dependencies: build a host-tar if no suitable tar can be found

Some toolchains, like the one built with buildroot itself, use hardlinks (for
example to link between the c++ and g++ binary). Unpacking such a toolchain
with the --strip-components options does not work correctly if the system tar
is too old (<1.17). Even recent releases of RedHat/CentOS still ship with
tar 1.15.

This patch checks for a suitable tar version (tar 1.17+) on the host system,
and adds host-tar to the host dependencies if none can be found.

host-tar is download and extracted as cpio.gz instead of tar.gz, to prevent
chicken-egg problem.

Signed-off-by: Thomas De Schampheleire <thomas.de.schampheleire@gmail.com>
v4 Acked-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

1 files changed, 35 insertions, 0 deletions

diff --git a/support/dependencies/check-host-tar.sh b/support/dependencies/check-host-tar.sh
new file mode 100755
index 000000000..2cfc2b3cc
--- /dev/null
+++ b/support/dependencies/check-host-tar.sh
@@ -0,0 +1,35 @@
+#!/bin/sh
+
+candidate="$1"
+
+tar=`which $candidate`
+if [ ! -x "$tar" ]; then
+	tar=`which tar`
+	if [ ! -x "$tar" ]; then
+		# echo nothing: no suitable tar found
+		exit 1
+	fi
+fi
+
+# Output of 'tar --version' examples:
+# tar (GNU tar) 1.15.1
+# tar (GNU tar) 1.25
+version=`$tar --version | head -n 1 | sed 's/^.*\s\([0-9]\+\.\S\+\).*$/\1/'`
+major=`echo "$version" | cut -d. -f1`
+minor=`echo "$version" | cut -d. -f2`
+bugfix=`echo "$version" | cut -d. -f3`
+
+# Minimal version = 1.17 (previous versions do not correctly unpack archives
+# containing hard-links if the --strip-components option is used).
+major_min=1
+minor_min=17
+if [ $major -gt $major_min ]; then
+	echo $tar
+else
+	if [ $major -eq $major_min -a $minor -ge $minor_min ]; then
+		echo $tar
+	else
+		# echo nothing: no suitable tar found
+		exit 1
+	fi
+fi