cmd/fscrypt: improve errors

In checkEncryptable(), check whether the directory is already encrypted
before checking whether it's empty.

Also improve the error message for when a directory is nonempty.

Finally, translate keyring.ErrKeyAddedByOtherUsers and
keyring.ErrKeyFilesOpen into errors which include the directory.

4 files changed, 40 insertions, 18 deletions

diff --git a/cli-tests/t_encrypt.out b/cli-tests/t_encrypt.out
index e3bace0..26cb451 100644
--- a/cli-tests/t_encrypt.out
+++ b/cli-tests/t_encrypt.out
@@ -7,11 +7,22 @@ ext4 filesystem "MNT" has 0 protectors and 0 policies
                         encrypted
 
 # Try to encrypt a nonempty directory
-[ERROR] fscrypt encrypt: MNT/dir: not an empty directory
-
-Encryption can only be setup on empty directories; files cannot be encrypted
-in-place. Instead, encrypt an empty directory, copy the files into that
-encrypted directory, and securely delete the originals with "shred".
+[ERROR] fscrypt encrypt: Directory "MNT/dir" cannot be
+                         encrypted because it is non-empty.
+
+Files cannot be encrypted in-place. Instead, encrypt a new directory, copy the
+files into it, and securely delete the original directory. For example:
+
+     mkdir MNT/dir.new
+     fscrypt encrypt MNT/dir.new
+     cp -a -T MNT/dir MNT/dir.new
+     find MNT/dir -type f -print0 | xargs -0 shred -n1 --remove=unlink
+     rm -rf MNT/dir
+     mv MNT/dir.new MNT/dir
+
+Caution: due to the nature of modern storage devices and filesystems, the
+original data may still be recoverable from disk. It's much better to encrypt
+your files from the start.
 ext4 filesystem "MNT" has 0 protectors and 0 policies
 
 [ERROR] fscrypt status: file or directory "MNT/dir" is not
diff --git a/cli-tests/t_lock.out b/cli-tests/t_lock.out
index c0f9279..b8c8dcb 100644
--- a/cli-tests/t_lock.out
+++ b/cli-tests/t_lock.out
@@ -33,11 +33,16 @@ desc2  No      custom protector "prot"
 contents
 
 # Try to lock directory while files busy
-[ERROR] fscrypt lock: some files using the key are still open
+[ERROR] fscrypt lock: Directory was incompletely locked because some files are
+                      still open. These files remain accessible.
 
-Directory was incompletely locked because some files are still open. These files
-remain accessible. Try killing any processes using files in the directory, then
-re-running 'fscrypt lock'.
+Try killing any processes using files in the directory, for example using:
+
+     find "MNT/dir" -print0 | xargs -0 fuser -k
+
+Then re-run:
+
+     fscrypt lock "MNT/dir"
 
 # => status should be incompletely locked
 "MNT/dir" is encrypted with fscrypt.
@@ -72,11 +77,12 @@ mkdir: cannot create directory 'MNT/dir/subdir': Required key not available
 
 # Try to lock directory while other user has unlocked
 Enter custom passphrase for protector "prot": "MNT/dir" is now unlocked and ready for use.
-[ERROR] fscrypt lock: other users have added the key too
+[ERROR] fscrypt lock: Directory "MNT/dir" couldn't be fully
+                      locked because other user(s) have unlocked it.
+
+If you want to force the directory to be locked, use:
 
-Directory couldn't be fully locked because other user(s) have unlocked it. If
-you want to force the directory to be locked, use 'sudo fscrypt lock --all-users
-DIR'.
+     sudo fscrypt lock --all-users "MNT/dir"
 contents
 "MNT/dir" is now locked.
 cat: MNT/dir/file: No such file or directory
diff --git a/cli-tests/t_setup.out b/cli-tests/t_setup.out
index ef0d133..943a781 100644
--- a/cli-tests/t_setup.out
+++ b/cli-tests/t_setup.out
@@ -26,7 +26,7 @@ Skipping creating MNT_ROOT/.fscrypt because it already exists.
 # fscrypt setup --quiet when fscrypt.conf already exists
 [ERROR] fscrypt setup: operation would be destructive
 
-Use --force to automatically run destructive operations.
+If desired, use --force to automatically run destructive operations.
 
 # fscrypt setup --quiet --force when fscrypt.conf already exists
 
diff --git a/cli-tests/t_v1_policy.out b/cli-tests/t_v1_policy.out
index e693bf5..b47bcca 100644
--- a/cli-tests/t_v1_policy.out
+++ b/cli-tests/t_v1_policy.out
@@ -101,11 +101,16 @@ cat: MNT/dir/file: No such file or directory
 # Testing incompletely locking v1-encrypted directory
 Enter custom passphrase for protector "prot": "MNT/dir" is now unlocked and ready for use.
 Encrypted data removed from filesystem cache.
-[ERROR] fscrypt lock: some files using the key are still open
+[ERROR] fscrypt lock: Directory was incompletely locked because some files are
+                      still open. These files remain accessible.
 
-Directory was incompletely locked because some files are still open. These files
-remain accessible. Try killing any processes using files in the directory, then
-re-running 'fscrypt lock'.
+Try killing any processes using files in the directory, for example using:
+
+     find "MNT/dir" -print0 | xargs -0 fuser -k
+
+Then re-run:
+
+     fscrypt lock "MNT/dir"
 "MNT/dir" is encrypted with fscrypt.
 
 Policy:   desc1