Add ostree composefs-generate command

This allows you to build a composefs based on a single commit, or
by unioning several commits on top of each others.

Makefile-ostree.am

@@ -27,6 +27,7 @@ ostree_SOURCES = src/ostree/main.c \
 	src/ostree/ot-builtin-checkout.c \
 	src/ostree/ot-builtin-checksum.c \
 	src/ostree/ot-builtin-commit.c \
+	src/ostree/ot-builtin-composefs.c \
 	src/ostree/ot-builtin-create-usb.c \
 	src/ostree/ot-builtin-diff.c \
 	src/ostree/ot-builtin-export.c \

bash/ostree

@@ -292,6 +292,55 @@ _ostree_checkout() {
     return 0
 }
 
+_ostree_composefs_generate() {
+    local boolean_options="
+        $main_boolean_options
+        --from-stdin
+        --union-add
+        --union-identical
+        --whiteouts
+    "
+
+    local options_with_args="
+        --from-file
+        --repo
+        --subpath
+    "
+
+    local options_with_args_glob=$( __ostree_to_extglob "$options_with_args" )
+
+    case "$prev" in
+        --from-file)
+            __ostree_compreply_all_files
+            return 0
+            ;;
+        --repo|--subpath)
+            __ostree_compreply_dirs_only
+            return 0
+            ;;
+        $options_with_args_glob )
+            return 0
+            ;;
+    esac
+
+    case "$cur" in
+        -*)
+            local all_options="$boolean_options $options_with_args"
+            __ostree_compreply_all_options
+            ;;
+        *)
+            local argpos=$( __ostree_pos_first_nonflag $( __ostree_to_alternatives "$options_with_args" ) )
+
+            if [ $cword -eq $argpos ]; then
+                __ostree_compreply_commits
+            elif [ $cword -eq $(($argpos + 1)) ]; then
+                __ostree_compreply_all_files
+            fi
+    esac
+
+    return 0
+}
+
 _ostree_checksum() {
     local boolean_options="
         $main_boolean_options
@@ -1852,6 +1901,7 @@ _ostree() {
         checkout
         checksum
         commit
+        composefs-generate
         config
         create-usb
         diff

man/ostree-composefs-generate.xml

@@ -0,0 +1,125 @@
+<?xml version='1.0'?> <!--*-nxml-*-->
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
+    "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+
+<!--
+Copyright 2014 Anne LoVerso <[email protected]>
+
+SPDX-License-Identifier: LGPL-2.0+
+
+This library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Lesser General Public
+License as published by the Free Software Foundation; either
+version 2 of the License, or (at your option) any later version.
+
+This library is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public
+License along with this library. If not, see <https://www.gnu.org/licenses/>.
+-->
+
+<refentry id="ostree">
+
+    <refentryinfo>
+        <title>ostree composefs-generate</title>
+        <productname>OSTree</productname>
+
+        <authorgroup>
+            <author>
+                <contrib>Developer</contrib>
+                <firstname>Colin</firstname>
+                <surname>Walters</surname>
+                <email>[email protected]</email>
+            </author>
+        </authorgroup>
+    </refentryinfo>
+
+    <refmeta>
+        <refentrytitle>ostree composefs-generate</refentrytitle>
+        <manvolnum>1</manvolnum>
+    </refmeta>
+
+    <refnamediv>
+        <refname>ostree-composefs-generate</refname>
+        <refpurpose>Create a composefs image out of commits</refpurpose>
+    </refnamediv>
+
+    <refsynopsisdiv>
+            <cmdsynopsis>
+                <command>ostree composefs-generate</command> <arg choice="opt" rep="repeat">OPTIONS</arg> <arg choice="req">COMMIT</arg> <arg choice="opt">DESTINATION</arg>
+            </cmdsynopsis>
+    </refsynopsisdiv>
+
+    <refsect1>
+        <title>Description</title>
+
+        <para>
+            Creates a composefs image out the given commit(s) into the filesystem under directory DESTINATION.  If DESTINATION is not specified, the COMMIT will become the destination checkout target.
+        </para>
+    </refsect1>
+
+    <refsect1>
+        <title>Options</title>
+
+        <variablelist>
+
+            <varlistentry>
+                <term><option>--subpath</option>="PATH"</term>
+
+                <listitem><para>
+                    Checkout sub-directory PATH.
+                </para></listitem>
+            </varlistentry>
+
+            <varlistentry>
+                <term><option>--union-add</option></term>
+
+                <listitem><para>
+                    When combining multiple commits, keep existing files. The default is to overwrite existing files.
+                </para></listitem>
+            </varlistentry>
+
+            <varlistentry>
+                <term><option>--union-identical</option></term>
+
+                <listitem><para>When combining multiple commits, error out
+                if a file would be replaced with a different file. Add new files
+                and directories, ignore identical files, and keep existing
+                directories.
+            </varlistentry>
+
+            <varlistentry>
+                <term><option>--whiteouts</option></term>
+
+                <listitem><para>
+                    Process whiteout files (Docker style).
+                </para></listitem>
+            </varlistentry>
+
+            <varlistentry>
+                <term><option>--from-stdin</option></term>
+
+                <listitem><para>
+                    Process many checkouts from standard input.
+                </para></listitem>
+            </varlistentry>
+
+            <varlistentry>
+                <term><option>--from-file</option>="FILE"</term>
+
+                <listitem><para>
+                    Process many checkouts from input file.
+                </para></listitem>
+            </varlistentry>
+
+        </variablelist>
+    </refsect1>
+
+    <refsect1>
+        <title>Example</title>
+        <para><command>$ ostree composefs-generate --repo=/my/repo my-branch image.cfs</command></para>
+    </refsect1>
+</refentry>

src/ostree/main.c

@@ -51,6 +51,9 @@ static OstreeCommand commands[] = {
   { "commit", OSTREE_BUILTIN_FLAG_NONE,
     ostree_builtin_commit,
     "Commit a new revision" },
+  { "composefs-generate", OSTREE_BUILTIN_FLAG_NONE,
+    ostree_builtin_composefs_generate,
+    "Create a composefs image from a commit" },
   { "config", OSTREE_BUILTIN_FLAG_NONE,
     ostree_builtin_config,
     "Change repo configuration settings" },