Handle SIGPIPE when unpack() extracts tar files through a pipe (bug #309001).

When checking ${PIPESTATUS[@]} for extraction of tar files in unpack(),
use a new assert_sigpipe_ok() function which behaves the same as the
existing assert() function except that it tolerates pipe writers being
killed by SIGPIPE.

3 files changed, 31 insertions, 3 deletions

diff --git a/bin/ebuild.sh b/bin/ebuild.sh
index 84a83fe40..b2ac5b419 100755
--- a/bin/ebuild.sh
+++ b/bin/ebuild.sh
@@ -348,7 +348,7 @@ unpack() {
 		_unpack_tar() {
 			if [ "${y}" == "tar" ]; then
 				$1 -dc "$srcdir$x" | tar xof -
-				assert "$myfail"
+				assert_sigpipe_ok "$myfail"
 			else
 				$1 -dc "${srcdir}${x}" > ${x%.*} || die "$myfail"
 			fi
@@ -364,7 +364,7 @@ unpack() {
 				;;
 			tbz|tbz2)
 				bzip2 -dc "$srcdir$x" | tar xof -
-				assert "$myfail"
+				assert_sigpipe_ok "$myfail"
 				;;
 			ZIP|zip|jar)
 				unzip -qo "${srcdir}${x}" || die "$myfail"
diff --git a/bin/isolated-functions.sh b/bin/isolated-functions.sh
index 53312dba8..a490f27c0 100644
--- a/bin/isolated-functions.sh
+++ b/bin/isolated-functions.sh
@@ -15,6 +15,32 @@ assert() {
 	done
 }
 
+assert_sigpipe_ok() {
+	# When extracting a tar file like this:
+	#
+	#     bzip2 -dc foo.tar.bz2 | tar xof -
+	#
+	# For some tar files (see bug #309001), tar will
+	# close its stdin pipe when the decompressor still has
+	# remaining data to be written to its stdout pipe. This
+	# causes the decompressor to be killed by SIGPIPE. In
+	# this case, we want to ignore pipe writers killed by
+	# SIGPIPE, and trust the exit status of tar. We refer
+	# to the bash manual section "3.7.5 Exit Status"
+	# which says, "When a command terminates on a fatal
+	# signal whose number is N, Bash uses the value 128+N
+	# as the exit status."
+
+	local x pipestatus=${PIPESTATUS[*]}
+	for x in $pipestatus ; do
+		# Allow SIGPIPE through (128 + 13)
+		[[ $x -ne 0 && $x -ne 141 ]] && die "$@"
+	done
+
+	# Require normal success for the last process (tar).
+	[[ $x -eq 0 ]] || die "$@"
+}
+
 shopt -s extdebug
 
 # dump_trace([number of funcs on stack to skip],
diff --git a/pym/_emerge/BinpkgExtractorAsync.py b/pym/_emerge/BinpkgExtractorAsync.py
index a4941fccf..3a2654ec1 100644
--- a/pym/_emerge/BinpkgExtractorAsync.py
+++ b/pym/_emerge/BinpkgExtractorAsync.py
@@ -12,10 +12,12 @@ class BinpkgExtractorAsync(SpawnProcess):
 	_shell_binary = portage.const.BASH_BINARY
 
 	def _start(self):
+		# SIGPIPE handling (status 141) should be compatible with
+		# assert_sigpipe_ok() that's used by the ebuild unpack() helper.
 		self.args = [self._shell_binary, "-c",
 			("bzip2 -dqc -- %s | tar -xp -C %s -f - ; " + \
 			"p=(${PIPESTATUS[@]}) ; " + \
-			"if [ ${p[0]} != 0 ] ; then " + \
+			"if [[ ${p[0]} != 0 && ${p[0]} != 141 ]] ; then " + \
 			"echo bzip2 failed with status ${p[0]} ; exit ${p[0]} ; fi ; " + \
 			"if [ ${p[1]} != 0 ] ; then " + \
 			"echo tar failed with status ${p[1]} ; exit ${p[1]} ; fi ; " + \