This is the mail archive of the
libc-alpha@sourceware.org
mailing list for the glibc project.
[PATCH v7 4/6] linux ttyname and ttyname_r: Make the TTY equivalence checks consistent
- From: Luke Shumaker <lukeshu at lukeshu dot com>
- To: libc-alpha at sourceware dot org
- Cc: christian dot brauner at mailbox dot org
- Date: Mon, 13 Nov 2017 16:28:39 -0500
- Subject: [PATCH v7 4/6] linux ttyname and ttyname_r: Make the TTY equivalence checks consistent
- Authentication-results: sourceware.org; auth=none
- References: <20171113212841.28518-1-lukeshu@lukeshu.com>
From: Luke Shumaker <lukeshu@parabola.nu>
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
15e9a4f378c8607c2ae1aa465436af4321db0e23 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.
v2:
- Rearrange commit order
- Expand commit message
- Reformat is_mytty
- Have is_pty and is_mytty return bool instead of int
- Specify 'const' on pointer arguments as necessary
v3:
- Revise commit message
- Revise ChangeLog message
- Split is_pty change into a separate commit
- Fix whitespace style
---
ChangeLog | 7 +++++++
sysdeps/unix/sysv/linux/ttyname.c | 40 ++++++++----------------------------
sysdeps/unix/sysv/linux/ttyname.h | 12 +++++++++++
sysdeps/unix/sysv/linux/ttyname_r.c | 41 ++++++++-----------------------------
4 files changed, 36 insertions(+), 64 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index 7035df540d..7b1e6462f6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,12 @@
2017-11-07 Luke Shumaker <lukeshu@parabola.nu>
+ [BZ #22145]
+ * sysdeps/unix/sysv/linux/ttyname.h (is_mytty): New function.
+ * sysdeps/unix/sysv/linux/ttyname.c (getttyname): Call is_mytty.
+ (ttyname): Likewise.
+ * sysdeps/unix/sysv/linux/ttyname_r.c (getttyname_r): Likewise.
+ (__ttyname_r): Likewise.
+
* sysdeps/unix/sysv/linux/ttyname.h (is_pty): Change return type from
int to bool.
diff --git a/sysdeps/unix/sysv/linux/ttyname.c b/sysdeps/unix/sysv/linux/ttyname.c
index 116cf350e5..6e97d2d455 100644
--- a/sysdeps/unix/sysv/linux/ttyname.c
+++ b/sysdeps/unix/sysv/linux/ttyname.c
@@ -35,14 +35,14 @@
char *__ttyname;
#endif
-static char *getttyname (const char *dev, dev_t mydev,
- ino64_t myino, int save, int *dostat);
+static char *getttyname (const char *dev, const struct stat64 *mytty,
+ int save, int *dostat);
libc_freeres_ptr (static char *getttyname_name);
static char *
attribute_compat_text_section
-getttyname (const char *dev, dev_t mydev, ino64_t myino, int save, int *dostat)
+getttyname (const char *dev, const struct stat64 *mytty, int save, int *dostat)
{
static size_t namelen;
struct stat64 st;
@@ -63,7 +63,7 @@ getttyname (const char *dev, dev_t mydev, ino64_t myino, int save, int *dostat)
*((char *) __mempcpy (getttyname_name, dev, devlen - 1)) = '/';
while ((d = __readdir64 (dirstream)) != NULL)
- if ((d->d_fileno == myino || *dostat)
+ if ((d->d_fileno == mytty->st_ino || *dostat)
&& strcmp (d->d_name, "stdin")
&& strcmp (d->d_name, "stdout")
&& strcmp (d->d_name, "stderr"))
@@ -85,12 +85,7 @@ getttyname (const char *dev, dev_t mydev, ino64_t myino, int save, int *dostat)
}
memcpy (&getttyname_name[devlen], d->d_name, dlen);
if (__xstat64 (_STAT_VER, getttyname_name, &st) == 0
-#ifdef _STATBUF_ST_RDEV
- && S_ISCHR (st.st_mode) && st.st_rdev == mydev
-#else
- && d->d_fileno == myino && st.st_dev == mydev
-#endif
- )
+ && is_mytty (mytty, &st))
{
(void) __closedir (dirstream);
#if 0
@@ -167,12 +162,7 @@ ttyname (int fd)
/* Verify readlink result, fall back on iterating through devices. */
if (ttyname_buf[0] == '/'
&& __xstat64 (_STAT_VER, ttyname_buf, &st1) == 0
-#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)
+ && is_mytty (&st, &st1))
return ttyname_buf;
/* If the link doesn't exist, then it points to a device in another
@@ -186,11 +176,7 @@ ttyname (int fd)
if (__xstat64 (_STAT_VER, "/dev/pts", &st1) == 0 && S_ISDIR (st1.st_mode))
{
-#ifdef _STATBUF_ST_RDEV
- name = getttyname ("/dev/pts", st.st_rdev, st.st_ino, save, &dostat);
-#else
