Implement Fallible API (#71)

* Fallible for `username()`, `realname()` and `_os` variants

* Minor fixes

* Add remaining planned fallible APIs

* Compile error fixes

* Fix unused imports

* Address self-feedback

* Address `clippy::needless_doctest_main`

https://rust-lang.github.io/rust-clippy/master/index.html#needless_doctest_main

* Fix possible memory leak in `distro()` on Windows

* More windows bugs

* Move fallbacks to lib.rs

* Clean up

* Fix wasm build

WASM.md

@@ -24,7 +24,7 @@ web-sys, and will instead return these mock values:
  - `devicename()`: "Unknown"
  - `hostname()`: "localhost"
  - `platform()`: "Unknown"
- - `distro()`: "Unknown Unknown"
+ - `distro()`: "Emulated"
  - `desktop_env()`: "Unknown WebAssembly"
  - `arch()`: "wasm32"
 

src/fake.rs

@@ -5,56 +5,56 @@ compile_error!("Unexpected pointer width for target platform");
 
 use std::ffi::OsString;
 
-use crate::{Arch, DesktopEnv, Platform};
+use crate::{Arch, DesktopEnv, Platform, Result};
 
 #[inline(always)]
 pub(crate) fn lang() -> impl Iterator<Item = String> {
     std::iter::once("en-US".to_string())
 }
 
 #[inline(always)]
-pub(crate) fn username_os() -> OsString {
-    username().into()
+pub(crate) fn username_os() -> Result<OsString> {
+    Ok(username()?.into())
 }
 
 #[inline(always)]
-pub(crate) fn realname_os() -> OsString {
-    realname().into()
+pub(crate) fn realname_os() -> Result<OsString> {
+    Ok(realname()?.into())
 }
 
 #[inline(always)]
-pub(crate) fn devicename_os() -> OsString {
-    devicename().into()
+pub(crate) fn devicename_os() -> Result<OsString> {
+    Ok(devicename()?.into())
 }
 
 #[inline(always)]
-pub(crate) fn distro_os() -> Option<OsString> {
-    distro().map(|a| a.into())
+pub(crate) fn distro_os() -> Result<OsString> {
+    Ok(distro()?.into())
 }
 
 #[inline(always)]
-pub(crate) fn username() -> String {
-    "anonymous".to_string()
+pub(crate) fn username() -> Result<String> {
+    Ok("anonymous".to_string())
 }
 
 #[inline(always)]
-pub(crate) fn realname() -> String {
-    "Anonymous".to_string()
+pub(crate) fn realname() -> Result<String> {
+    Ok("Anonymous".to_string())
 }
 
 #[inline(always)]
-pub(crate) fn devicename() -> String {
-    "Unknown".to_string()
+pub(crate) fn devicename() -> Result<String> {
+    Ok("Unknown".to_string())
 }
 
 #[inline(always)]
-pub(crate) fn hostname() -> String {
-    "localhost".to_string()
+pub(crate) fn hostname() -> Result<String> {
+    Ok("localhost".to_string())
 }
 
 #[inline(always)]
-pub(crate) fn distro() -> Option<String> {
-    None
+pub(crate) fn distro() -> Result<String> {
+    Ok("Emulated".to_string())
 }
 
 #[inline(always)]

src/fallible.rs

@@ -0,0 +1,97 @@
+//! Fallible versions of the whoami APIs.
+//!
+//! Some of the functions in the root module will return "Unknown" or
+//! "localhost" on error.  This might not be desirable in some situations.  The
+//! functions in this module all return a [`Result`].
+
+use std::ffi::OsString;
+
+use crate::{platform, Result};
+
+/// Get the user's username.
+///
+/// On unix-systems this differs from [`realname()`] most notably in that spaces
+/// are not allowed in the username.
+#[inline(always)]
+pub fn username() -> Result<String> {
+    platform::username()
+}
+
+/// Get the user's username.
+///
+/// On unix-systems this differs from [`realname_os()`] most notably in that
+/// spaces are not allowed in the username.
+#[inline(always)]
+pub fn username_os() -> Result<OsString> {
+    platform::username_os()
+}
+
+/// Get the user's real (full) name.
+#[inline(always)]
+pub fn realname() -> Result<String> {
+    platform::realname()
+}
+
+/// Get the user's real (full) name.
+#[inline(always)]
+pub fn realname_os() -> Result<OsString> {
+    platform::realname_os()
+}
+
+/// Get the name of the operating system distribution and (possibly) version.
+///
+/// Example: "Windows 10" or "Fedora 26 (Workstation Edition)"
+#[inline(always)]
+pub fn distro() -> Result<String> {
+    platform::distro()
+}
+
+/// Get the name of the operating system distribution and (possibly) version.
+///
+/// Example: "Windows 10" or "Fedora 26 (Workstation Edition)"
+#[inline(always)]
+pub fn distro_os() -> Result<OsString> {
+    platform::distro_os()
+}
+
+/// Get the device name (also known as "Pretty Name").
+///
+/// Often used to identify device for bluetooth pairing.
+#[inline(always)]
+pub fn devicename() -> Result<String> {
+    platform::devicename()
+}
+
+/// Get the device name (also known as "Pretty Name").
+///
+/// Often used to identify device for bluetooth pairing.
+#[inline(always)]
+pub fn devicename_os() -> Result<OsString> {
+    platform::devicename_os()
+}
+
+/// Get the host device's hostname.
+///
+/// Limited to a-z (case insensitve), 0-9, and dashes.  This limit also applies
+/// to `devicename()` when targeting Windows.  Since the hostname is
+/// case-insensitive, this method normalizes to lowercase (unlike
+/// [`devicename()`]).
+#[inline(always)]
+pub fn hostname() -> Result<String> {
+    let mut hostname = platform::hostname()?;
+
+    hostname.make_ascii_lowercase();
+
+    Ok(hostname)
+}
+
+/// Get the host device's hostname.
+///
+/// Limited to a-z (case insensitve), 0-9, and dashes.  This limit also applies
+/// to `devicename()` when targeting Windows.  Since the hostname is
+/// case-insensitive, this method normalizes to lowercase (unlike
+/// [`devicename()`]).
+#[inline(always)]
+pub fn hostname_os() -> Result<OsString> {
+    Ok(hostname()?.into())
+}