Using Mutexes and ServiceHandler

ctru-rs/src/error.rs

@@ -9,7 +9,7 @@ pub type Result<T> = ::std::result::Result<T, Error>;
 #[non_exhaustive]
 pub enum Error {
     Os(ctru_sys::Result),
-    ServiceAlreadyActive(&'static str),
+    ServiceAlreadyActive,
 }
 
 impl From<ctru_sys::Result> for Error {
@@ -29,10 +29,7 @@ impl fmt::Debug for Error {
                 .field("summary", &R_SUMMARY(err))
                 .field("level", &R_LEVEL(err))
                 .finish(),
-            Error::ServiceAlreadyActive(service) => f
-                .debug_tuple("ServiceAlreadyActive")
-                .field(&String::from(service))
-                .finish(),
+            Error::ServiceAlreadyActive => f.debug_tuple("ServiceAlreadyActive").finish(),
         }
     }
 }
@@ -44,7 +41,7 @@ impl fmt::Display for Error {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match *self {
             Error::Os(err) => write!(f, "libctru result code: 0x{:08X}", err),
-            Error::ServiceAlreadyActive(service) => write!(f, "Service {service} already active"),
+            Error::ServiceAlreadyActive => write!(f, "Service already active"),
         }
     }
 }

ctru-rs/src/gfx.rs

@@ -1,12 +1,13 @@
 //! LCD screens manipulation helper
 
 use std::cell::RefCell;
+use std::lazy::SyncLazy;
 use std::marker::PhantomData;
-use std::ops::Drop;
-use std::sync::atomic::{AtomicBool, Ordering};
+use std::sync::Mutex;
 
 use crate::error::{Error, Result};
 use crate::services::gspgpu::{self, FramebufferFormat};
+use crate::services::ServiceHandler;
 
 /// Trait implemented by TopScreen and BottomScreen for common methods
 pub trait Screen {
@@ -72,9 +73,10 @@ pub enum Side {
 pub struct Gfx {
     pub top_screen: RefCell<TopScreen>,
     pub bottom_screen: RefCell<BottomScreen>,
+    _service_handler: ServiceHandler,
 }
 
-static GFX_ACTIVE: AtomicBool = AtomicBool::new(false);
+static GFX_ACTIVE: SyncLazy<Mutex<usize>> = SyncLazy::new(|| Mutex::new(0));
 
 impl Gfx {
     /// Initialize the Gfx module with the chosen framebuffer formats for the top and bottom
@@ -86,20 +88,23 @@ impl Gfx {
         bottom_fb_fmt: FramebufferFormat,
         use_vram_buffers: bool,
     ) -> Result<Self> {
-        match GFX_ACTIVE.compare_exchange(false, true, Ordering::SeqCst, Ordering::SeqCst) {
-            Ok(_) => {
-                unsafe {
+        let _service_handler = ServiceHandler::new(
+            &GFX_ACTIVE,
+            false,
+            || unsafe {
                 ctru_sys::gfxInit(top_fb_fmt.into(), bottom_fb_fmt.into(), use_vram_buffers);
-                }
 
-                Ok(Gfx {
+                Ok(())
+            },
+            || unsafe { ctru_sys::gfxExit() },
+        )?;
+
+        Ok(Self {
             top_screen: RefCell::new(TopScreen),
             bottom_screen: RefCell::new(BottomScreen),
+            _service_handler,
         })
     }
-            Err(_) => Err(Error::ServiceAlreadyActive("Gfx")),
-        }
-    }
 
     /// Creates a new Gfx instance with default init values
     /// It's the same as calling: `Gfx::with_formats(FramebufferFormat::Bgr8, FramebufferFormat::Bgr8, false)
@@ -212,14 +217,6 @@ impl From<Side> for ctru_sys::gfx3dSide_t {
     }
 }
 
-impl Drop for Gfx {
-    fn drop(&mut self) {
-        unsafe { ctru_sys::gfxExit() };
-
-        GFX_ACTIVE.store(false, Ordering::SeqCst);
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -227,9 +224,6 @@ mod tests {
     #[test]
     fn gfx_duplicate() {
         // We don't need to build a `Gfx` because the test runner has one already
-        match Gfx::init() {
-            Err(Error::ServiceAlreadyActive("Gfx")) => return,
-            _ => panic!(),
-        }
+        assert!(matches!(Gfx::init(), Err(Error::ServiceAlreadyActive)))
     }
 }

ctru-rs/src/lib.rs

@@ -3,6 +3,7 @@
 #![feature(test)]
 #![feature(custom_test_frameworks)]
 #![test_runner(test_runner::run)]
+#![feature(once_cell)]
 
 extern "C" fn services_deinit() {
     unsafe {
@@ -28,6 +29,7 @@ pub fn init() {
 
     use std::panic::PanicInfo;
 
