Signed-off-by: Christian Brauner <christian.brauner@xxxxxxxxxx> --- man3/ttyname.3 | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) diff --git a/man3/ttyname.3 b/man3/ttyname.3 index 0be50c62a..f184b4505 100644 --- a/man3/ttyname.3 +++ b/man3/ttyname.3 @@ -75,7 +75,7 @@ was too small to allow storing the pathname. .\" glibc commit 15e9a4f378c8607c2ae1aa465436af4321db0e23 .B ENODEV File descriptor refers to a slave pseudoterminal device -but the corresponding pathname could not be found. +but the corresponding pathname could not be found (see NOTES). .SH ATTRIBUTES For an explanation of the terms used in this section, see .BR attributes (7). @@ -93,6 +93,22 @@ T} Thread safety MT-Safe .TE .SH CONFORMING TO POSIX.1-2001, POSIX.1-2008, 4.2BSD. +.SH NOTES +Processes keeping a file descriptor to a +.BR pts (4) +device open when switching to +.BR mount_namespaces (7) +that use a different +.IR /dev/ptmx +instance may still accidently find that a device path of the same name +for that file descriptor exists. However, this device path refers to a +different device and thus cannot not be used to modify the device that +the file descriptor refers to. Calling +.BR ttyname (7) +or +.BR ttyname_r (7) +on the file descriptor in such a mount namespace will cause these +functions to return NULL and set errno to ENODEV. .SH SEE ALSO .BR tty (1), .BR fstat (2), -- 2.11.0 -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
