| Message ID | 20171110200827.32265-5-lukeshu@lukeshu.com |
|---|---|
| State | New |
| Headers | show |
| Series | Fixup linux ttyname and ttyname_r [BZ #22145] | expand |
On Fri, Nov 10, 2017 at 03:08:25PM -0500, Luke Shumaker wrote: > 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(-) Reviewed-by: Christian Brauner <christian.brauner@ubuntu.com> > > diff --git a/ChangeLog b/ChangeLog > index 11709a01ac..f28c7c1afc 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 ce4845a587..c290bfab36 100644 > --- a/sysdeps/unix/sysv/linux/ttyname.h > +++ b/sysdeps/unix/sysv/linux/ttyname.h > @@ -33,3 +33,15 @@ 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 >
diff --git a/ChangeLog b/ChangeLog index 11709a01ac..f28c7c1afc 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 ce4845a587..c290bfab36 100644 --- a/sysdeps/unix/sysv/linux/ttyname.h +++ b/sysdeps/unix/sysv/linux/ttyname.h @@ -33,3 +33,15 @@ 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;
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(-)