+    #[cfg(not(test))]
     let main_thread = thread::current().id();
 
     // Panic Hook setup
@@ -36,6 +38,7 @@ pub fn init() {
         default_hook(info);
 
         // Only for panics in the main thread
+        #[cfg(not(test))]
         if main_thread == thread::current().id() && console::Console::exists() {
             println!("\nPress SELECT to exit the software");
 

ctru-rs/src/romfs.rs

@@ -11,39 +11,39 @@
 //! ```
 
 use std::ffi::CStr;
-use std::sync::atomic::{AtomicBool, Ordering};
+use std::lazy::SyncLazy;
+use std::sync::Mutex;
 
-use crate::error::Error;
+use crate::services::ServiceHandler;
 
 #[non_exhaustive]
-pub struct RomFS;
+pub struct RomFS {
+    _service_handler: ServiceHandler,
+}
 
-static ROMFS_ACTIVE: AtomicBool = AtomicBool::new(false);
+static ROMFS_ACTIVE: SyncLazy<Mutex<usize>> = SyncLazy::new(|| Mutex::new(0));
 
 impl RomFS {
     pub fn init() -> crate::Result<Self> {
-        match ROMFS_ACTIVE.compare_exchange(false, true, Ordering::SeqCst, Ordering::SeqCst) {
-            Ok(_) => {
+        let _service_handler = ServiceHandler::new(
+            &ROMFS_ACTIVE,
+            true,
+            || {
                 let mount_name = CStr::from_bytes_with_nul(b"romfs\0").unwrap();
-                let result = unsafe { ctru_sys::romfsMountSelf(mount_name.as_ptr()) };
-
-                if result < 0 {
-                    Err(result.into())
-                } else {
-                    Ok(Self)
-                }
-            }
-            Err(_) => Err(Error::ServiceAlreadyActive("RomFS")),
-        }
+                let r = unsafe { ctru_sys::romfsMountSelf(mount_name.as_ptr()) };
+                if r < 0 {
+                    return Err(r.into());
                 }
-}
 
-impl Drop for RomFS {
-    fn drop(&mut self) {
+                Ok(())
+            },
+            || {
                 let mount_name = CStr::from_bytes_with_nul(b"romfs\0").unwrap();
                 unsafe { ctru_sys::romfsUnmount(mount_name.as_ptr()) };
+            },
+        )?;
 
-        ROMFS_ACTIVE.store(false, Ordering::SeqCst);
+        Ok(Self { _service_handler })
     }
 }
 
@@ -54,10 +54,14 @@ mod tests {
     #[test]
     fn romfs_duplicate() {
         let _romfs = RomFS::init().unwrap();
+        let lock = *ROMFS_ACTIVE.lock().unwrap();
 
-        match RomFS::init() {
-            Err(Error::ServiceAlreadyActive("RomFS")) => return,
-            _ => panic!(),
-        }
+        assert_eq!(lock, 1);
+
+        drop(_romfs);
+
+        let lock = *ROMFS_ACTIVE.lock().unwrap();
+
+        assert_eq!(lock, 0);
     }
 }

ctru-rs/src/services/apt.rs

@@ -1,25 +1,38 @@
-use std::sync::atomic::{AtomicBool, Ordering};
+use std::lazy::SyncLazy;
+use std::sync::Mutex;
 
-use crate::error::Error;
+use crate::services::ServiceHandler;
 
 #[non_exhaustive]
-pub struct Apt(());
+pub struct Apt {
+    _service_handler: ServiceHandler,
+}
 
