From patchwork Sat Aug 6 15:00:02 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Serge E. Hallyn" X-Patchwork-Id: 14370 Received: (qmail 28295 invoked by alias); 6 Aug 2016 15:00:18 -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 28266 invoked by uid 89); 6 Aug 2016 15:00:15 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.8 required=5.0 tests=AWL, BAYES_00, KAM_LAZY_DOMAIN_SECURITY, RP_MATCHES_RCVD autolearn=ham version=3.3.2 spammy=Hx-languages-length:4527, HTo:D*gentoo.org, H*Ad:D*gentoo.org X-HELO: h2.hallyn.com Date: Sat, 6 Aug 2016 10:00:02 -0500 From: "Serge E. Hallyn" To: "Serge E. Hallyn" , libc-alpha@sourceware.org, vapier@gentoo.org Subject: Re: [PATCH] linux ttyname and ttyname_r: return link if appropriate Message-ID: <20160806150002.GA24315@mail.hallyn.com> References: <20160415195938.GP6588@vapier.lan> <20160418195318.GB30476@ubuntumail> <20160418200222.GY5369@vapier.lan> <20160418202301.GA30919@ubuntumail> <20160420021012.GA19449@ubuntumail> <20160420022823.GT5369@vapier.lan> <20160420185141.GA31095@ubuntumail> <20160727165711.GA27815@altlinux.org> <20160806020855.GA19897@mail.hallyn.com> <20160806084559.GS6702@vapier.lan> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20160806084559.GS6702@vapier.lan> User-Agent: Mutt/1.5.21 (2010-09-15) Quoting Mike Frysinger (vapier@gentoo.org): > On 05 Aug 2016 21:08, Serge E. Hallyn wrote: > > #ifdef _STATBUF_ST_RDEV > > && S_ISCHR (st1.st_mode) > > && st1.st_rdev == st.st_rdev > > + && st1.st_dev == st.st_dev > > + && st1.st_ino == st.st_ino > > #else > > && st1.st_ino == st.st_ino > > && st1.st_dev == st.st_dev > > #endif > > wouldn't it be better to shuffle the ifdef then ? > #ifdef _STATBUF_ST_RDEV > && S_ISCHR (st1.st_mode) > && st1.st_rdev == st.st_rdev > #endif > && st1.st_ino == st.st_ino > && st1.st_dev == st.st_dev) That occurred to me when I looked at it again after sending, seems reasonable. Subject: [PATCH] linux ttyname and ttyname_r: return link if appropriate 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. --- sysdeps/unix/sysv/linux/ttyname.c | 25 ++++++++++++++++++++++--- sysdeps/unix/sysv/linux/ttyname_r.c | 26 ++++++++++++++++++++++++-- 2 files changed, 46 insertions(+), 5 deletions(-) diff --git a/sysdeps/unix/sysv/linux/ttyname.c b/sysdeps/unix/sysv/linux/ttyname.c index 7a001b4..3065ed4 100644 --- a/sysdeps/unix/sysv/linux/ttyname.c +++ b/sysdeps/unix/sysv/linux/ttyname.c @@ -25,6 +25,7 @@ #include #include #include +#include #include <_itoa.h> @@ -33,6 +34,19 @@ char *__ttyname; #endif +/* Return true if this is a UNIX98 pty device, as defined in + linux/Documentation/devices.txt. */ +static int +is_pty (struct stat64 *sb) +{ +#ifdef _STATBUF_ST_RDEV + int m = major (sb->st_rdev); + return (136 <= m && m <= 143); +#else + return false; +#endif +} + static char *getttyname (const char *dev, dev_t mydev, ino64_t myino, int save, int *dostat) internal_function; @@ -170,12 +184,17 @@ ttyname (int fd) #ifdef _STATBUF_ST_RDEV && S_ISCHR (st1.st_mode) && st1.st_rdev == st.st_rdev -#else - && st1.st_ino == st.st_ino - && st1.st_dev == st.st_dev #endif + && st1.st_dev == st.st_dev + && st1.st_ino == st.st_ino ) return ttyname_buf; + + /* If the link doesn't exist, then it points to a device in another + namespace. If it is a UNIX98 pty, then return the /proc/self + fd, as it points to a name unreachable in our namespace. */ + if (is_pty (&st) && strlen (procname) < buflen - 1) + return strcpy (ttyname_buf, procname); } if (__xstat64 (_STAT_VER, "/dev/pts", &st1) == 0 && S_ISDIR (st1.st_mode)) diff --git a/sysdeps/unix/sysv/linux/ttyname_r.c b/sysdeps/unix/sysv/linux/ttyname_r.c index d15bc74..97527c0 100644 --- a/sysdeps/unix/sysv/linux/ttyname_r.c +++ b/sysdeps/unix/sysv/linux/ttyname_r.c @@ -25,6 +25,7 @@ #include #include #include +#include #include <_itoa.h> @@ -32,6 +33,19 @@ static int getttyname_r (char *buf, size_t buflen, dev_t mydev, ino64_t myino, int save, int *dostat) internal_function; +/* Return true if this is a UNIX98 pty device, as defined in + linux/Documentation/devices.txt. */ +static int +is_pty (struct stat64 *sb) +{ +#ifdef _STATBUF_ST_RDEV + int m = major (sb->st_rdev); + return (136 <= m && m <= 143); +#else + return false; +#endif +} + static int internal_function attribute_compat_text_section getttyname_r (char *buf, size_t buflen, dev_t mydev, ino64_t myino, @@ -152,12 +166,20 @@ __ttyname_r (int fd, char *buf, size_t buflen) #ifdef _STATBUF_ST_RDEV && S_ISCHR (st1.st_mode) && st1.st_rdev == st.st_rdev -#else +#endif && st1.st_ino == st.st_ino && st1.st_dev == st.st_dev -#endif ) return 0; + + /* If the link doesn't exist, then it points to a device in another + namespace. If it is a UNIX98 pty, then return the /proc/self + fd, as it points to a name unreachable in our namespace. */ + if (is_pty (&st) && strlen (procname) < buflen - 1) + { + strcpy (buf, procname); + return 0; + } } /* Prepare the result buffer. */