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.

1 files changed, 6 insertions, 0 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_()