-static APT_ACTIVE: AtomicBool = AtomicBool::new(false);
+static APT_ACTIVE: SyncLazy<Mutex<usize>> = SyncLazy::new(|| Mutex::new(0));
 
 impl Apt {
     pub fn init() -> crate::Result<Self> {
-        match APT_ACTIVE.compare_exchange(false, true, Ordering::SeqCst, Ordering::SeqCst) {
-            Ok(_) => {
+        let _service_handler = ServiceHandler::new(
+            &APT_ACTIVE,
+            true,
+            || {
                 let r = unsafe { ctru_sys::aptInit() };
                 if r < 0 {
-                    Err(r.into())
-                } else {
-                    Ok(Self(()))
-                }
-            }
-            Err(_) => Err(Error::ServiceAlreadyActive("Apt")),
+                    return Err(r.into());
                 }
+
+                Ok(())
+            },
+            // `socExit` returns an error code. There is no documentantion of when errors could happen,
+            // but we wouldn't be able to handle them in the `Drop` implementation anyways.
+            // Surely nothing bad will happens :D
+            || unsafe {
+                // The socket buffer is freed automatically by `socExit`
+                ctru_sys::aptExit();
+            },
+        )?;
+
+        Ok(Self { _service_handler })
     }
 
     pub fn main_loop(&self) -> bool {
@@ -36,14 +49,6 @@ impl Apt {
     }
 }
 
-impl Drop for Apt {
-    fn drop(&mut self) {
-        unsafe { ctru_sys::aptExit() };
-
-        APT_ACTIVE.store(false, Ordering::SeqCst);
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -51,9 +56,8 @@ mod tests {
     #[test]
     fn apt_duplicate() {
         // We don't need to build a `Apt` because the test runner has one already
-        match Apt::init() {
-            Err(Error::ServiceAlreadyActive("Apt")) => return,
-            _ => panic!(),
-        }
+        let lock = *APT_ACTIVE.lock().unwrap();
+
+        assert_eq!(lock, 1);
     }
 }

ctru-rs/src/services/fs.rs

@@ -9,15 +9,16 @@ use std::io::Error as IoError;
 use std::io::ErrorKind as IoErrorKind;
 use std::io::Result as IoResult;
 use std::io::{Read, Seek, SeekFrom, Write};
+use std::lazy::SyncLazy;
 use std::mem;
 use std::path::{Path, PathBuf};
 use std::ptr;
 use std::slice;
-use std::sync::atomic::{AtomicBool, Ordering};
-use std::sync::Arc;
+use std::sync::{Arc, Mutex};
+
 use widestring::{WideCStr, WideCString};
 
-use crate::error::Error;
+use crate::services::ServiceHandler;
 
 bitflags! {
     #[derive(Default)]
@@ -86,9 +87,11 @@ pub enum ArchiveID {
 ///
 /// The service exits when all instances of this struct go out of scope.
 #[non_exhaustive]
-pub struct Fs(());
+pub struct Fs {
+    _service_handler: ServiceHandler,
+}
 
-static FS_ACTIVE: AtomicBool = AtomicBool::new(false);
+static FS_ACTIVE: SyncLazy<Mutex<usize>> = SyncLazy::new(|| Mutex::new(0));
 
 /// Handle to an open filesystem archive.
 ///
@@ -308,17 +311,27 @@ impl Fs {
     /// as many times as desired and the service will not exit until all
     /// instances of Fs drop out of scope.
     pub fn init() -> crate::Result<Self> {
-        match FS_ACTIVE.compare_exchange(false, true, Ordering::SeqCst, Ordering::SeqCst) {
-            Ok(_) => {
+        let _service_handler = ServiceHandler::new(
+            &FS_ACTIVE,
+            true,
+            || {
                 let r = unsafe { ctru_sys::fsInit() };
                 if r < 0 {
-                    Err(r.into())
-                } else {
-                    Ok(Self(()))
-                }
-            }
-            Err(_) => Err(Error::ServiceAlreadyActive("Fs")),
+                    return Err(r.into());
                 }
+
+                Ok(())
+            },
+            // `socExit` returns an error code. There is no documentantion of when errors could happen,
+            // but we wouldn't be able to handle them in the `Drop` implementation anyways.
+            // Surely nothing bad will happens :D
+            || unsafe {
+                // The socket buffer is freed automatically by `socExit`
+                ctru_sys::fsExit();
+            },
+        )?;
+
+        Ok(Self { _service_handler })
     }
 
     /// Returns a handle to the SDMC (memory card) Archive.
@@ -998,16 +1011,6 @@ impl Seek for File {
     }
 }
 
-impl Drop for Fs {
-    fn drop(&mut self) {
-        unsafe {
-            ctru_sys::fsExit();
-        }
-
-        FS_ACTIVE.store(false, Ordering::SeqCst);
-    }
-}
-
 impl Drop for Archive {
     fn drop(&mut self) {
         unsafe {
@@ -1083,9 +1086,14 @@ mod tests {
     fn fs_duplicate() {
         let _fs = Fs::init().unwrap();
 
