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linux ttyname{_r}: Make tty checks consistent
In the ttyname and ttyname_r routines on Linux, at several points it needs to
check if a given TTY is the TTY we are looking for. It used to be that this
check was (to see if `maybe` is `mytty`):
__xstat64(_STAT_VER, maybe_filename, &maybe) == 0
#ifdef _STATBUF_ST_RDEV
&& S_ISCHR(maybe.st_mode) && maybe.st_rdev == mytty.st_rdev
#else
&& maybe.st_ino == mytty.st_ino && maybe.st_dev == mytty.st_dev
#endif
This check appears in several places.
Then, one of the changes made in commit 15e9a4f378
was to change that check to:
__xstat64(_STAT_VER, maybe_filename, &maybe) == 0
#ifdef _STATBUF_ST_RDEV
&& S_ISCHR(maybe.st_mode) && maybe.st_rdev == mytty.st_rdev
#endif
&& maybe.st_ino == mytty.st_ino && maybe.st_dev == mytty.st_dev
That is, it made the st_ino and st_dev parts of the check happen even if we have
the st_rdev member. This is an important change, because the kernel allows
multiple devpts filesystem instances to be created; a device file in one devpts
instance may share the same st_rdev with a file in another devpts instance, but
they aren't the same file.
This check appears twice in each file (ttyname.c and ttyname_r.c), once (in
ttyname and __ttyname_r) to check if a candidate file found by inspecting /proc
is the desired TTY, and once (in getttyname and getttyname_r) to check if a
candidate file found by searching /dev is the desired TTY. However, 15e9a4f
only updated the checks for files found via /proc; but the concern about
collisions between devpts instances is just as valid for files found via /dev.
So, update all 4 occurrences the check to be consistent with the version of the
check introduced in 15e9a4f. Make it easy to keep all 4 occurrences of the
check consistent by pulling it in to a static inline function, is_mytty.
Reviewed-by: Christian Brauner <christian.brauner@ubuntu.com>
(cherry picked from commit 2fbce9c203)
This commit is contained in:
Luke Shumaker
Florian Weimer
parent
bd81a9d1e9
commit
f43ead291c
@ -1,3 +1,12 @@
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2017-11-15 Luke Shumaker <lukeshu@parabola.nu>
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[BZ #22145]
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* sysdeps/unix/sysv/linux/ttyname.h (is_mytty): New function.
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* sysdeps/unix/sysv/linux/ttyname.c (getttyname): Call is_mytty.
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(ttyname): Likewise.
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* sysdeps/unix/sysv/linux/ttyname_r.c (getttyname_r): Likewise.
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(__ttyname_r): Likewise.
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2017-11-15 Luke Shumaker <lukeshu@parabola.nu>
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* sysdeps/unix/sysv/linux/ttyname.h (is_pty): Change return type from
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1
NEWS
1
NEWS
@ -80,6 +80,7 @@ The following bugs are resolved with this release:
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[22095] resolv: Fix memory leak with OOM during resolv.conf parsing
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[22096] resolv: __resolv_conf_attach must not free passed conf object
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[22111] malloc: per thread cache is not returned when thread exits
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[22145] ttyname gives up too early in the face of namespaces
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[22146] Let fpclassify use the builtin when optimizing for size in C++ mode
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[22225] math: nearbyint arithmetic moved before feholdexcept
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[22235] Add C++ versions of iscanonical for ldbl-96 and ldbl-128ibm
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@ -35,16 +35,14 @@
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char *__ttyname;
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#endif
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static char *getttyname (const char *dev, dev_t mydev,
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ino64_t myino, int save, int *dostat)
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internal_function;
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static char *getttyname (const char *dev, const struct stat64 *mytty,
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int save, int *dostat);
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libc_freeres_ptr (static char *getttyname_name);
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static char *
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internal_function attribute_compat_text_section
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getttyname (const char *dev, dev_t mydev, ino64_t myino, int save, int *dostat)
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attribute_compat_text_section
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getttyname (const char *dev, const struct stat64 *mytty, int save, int *dostat)
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{
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static size_t namelen;
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struct stat64 st;
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@ -65,7 +63,7 @@ getttyname (const char *dev, dev_t mydev, ino64_t myino, int save, int *dostat)
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*((char *) __mempcpy (getttyname_name, dev, devlen - 1)) = '/';
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while ((d = __readdir64 (dirstream)) != NULL)
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if ((d->d_fileno == myino || *dostat)
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if ((d->d_fileno == mytty->st_ino || *dostat)
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&& strcmp (d->d_name, "stdin")
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&& strcmp (d->d_name, "stdout")
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&& strcmp (d->d_name, "stderr"))
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@ -87,12 +85,7 @@ getttyname (const char *dev, dev_t mydev, ino64_t myino, int save, int *dostat)
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}
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memcpy (&getttyname_name[devlen], d->d_name, dlen);
