE);
+			if (error)
+				goto mnt_drop_write_and_out;
+		}
+	}
+retry_deleg:
+	mutex_lock(&inode->i_mutex);
+	error = notify_change(path->dentry, &newattrs, &delegated_inode);
+	mutex_unlock(&inode->i_mutex);
+	if (delegated_inode) {
+		error = break_deleg_wait(&delegated_inode);
+		if (!error)
+			goto retry_deleg;
+	}
+
+mnt_drop_write_and_out:
+	mnt_drop_write(path->mnt);
+out:
+	return error;
+}
+
+/*
+ * do_utimes - change times on filename or file descriptor
+ * @dfd: open file descriptor, -1 or AT_FDCWD
+ * @filename: path name or NULL
+ * @times: new times or NULL
+ * @flags: zero or more flags (only AT_SYMLINK_NOFOLLOW for the moment)
+ *
+ * If filename is NULL and dfd refers to an open file, then operate on
+ * the file.  Otherwise look up filename, possibly using dfd as a
+ * starting point.
+ *
+ * If times==NULL, set access and modification to current time,
+ * must be owner or have write permission.
+ * Else, update from *times, must be owner or super user.
+ */
+long do_utimes(int dfd, const char __user *filename, struct timespec *times,
+	       int flags)
+{
+	int error = -EINVAL;
+
+	if (times && (!nsec_valid(times[0].tv_nsec) ||
+		      !nsec_valid(times[1].tv_nsec))) {
+		goto out;
+	}
+
+	if (flags & ~AT_SYMLINK_NOFOLLOW)
+		goto out;
+
+	if (filename == NULL && dfd != AT_FDCWD) {
+		struct fd f;
+
+		if (flags & AT_SYMLINK_NOFOLLOW)
+			goto out;
+
+		f = fdget(dfd);
+		error = -EBADF;
+		if (!f.file)
+			goto out;
+
+		error = utimes_common(&f.file->f_path, times);
+		fdput(f);
+	} else {
+		struct path path;
+		int lookup_flags = 0;
+
+		if (!(flags & AT_SYMLINK_NOFOLLOW))
+			lookup_flags |= LOOKUP_FOLLOW;
+retry:
+		error = user_path_at(dfd, filename, lookup_flags, &path);
+		if (error)
+			goto out;
+
+		error = utimes_common(&path, times);
+		path_put(&path);
+		if (retry_estale(error, lookup_flags)) {
+			lookup_flags |= LOOKUP_REVAL;
+			goto retry;
+		}
+	}
+
+out:
+	return error;
+}
+
+SYSCALL_DEFINE4(utimensat, int, dfd, const char __user *, filename,
+		struct timespec __user *, utimes, int, flags)
+{
+	struct timespec tstimes[2];
+
+	if (utimes) {
+		if (copy_from_user(&tstimes, utimes, sizeof(tstimes)))
+			return -EFAULT;
+
+		/* Nothing to do, we must not even check the path.  */
+		if (tstimes[0].tv_nsec == UTIME_OMIT &&
+		    tstimes[1].tv_nsec == UTIME_OMIT)
+			return 0;
+	}
+
+	return do_utimes(dfd, filename, utimes ? tstimes : NULL, flags);
+}
+
+SYSCALL_DEFINE3(futimesat, int, dfd, const char __user *, filename,
+		struct timeval __user *, utimes)
+{
+	struct timeval times[2];
+	struct timespec tstimes[2];
+
+	if (utimes) {
+		if (copy_from_user(&times, utimes, sizeof(times)))
+			return -EFAULT;
+
+		/* This test is needed to catch all invalid values.  If we
+		   would test only in do_utimes we would miss those invalid
+		   values truncated by the multiplication with 1000.  Note
+		   that we also catch UTIME_{NOW,OMIT} here which are only
+		   valid for utimensat.  */
+		if (times[0].tv_usec >= 1000000 || times[0].tv_usec < 0 ||
+		    times[1].tv_usec >= 1000000 || times[1].tv_usec < 0)
+			return -EINVAL;
+
+		tstimes[0].tv_sec = times[0].tv_sec;
+		tstimes[0].tv_nsec = 1000 * times[0].tv_usec;
+		tstimes[1].tv_sec = times[1].tv_sec;
+		tstimes[1].tv_nsec = 1000 * times[1].tv_usec;
+	}
+
+	return do_utimes(dfd, filename, utimes ? tstimes : NULL, 0);
+}
+
+SYSCALL_DEFINE2(utimes, char __user *, filename,
+		struct timeval __user *, utimes)
+{
+	return sys_futimesat(AT_FDCWD, filename, utimes);
+}