From 3f6b66c14467c0f8c7459e32c576618155ca89f3 Mon Sep 17 00:00:00 2001
From: Tony Cook <tony@develop-help.com>
Date: Thu, 16 Jun 2016 14:08:18 +1000
Subject: [PATCH] (perl #128316) preserve errno from failed system calls
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Signed-off-by: Petr Písař <ppisar@redhat.com>
---
 pp_sys.c      |  4 ++--
 t/io/socket.t | 22 ++++++++++++++++++++++
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/pp_sys.c b/pp_sys.c
index 33cba46..3bf2673 100644
--- a/pp_sys.c
+++ b/pp_sys.c
@@ -2497,7 +2497,6 @@ PP(pp_socket)
     TAINT_PROPER("socket");
     fd = PerlSock_socket(domain, type, protocol);
     if (fd < 0) {
-        SETERRNO(EBADF,RMS_IFI);
 	RETPUSHUNDEF;
     }
     IoIFP(io) = PerlIO_fdopen(fd, "r"SOCKET_OPEN_MODE);	/* stdio gets confused about sockets */
@@ -3531,8 +3530,9 @@ PP(pp_fttext)
         }
 	PL_laststatval = PerlLIO_fstat(fd, &PL_statcache);
 	if (PL_laststatval < 0)	{
+            dSAVE_ERRNO;
 	    (void)PerlIO_close(fp);
-            SETERRNO(EBADF,RMS_IFI);
+            RESTORE_ERRNO;
 	    FT_RETURNUNDEF;
 	}
 	PerlIO_binmode(aTHX_ fp, '<', O_BINARY, NULL);
diff --git a/t/io/socket.t b/t/io/socket.t
index b51079a..54e4438 100644
--- a/t/io/socket.t
+++ b/t/io/socket.t
@@ -128,6 +128,28 @@ SKIP: {
     }
 }
 
+SKIP:
+{
+    eval { require Errno; defined &Errno::EMFILE }
+      or skip "Can't load Errno or EMFILE not defined", 1;
+    my @socks;
+    my $sock_limit = 1000; # don't consume every file in the system
+    # Default limits on various systems I have:
+    #  65536 - Linux
+    #    256 - Solaris
+    #    128 - NetBSD
+    #    256 - Cygwin
+    #    256 - darwin
+    while (@socks < $sock_limit) {
+        socket my $work, PF_INET, SOCK_STREAM, $tcp
+          or last;
+        push @socks, $work;
+    }
+    @socks == $sock_limit
+      and skip "Didn't run out of open handles", 1;
+    is(0+$!, Errno::EMFILE(), "check correct errno for too many files");
+}
+
 done_testing();
 
 my @child_tests;
-- 
2.5.5