From fa50623394f491b975dbd7ad73193519dd721771 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 46/87] 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.
---
 init.cfg                      |  6 ++++++
 src/tail.c                    | 12 ++++++++++--
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/init.cfg b/init.cfg
index d99a0e3dd..739ba33df 100644
--- a/init.cfg
+++ b/init.cfg
@@ -610,6 +610,12 @@ 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 c63b61631..b8064853f 100644
--- a/src/tail.c
+++ b/src/tail.c
@@ -330,6 +330,14 @@ 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)
   /* 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();
 }

 static bool
@@ -1645,7 +1653,7 @@ 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;
-- 
2.19.1