signal: Add 'signal block' support

This allows a signal to be blocked by setting it's handler to SIG_IGN

Can be used to block SIGPIPE for exec

Signed-off-by: Steve Bennett <steveb@workware.net.au>

1 files changed, 25 insertions, 7 deletions

diff --git a/tests/exec2.test b/tests/exec2.test
index 08f3d11..b4b42cc 100644
--- a/tests/exec2.test
+++ b/tests/exec2.test
@@ -5,12 +5,15 @@
 source [file dirname [info script]]/testing.tcl
 
 needs cmd exec
+foreach i {pipe signal wait} {
+	testConstraint $i [expr {[info commands $i] ne ""}]
+}
 # Some Windows platforms (e.g. AppVeyor) produce ENOSPC rather than killing
 # the child with SIGPIPE). So turn off this test for that platform
-if {[info commands pipe] ne "" && [env MSYSTEM ""] ne "MINGW32"} {
-	testConstraint pipe 1
+if {[info exists env(MSYSTEM)] && $env(MSYSTEM) eq "MINGW32"} {
+	testConstraint nomingw32 0
 } else {
-	testConstraint pipe 0
+	testConstraint nomingw32 1
 }
 
 set d \"
@@ -58,7 +61,7 @@ test exec2-3.1 "close pipeline return value" {
 	list $rc $msg $status $exitcode
 } {1 {child process exited abnormally} CHILDSTATUS 1}
 
-test exec2-3.2 "close pipeline return value" -constraints pipe -body {
+test exec2-3.2 "close pipeline return value" -constraints {pipe nomingw32} -body {
 	# Create a pipe and immediately close the read end
 	lassign [pipe] r w
 	close $r
@@ -71,7 +74,23 @@ test exec2-3.2 "close pipeline return value" -constraints pipe -body {
 	list $rc $msg $status $exitcode
 } -match glob -result {1 {child killed*} CHILDKILLED SIGPIPE}
 
-test exec2-3.4 "wait for background task" {
+test exec2-3.3 "close pipeline with SIGPIPE blocked" -constraints {pipe signal nomingw32} -body {
+	# Create a pipe and immediately close the read end
+	lassign [pipe] r w
+	close $r
+	signal block SIGPIPE
+	# Write more than 64KB which is maximum size of the pipe buffers
+	# on all systems we have seen
+	set bigstring [string repeat a 100000]
+	set f [open [list |cat << $bigstring >$@w 2>/dev/null]]
+	set rc [catch {close $f} msg opts]
+	lassign [dict get $opts -errorcode] status pid exitcode
+	list $rc $msg $status $exitcode
+} -match glob -result {1 {child process exited*} CHILDSTATUS 1} -cleanup {
+	signal default SIGPIPE
+}
+
+test exec2-3.4 "wait for background task" -constraints wait -body {
 	set pid [exec sleep 0.1 &]
 	lassign [wait $pid] status newpid exitcode
 	if {$pid != $newpid} {
@@ -79,7 +98,6 @@ test exec2-3.4 "wait for background task" {
 	} else {
 		list $status $exitcode
 	}
-} {CHILDSTATUS 0}
-
+} -result {CHILDSTATUS 0}
 
 testreport