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Linux: Require properly configured /dev/pts for PTYs

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Current systems do not have BSD terminals, so the fallback code in
posix_openpt/getpt does not do anything.  Also remove the file system
check for /dev/pts.  Current systems always have a devpts file system
mounted there if /dev/ptmx exists.

grantpt is now essentially a no-op.  It only verifies that the
argument is a ptmx-descriptor.  Therefore, this change indirectly
addresses bug 24941.

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
This commit is contained in:
Florian Weimer
2020-10-07 14:55:04 +02:00
parent 0f9793a556
commit 27fe5f2e67
6 changed files with 60 additions and 209 deletions
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67
sysdeps/unix/sysv/linux/getpt.c
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@ -16,69 +16,18 @@
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <paths.h>
#include <sys/statfs.h>
#include "linux_fsinfo.h"
/* Path to the master pseudo terminal cloning device. */
#define _PATH_DEVPTMX _PATH_DEV "ptmx"
/* Directory containing the UNIX98 pseudo terminals. */
#define _PATH_DEVPTS _PATH_DEV "pts"
/* Prototype for function that opens BSD-style master pseudo-terminals. */
extern int __bsd_getpt (void) attribute_hidden;
/* Open a master pseudo terminal and return its file descriptor. */
int
__posix_openpt (int oflag)
{
static int have_no_dev_ptmx;
int fd;
if (!have_no_dev_ptmx)
{
fd = __open (_PATH_DEVPTMX, oflag);
if (fd != -1)
{
struct statfs fsbuf;
static int devpts_mounted;
/* Check that the /dev/pts filesystem is mounted
or if /dev is a devfs filesystem (this implies /dev/pts). */
if (devpts_mounted
|| (__statfs (_PATH_DEVPTS, &fsbuf) == 0
&& fsbuf.f_type == DEVPTS_SUPER_MAGIC)
|| (__statfs (_PATH_DEV, &fsbuf) == 0
&& fsbuf.f_type == DEVFS_SUPER_MAGIC))
{
/* Everything is ok. */
devpts_mounted = 1;
return fd;
}
/* If /dev/pts is not mounted then the UNIX98 pseudo terminals
are not usable. */
__close (fd);
have_no_dev_ptmx = 1;
__set_errno (ENOENT);
}
else
{
if (errno == ENOENT || errno == ENODEV)
have_no_dev_ptmx = 1;
else
return -1;
}
}
else
__set_errno (ENOENT);
return -1;
return __open (_PATH_DEVPTMX, oflag);
}
weak_alias (__posix_openpt, posix_openpt)
@ -86,16 +35,6 @@ weak_alias (__posix_openpt, posix_openpt)
int
__getpt (void)
{
int fd = __posix_openpt (O_RDWR);
if (fd == -1)
fd = __bsd_getpt ();
return fd;
return __posix_openpt (O_RDWR);
}
#define PTYNAME1 "pqrstuvwxyzabcde";
#define PTYNAME2 "0123456789abcdef";
#define __getpt __bsd_getpt
#define HAVE_POSIX_OPENPT
#include <sysdeps/unix/bsd/getpt.c>
weak_alias (__getpt, getpt)