From 95f427178720d047316e95f44777cfdf2ecf2b46 Mon Sep 17 00:00:00 2001

From: =?UTF-8?q?P=C3=A1draig=20Brady?= <P@draigBrady.com>

Date: Fri, 4 Jan 2019 09:29:13 -0800

Subject: [PATCH 1/4] tail: don't exit immediately with filters on AIX

* src/tail.c: Fix the check_output_available check on AIX.

Note we don't use poll for all systems as the overhead

of adding the gnulib poll module wouldn't be worth it

just for this single use.

* tests/tail-2/pipe-f.sh: Fix the test which always passed

due to only the exit code of sleep being checked.

* NEWS: Mention the bug fix and rearrange alphabetically.

Fixes http://bugs.gnu.org/33946

Upstream-commit: d5ab4cbe424e3e95140eec22ef828f50b2fb3067

Signed-off-by: Kamil Dudka <kdudka@redhat.com>

---

 src/tail.c             | 13 +++++++++++++

 tests/tail-2/pipe-f.sh |  5 ++++-

 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/src/tail.c b/src/tail.c

index ac001d7..d63aacc 100644

--- a/src/tail.c

+++ b/src/tail.c

@@ -30,6 +30,9 @@

 #include <getopt.h>

 #include <sys/types.h>

 #include <signal.h>

+#ifdef _AIX

+# include <poll.h>

+#endif

 #include "system.h"

 #include "argmatch.h"

@@ -335,6 +338,16 @@ named file in a way that accommodates renaming, removal and creation.\n\

 static void

 check_output_alive (void)

 {

+#ifdef _AIX

+  /* select on AIX was seen to give a readable event immediately.  */

+  struct pollfd pfd;

+  pfd.fd = STDOUT_FILENO;

+  pfd.events = POLLERR;

+

+  if (poll (&pfd, 1, 0) >= 0 && (pfd.revents & POLLERR))

+    raise (SIGPIPE);

+#endif

+

   if (! monitor_output)

     return;

diff --git a/tests/tail-2/pipe-f.sh b/tests/tail-2/pipe-f.sh

index 76b0d90..1126c93 100755

--- a/tests/tail-2/pipe-f.sh

+++ b/tests/tail-2/pipe-f.sh

@@ -37,7 +37,10 @@ compare exp out || fail=1

 # This would wait indefinitely before v8.28 due to no EPIPE being

 # generated due to no data written after the first small amount

-timeout 10 tail -f $mode $fastpoll out | sleep .1 || fail=1

+(returns_ 124 timeout 10 tail -n2 -f $mode $fastpoll out && touch timed_out) |

+ sed 2q > out2

+test -e timed_out && fail=1

+compare exp out2 || fail=1

 # This would wait indefinitely before v8.28 (until first write)

 (returns_ 1 timeout 10 tail -f $mode $fastpoll /dev/null >&-) || fail=1

-- 

2.31.1

From 125bb79d3e9f414533b1c29237ee3f647053d0d6 Mon Sep 17 00:00:00 2001

From: Ayappan <ayappap2@in.ibm.com>

Date: Sun, 20 Jan 2019 00:17:33 -0800

Subject: [PATCH 2/4] tail: fix recent ineffective AIX change

* src/tail.c: Fix commit v8.30-40-gd5ab4cb which was ineffective.

Fixes http://bugs.gnu.org/33946

Upstream-commit: 17983b2cb3bccbb4fa69691178caddd99269bda9

Signed-off-by: Kamil Dudka <kdudka@redhat.com>

---

 src/tail.c | 10 +++++-----

 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/tail.c b/src/tail.c

index d63aacc..9ed6d48 100644

--- a/src/tail.c

+++ b/src/tail.c

@@ -338,6 +338,9 @@ named file in a way that accommodates renaming, removal and creation.\n\

 static void

 check_output_alive (void)

 {

+  if (! monitor_output)

+    return;

+

 #ifdef _AIX

   /* select on AIX was seen to give a readable event immediately.  */

   struct pollfd pfd;

@@ -346,11 +349,7 @@ check_output_alive (void)

   if (poll (&pfd, 1, 0) >= 0 && (pfd.revents & POLLERR))

     raise (SIGPIPE);

-#endif

-

-  if (! monitor_output)

-    return;

-

+#else

   struct timeval delay;

   delay.tv_sec = delay.tv_usec = 0;

@@ -362,6 +361,7 @@ check_output_alive (void)

      and implies an error condition on output like broken pipe.  */

   if (select (STDOUT_FILENO + 1, &rfd, NULL, NULL, &delay) == 1)

     raise (SIGPIPE);

+#endif

 }

 static bool

-- 

2.31.1

From 7741989c3e633aa44f01d8f91332cb65a9280ba3 Mon Sep 17 00:00:00 2001

From: =?UTF-8?q?P=C3=A1draig=20Brady?= <P@draigBrady.com>

Date: Sun, 20 Jan 2019 00:13:15 -0800

Subject: [PATCH 3/4] tail: fix handling of broken pipes with SIGPIPE ignored

* init.cfg (trap_sigpipe_or_skip_): A new function refactored from...

