test supported zfs send options

bin/zfs-autobackup

@@ -855,10 +855,17 @@ class ZfsDataset():
         cmd.extend(["zfs", "send",  ])
 
         #all kind of performance options:
+        if "-L" in self.zfs_node.supported_send_options:
             cmd.append("-L") # large block support
+
+        if "-e" in self.zfs_node.supported_send_options:
             cmd.append("-e") # WRITE_EMBEDDED, more compact stream
+
+        if "-c" in self.zfs_node.supported_send_options:
             cmd.append("-c") # use compressed WRITE records
+
         if not resume:
+            if "-D" in self.zfs_node.supported_send_options:
                 cmd.append("-D") # dedupped stream, sends less duplicate data
 
         #raw? (for encryption)
@@ -1267,6 +1274,28 @@ class ZfsNode(ExecuteNode):
 
         ExecuteNode.__init__(self, ssh_config=ssh_config, ssh_to=ssh_to, readonly=readonly, debug_output=debug_output)
 
+    @cached_property
+    def supported_send_options(self):
+        """list of supported options, for optimizing sends"""
+        #not every zfs implementation supports them all
+
+        ret=[]
+        for option in ["-L", "-e", "-c" , "-D" ]:
+            if self.valid_command(["zfs","send", option, "zfs_autobackup_option_test"]):
+                ret.append(option)
+        return(ret)
+
+
+    def valid_command(self, cmd):
+        """test if a specified zfs options are valid exit code. use this to determine support options"""
+
+        try:
+            self.run(cmd, hide_errors=True, valid_exitcodes=[0,1])
+        except subprocess.CalledProcessError as e:
+            return False
+
+        return True
+
 
     def reset_progress(self):
         """reset progress output counters"""

test_zfsnode.py

@@ -91,6 +91,23 @@ test_target1
  (local): test_source2/fs2/sub]""")
 
 
+    def test_validcommand(self):
+        logger=Logger()
+        description="[Source]"
+        node=ZfsNode("test", logger, description=description)
+
+
+        with self.subTest("test invalid option"):
+            self.assertFalse(node.valid_command(["zfs", "send", "--invalid-option", "nonexisting"]))
+        with self.subTest("test valid option"):
+            self.assertTrue(node.valid_command(["zfs", "send", "-v", "nonexisting"]))
+
+    def test_supportedsendoptions(self):
+        logger=Logger()
+        description="[Source]"
+        node=ZfsNode("test", logger, description=description)
+        print(node.supported_send_options)
+