sanity: check for GNU tar specifically

We need the system tar to be GNU tar, as we reply on --xattrs.  Some
distributions may be using libarchive's tar binary, which is definitely
not as featureful, so check for this and abort early with a clear
message instead of later with mysterious errors.

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

diff --git a/meta/classes-global/sanity.bbclass b/meta/classes-global/sanity.bbclass
index 8394213b63ae2981b2cedd65ebb90e91bd0c09e0..a52f2016cc84c9c486e1975f09a1212233f6c532 100644 (file)
--- a/meta/classes-global/sanity.bbclass
+++ b/meta/classes-global/sanity.bbclass
@@ -504,6 +504,14 @@ def check_tar_version(sanity_data):
     version = result.split()[3]
     if bb.utils.vercmp_string_op(version, "1.28", "<"):
         return "Your version of tar is older than 1.28 and does not have the support needed to enable reproducible builds. Please install a newer version of tar (you could use the project's buildtools-tarball from our last release or use scripts/install-buildtools).\n"
+
+    try:
+        result = subprocess.check_output(["tar", "--help"], stderr=subprocess.STDOUT).decode('utf-8')
+        if "--xattrs" not in result:
+            return "Your tar doesn't support --xattrs, please use GNU tar.\n"
+    except subprocess.CalledProcessError as e:
+        return "Unable to execute tar --help, exit code %d\n%s\n" % (e.returncode, e.output)
+
     return None
 
 # We use git parameters and functionality only found in 1.7.8 or later