Introduce an LXC specific public API & library

This patch introduces support for LXC specific public APIs. In
common with what was done for QEMU, this creates a libvirt_lxc.so
library and libvirt/libvirt-lxc.h header file.

The actual APIs are

  int virDomainLxcOpenNamespace(virDomainPtr domain,
                                int **fdlist,
                                unsigned int flags);

  int virDomainLxcEnterNamespace(virDomainPtr domain,
                                 unsigned int nfdlist,
                                 int *fdlist,
                                 unsigned int *noldfdlist,
                                 int **oldfdlist,
                                 unsigned int flags);

which provide a way to use the setns() system call to move the
calling process into the container's namespace. It is not
practical to write in a generically applicable manner. The
nearest that we could get to such an API would be an API which
allows to pass a command + argv to be executed inside a
container. Even if we had such a generic API, this LXC specific
API is still useful, because it allows the caller to maintain
the current process context, in particular any I/O streams they
have open.

NB the virDomainLxcEnterNamespace() API is special in that it
runs client side, so does not involve the internal driver API.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

docs/Makefile.am

@@ -95,8 +95,12 @@ qemu_xml = \
   libvirt-qemu-api.xml \
   libvirt-qemu-refs.xml
 
+lxc_xml = \
+  libvirt-lxc-api.xml \
+  libvirt-lxc-refs.xml
+
 apidir = $(pkgdatadir)/api
-api_DATA = libvirt-api.xml libvirt-qemu-api.xml
+api_DATA = libvirt-api.xml libvirt-qemu-api.xml libvirt-lxc-api.xml
 
 fig = \
   libvirt-net-logical.fig \
@@ -133,6 +137,7 @@ all-am: web
 
 api: $(srcdir)/libvirt-api.xml $(srcdir)/libvirt-refs.xml
 qemu_api: $(srcdir)/libvirt-qemu-api.xml $(srcdir)/libvirt-qemu-refs.xml
+lxc_api: $(srcdir)/libvirt-lxc-api.xml $(srcdir)/libvirt-lxc-refs.xml
 
 web: $(dot_html) $(internals_html) html/index.html devhelp/index.html \
   $(dot_php)
@@ -152,7 +157,8 @@ todo:
 	$(MAKE) todo.html
 
 hvsupport.html.in: $(srcdir)/hvsupport.pl $(srcdir)/../src/libvirt_public.syms \
-	 $(srcdir)/../src/libvirt_qemu.syms $(srcdir)/../src/driver.h
+	$(srcdir)/../src/libvirt_qemu.syms $(srcdir)/../src/libvirt_lxc.syms \
+	$(srcdir)/../src/driver.h
 	$(AM_V_GEN)$(PERL) $(srcdir)/hvsupport.pl $(srcdir)/../src > $@ || { rm $@ && exit 1; }
 
 .PHONY: todo
@@ -220,12 +226,16 @@ $(addprefix $(srcdir)/,$(devhelphtml)): $(srcdir)/libvirt-api.xml $(devhelpxsl)
 
 python_generated_files = \
 		$(srcdir)/html/libvirt-libvirt.html \
+		$(srcdir)/html/libvirt-libvirt-lxc.html \
 		$(srcdir)/html/libvirt-libvirt-qemu.html \
 		$(srcdir)/html/libvirt-virterror.html \
 		$(srcdir)/libvirt-api.xml \
 		$(srcdir)/libvirt-refs.xml \
+		$(srcdir)/libvirt-lxc-api.xml \
+		$(srcdir)/libvirt-lxc-refs.xml \
 		$(srcdir)/libvirt-qemu-api.xml \
-		$(srcdir)/libvirt-qemu-refs.xml
+		$(srcdir)/libvirt-qemu-refs.xml \
+		$(NULL)
 
 APIBUILD=$(srcdir)/apibuild.py
 APIBUILD_STAMP=$(APIBUILD).stamp
@@ -235,9 +245,11 @@ $(python_generated_files): $(APIBUILD_STAMP)
 
