From: Jarkko Hietaniemi <jhi@iki.fi>
Date: Sun, 14 Jun 2009 16:53:22 +0000 (-0400)
Subject: The attached patch to perlio.c fixes the problem of errno getting set.
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=c6757210fa44035178e0a2501e1022995a42b70d;p=p5sagit%2Fp5-mst-13.2.git

The attached patch to perlio.c fixes the problem of errno getting set.

While I am firmly in the school of "do not look at $! except immediately
after a failure", I also agree that spuriously setting it is messy.  But
there is just no way of knowing where your errno might have been.

The problem was that PerlIO_fast_gets() (and other nearby similar
capability-checking PerlIO routines) set the errno (and it was being
called a lot, from sv_gets()).  I think setting the errno here was
a mistake: checking for "can has FOO" should not set external state,
such as the errno.  The patch removes that errno trashing from all those
routines.
---

diff --git a/perlio.c b/perlio.c
index 10a32c1..4fe4fa7 100644
--- a/perlio.c
+++ b/perlio.c
@@ -1773,10 +1773,7 @@ PerlIO_has_base(PerlIO *f)
 
 	  if (tab)
 	       return (tab->Get_base != NULL);
-	  SETERRNO(EINVAL, LIB_INVARG);
      }
-     else
-	  SETERRNO(EBADF, SS_IVCHAN);
 
      return 0;
 }
@@ -1790,11 +1787,8 @@ PerlIO_fast_gets(PerlIO *f)
 
 	     if (tab)
 		  return (tab->Set_ptrcnt != NULL);
-	     SETERRNO(EINVAL, LIB_INVARG);
 	 }
     }
-    else
-	 SETERRNO(EBADF, SS_IVCHAN);
 
     return 0;
 }
@@ -1807,10 +1801,7 @@ PerlIO_has_cntptr(PerlIO *f)
 
 	if (tab)
 	     return (tab->Get_ptr != NULL && tab->Get_cnt != NULL);
-	  SETERRNO(EINVAL, LIB_INVARG);
     }
-    else
-	 SETERRNO(EBADF, SS_IVCHAN);
 
     return 0;
 }
@@ -1823,10 +1814,7 @@ PerlIO_canset_cnt(PerlIO *f)
 
 	  if (tab)
 	       return (tab->Set_ptrcnt != NULL);
-	  SETERRNO(EINVAL, LIB_INVARG);
     }
-    else
-	 SETERRNO(EBADF, SS_IVCHAN);
 
     return 0;
 }