* tests/misc/printf-surprise.sh: ...here.

* tests/misc/seq-epipe.sh. Likewise.

* src/tail.c (die_pipe): Ensure we exit upon sending SIGPIPE.

* tests/tail-2/pipe-f.sh: Ensure we exit even if SIGPIPE is ignored.

* NEWS: Mention the bug fix.

Upstream-commit: fa50623394f491b975dbd7ad73193519dd721771

Signed-off-by: Kamil Dudka <kdudka@redhat.com>

---

 init.cfg                      |  6 ++++++

 src/tail.c                    | 14 +++++++++++---

 tests/misc/printf-surprise.sh |  4 +---

 tests/misc/seq-epipe.sh       |  4 +---

 tests/tail-2/pipe-f.sh        | 19 ++++++++++++++-----

 5 files changed, 33 insertions(+), 14 deletions(-)

diff --git a/init.cfg b/init.cfg

index b6c81ab..985c8d3 100644

--- a/init.cfg

+++ b/init.cfg

@@ -613,6 +613,12 @@ mkfifo_or_skip_()

   fi

 }

+trap_sigpipe_or_skip_()

+{

+  (trap '' PIPE && yes | :) 2>&1 | grep -qF 'Broken pipe' ||

+    skip_ 'trapping SIGPIPE is not supported'

+}

+

 # Disable the current test if the working directory seems to have

 # the setgid bit set.

 skip_if_setgid_()

diff --git a/src/tail.c b/src/tail.c

index 9ed6d48..16e0d73 100644

--- a/src/tail.c

+++ b/src/tail.c

@@ -333,6 +333,14 @@ named file in a way that accommodates renaming, removal and creation.\n\

   exit (status);

 }

+/* Ensure exit, either with SIGPIPE or EXIT_FAILURE status.  */

+static void ATTRIBUTE_NORETURN

+die_pipe (void)

+{

+  raise (SIGPIPE);

+  exit (EXIT_FAILURE);

+}

+

 /* If the output has gone away, then terminate

    as we would if we had written to this output.  */

 static void

@@ -348,7 +356,7 @@ check_output_alive (void)

   pfd.events = POLLERR;

   if (poll (&pfd, 1, 0) >= 0 && (pfd.revents & POLLERR))

-    raise (SIGPIPE);

+    die_pipe ();

 #else

   struct timeval delay;

   delay.tv_sec = delay.tv_usec = 0;

@@ -360,7 +368,7 @@ check_output_alive (void)

   /* readable event on STDOUT is equivalent to POLLERR,

      and implies an error condition on output like broken pipe.  */

   if (select (STDOUT_FILENO + 1, &rfd, NULL, NULL, &delay) == 1)

-    raise (SIGPIPE);

+    die_pipe ();

 #endif

 }

@@ -1658,7 +1666,7 @@ tail_forever_inotify (int wd, struct File_spec *f, size_t n_files,

              {

                /* readable event on STDOUT is equivalent to POLLERR,

                   and implies an error on output like broken pipe.  */

-               raise (SIGPIPE);

+               die_pipe ();

              }

            else

              break;

diff --git a/tests/misc/printf-surprise.sh b/tests/misc/printf-surprise.sh

index fd88133..acac0b1 100755

--- a/tests/misc/printf-surprise.sh

+++ b/tests/misc/printf-surprise.sh

@@ -49,9 +49,7 @@ vm=$(get_min_ulimit_v_ env $prog %20f 0) \

 # triggering the printf(3) misbehavior -- which, btw, is required by ISO C99.

 mkfifo_or_skip_ fifo

-

-(trap '' PIPE && yes | :) 2>&1 | grep -qF 'Broken pipe' ||

-    skip_ 'trapping SIGPIPE is not supported'

+trap_sigpipe_or_skip_

 # Disable MALLOC_PERTURB_, to avoid triggering this bug

 # https://bugs.debian.org/481543#77

diff --git a/tests/misc/seq-epipe.sh b/tests/misc/seq-epipe.sh

index 3e89158..127d61c 100755

--- a/tests/misc/seq-epipe.sh

+++ b/tests/misc/seq-epipe.sh

@@ -18,9 +18,7 @@

 . "${srcdir=.}/tests/init.sh"; path_prepend_ ./src

 print_ver_ seq

-

-(trap '' PIPE && yes | :) 2>&1 | grep -qF 'Broken pipe' ||

-    skip_ 'trapping SIGPIPE is not supported'

