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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