From 2256b4671d48bcddff5145904d50c91fd91f00a2 Mon Sep 17 00:00:00 2001
From: Niko Tyni <ntyni@debian.org>
Date: Fri, 11 Feb 2022 21:55:29 +0200
Subject: [PATCH] syswrite test: unclog the pipe harder

Reading out 4 kB from a full pipe is not enough to unblock
it on all systems.

On Linux, the pipe size is by default 16 * page size, and
at least the Debian (and apparently Alpine too) ppc64le port
has a page size of 64 kB instead of the more usual 4 kB.

Bug: https://rt.cpan.org/Public/Bug/Display.html?id=140489
Forwarded: https://rt.cpan.org/Public/Bug/Display.html?id=140489
Bug-Debian: https://bugs.debian.org/1004146
Last-Update: 2025-09-15

--- a/lib/Test/Future/IO/Impl.pm
+++ b/lib/Test/Future/IO/Impl.pm
@@ -332,8 +332,11 @@ sub run_send_test
          or die "Cannot socketpair() - $!";
       $wr->blocking( 0 );
 
+      my $i = 0;
       # Attempt to fill the buffer
-      $wr->write( "X" x 4096 ) for 1..256;
+      $i++ while $wr->write( "X" x 4096 );
+      $! == Errno::EAGAIN or $! == Errno::EWOULDBLOCK or
+        die "Expected EAGAIN, got $!";
 
       my $f = Future::IO->send( $wr, "more" );
 
@@ -342,7 +345,7 @@ sub run_send_test
       # Now make some space. We need to drain it quite a lot for mechanisms
       # like ppoll() to be happy that the socket is actually writable
       $rd->blocking( 0 );
-      $rd->read( my $buf, 4096 ) for 1..256;
+      $rd->read( my $buf, 4096 ) while !$f->is_ready and $i-- > 0;
 
       is( scalar $f->get, 4, 'Future::IO->send yields written count' );
    }
@@ -505,15 +508,18 @@ sub _run_write_test
       pipe my ( $rd, $wr ) or die "Cannot pipe() - $!";
       $wr->blocking( 0 );
 
+      my $i = 0;
       # Attempt to fill the pipe
-      $wr->$method( "X" x 4096 ) for 1..256;
+      $i++ while $wr->$method( "X" x 4096 );
+      $! == Errno::EAGAIN or $! == Errno::EWOULDBLOCK or
+        die "Expected EAGAIN, got $!";
 
       my $f = Future::IO->$method( $wr, "more" );
 
       ok( !$f->is_ready, '$f is still pending' );
 
       # Now make some space
-      $rd->read( my $buf, 4096 );
+      $rd->read( my $buf, 4096 ) while !$f->is_ready and $i-- > 0;
 
       is( scalar $f->get, 4, "Future::IO->$method yields written count" );
    }