-        match Fs::init() {
-            Err(Error::ServiceAlreadyActive("Fs")) => return,
-            _ => panic!(),
-        }
+        let lock = *FS_ACTIVE.lock().unwrap();
+
+        assert_eq!(lock, 1);
+
+        drop(_fs);
+
+        let lock = *FS_ACTIVE.lock().unwrap();
+
+        assert_eq!(lock, 0);
     }
 }

ctru-rs/src/services/hid.rs

@@ -4,9 +4,10 @@
 //! and circle pad information. It also provides information from the sound volume slider,
 //! the accelerometer, and the gyroscope.
 
-use std::sync::atomic::{AtomicBool, Ordering};
+use std::lazy::SyncLazy;
+use std::sync::Mutex;
 
-use crate::error::Error;
+use crate::services::ServiceHandler;
 
 bitflags::bitflags! {
     /// A set of flags corresponding to the button and directional pad
@@ -49,9 +50,11 @@ bitflags::bitflags! {
 ///
 /// This service requires no special permissions to use.
 #[non_exhaustive]
-pub struct Hid(());
+pub struct Hid {
+    _service_handler: ServiceHandler,
+}
 
-static HID_ACTIVE: AtomicBool = AtomicBool::new(false);
+static HID_ACTIVE: SyncLazy<Mutex<usize>> = SyncLazy::new(|| Mutex::new(0));
 
 /// Represents user input to the touchscreen.
 #[non_exhaustive]
@@ -70,17 +73,23 @@ pub struct CirclePosition(ctru_sys::circlePosition);
 /// rare in practice.
 impl Hid {
     pub fn init() -> crate::Result<Self> {
-        match HID_ACTIVE.compare_exchange(false, true, Ordering::SeqCst, Ordering::SeqCst) {
-            Ok(_) => {
+        let _service_handler = ServiceHandler::new(
+            &HID_ACTIVE,
+            true,
+            || {
                 let r = unsafe { ctru_sys::hidInit() };
                 if r < 0 {
-                    Err(r.into())
-                } else {
-                    Ok(Self(()))
-                }
-            }
-            Err(_) => Err(Error::ServiceAlreadyActive("Hid")),
+                    return Err(r.into());
                 }
+
+                Ok(())
+            },
+            || unsafe {
+                ctru_sys::hidExit();
+            },
+        )?;
+
+        Ok(Self { _service_handler })
     }
 
     /// Scans the HID service for all user input occurring on the current
@@ -160,14 +169,6 @@ impl CirclePosition {
     }
 }
 
-impl Drop for Hid {
-    fn drop(&mut self) {
-        unsafe { ctru_sys::hidExit() };
-
-        HID_ACTIVE.store(false, Ordering::SeqCst);
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -175,9 +176,8 @@ mod tests {
     #[test]
     fn hid_duplicate() {
         // We don't need to build a `Hid` because the test runner has one already
-        match Hid::init() {
-            Err(Error::ServiceAlreadyActive("Hid")) => return,
-            _ => panic!(),
-        }
+        let lock = *HID_ACTIVE.lock().unwrap();
+
+        assert_eq!(lock, 1);
     }
 }

ctru-rs/src/services/mod.rs

@@ -9,3 +9,48 @@ pub mod sslc;
 pub use self::apt::Apt;
 pub use self::hid::Hid;
 pub use self::sslc::SslC;
+
+use crate::Error;
+use std::sync::Mutex;
+pub(crate) struct ServiceHandler {
+    counter: &'static Mutex<usize>,
+    close: Box<dyn Fn()>,
+}
+
+impl ServiceHandler {
+    pub fn new<S, E>(
+        counter: &'static Mutex<usize>,
+        allow_multiple: bool,
+        start: S,
+        close: E,
+    ) -> crate::Result<Self>
+    where
+        S: FnOnce() -> crate::Result<()>,
+        E: Fn() + 'static,
+    {
+        let mut value = counter.lock().unwrap(); // todo: handle poisoning
+
+        if *value == 0 {
+            start()?;
+        } else if !allow_multiple {
+            return Err(Error::ServiceAlreadyActive);
+        }
+
+        *value += 1;
+
+        Ok(Self {
+            counter,
+            close: Box::new(close),
+        })
+    }
+}
+
+impl Drop for ServiceHandler {
+    fn drop(&mut self) {
+        let mut value = self.counter.lock().unwrap(); // should probably handle poisoning - could just map_err to ignore it.
+        *value -= 1;
+        if *value == 0 {
+            (self.close)();
+        }
+    }
+}

