fix: make sure io::Error is always converted to an errno

src/format/io.rs

@@ -1,5 +1,5 @@
-use std::{slice, convert::TryInto, io::{Read, Write, Seek, SeekFrom}, ptr};
-use libc::{c_void, c_int, SEEK_CUR, SEEK_END, SEEK_SET};
+use std::{slice, convert::TryInto, io::{self, Read, Write, Seek, SeekFrom}, ptr};
+use libc::{c_void, c_int, SEEK_CUR, SEEK_END, SEEK_SET, EINVAL};
 use crate::{ffi::*, format::context, Error};
 
 pub enum Proxy {
@@ -57,6 +57,15 @@ impl Io {
 	}
 }
 
+fn as_error(err: io::Error) -> c_int {
+	if let Some(value) = err.raw_os_error() {
+		value.try_into().unwrap()
+	}
+	else {
+		EINVAL
+	}
+}
+
 unsafe extern "C" fn read_packet(opaque: *mut c_void, buf: *mut u8, size: c_int) -> c_int {
 	let mut proxy = Box::<Proxy>::from_raw(opaque.cast());
 	let buffer = slice::from_raw_parts_mut(buf, size.try_into().unwrap());
@@ -64,7 +73,7 @@ unsafe extern "C" fn read_packet(opaque: *mut c_void, buf: *mut u8, size: c_int)
 	let result = match proxy.as_read().read(buffer) {
 		Ok(0) => AVERROR_EOF,
 		Ok(size) => size.try_into().unwrap(),
-		Err(err) => err.raw_os_error().unwrap().try_into().unwrap(),
+		Err(err) => as_error(err),
 	};
 
 	Box::into_raw(proxy);
@@ -74,11 +83,11 @@ unsafe extern "C" fn read_packet(opaque: *mut c_void, buf: *mut u8, size: c_int)
 unsafe extern "C" fn seek(opaque: *mut c_void, offset: i64, whence: c_int) -> i64 {
 	let mut proxy = Box::<Proxy>::from_raw(opaque.cast());
 
-	let result = if whence == AVSEEK_SIZE {
+	let result: i64 = if whence == AVSEEK_SIZE {
 		#[cfg(feature = "unstable")]
 		match proxy.as_seek().stream_len() {
 			Ok(size) => size,
-			Err(err) => err.raw_os_error().unwrap().try_into().unwrap(),
+			Err(err) => as_error(err),
 		}
 
 		#[cfg(not(feature = "unstable"))]
@@ -93,26 +102,26 @@ unsafe extern "C" fn seek(opaque: *mut c_void, offset: i64, whence: c_int) -> i6
 		};
 
 		match proxy.as_seek().seek(whence) {
-			Ok(size) => size,
-			Err(err) => err.raw_os_error().unwrap().try_into().unwrap(),
+			Ok(size) => size.try_into().unwrap(),
+			Err(err) => as_error(err).into(),
 		}
 	};
 
 	Box::into_raw(proxy);
-	result.try_into().unwrap()
+	result
 }
 
 unsafe extern "C" fn write_packet(opaque: *mut c_void, buf: *mut u8, size: c_int) -> c_int {
 	let mut proxy = Box::<Proxy>::from_raw(opaque.cast());
 	let buffer = slice::from_raw_parts(buf, size.try_into().unwrap());
 
-	let result = match proxy.as_write().write(buffer) {
-		Ok(size) => size,
-		Err(err) => err.raw_os_error().unwrap().try_into().unwrap(),
+	let result: c_int = match proxy.as_write().write(buffer) {
+		Ok(size) => size.try_into().unwrap(),
+		Err(err) => as_error(err),
 	};
 
 	Box::into_raw(proxy);
-	result.try_into().unwrap()
+	result
 }
 
 impl Io {