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if (__xstat64 (_STAT_VER, getttyname_name, &st) == 0
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#ifdef _STATBUF_ST_RDEV
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&& S_ISCHR (st.st_mode) && st.st_rdev == mydev
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#else
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&& d->d_fileno == myino && st.st_dev == mydev
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#endif
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)
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&& is_mytty (mytty, &st))
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{
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(void) __closedir (dirstream);
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#if 0
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@ -169,12 +162,7 @@ ttyname (int fd)
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/* Verify readlink result, fall back on iterating through devices. */
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if (ttyname_buf[0] == '/'
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&& __xstat64 (_STAT_VER, ttyname_buf, &st1) == 0
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#ifdef _STATBUF_ST_RDEV
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&& S_ISCHR (st1.st_mode)
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&& st1.st_rdev == st.st_rdev
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#endif
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&& st1.st_ino == st.st_ino
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&& st1.st_dev == st.st_dev)
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&& is_mytty (&st, &st1))
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return ttyname_buf;
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/* If the link doesn't exist, then it points to a device in another
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@ -188,11 +176,7 @@ ttyname (int fd)
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if (__xstat64 (_STAT_VER, "/dev/pts", &st1) == 0 && S_ISDIR (st1.st_mode))
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{
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#ifdef _STATBUF_ST_RDEV
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name = getttyname ("/dev/pts", st.st_rdev, st.st_ino, save, &dostat);
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#else
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name = getttyname ("/dev/pts", st.st_dev, st.st_ino, save, &dostat);
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#endif
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name = getttyname ("/dev/pts", &st, save, &dostat);
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}
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else
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{
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@ -202,21 +186,13 @@ ttyname (int fd)
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if (!name && dostat != -1)
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{
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#ifdef _STATBUF_ST_RDEV
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name = getttyname ("/dev", st.st_rdev, st.st_ino, save, &dostat);
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#else
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name = getttyname ("/dev", st.st_dev, st.st_ino, save, &dostat);
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#endif
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name = getttyname ("/dev", &st, save, &dostat);
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}
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if (!name && dostat != -1)
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{
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dostat = 1;
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#ifdef _STATBUF_ST_RDEV
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name = getttyname ("/dev", st.st_rdev, st.st_ino, save, &dostat);
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#else
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name = getttyname ("/dev", st.st_dev, st.st_ino, save, &dostat);
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#endif
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name = getttyname ("/dev", &st, save, &dostat);
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}
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return name;
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@ -34,3 +34,15 @@ is_pty (struct stat64 *sb)
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return false;
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#endif
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}
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static inline bool
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is_mytty (const struct stat64 *mytty, const struct stat64 *maybe)
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{
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return (maybe->st_ino == mytty->st_ino
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&& maybe->st_dev == mytty->st_dev
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#ifdef _STATBUF_ST_RDEV
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&& S_ISCHR (maybe->st_mode)
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&& maybe->st_rdev == mytty->st_rdev
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#endif
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);
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}
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@ -31,12 +31,12 @@
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#include "ttyname.h"
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static int getttyname_r (char *buf, size_t buflen,
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dev_t mydev, ino64_t myino, int save,
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int *dostat) internal_function;
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const struct stat64 *mytty, int save,
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int *dostat);
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static int
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internal_function attribute_compat_text_section
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getttyname_r (char *buf, size_t buflen, dev_t mydev, ino64_t myino,
