Merge pull request #10 from nazar-pc/error-instead-of-panic

Error instead of panic

Cargo.toml

@@ -1,10 +1,12 @@
 [package]
 name = "fdlimit"
-version = "0.2.1"
+version = "0.3.0"
 authors = ["Parity Technologies<admin@parity.io>"]
+edition = "2021"
 license = "Apache-2.0"
 description = "Utility crate for raising file descriptors limit for OSX and Linux"
 repository = "https://github.com/paritytech/fdlimit"
 
 [dependencies]
 libc = "0.2"
+thiserror = "1.0.50"

src/lib.rs

@@ -12,25 +12,51 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-extern crate libc;
+/// Outcome of raising file descriptor resource limit
+pub enum Outcome {
+	/// Limit was raised successfully
+	LimitRaised {
+		/// Previous limit (likely soft limit)
+		from: u64,
+		/// New limit (likely hard limit)
+		to: u64,
+	},
+	/// Raising limit is not supported on this platform
+	Unsupported,
+}
+
+/// Errors that happen when trying to raise file descriptor resource limit
+#[derive(Debug, thiserror::Error)]
+pub enum Error {
+	/// Failed to call sysctl to get max supported value configured in sysctl
+	#[error("Failed to call sysctl to get max supported value configured in sysctl: {0}")]
+	#[cfg(any(target_os = "macos", target_os = "ios"))]
+	FailedToCallSysctl(std::io::Error),
+	/// Failed to get current limit
+	#[error("Failed to get current limit: {0}")]
+	FailedToGetLimit(std::io::Error),
+	/// Failed to set new limit
+	#[error("Failed to set new limit ({from}->{to}): {error}")]
+	FailedToSetLimit {
+		/// Current limit
+		from: u64,
+		/// New desired limit
+		to: u64,
+		/// Low level OS error
+		error: std::io::Error,
+	},
+}
 
 /// Raise the soft open file descriptor resource limit to the smaller of the
 /// kernel limit and the hard resource limit.
 ///
-/// Returns [`Some`] with the new limit.
-///
-/// # Panics
-///
-/// Panics if [`libc::sysctl`], [`libc::getrlimit`] or [`libc::setrlimit`]
-/// fail.
-///
 /// darwin_fd_limit exists to work around an issue where launchctl on Mac OS X
 /// defaults the rlimit maxfiles to 256/unlimited. The default soft limit of 256
 /// ends up being far too low for our multithreaded scheduler testing, depending
 /// on the number of cores available.
 #[cfg(any(target_os = "macos", target_os = "ios"))]
-#[allow(non_camel_case_types)]
-pub fn raise_fd_limit() -> Option<u64> {
+#[allow(clippy::useless_conversion, non_camel_case_types)]
+pub fn raise_fd_limit() -> Result<Outcome, Error> {
 	use std::cmp;
 	use std::io;
 	use std::mem::size_of_val;
@@ -48,69 +74,71 @@ pub fn raise_fd_limit() -> Option<u64> {
 		let mut mib: [libc::c_int; 2] = [CTL_KERN, KERN_MAXFILESPERPROC];
 		let mut maxfiles: libc::c_int = 0;
 		let mut size: libc::size_t = size_of_val(&maxfiles) as libc::size_t;
-		if libc::sysctl(&mut mib[0], 2, &mut maxfiles as *mut _ as *mut _, &mut size,
-				  null_mut(), 0) != 0 {
-			let err = io::Error::last_os_error();
-			panic!("raise_fd_limit: error calling sysctl: {}", err);
+		if libc::sysctl(&mut mib[0], 2, &mut maxfiles as *mut _ as *mut _, &mut size, null_mut(), 0)
+			!= 0
+		{
+			return Err(Error::FailedToCallSysctl(io::Error::last_os_error()));
 		}
 
 		// Fetch the current resource limits
-		let mut rlim = libc::rlimit{rlim_cur: 0, rlim_max: 0};
+		let mut rlim = libc::rlimit { rlim_cur: 0, rlim_max: 0 };
 		if libc::getrlimit(libc::RLIMIT_NOFILE, &mut rlim) != 0 {
-			let err = io::Error::last_os_error();
-			panic!("raise_fd_limit: error calling getrlimit: {}", err);
+			return Err(Error::FailedToGetLimit(io::Error::last_os_error()));
 		}
 
+		let old_value = rlim.rlim_cur;
+
 		// Bump the soft limit to the smaller of kern.maxfilesperproc and the hard
 		// limit
 		rlim.rlim_cur = cmp::min(maxfiles as libc::rlim_t, rlim.rlim_max);
 
 		// Set our newly-increased resource limit
 		if libc::setrlimit(libc::RLIMIT_NOFILE, &rlim) != 0 {
-			let err = io::Error::last_os_error();
-			panic!("raise_fd_limit: error calling setrlimit: {}", err);
+			return Err(Error::FailedToSetLimit {
+				from: old_value.into(),
+				to: rlim.rlim_cur.into(),
+				error: io::Error::last_os_error(),
+			});
 		}
 
-		Some(rlim.rlim_cur)
+		Ok(Outcome::LimitRaised { from: old_value.into(), to: rlim.rlim_cur.into() })
 	}
 }
 
 /// Raise the soft open file descriptor resource limit to the hard resource
 /// limit.
-///
-/// Returns [`Some`] with the new limit.
-///
-/// # Panics
-///
-/// Panics if [`libc::getrlimit`] or [`libc::setrlimit`] fail.
-#[cfg(any(target_os = "linux"))]
-#[allow(non_camel_case_types)]
-pub fn raise_fd_limit() -> Option<u64> {
+#[cfg(target_os = "linux")]
+#[allow(clippy::useless_conversion, non_camel_case_types)]
+pub fn raise_fd_limit() -> Result<Outcome, Error> {
 	use std::io;
 
 	unsafe {
 		// Fetch the current resource limits
-		let mut rlim = libc::rlimit{rlim_cur: 0, rlim_max: 0};
+		let mut rlim = libc::rlimit { rlim_cur: 0, rlim_max: 0 };
 		if libc::getrlimit(libc::RLIMIT_NOFILE, &mut rlim) != 0 {
-			let err = io::Error::last_os_error();
-			panic!("raise_fd_limit: error calling getrlimit: {}", err);
+			return Err(Error::FailedToGetLimit(io::Error::last_os_error()));
 		}
 
+		let old_value = rlim.rlim_cur;
+
 		// Set soft limit to hard imit
 		rlim.rlim_cur = rlim.rlim_max;
 
 		// Set our newly-increased resource limit
 		if libc::setrlimit(libc::RLIMIT_NOFILE, &rlim) != 0 {
-			let err = io::Error::last_os_error();
-			panic!("raise_fd_limit: error calling setrlimit: {}", err);
+			return Err(Error::FailedToSetLimit {
+				from: old_value.into(),
+				to: rlim.rlim_cur.into(),
+				error: io::Error::last_os_error(),
+			});
 		}
 
-		Some(rlim.rlim_cur.into())
+		Ok(Outcome::LimitRaised { from: old_value.into(), to: rlim.rlim_cur.into() })
 	}
 }
 
-/// Returns [`None`].
+/// Does nothing on unsupported platform
 #[cfg(not(any(target_os = "macos", target_os = "ios", target_os = "linux")))]
-pub fn raise_fd_limit() -> Option<u64> {
-	None
+pub fn raise_fd_limit() -> Result<Outcome, Error> {
+	Ok(Outcome::Unsupported)
 }