From patchwork Fri Apr 15 15:29:29 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Serge Hallyn X-Patchwork-Id: 11761 Received: (qmail 56103 invoked by alias); 15 Apr 2016 15:29:47 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 56083 invoked by uid 89); 15 Apr 2016 15:29:46 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-0.9 required=5.0 tests=BAYES_00, KAM_LAZY_DOMAIN_SECURITY autolearn=no version=3.3.2 spammy= X-HELO: youngberry.canonical.com Date: Fri, 15 Apr 2016 15:29:29 +0000 From: Serge Hallyn To: libc-alpha@sourceware.org Cc: Serge Hallyn Subject: [PATCH 1/1] linux ttyname: return link if appropriate Message-ID: <20160415152929.GA7932@ubuntumail> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) The current ttyname does the wrong thing in two cases: 1. If the passed-in link (say /proc/self/fd/0) points to a device, say /dev/pts/2, in a parent mount namespace, and a /dev/pts/2 exists (in a different devpts) in the current namespace, then it returns /dev/pts/2. But /dev/pts/2 is NOT the current tty, it is a different file and device. 2. If the passed-in link (say /proc/self/fd/0) points to a device, say /dev/pts/2, in a parent mount namespace, and /dev/pts/2 does not exist in the current namespace, it returns success but an empty name. As far as I can tell, there is no reason for it to not return /proc/self/fd/0. http://pubs.opengroup.org/onlinepubs/009695399/functions/ttyname.html does not say anything about not returning a link. Signed-off-by: Serge Hallyn --- sysdeps/unix/sysv/linux/ttyname.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/sysdeps/unix/sysv/linux/ttyname.c b/sysdeps/unix/sysv/linux/ttyname.c index 7a001b4..b0500a9 100644 --- a/sysdeps/unix/sysv/linux/ttyname.c +++ b/sysdeps/unix/sysv/linux/ttyname.c @@ -170,12 +170,21 @@ ttyname (int fd) #ifdef _STATBUF_ST_RDEV && S_ISCHR (st1.st_mode) && st1.st_rdev == st.st_rdev + && st1.st_dev == st.st_dev #else && st1.st_ino == st.st_ino && st1.st_dev == st.st_dev #endif ) return ttyname_buf; + /* If the link doesn't exist, then it points to a dvice in another + * namespace. We've already verified it's a tty. Just return the + * link itself. */ + if (strlen(procname) < buflen - 1) { + memcpy(ttyname_buf, procname, strlen(procname)); + ttyname_buf[strlen(procname)] = '\0'; + return ttyname_buf; + } } if (__xstat64 (_STAT_VER, "/dev/pts", &st1) == 0 && S_ISDIR (st1.st_mode))