hare

commit 652f7aa04033bb6091378168fb45ce6970f72473
parent 64f03254705d37d95ccde4040c9d5b07716b3bd4
Author: Drew DeVault <sir@cmpwn.com>
Date:   Tue,  2 Feb 2021 16:14:37 -0500

io::copy: use io::unsupported to force fallback

Diffstat:
M
io/copy.ha
 | 
8
+++++++-
M
io/types.ha
 | 
6
++++--
M
os/+linux/fdstream.ha
 | 
14
+++++---------

3 files changed, 16 insertions(+), 12 deletions(-)
diff --git a/io/copy.ha b/io/copy.ha
@@ -3,7 +3,13 @@
 export fn copy(dest: *stream, src: *stream) (error | size) = {
 	match (dest.copier) {
 		null       => void,
-		c: *copier => return c(dest, src),
+		c: *copier => match (c(dest, src)) {
+			err: error => match (err) {
+				unsupported => void, // Use fallback
+				* => return err,
+			},
+			s: size    => return s,
+		},
 	};
 
 	let w = 0z;
diff --git a/io/types.ha b/io/types.ha
@@ -53,6 +53,8 @@ export type closer = fn(s: *stream) void;
 // with a stream which does not implement this (it falls back to calling read
 // and write in a loop).
 //
-// Returns the number of bytes copied, or an error if one occured. Does not
-// close either stream.
+// Returns the number of bytes copied, or an error if one occured. Do not close
+// either stream. If the operation is unsupported for this particular pair of
+// streams, return [io::unsupported] to have [io::copy] proceed with its
+// fallback implementation.
 export type copier = fn(to: *stream, from: *stream) (size | error);
diff --git a/os/+linux/fdstream.ha b/os/+linux/fdstream.ha
@@ -91,7 +91,7 @@ def SENDFILE_MAX: size = 2147479552z;
 
 fn fd_copy(_to: *io::stream, _from: *io::stream) (size | io::error) = {
 	if (!is_fdstream(_from)) {
-		return copy_fallback(_to, _from);
+		return io::unsupported;
 	};
 
 	let to = _to: *fd_stream, from = _from: *fd_stream;
@@ -102,8 +102,10 @@ fn fd_copy(_to: *io::stream, _from: *io::stream) (size | io::error) = {
 		let n = match(rt::wrap_return(r)) {
 			err: rt::errno => switch (err) {
 				rt::EINVAL => {
-					assert(sum == 0z);
-					return copy_fallback(_to, _from);
+					if (sum == 0z) {
+						return io::unsupported;
+					};
+					return errno_to_io(err);
 				},
 				* => return errno_to_io(err),
 			},
@@ -119,9 +121,3 @@ fn fd_copy(_to: *io::stream, _from: *io::stream) (size | io::error) = {
 	};
 	return sum;
 };
-
-fn copy_fallback(_to: *io::stream, _from: *io::stream) (size | io::error) = {
-	let to = _to: *fd_stream, temp = *to;
-	temp.stream.copier = null;
-	return io::copy(&temp.stream, _from);
-};