From da8727996efacec4280696caefee3feecea4eae7 Mon Sep 17 00:00:00 2001
From: Robin Krahl <robin.krahl@ireas.org>
Date: Tue, 28 Jan 2020 10:07:23 +0100
Subject: Add String value to the Error::UnexpectedError variant

To make debugging of unexpected errors easier, this patch adds an
associated String value with a description of the unexpected behavior to
the UnexpectedError variant of the Error enum.
---
 src/util.rs | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

(limited to 'src/util.rs')

diff --git a/src/util.rs b/src/util.rs
index 5a56c55..1b52c3d 100644
--- a/src/util.rs
+++ b/src/util.rs
@@ -39,7 +39,9 @@ pub fn owned_str_from_ptr(ptr: *const c_char) -> Result<String, Error> {
 
 pub fn result_from_string(ptr: *const c_char) -> Result<String, Error> {
     if ptr.is_null() {
-        return Err(Error::UnexpectedError);
+        return Err(Error::UnexpectedError(
+            "libnitrokey returned a null pointer".to_owned(),
+        ));
     }
     let s = owned_str_from_ptr(ptr)?;
     unsafe { free(ptr as *mut c_void) };
@@ -69,10 +71,9 @@ pub fn get_last_result() -> Result<(), Error> {
 }
 
 pub fn get_last_error() -> Error {
-    match get_last_result() {
-        Ok(()) => Error::UnexpectedError,
-        Err(err) => err,
-    }
+    get_last_result().err().unwrap_or_else(|| {
+        Error::UnexpectedError("Expected an error, but command status is zero".to_owned())
+    })
 }
 
 pub fn generate_password(length: usize) -> Result<Vec<u8>, Error> {
-- 
cgit v1.2.1


From d905aafe208536203dd319e5dc48bd250180a8ef Mon Sep 17 00:00:00 2001
From: Robin Krahl <robin.krahl@ireas.org>
Date: Tue, 28 Jan 2020 17:56:53 +0100
Subject: Refactor string handling in util

The util module provides helper methods to deal with the C strings
returned by libnitrokey.  The current implementation has to problems:
- It causes unnecessary allocations if we only want to look at the
  string, for example in get_serial_number.
- If the conversion from a CStr to a String fails, the string pointer
  is not freed.

Therefore this patch introduces the run_with_str function that executes
a function with the string returned by libnitrokey and then makes sure
that the pointer is freed correctly.
---
 src/util.rs | 36 +++++++++++++++++++++++-------------
 1 file changed, 23 insertions(+), 13 deletions(-)

(limited to 'src/util.rs')

diff --git a/src/util.rs b/src/util.rs
index 08946d6..b17b071 100644
--- a/src/util.rs
+++ b/src/util.rs
@@ -30,28 +30,38 @@ pub enum LogLevel {
     DebugL2,
 }
 
+pub fn str_from_ptr<'a>(ptr: *const c_char) -> Result<&'a str, Error> {
+    unsafe { CStr::from_ptr(ptr) }.to_str().map_err(Error::from)
+}
+
 pub fn owned_str_from_ptr(ptr: *const c_char) -> Result<String, Error> {
-    unsafe { CStr::from_ptr(ptr) }
-        .to_str()
-        .map(String::from)
-        .map_err(Error::from)
+    str_from_ptr(ptr).map(ToOwned::to_owned)
 }
 
-pub fn result_from_string(ptr: *const c_char) -> Result<String, Error> {
+pub fn run_with_string<R, F>(ptr: *const c_char, op: F) -> Result<R, Error>
+where
+    F: FnOnce(&str) -> Result<R, Error>,
+{
     if ptr.is_null() {
         return Err(Error::UnexpectedError(
             "libnitrokey returned a null pointer".to_owned(),
         ));
     }
-    let s = owned_str_from_ptr(ptr)?;
+    let result = str_from_ptr(ptr).and_then(op);
     unsafe { free(ptr as *mut c_void) };
-    // An empty string can both indicate an error or be a valid return value.  In this case, we
-    // have to check the last command status to decide what to return.
-    if s.is_empty() {
-        get_last_result().map(|_| s)
-    } else {
-        Ok(s)
-    }
+    result
+}
+
+pub fn result_from_string(ptr: *const c_char) -> Result<String, Error> {
+    run_with_string(ptr, |s| {
+        // An empty string can both indicate an error or be a valid return value.  In this case, we
+        // have to check the last command status to decide what to return.
+        if s.is_empty() {
+            get_last_result().map(|_| s.to_owned())
+        } else {
+            Ok(s.to_owned())
+        }
+    })
 }
 
 pub fn result_or_error<T>(value: T) -> Result<T, Error> {
-- 
cgit v1.2.1