From: Serge Hallyn <serge.hallyn@ubuntu.com>
To: libc-alpha@sourceware.org
Subject: [PATCH] linux ttyname and ttyname_r: return link if appropriate
Date: Wed, 20 Apr 2016 02:10:00 -0000 [thread overview]
Message-ID: <20160420021012.GA19449@ubuntumail> (raw)
In-Reply-To: <20160418202301.GA30919@ubuntumail>
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 | 20 ++++++++++++++++++++
sysdeps/unix/sysv/linux/ttyname_r.c | 22 ++++++++++++++++++++++
2 files changed, 42 insertions(+)
diff --git a/sysdeps/unix/sysv/linux/ttyname.c b/sysdeps/unix/sysv/linux/ttyname.c
index 7a001b4..932140a 100644
--- a/sysdeps/unix/sysv/linux/ttyname.c
+++ b/sysdeps/unix/sysv/linux/ttyname.c
@@ -33,6 +33,19 @@
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 +183,19 @@ 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 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..e3d0c8b 100644
--- a/sysdeps/unix/sysv/linux/ttyname_r.c
+++ b/sysdeps/unix/sysv/linux/ttyname_r.c
@@ -32,6 +32,19 @@ 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,
@@ -158,6 +171,15 @@ __ttyname_r (int fd, char *buf, size_t buflen)
#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. */
--
2.7.4
next prev parent reply other threads:[~2016-04-20 2:10 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-15 15:29 [PATCH 1/1] linux ttyname: " Serge Hallyn
2016-04-15 16:27 ` Florian Weimer
2016-04-15 16:47 ` Serge Hallyn
2016-04-15 17:06 ` Florian Weimer
2016-04-15 17:43 ` Serge Hallyn
2016-04-15 18:48 ` Serge Hallyn
2016-04-15 19:59 ` Mike Frysinger
2016-04-18 19:53 ` Serge Hallyn
2016-04-18 19:53 ` [PATCH 1/2] " Serge Hallyn
2016-04-18 20:02 ` Mike Frysinger
2016-04-18 20:23 ` Serge Hallyn
2016-04-20 2:10 ` Serge Hallyn [this message]
2016-04-20 2:28 ` [PATCH] linux ttyname and ttyname_r: " Mike Frysinger
2016-04-20 18:51 ` Serge Hallyn
2016-07-27 13:43 ` Serge E. Hallyn
2016-07-27 17:28 ` Dmitry V. Levin
2016-08-06 2:09 ` Serge E. Hallyn
2016-08-06 8:46 ` Mike Frysinger
2016-08-06 15:00 ` Serge E. Hallyn
2016-08-09 20:41 ` Serge E. Hallyn
2016-08-09 21:18 ` Dmitry V. Levin
2016-08-09 21:39 ` Serge E. Hallyn
2016-08-09 23:26 ` Dmitry V. Levin
2016-08-10 23:24 ` Serge E. Hallyn
2016-08-10 23:48 ` Dmitry V. Levin
2016-08-10 6:38 ` Florian Weimer
2016-08-10 23:03 ` Serge E. Hallyn
2016-08-10 23:18 ` Dmitry V. Levin
2016-08-10 23:26 ` Serge E. Hallyn
2016-10-03 6:16 ` Serge E. Hallyn
2016-10-03 7:29 ` Andreas Schwab
2016-10-03 14:05 ` [PATCH 1/1] linux ttyname and ttyname_r: do not return wrong results Serge E. Hallyn
2016-10-04 9:53 ` [PATCH] linux ttyname and ttyname_r: return link if appropriate Florian Weimer
2016-10-04 12:47 ` Serge E. Hallyn
2016-04-18 19:54 ` [PATCH 2/2] linux " Serge Hallyn
2016-04-18 20:03 ` Mike Frysinger
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