Print SD card usage in Storage status

The Storage device keeps track of the areas of the SD card that have
been written to during this power cycle. This data can be accessed using
the NK_get_SD_usage_data function that returns a range of the SD card
that has not been written. This data can be used as a guide line when
creating new hidden volumes.
This patch adds the SD card usage data to the output of the status
command for Nitrokey Storage devices.

6 files changed, 20 insertions, 3 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 83fc8d9..6a7cd93 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,8 @@ Unreleased
     device to connect to
   - Added `--usb-path` option that restricts the USB path of the device to
     connect to
+- Added SD card usage information to the output of the `status` command for
+  Storage devices
 - Bumped `structopt` dependency to `0.3.17`
 
 
diff --git a/README.md b/README.md
index e6500f0..39cfcf2 100644
--- a/README.md
+++ b/README.md
@@ -58,11 +58,12 @@ $ nitrocli status
 Status:
   model:             Storage
   serial number:     0x00053141
-  firmware version:  0.47
+  firmware version:  v0.54
   user retry count:  3
   admin retry count: 3
   Storage:
     SD card ID:        0x05dcad1d
+    SD card usage:     24% .. 99% not written
     firmware:          unlocked
     storage keys:      created
     volumes:
diff --git a/doc/nitrocli.1 b/doc/nitrocli.1
index 6fb1fd9..b07b36a 100644
--- a/doc/nitrocli.1
+++ b/doc/nitrocli.1
@@ -70,7 +70,8 @@ them, set the \fB\-\-no-connect\fR option.
 Print the status of the connected Nitrokey device, including the stick serial
 number, the firmware version, and the PIN retry count. If the device is a
 Nitrokey Storage, also print storage related information including the SD card
-serial number, the encryption status, and the status of the volumes.
+serial number, the SD card usage during this power cycle, the encryption
+status, and the status of the volumes.
 .TP
 .B nitrocli lock
 Lock the Nitrokey.
@@ -121,6 +122,10 @@ respectively, the start and end position of the hidden volume inside the
 encrypted volume, as a percentage of the encrypted volume's size.
 This command requires a password which is later used to look up the hidden
 volume to open. Unlike a PIN, this password is not cached by \fBgpg\-agent\fR(1).
+
+As a guide line for creating new hidden volumes, the \fBstatus\fR command
+provides a range of the SD card that has not been written to during this power
+cycle.
 .TP
 \fBnitrocli hidden open
 Open a hidden volume. The volume to open is determined based on the password
diff --git a/doc/nitrocli.1.pdf b/doc/nitrocli.1.pdf
index d98ab41..be86627 100644
--- a/doc/nitrocli.1.pdf
+++ b/doc/nitrocli.1.pdf
diff --git a/src/commands.rs b/src/commands.rs
index ebb28ca..07ba652 100644
--- a/src/commands.rs
+++ b/src/commands.rs
@@ -6,6 +6,7 @@
 use std::convert::TryFrom as _;
 use std::fmt;
 use std::mem;
+use std::ops;
 use std::ops::Deref as _;
 use std::thread;
 use std::time;
@@ -334,11 +335,13 @@ where
 fn print_storage_status(
   ctx: &mut Context<'_>,
   status: &nitrokey::StorageStatus,
+  sd_card_usage: &ops::Range<u8>,
 ) -> anyhow::Result<()> {
   println!(
     ctx,
     r#"  Storage:
     SD card ID:        {id:#x}
+    SD card usage:     {usagestart}% .. {usageend}% not written
     firmware:          {fw}
     storage keys:      {sk}
     volumes:
@@ -346,6 +349,8 @@ fn print_storage_status(
       encrypted:       {ve}
       hidden:          {vh}"#,
     id = status.serial_number_sd_card,
+    usagestart = sd_card_usage.start,
+    usageend = sd_card_usage.end,
     fw = if status.firmware_locked {
       "locked"
     } else {
@@ -398,8 +403,11 @@ fn print_status(
     let status = device
       .get_storage_status()
       .context("Failed to retrieve storage status")?;
+    let sd_card_usage = device
+      .get_sd_card_usage()
+      .context("Failed to retrieve SD card usage")?;
 
-    print_storage_status(ctx, &status)
+    print_storage_status(ctx, &status, &sd_card_usage)
   } else {
     Ok(())
   }
diff --git a/src/tests/status.rs b/src/tests/status.rs
index fe69d78..ca16121 100644
--- a/src/tests/status.rs
+++ b/src/tests/status.rs
@@ -50,6 +50,7 @@ fn output_storage(model: nitrokey::Model) -> anyhow::Result<()> {
   admin retry count: [0-3]
   Storage:
     SD card ID:        0x[[:xdigit:]]{8}
+    SD card usage:     \d+% .. \d+% not written
     firmware:          (un)?locked
     storage keys:      (not )?created
     volumes: