Start using libglnx

The high level goal is to deprecate libgsystem.  I was trying to share
code between ostree/rpm-ostree, but it was too painful to commit to
forver frozen ABI for new utility APIs.

The git submodule approach will much more easily allow breaking
API/ABI, and iterate on APIs until they either land in GLib or not.

Note that libglnx will not use GFile*, so a full port to it will
involve also not using that.  Thus, it will be necessarily
incremental; in the meantime we'll link to both libgsystem and
libglnx.

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "libglnx"]
+	path = libglnx
+	url = https://git.gnome.org/browse/libglnx

Makefile-rpm-ostree.am

@@ -46,8 +46,8 @@ librpmostree_la_SOURCES += \
 	src/rpmostree-treepkgdiff.h \
 	$(NULL)
 endif
-librpmostree_la_CFLAGS = $(AM_CFLAGS) -I$(srcdir)/src -DPKGLIBDIR=\"$(pkglibdir)\" $(PKGDEP_RPMOSTREE_CFLAGS)
+librpmostree_la_CFLAGS = $(AM_CFLAGS) -I$(srcdir)/src -I$(libglnx_srcpath) -DPKGLIBDIR=\"$(pkglibdir)\" $(PKGDEP_RPMOSTREE_CFLAGS)
-librpmostree_la_LIBADD = $(AM_LDFLAGS) $(PKGDEP_RPMOSTREE_LIBS) $(CAP_LIBS)
+librpmostree_la_LIBADD = $(AM_LDFLAGS) $(PKGDEP_RPMOSTREE_LIBS) libglnx.la $(CAP_LIBS)
 
 rpm_ostree_SOURCES = src/main.c \
 	src/rpmostree-builtins.h \
@@ -70,7 +70,7 @@ rpm_ostree_SOURCES += \
 	$(NULL)
 endif
 
-rpm_ostree_CFLAGS = $(AM_CFLAGS) -I$(srcdir)/src -DPKGLIBDIR=\"$(pkglibdir)\" $(PKGDEP_RPMOSTREE_CFLAGS)
+rpm_ostree_CFLAGS = $(AM_CFLAGS) -I$(srcdir)/src -I$(libglnx_srcpath) -DPKGLIBDIR=\"$(pkglibdir)\" $(PKGDEP_RPMOSTREE_CFLAGS)
 rpm_ostree_LDADD = $(AM_LDFLAGS) $(PKGDEP_RPMOSTREE_LIBS) librpmostree.la
 
 privdatadir=$(pkglibdir)

Makefile.am

@@ -29,6 +29,12 @@ AM_CFLAGS += $(WARN_CFLAGS)
 
 EXTRA_DIST += autogen.sh COPYING
 
+libglnx_srcpath := $(srcdir)/libglnx
+libglnx_cflags := $(PKGDEP_GIO_UNIX_CFLAGS) -I$(libglnx_srcpath)
+libglnx_libs := $(PKGDEP_GIO_UNIX_LIBS)
+
+include libglnx/Makefile-libglnx.am
+noinst_LTLIBRARIES += libglnx.la
 include Makefile-rpm-ostree.am
 include Makefile-tests.am
 include Makefile-man.am

libglnx

@@ -0,0 +1 @@
+Subproject commit ba67dd39a7d5cc779f83bb22512740cdb4c61b33

src/rpmostree-cleanup.h

@@ -34,6 +34,7 @@
 #include "rpmostree-util.h"
 
 #include "libgsystem.h"
+#include "libglnx.h"
 
 GS_DEFINE_CLEANUP_FUNCTION0(HySack, _cleanup_hy_sack_free, hy_sack_free);
 GS_DEFINE_CLEANUP_FUNCTION0(HyQuery, _cleanup_hy_query_free, hy_query_free);

src/rpmostree-compose-builtin-tree.c

@@ -27,6 +27,7 @@
 #include <libhif.h>
 #include <libhif/hif-utils.h>
 #include <stdio.h>
+#include <libglnx.h>
 #include <rpm/rpmmacro.h>
 
 #include "rpmostree-compose-builtins.h"
@@ -87,6 +88,7 @@ typedef struct {
   GPtrArray *treefile_context_dirs;
   
   GFile *workdir;
+  int workdir_dfd;
   OstreeRepo *repo;
   char *previous_checksum;
 
@@ -595,7 +597,6 @@ rpmostree_compose_builtin_tree (int             argc,
   gs_unref_object GFile *previous_root = NULL;
   gs_free char *previous_checksum = NULL;
   gs_unref_object GFile *yumroot = NULL;
-  gs_unref_object GFile *targetroot = NULL;
   gs_unref_object GFile *yumroot_varcache = NULL;
   gs_unref_object OstreeRepo *repo = NULL;
   gs_unref_ptrarray GPtrArray *bootstrap_packages = NULL;
@@ -703,6 +704,10 @@ rpmostree_compose_builtin_tree (int             argc,
         }
     }
 
+  if (!glnx_opendirat (AT_FDCWD, gs_file_get_path_cached (self->workdir),
+                       FALSE, &self->workdir_dfd, error))
+    goto out;
+
   if (opt_cachedir)
     {
       cachedir = g_file_new_for_path (opt_cachedir);
@@ -717,12 +722,9 @@ rpmostree_compose_builtin_tree (int             argc,
         goto out;
     }
 
-  if (chdir (gs_file_get_path_cached (self->workdir)) != 0)
+  if (fchdir (self->workdir_dfd) != 0)
     {
-      g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,
+      glnx_set_error_from_errno (error);
-                   "Failed to chdir to '%s': %s",
-                   gs_file_get_path_cached (self->workdir),
-                   strerror (errno));
       goto out;
     }
 
@@ -782,9 +784,8 @@ rpmostree_compose_builtin_tree (int             argc,
   self->previous_checksum = previous_checksum;
 
   yumroot = g_file_get_child (self->workdir, "rootfs.tmp");
-  if (!gs_shutil_rm_rf (yumroot, cancellable, error))
+  if (!glnx_shutil_rm_rf_at (self->workdir_dfd, "rootfs.tmp", cancellable, error))
     goto out;
-  targetroot = g_file_get_child (self->workdir, "rootfs");
 
   if (json_object_has_member (treefile, "automatic_version_prefix") &&
       !compose_strv_contains_prefix (opt_metadata_strings, "version="))