From de004e3a5cbaf4ae586e493a2b6911f463ffe6e3 Mon Sep 17 00:00:00 2001 From: nobu Date: Sun, 20 Oct 2013 06:41:24 +0000 Subject: [PATCH] io.c: make IO#reopen("pathname") atomic * io.c (rb_io_reopen): create a new, temporary FD via rb_sysopen and call rb_cloexec_dup2 on it to atomically replace the file fptr->fd points to. This leaves no possible window where fptr->fd is invalid to userspace (even for any threads running w/o GVL). based on the patch by Eric Wong at [ruby-core:57943]. [Bug #9036] git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43373 b2dd03c8-39d4-4d8f-98ff-823fe69b080e --- ChangeLog | 9 +++++++++ io.c | 12 ++++++++---- 2 files changed, 17 insertions(+), 4 deletions(-) diff --git a/ChangeLog b/ChangeLog index 168c89f85f..4f45a6e0ca 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,12 @@ +Sun Oct 20 15:41:22 2013 Nobuyoshi Nakada + + * io.c (rb_io_reopen): create a new, temporary FD via rb_sysopen and + call rb_cloexec_dup2 on it to atomically replace the file fptr->fd + points to. This leaves no possible window where fptr->fd is invalid + to userspace (even for any threads running w/o GVL). based on the + patch by Eric Wong at [ruby-core:57943]. + [Bug #9036] + Sun Oct 20 15:29:05 2013 Nobuyoshi Nakada * error.c (rb_syserr_fail_path_in): new function split from diff --git a/io.c b/io.c index 47b86ed240..9ad7bff972 100644 --- a/io.c +++ b/io.c @@ -6665,10 +6665,14 @@ rb_io_reopen(int argc, VALUE *argv, VALUE file) } } else { - if (close(fptr->fd) < 0) - rb_sys_fail_path(fptr->pathv); - fptr->fd = -1; - fptr->fd = rb_sysopen(fptr->pathv, oflags, 0666); + int tmpfd = rb_sysopen(fptr->pathv, oflags, 0666); + int err = 0; + if (rb_cloexec_dup2(tmpfd, fptr->fd) < 0) + err = errno; + (void)close(tmpfd); + if (err) { + rb_syserr_fail_path(err, fptr->pathv); + } } return file;