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attribute_compat_text_section
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getttyname_r (char *buf, size_t buflen, const struct stat64 *mytty,
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int save, int *dostat)
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{
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struct stat64 st;
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@ -52,7 +52,7 @@ getttyname_r (char *buf, size_t buflen, dev_t mydev, ino64_t myino,
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}
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while ((d = __readdir64 (dirstream)) != NULL)
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if ((d->d_fileno == myino || *dostat)
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if ((d->d_fileno == mytty->st_ino || *dostat)
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&& strcmp (d->d_name, "stdin")
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&& strcmp (d->d_name, "stdout")
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&& strcmp (d->d_name, "stderr"))
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@ -72,12 +72,7 @@ getttyname_r (char *buf, size_t buflen, dev_t mydev, ino64_t myino,
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cp[0] = '\0';
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if (__xstat64 (_STAT_VER, buf, &st) == 0
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#ifdef _STATBUF_ST_RDEV
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&& S_ISCHR (st.st_mode) && st.st_rdev == mydev
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#else
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&& d->d_fileno == myino && st.st_dev == mydev
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#endif
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)
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&& is_mytty (mytty, &st))
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{
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(void) __closedir (dirstream);
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__set_errno (save);
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@ -151,12 +146,7 @@ __ttyname_r (int fd, char *buf, size_t buflen)
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/* Verify readlink result, fall back on iterating through devices. */
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if (buf[0] == '/'
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&& __xstat64 (_STAT_VER, buf, &st1) == 0
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#ifdef _STATBUF_ST_RDEV
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&& S_ISCHR (st1.st_mode)
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&& st1.st_rdev == st.st_rdev
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#endif
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&& st1.st_ino == st.st_ino
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&& st1.st_dev == st.st_dev)
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&& is_mytty (&st, &st1))
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return 0;
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/* If the link doesn't exist, then it points to a device in another
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@ -175,13 +165,8 @@ __ttyname_r (int fd, char *buf, size_t buflen)
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if (__xstat64 (_STAT_VER, buf, &st1) == 0 && S_ISDIR (st1.st_mode))
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{
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#ifdef _STATBUF_ST_RDEV
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ret = getttyname_r (buf, buflen, st.st_rdev, st.st_ino, save,
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ret = getttyname_r (buf, buflen, &st, save,
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&dostat);
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#else
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ret = getttyname_r (buf, buflen, st.st_dev, st.st_ino, save,
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&dostat);
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#endif
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}
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else
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{
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@ -193,26 +178,16 @@ __ttyname_r (int fd, char *buf, size_t buflen)
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{
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buf[sizeof ("/dev/") - 1] = '\0';
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buflen += sizeof ("pts/") - 1;
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#ifdef _STATBUF_ST_RDEV
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ret = getttyname_r (buf, buflen, st.st_rdev, st.st_ino, save,
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ret = getttyname_r (buf, buflen, &st, save,
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&dostat);
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#else
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ret = getttyname_r (buf, buflen, st.st_dev, st.st_ino, save,
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&dostat);
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#endif
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}
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if (ret && dostat != -1)
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{
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buf[sizeof ("/dev/") - 1] = '\0';
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dostat = 1;
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#ifdef _STATBUF_ST_RDEV
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ret = getttyname_r (buf, buflen, st.st_rdev, st.st_ino,
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ret = getttyname_r (buf, buflen, &st,
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save, &dostat);
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#else
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ret = getttyname_r (buf, buflen, st.st_dev, st.st_ino,
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save, &dostat);
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#endif
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}
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return ret;
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