Thread-protection for dup/fclose/dup2 scheme of stdio leak

avoidance.

p4raw-id: //depot/perlio@18507

1 files changed, 10 insertions, 1 deletions

diff --git a/perlio.c b/perlio.c
index de6950b4bc..2d5785baa9 100644
--- a/perlio.c
+++ b/perlio.c
@@ -2708,6 +2708,13 @@ PerlIOStdio_close(pTHX_ PerlIO *f)
 	    }
 	    else {
             	/* Tricky - must fclose(stdio) to free memory but not close(fd) */ 
+#ifdef USE_THREADS
+    	    	/* Sarathy pointed out that another thread could reuse
+		   fd after fclose() but before we dup2() below
+		   so take out a MUTEX to shut them out 
+		 */  
+    	    	MUTEX_LOCK(&PerlIO_mutex);
+#endif
 	    	dupfd = PerlLIO_dup(fd);
 	    }
 	}    
@@ -2725,12 +2732,14 @@ PerlIOStdio_close(pTHX_ PerlIO *f)
 	    /* We need to restore fd from the saved copy */
 	    if (PerlLIO_dup2(dupfd,fd) != fd)
 	      result = -1;
+#ifdef USE_THREADS
+    	    MUTEX_UNLOCK(&PerlIO_mutex);
+#endif
 	    if (PerlLIO_close(dupfd) != 0)
 	      result = -1; 
 	}
 	return result;
     } 
-
 }