ovs-brcompatd: Run ovs-vsctl instead of accessing database directly.

ovs-vsctl is carefully written to avoid races in database access.  It is
much simpler to just call it than to reimplement its capabilities.

This eliminates the requirement that bridges managed by ovs-brcompatd have
no ports at ovs-brcompatd startup time.  It also eliminates races between
competing brctl and ovs-vsctl processes.

ChangeLog

@@ -4,6 +4,7 @@ post v1.1.0
       counters for each port.
     - ovs-vsctl:
       - New "show" command to print an overview of configuration.
+    - ovs-brcompatd has been rewritten to fix long-standing bugs.
     - ovs-openflowd has been renamed test-openflowd and moved into the
       tests directory.  Its presence confused too many users.  Please
       use ovs-vswitchd instead.

vswitchd/ovs-brcompatd.8.in

@@ -6,7 +6,7 @@ ovs\-brcompatd \- Bridge compatibility front-end for ovs\-vswitchd
 .
 .SH SYNOPSIS
 .B ovs\-brcompatd
-[\fIoptions\fR] \fIdatabase\fR
+[\fIoptions\fR]
 .
 .SH DESCRIPTION
 A daemon that provides a legacy bridge front-end for \fBovs\-vswitchd\fR.  It
@@ -14,48 +14,32 @@ does this by listening for bridge ioctl commands (e.g., those generated by
 the \fBbrctl\fR program) to add or remove datapaths and the interfaces
 that attach to them.
 .PP
-The mandatory \fIdatabase\fR argument specifies the
-\fBovsdb\-server\fR from which \fBovs\-vswitchd\fR's configuration is
-retrieved.  It should take the form \fBunix:\fIfile\fR, to connect to
-the Unix domain server socket named \fIfile\fR.
-.PP
 .SH OPTIONS
-.IP "\fB\-\-appctl\-command=\fIcommand\fR"
-Sets the command that \fBovs\-brcompatd\fR runs to communicate with
-\fBovs\-vswitchd\fR.  The command is run in \fB/bin/sh\fR as a shell
-command, so \fIcommand\fR may contain arbitrary shell metacharacters,
-etc.  The \fB\-\-help\fR option displays the default command.
-.IP
-\fIcommand\fR must contain exactly one instance of \fB%s\fR, which
-\fBovs\-brcompatd\fR replaces by a command from the set understood by
-\fBovs\-vswitchd\fR.  Any instances of \fB%%\fR in \fIcommand\fR are
-replaced by a single \fB%\fR.  The \fB%\fR character may not otherwise
-appear in \fIcommand\fR.
-.IP
-The commands that are substituted into \fIcommand\fR are those that
-can be listed by passing \fBhelp\fR to \fBovs\-appctl\fR with
-\fBovs\-vswitchd\fR as target.
-.IP
-\fIcommand\fR must not redirect \fBovs\-appctl\fR's standard output or
-standard error streams, because \fBovs\-brcompatd\fR expects to read
-both of these streams separately.
+.IP "\fB\-\-appctl=\fIprogram\fR"
+Sets the name to the program that \fBovs\-brcompatd\fR runs to
+communicate with \fBovs\-vswitchd\fR.  The default is
+\fBovs\-appctl\fR.  Unless \fIprogram\fR contains \fB/\fR,
+\fBovs\-brcompatd\fR will search the \fBPATH\fR environment variable
+to find it.
+.
+.IP "\fB\-\-vsctl=\fIprogram\fR"
+Sets the name to the program that \fBovs\-brcompatd\fR runs to
+communicate with \fBovsdb\-server\fR.  The default is
+\fBovs\-vsctl\fR.  Unless \fIprogram\fR contains \fB/\fR,
+\fBovs\-brcompatd\fR will search the \fBPATH\fR environment variable
+to find it.
 .
 .so lib/daemon.man
 .so lib/vlog.man
 .so lib/common.man
 .so lib/leak-checker.man
 .
-.SH BUGS
-.
-\fBovs\-brcompatd\fR requires the bridges that it manages to initially
-have no ports listed in their database records when it starts up.
-Otherwise, it may add duplicate ports to bridges.
-.
 .SH NOTES
 \fBovs\-brcompatd\fR requires the \fBbrcompat_mod.ko\fR kernel module to be
 loaded.
 .SH "SEE ALSO"
 .BR ovs\-appctl (8),
+.BR ovs\-vsctl (8),
 .BR ovs\-vswitchd (8),
 .BR ovsdb\-server (1),
 \fBINSTALL.bridge\fR in the Open vSwitch distribution.