From: Tanaka Akira <akr@...>
Date: 2008-02-07T14:13:29+09:00
Subject: Re: reopen: can't change access mode from "w+" to "w"?

In article <20080206043831.7F10DE067F@mail.bc9.jp>,
  Nobuyoshi Nakada <nobu@ruby-lang.org> writes:

> Here, the mode of STDOUT was changed to "w+" by previos reopen,
> and this is trying to change the mode to "w" back, or "shrink"
> in other words.

This patch makes the first reopen doesn't change to "w+".

Index: io.c
===================================================================
--- io.c	(revision 15392)
+++ io.c	(working copy)
@@ -4132,7 +4132,13 @@ io_reopen(VALUE io, VALUE nfile)
     }
 
     /* copy rb_io_t structure */
-    fptr->mode = orig->mode | (fptr->mode & FMODE_PREP);
+    if (fptr->mode & FMODE_PREP) {
+        int mask = FMODE_PREP|FMODE_READWRITE;
+        fptr->mode = (orig->mode & ~mask)|(fptr->mode & mask);
+    }
+    else {
+        fptr->mode = orig->mode;
+    }
     fptr->pid = orig->pid;
     fptr->lineno = orig->lineno;
     if (fptr->path) free(fptr->path);
-- 
Tanaka Akira