ctru-rs/src/services/soc.rs

@@ -1,18 +1,18 @@
-use libc::{free, memalign};
+use libc::memalign;
+use std::lazy::SyncLazy;
 use std::net::Ipv4Addr;
-use std::sync::atomic::{AtomicBool, Ordering};
+use std::sync::Mutex;
 
-use crate::error::Error;
-use ctru_sys::{socExit, socInit};
+use crate::services::ServiceHandler;
 
 /// Soc service. Initializing this service will enable the use of network sockets and utilities
 /// such as those found in `std::net`. The service will be closed when this struct is is dropped.
 #[non_exhaustive]
 pub struct Soc {
-    soc_mem: *mut u32,
+    _service_handler: ServiceHandler,
 }
 
-static SOC_ACTIVE: AtomicBool = AtomicBool::new(false);
+static SOC_ACTIVE: SyncLazy<Mutex<usize>> = SyncLazy::new(|| Mutex::new(0));
 
 impl Soc {
     /// Initialize the Soc service with a default buffer size of 0x100000 bytes
@@ -31,20 +31,28 @@ impl Soc {
     ///
     /// This function will return an error if the `Soc` service is already initialized
     pub fn init_with_buffer_size(num_bytes: usize) -> crate::Result<Self> {
-        match SOC_ACTIVE.compare_exchange(false, true, Ordering::SeqCst, Ordering::SeqCst) {
-            Ok(_) => unsafe {
-                let soc_mem = memalign(0x1000, num_bytes) as *mut u32;
-
-                let r = socInit(soc_mem, num_bytes as u32);
+        let _service_handler = ServiceHandler::new(
+            &SOC_ACTIVE,
+            true,
+            || {
+                let soc_mem = unsafe { memalign(0x1000, num_bytes) } as *mut u32;
+                let r = unsafe { ctru_sys::socInit(soc_mem, num_bytes as u32) };
                 if r < 0 {
-                    free(soc_mem as *mut _);
-                    Err(r.into())
-                } else {
-                    Ok(Self { soc_mem })
+                    return Err(r.into());
                 }
+
+                Ok(())
             },
-            Err(_) => Err(Error::ServiceAlreadyActive("Soc")),
-        }
+            // `socExit` returns an error code. There is no documentantion of when errors could happen,
+            // but we wouldn't be able to handle them in the `Drop` implementation anyways.
+            // Surely nothing bad will happens :D
+            || unsafe {
+                // The socket buffer is freed automatically by `socExit`
+                ctru_sys::socExit();
+            },
+        )?;
+
+        Ok(Self { _service_handler })
     }
 
     /// IP Address of the Nintendo 3DS system.
@@ -54,17 +62,6 @@ impl Soc {
     }
 }
 
-impl Drop for Soc {
-    fn drop(&mut self) {
-        unsafe {
-            socExit();
-            free(self.soc_mem as *mut _);
-        }
-
-        SOC_ACTIVE.store(false, Ordering::SeqCst);
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -72,10 +69,14 @@ mod tests {
     #[test]
     fn soc_duplicate() {
         let _soc = Soc::init().unwrap();
+        let lock = *SOC_ACTIVE.lock().unwrap();
 
-        match Soc::init() {
-            Err(Error::ServiceAlreadyActive("Soc")) => return,
-            _ => panic!(),
-        }
+        assert_eq!(lock, 1);
+
+        drop(_soc);
+
+        let lock = *SOC_ACTIVE.lock().unwrap();
+
+        assert_eq!(lock, 0);
     }
 }

ctru-rs/src/services/sslc.rs

@@ -1,28 +1,41 @@
 // TODO: Implement remaining functions
 
-use std::sync::atomic::{AtomicBool, Ordering};
+use std::lazy::SyncLazy;
+use std::sync::Mutex;
 
-use crate::error::Error;
+use crate::services::ServiceHandler;
 
 #[non_exhaustive]
-pub struct SslC(());
+pub struct SslC {
+    _service_handler: ServiceHandler,
+}
 