 $(APIBUILD_STAMP): $(srcdir)/apibuild.py \
 		$(srcdir)/../include/libvirt/libvirt.h.in \
+		$(srcdir)/../include/libvirt/libvirt-lxc.h \
 		$(srcdir)/../include/libvirt/libvirt-qemu.h \
 		$(srcdir)/../include/libvirt/virterror.h \
 		$(srcdir)/../src/libvirt.c \
+		$(srcdir)/../src/libvirt-lxc.c \
 		$(srcdir)/../src/libvirt-qemu.c \
 		$(srcdir)/../src/util/virerror.c
 	$(AM_V_GEN)srcdir=$(srcdir) $(PYTHON) $(APIBUILD)
@@ -252,9 +264,10 @@ clean-local:
 maintainer-clean-local: clean-local
 	rm -rf $(srcdir)/libvirt-api.xml $(srcdir)/libvirt-refs.xml todo.html.in hvsupport.html.in
 	rm -rf $(srcdir)/libvirt-qemu-api.xml $(srcdir)/libvirt-qemu-refs.xml
+	rm -rf $(srcdir)/libvirt-lxc-api.xml $(srcdir)/libvirt-lxc-refs.xml
 	rm -rf $(APIBUILD_STAMP)
 
-rebuild: api qemu_api all
+rebuild: api qemu_api lxc_api all
 
 install-data-local:
 	$(mkinstalldirs) $(DESTDIR)$(HTML_DIR)

docs/apibuild.py

@@ -33,6 +33,11 @@ qemu_included_files = {
   "libvirt-qemu.c": "Implementations for the QEMU specific APIs",
 }
 
+lxc_included_files = {
+  "libvirt-lxc.h": "header with LXC specific API definitions",
+  "libvirt-lxc.c": "Implementations for the LXC specific APIs",
+}
+
 ignored_words = {
   "ATTRIBUTE_UNUSED": (0, "macro keyword"),
   "ATTRIBUTE_SENTINEL": (0, "macro keyword"),
@@ -1945,6 +1950,8 @@ class docBuilder:
             self.includes = includes + included_files.keys()
         elif name == "libvirt-qemu":
             self.includes = includes + qemu_included_files.keys()
+        elif name == "libvirt-lxc":
+            self.includes = includes + lxc_included_files.keys()
         self.modules = {}
         self.headers = {}
         self.idx = index()
@@ -2463,7 +2470,7 @@ class docBuilder:
 
 
 def rebuild(name):
-    if name not in ["libvirt", "libvirt-qemu"]:
+    if name not in ["libvirt", "libvirt-qemu", "libvirt-lxc"]:
         self.warning("rebuild() failed, unknown module %s") % name
         return None
     builder = None
@@ -2506,6 +2513,7 @@ if __name__ == "__main__":
     else:
         rebuild("libvirt")
         rebuild("libvirt-qemu")
+        rebuild("libvirt-lxc")
     if warnings > 0:
         sys.exit(2)
     else:

docs/hvsupport.pl

@@ -11,6 +11,7 @@ my $srcdir = shift @ARGV;
 
 my $symslibvirt = "$srcdir/libvirt_public.syms";
 my $symsqemu = "$srcdir/libvirt_qemu.syms";
+my $symslxc = "$srcdir/libvirt_lxc.syms";
 my $drivertable = "$srcdir/driver.h";
 
 my %groupheaders = (
@@ -112,6 +113,45 @@ while (defined($line = <FILE>)) {
 close FILE;
 
 
+# And the same for the LXC specific APIs
+
+open FILE, "<$symslxc"
+    or die "cannot read $symslxc: $!";
+
+$prevvers = undef;
+$vers = undef;
+while (defined($line = <FILE>)) {
+    chomp $line;
+    next if $line =~ /^\s*#/;
+    next if $line =~ /^\s*$/;
+    next if $line =~ /^\s*(global|local):/;
+    if ($line =~ /^\s*LIBVIRT_LXC_(\d+\.\d+\.\d+)\s*{\s*$/) {
+        if (defined $vers) {
+            die "malformed syms file";
+        }
+        $vers = $1;
+    } elsif ($line =~ /\s*}\s*;\s*$/) {
+        if (defined $prevvers) {
+            die "malformed syms file";
+        }
+        $prevvers = $vers;
+        $vers = undef;
+    } elsif ($line =~ /\s*}\s*LIBVIRT_LXC_(\d+\.\d+\.\d+)\s*;\s*$/) {
+        if ($1 ne $prevvers) {
+            die "malformed syms file $1 != $vers";
+        }
+        $prevvers = $vers;
+        $vers = undef;
+    } elsif ($line =~ /\s*(\w+)\s*;\s*$/) {
+        $apis{$1} = $vers;
+    } else {
+        die "unexpected data $line\n";
+    }
+}
+
+close FILE;
+
+
 # Some special things which aren't public APIs,
 # but we want to report
 $apis{virConnectDrvSupportsFeature} = "0.3.2";