+trap_sigpipe_or_skip_

 # upon EPIPE with signals ignored, 'seq' should exit with an error.

 timeout 10 sh -c \

diff --git a/tests/tail-2/pipe-f.sh b/tests/tail-2/pipe-f.sh

index 1126c93..f734a61 100755

--- a/tests/tail-2/pipe-f.sh

+++ b/tests/tail-2/pipe-f.sh

@@ -18,6 +18,7 @@

 . "${srcdir=.}/tests/init.sh"; path_prepend_ ./src

 print_ver_ tail

+trap_sigpipe_or_skip_

 # Speedup the non inotify case

 fastpoll='-s.1 --max-unchanged-stats=1'

@@ -36,11 +37,19 @@ echo bar | returns_ 1 \

 compare exp out || fail=1

 # This would wait indefinitely before v8.28 due to no EPIPE being

-# generated due to no data written after the first small amount

-(returns_ 124 timeout 10 tail -n2 -f $mode $fastpoll out && touch timed_out) |

- sed 2q > out2

-test -e timed_out && fail=1

-compare exp out2 || fail=1

+# generated due to no data written after the first small amount.

+# Also check tail exits if SIGPIPE is being ignored.

+# Note 'trap - SIGPIPE' is ineffective if the initiating shell

+# has ignored SIGPIPE, but that's not the normal case.

+for disposition in '' '-'; do

+  (trap "$disposition" PIPE;

+   returns_ 124 timeout 10 \

+    tail -n2 -f $mode $fastpoll out && touch timed_out) |

+  sed 2q > out2

+  test -e timed_out && fail=1

+  compare exp out2 || fail=1

+  rm -f timed_out

+done

 # This would wait indefinitely before v8.28 (until first write)

 (returns_ 1 timeout 10 tail -f $mode $fastpoll /dev/null >&-) || fail=1

-- 

2.31.1

From 0f5760466d167e955d28a1250ffd0af347d48dc9 Mon Sep 17 00:00:00 2001

From: Paul Eggert <eggert@cs.ucla.edu>

Date: Sat, 26 Jun 2021 18:23:52 -0700

Subject: [PATCH 4/4] tail: use poll, not select

MIME-Version: 1.0

Content-Type: text/plain; charset=UTF-8

Content-Transfer-Encoding: 8bit

This fixes an unlikely stack out-of-bounds write reported by

Stepan Broz via Kamil Dudka (Bug#49209).

* src/tail.c: Do not include <sys/select.h>.

[!_AIX]: Include poll.h.

(check_output_alive) [!_AIX]: Use poll instead of select.

(tail_forever_inotify): Likewise.  Simplify logic, as there is no

need for a ‘while (len <= evbuf_off)’ loop.

Upstream-commit: da0d448bca62c6305fc432f67e2c5ccc2da75346

Signed-off-by: Kamil Dudka <kdudka@redhat.com>

---

 src/tail.c | 101 +++++++++++++++++++++--------------------------------

 1 file changed, 39 insertions(+), 62 deletions(-)

diff --git a/src/tail.c b/src/tail.c

index 16e0d73..d77c660 100644

--- a/src/tail.c

+++ b/src/tail.c

@@ -29,10 +29,8 @@

 #include <assert.h>

 #include <getopt.h>

 #include <sys/types.h>

+#include <poll.h>

 #include <signal.h>

-#ifdef _AIX

-# include <poll.h>

-#endif

 #include "system.h"

 #include "argmatch.h"

@@ -55,8 +53,6 @@

 #if HAVE_INOTIFY

 # include "hash.h"

 # include <sys/inotify.h>

-/* 'select' is used by tail_forever_inotify.  */

-# include <sys/select.h>

 /* inotify needs to know if a file is local.  */

 # include "fs.h"

@@ -349,27 +345,12 @@ check_output_alive (void)

   if (! monitor_output)

     return;

-#ifdef _AIX

-  /* select on AIX was seen to give a readable event immediately.  */

   struct pollfd pfd;

   pfd.fd = STDOUT_FILENO;

   pfd.events = POLLERR;

   if (poll (&pfd, 1, 0) >= 0 && (pfd.revents & POLLERR))

     die_pipe ();

-#else

-  struct timeval delay;

-  delay.tv_sec = delay.tv_usec = 0;

-

-  fd_set rfd;

-  FD_ZERO (&rfd;;

-  FD_SET (STDOUT_FILENO, &rfd;;

-

-  /* readable event on STDOUT is equivalent to POLLERR,

-     and implies an error condition on output like broken pipe.  */

-  if (select (STDOUT_FILENO + 1, &rfd, NULL, NULL, &delay) == 1)

-    die_pipe ();

-#endif

 }

 static bool

@@ -1609,7 +1590,7 @@ tail_forever_inotify (int wd, struct File_spec *f, size_t n_files,

   /* Wait for inotify events and handle them.  Events on directories

      ensure that watched files can be re-added when following by name.