-static SSLC_ACTIVE: AtomicBool = AtomicBool::new(false);
+static SSLC_ACTIVE: SyncLazy<Mutex<usize>> = SyncLazy::new(|| Mutex::new(0));
 
 impl SslC {
     /// Initialize sslc
     pub fn init() -> crate::Result<Self> {
-        match SSLC_ACTIVE.compare_exchange(false, true, Ordering::SeqCst, Ordering::SeqCst) {
-            Ok(_) => {
+        let _service_handler = ServiceHandler::new(
+            &SSLC_ACTIVE,
+            true,
+            || {
                 let r = unsafe { ctru_sys::sslcInit(0) };
                 if r < 0 {
-                    Err(r.into())
-                } else {
-                    Ok(Self(()))
-                }
-            }
-            Err(_) => Err(Error::ServiceAlreadyActive("SslC")),
+                    return Err(r.into());
                 }
+
+                Ok(())
+            },
+            // `socExit` returns an error code. There is no documentantion of when errors could happen,
+            // but we wouldn't be able to handle them in the `Drop` implementation anyways.
+            // Surely nothing bad will happens :D
+            || unsafe {
+                // The socket buffer is freed automatically by `socExit`
+                ctru_sys::sslcExit();
+            },
+        )?;
+
+        Ok(Self { _service_handler })
     }
 
     /// Fill `buf` with `buf.len()` random bytes
@@ -36,14 +49,6 @@ impl SslC {
     }
 }
 
-impl Drop for SslC {
-    fn drop(&mut self) {
-        unsafe { ctru_sys::sslcExit() };
-
-        SSLC_ACTIVE.store(false, Ordering::SeqCst);
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -52,9 +57,14 @@ mod tests {
     fn sslc_duplicate() {
         let _sslc = SslC::init().unwrap();
 
-        match SslC::init() {
-            Err(Error::ServiceAlreadyActive("SslC")) => return,
-            _ => panic!(),
-        }
+        let lock = *SSLC_ACTIVE.lock().unwrap();
+
+        assert_eq!(lock, 1);
+
+        drop(_sslc);
+
+        let lock = *SSLC_ACTIVE.lock().unwrap();
+
+        assert_eq!(lock, 0);
     }
 }

ctru-rs/src/srv.rs

@@ -1,33 +1,34 @@
-use std::sync::atomic::{AtomicBool, Ordering};
+use std::lazy::SyncLazy;
+use std::sync::Mutex;
 
-use crate::error::Error;
+use crate::services::ServiceHandler;
 
 #[non_exhaustive]
-pub struct Srv(());
+pub struct Srv {
+    _service_handler: ServiceHandler,
+}
 
-static SRV_ACTIVE: AtomicBool = AtomicBool::new(false);
+static SRV_ACTIVE: SyncLazy<Mutex<usize>> = SyncLazy::new(|| Mutex::new(0));
 
 impl Srv {
     pub fn init() -> crate::Result<Self> {
-        match SRV_ACTIVE.compare_exchange(false, true, Ordering::SeqCst, Ordering::SeqCst) {
-            Ok(_) => {
+        let _service_handler = ServiceHandler::new(
+            &SRV_ACTIVE,
+            true,
+            || {
                 let r = unsafe { ctru_sys::srvInit() };
                 if r < 0 {
-                    Err(r.into())
-                } else {
-                    Ok(Self(()))
-                }
-            }
-            Err(_) => Err(Error::ServiceAlreadyActive("Srv")),
+                    return Err(r.into());
                 }
-    }
-}
 
-impl Drop for Srv {
-    fn drop(&mut self) {
-        unsafe { ctru_sys::srvExit() };
+                Ok(())
+            },
+            || unsafe {
+                ctru_sys::srvExit();
+            },
+        )?;
 
-        SRV_ACTIVE.store(false, Ordering::SeqCst);
+        Ok(Self { _service_handler })
     }
 }
 
@@ -39,9 +40,14 @@ mod tests {
     fn srv_duplicate() {
         let _srv = Srv::init().unwrap();
 
-        match Srv::init() {
-            Err(Error::ServiceAlreadyActive("Srv")) => return,
-            _ => panic!(),
-        }
+        let lock = *SRV_ACTIVE.lock().unwrap();
+
+        assert_eq!(lock, 1);
+
+        drop(_srv);
+
+        let lock = *SRV_ACTIVE.lock().unwrap();
+
+        assert_eq!(lock, 0);
     }
 }