Re: [PATCH v4 14/30] util: new functions to support adding individual firewall rollback commands

In the past virFirewall required all rollback commands for a group (those commands necessary to "undo" any rules that had been added in that group in case of a later failure) to be manually added by switching into the virFirewall object into "rollback mode" and then re-calling the inverse of the exact virFirewallAddCmd*() APIs that had been called to add the original rules (ie. for each "iptables --insert" command, for rollback we would need to add a command with all arguments identical except that "--insert" would be replaced by "--delete"). Because nftables can't search for rules to remove by comparing all the arguments (it instead expects *only* a handle that is provided via stdout when the rule was originally added), we won't be able to follow the iptables method and manually construct the command to undo any given nft command by just duplicating all the args of the command (except the action). Instead we will need to be able to automatically create a rollback command at the time the rule-adding command is executed (e.g. an "nft delete rule" command that would include the rule handle returned in stdout by an "nft add rule" command). In order to make this happen, we need to be able to 1) learn whether the user of the virFirewall API desires this behavior (handled by a new transaction flag called VIR_FIREWALL_TRANSACTION_AUTO_ROLLBACK that can be retrieved with the new virFirewallTransactionGetFlags() API), and 2) add a new command to the current group's rollback command list (with the new virFirewallAddRollbackCmd()). We will actually use this capability in an upcoming patch. Signed-off-by: Laine Stump <laine(a)redhat.com&gt; --- src/libvirt_private.syms | 1 + src/util/virfirewall.c | 55 +++++++++++++++++++++++++++++++++++----- src/util/virfirewall.h | 7 +++++ 3 files changed, 57 insertions(+), 6 deletions(-)