      This loop blocks on the 'safe_read' call until a new event is notified.

-     But when --pid=P is specified, tail usually waits via the select.  */

+     But when --pid=P is specified, tail usually waits via poll.  */

   while (1)

     {

       struct File_spec *fspec;

@@ -1626,54 +1607,51 @@ tail_forever_inotify (int wd, struct File_spec *f, size_t n_files,

           return false;

         }

-      /* When watching a PID, ensure that a read from WD will not block

-         indefinitely.  */

-      while (len <= evbuf_off)

+      if (len <= evbuf_off)

         {

-          struct timeval delay; /* how long to wait for file changes.  */

+          /* Poll for inotify events.  When watching a PID, ensure

+             that a read from WD will not block indefinitely.

+             If MONITOR_OUTPUT, also poll for a broken output pipe.  */

-          if (pid)

+          int file_change;

+          struct pollfd pfd[2];

+          do

             {

-              if (writer_is_dead)

-                exit (EXIT_SUCCESS);

+              /* How many ms to wait for changes.  -1 means wait forever.  */

+              int delay = -1;

-              writer_is_dead = (kill (pid, 0) != 0 && errno != EPERM);

-

-              if (writer_is_dead)

-                delay.tv_sec = delay.tv_usec = 0;

-              else

+              if (pid)

                 {

-                  delay.tv_sec = (time_t) sleep_interval;

-                  delay.tv_usec = 1000000 * (sleep_interval - delay.tv_sec);

+                  if (writer_is_dead)

+                    exit (EXIT_SUCCESS);

+

+                  writer_is_dead = (kill (pid, 0) != 0 && errno != EPERM);

+

+                  if (writer_is_dead || sleep_interval <= 0)

+                    delay = 0;

+                  else if (sleep_interval < INT_MAX / 1000 - 1)

+                    {

+                      /* delay = ceil (sleep_interval * 1000), sans libm.  */

+                      double ddelay = sleep_interval * 1000;

+                      delay = ddelay;

+                      delay += delay < ddelay;

+                    }

                 }

+

+              pfd[0].fd = wd;

+              pfd[0].events = POLLIN;

+              pfd[1].fd = STDOUT_FILENO;

+              pfd[1].events = pfd[1].revents = 0;

+              file_change = poll (pfd, monitor_output + 1, delay);

             }

+          while (file_change == 0);

-           fd_set rfd;

-           FD_ZERO (&rfd;;

-           FD_SET (wd, &rfd;;

-           if (monitor_output)

-             FD_SET (STDOUT_FILENO, &rfd;;

-

-           int file_change = select (MAX (wd, STDOUT_FILENO) + 1,

-                                     &rfd, NULL, NULL, pid ? &delay: NULL);

-

-           if (file_change == 0)

-             continue;

-           else if (file_change == -1)

-             die (EXIT_FAILURE, errno,

-                  _("error waiting for inotify and output events"));

-           else if (FD_ISSET (STDOUT_FILENO, &rfd))

-             {

-               /* readable event on STDOUT is equivalent to POLLERR,

-                  and implies an error on output like broken pipe.  */

-               die_pipe ();

-             }

-           else

-             break;

-        }

+          if (file_change < 0)

+            die (EXIT_FAILURE, errno,

+                 _("error waiting for inotify and output events"));

+          if (pfd[1].revents)

+            die_pipe ();

-      if (len <= evbuf_off)

-        {

           len = safe_read (wd, evbuf, evlen);

           evbuf_off = 0;

@@ -2434,8 +2412,7 @@ main (int argc, char **argv)

   if (forever && ignore_fifo_and_pipe (F, n_files))

     {

       /* If stdout is a fifo or pipe, then monitor it

-         so that we exit if the reader goes away.

-         Note select() on a regular file is always readable.  */

+         so that we exit if the reader goes away.  */

       struct stat out_stat;

       if (fstat (STDOUT_FILENO, &out_stat) < 0)

         die (EXIT_FAILURE, errno, _("standard output"));

-- 

2.31.1