- name = getttyname ("/dev/pts", st.st_dev, st.st_ino, save, &dostat);
-#endif
+ name = getttyname ("/dev/pts", &st, save, &dostat);
}
else
{
@@ -200,21 +186,13 @@ ttyname (int fd)
if (!name && dostat != -1)
{
-#ifdef _STATBUF_ST_RDEV
- name = getttyname ("/dev", st.st_rdev, st.st_ino, save, &dostat);
-#else
- name = getttyname ("/dev", st.st_dev, st.st_ino, save, &dostat);
-#endif
+ name = getttyname ("/dev", &st, save, &dostat);
}
if (!name && dostat != -1)
{
dostat = 1;
-#ifdef _STATBUF_ST_RDEV
- name = getttyname ("/dev", st.st_rdev, st.st_ino, save, &dostat);
-#else
- name = getttyname ("/dev", st.st_dev, st.st_ino, save, &dostat);
-#endif
+ name = getttyname ("/dev", &st, save, &dostat);
}
return name;
diff --git a/sysdeps/unix/sysv/linux/ttyname.h b/sysdeps/unix/sysv/linux/ttyname.h
index cdaf60fb87..48181330a9 100644
--- a/sysdeps/unix/sysv/linux/ttyname.h
+++ b/sysdeps/unix/sysv/linux/ttyname.h
@@ -34,3 +34,15 @@ is_pty (struct stat64 *sb)
return false;
#endif
}
+
+static inline bool
+is_mytty (const struct stat64 *mytty, const struct stat64 *maybe)
+{
+ return (maybe->st_ino == mytty->st_ino
+ && maybe->st_dev == mytty->st_dev
+#ifdef _STATBUF_ST_RDEV
+ && S_ISCHR (maybe->st_mode)
+ && maybe->st_rdev == mytty->st_rdev
+#endif
+ );
+}
diff --git a/sysdeps/unix/sysv/linux/ttyname_r.c b/sysdeps/unix/sysv/linux/ttyname_r.c
index 18f35ef2b7..58eb919c3f 100644
--- a/sysdeps/unix/sysv/linux/ttyname_r.c
+++ b/sysdeps/unix/sysv/linux/ttyname_r.c
@@ -31,12 +31,12 @@
#include "ttyname.h"
static int getttyname_r (char *buf, size_t buflen,
- dev_t mydev, ino64_t myino, int save,
+ const struct stat64 *mytty, int save,
int *dostat);
static int
attribute_compat_text_section
-getttyname_r (char *buf, size_t buflen, dev_t mydev, ino64_t myino,
+getttyname_r (char *buf, size_t buflen, const struct stat64 *mytty,
int save, int *dostat)
{
struct stat64 st;
@@ -52,7 +52,7 @@ getttyname_r (char *buf, size_t buflen, dev_t mydev, ino64_t myino,
}
while ((d = __readdir64 (dirstream)) != NULL)
- if ((d->d_fileno == myino || *dostat)
+ if ((d->d_fileno == mytty->st_ino || *dostat)
&& strcmp (d->d_name, "stdin")
&& strcmp (d->d_name, "stdout")
&& strcmp (d->d_name, "stderr"))
@@ -72,12 +72,7 @@ getttyname_r (char *buf, size_t buflen, dev_t mydev, ino64_t myino,
cp[0] = '\0';
if (__xstat64 (_STAT_VER, buf, &st) == 0
-#ifdef _STATBUF_ST_RDEV
- && S_ISCHR (st.st_mode) && st.st_rdev == mydev
-#else
- && d->d_fileno == myino && st.st_dev == mydev
-#endif
- )
+ && is_mytty (mytty, &st))
{
(void) __closedir (dirstream);
__set_errno (save);
@@ -151,12 +146,7 @@ __ttyname_r (int fd, char *buf, size_t buflen)
/* Verify readlink result, fall back on iterating through devices. */
if (buf[0] == '/'
&& __xstat64 (_STAT_VER, buf, &st1) == 0
-#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)
+ && is_mytty (&st, &st1))
return 0;
/* If the link doesn't exist, then it points to a device in another
@@ -175,13 +165,8 @@ __ttyname_r (int fd, char *buf, size_t buflen)
if (__xstat64 (_STAT_VER, buf, &st1) == 0 && S_ISDIR (st1.st_mode))
{
-#ifdef _STATBUF_ST_RDEV
- ret = getttyname_r (buf, buflen, st.st_rdev, st.st_ino, save,
+ ret = getttyname_r (buf, buflen, &st, save,
&dostat);
-#else
- ret = getttyname_r (buf, buflen, st.st_dev, st.st_ino, save,
- &dostat);
-#endif
}
else
{
@@ -193,26 +178,16 @@ __ttyname_r (int fd, char *buf, size_t buflen)
{
buf[sizeof ("/dev/") - 1] = '\0';
buflen += sizeof ("pts/") - 1;
-#ifdef _STATBUF_ST_RDEV
- ret = getttyname_r (buf, buflen, st.st_rdev, st.st_ino, save,
- &dostat);
-#else
- ret = getttyname_r (buf, buflen, st.st_dev, st.st_ino, save,
+ ret = getttyname_r (buf, buflen, &st, save,
&dostat);
-#endif
}
if (ret && dostat != -1)
{
buf[sizeof ("/dev/") - 1] = '\0';
dostat = 1;
-#ifdef _STATBUF_ST_RDEV
- ret = getttyname_r (buf, buflen, st.st_rdev, st.st_ino,
- save, &dostat);
-#else
- ret = getttyname_r (buf, buflen, st.st_dev, st.st_ino,
+ ret = getttyname_r (buf, buflen, &st,
save, &dostat);
-#endif
}
return ret;
--
2.15.0