build: honor autogen.sh --no-git

Based on a report by Chandrashekar Shastri, at
https://bugzilla.redhat.com/show_bug.cgi?id=979360

On systems where git cannot access the outside world, a developer
can instead arrange to get a copy of gnulib at the right commit
via side channels (such as NFS share drives), set GNULIB_SRCDIR,
then use ./autogen.sh --no-git.  In this setup, we will now
avoid direct use of git.  Of course, this means no automatic
gnulib updates when libvirt.git updates its submodule, but it
is expected that any developer in such a situation is already
prepared to deal with the fallout.

* .gnulib: Update to latest, for bootstrap.
* bootstrap: Synchronize from gnulib.
* autogen.sh (no_git): Avoid git when requested.
* cfg.mk (_update_required): Skip automatic rerun of bootstrap if
we can't use git.
* docs/compiling.html.in: Document this setup.
* docs/hacking.html.in: Mention this.
* HACKING: Regenerate.

Signed-off-by: Eric Blake <eblake@redhat.com>

.gnulib

@@ -1 +1 @@
-Subproject commit f40e61ea0c4940b027aade7dd48948aa93f133a4
+Subproject commit b72ff2a45efde544c406804186d37a3254728571

HACKING

@@ -36,7 +36,8 @@ developer is:
   git checkout -t origin -b workbranch
   Hack, committing any changes along the way
 
-Then, when you want to post your patches:
+More hints on compiling can be found here <compiling.html>. When you want to
+post your patches:
 
   git pull --rebase
   (fix any conflicts)

autogen.sh

@@ -49,6 +49,10 @@ fi
 # we rerun bootstrap to pull in those diffs.
 bootstrap_hash()
 {
+    if test "$no_git"; then
+        echo no-git
+        return
+    fi
     git submodule status | sed 's/^[ +-]//;s/ .*//'
     git hash-object bootstrap.conf
     git ls-tree -d HEAD gnulib/local | awk '{print $3}'
@@ -62,7 +66,9 @@ bootstrap_hash()
 # Only run bootstrap from a git checkout, never from a tarball.
 if test -d .git; then
     curr_status=.git-module-status t=
-    if test -d .gnulib; then
+    if test "$no_git"; then
+        t=no-git
+    elif test -d .gnulib; then
         t=$(bootstrap_hash; git diff .gnulib)
     fi
     case $t:${CLEAN_SUBMODULE+set} in
@@ -78,7 +84,7 @@ if test -d .git; then
         # good, it's up to date, all we need is autoreconf
         autoreconf -if
     else
-        if test ${CLEAN_SUBMODULE+set}; then
+        if test -z "$no_git" && test ${CLEAN_SUBMODULE+set}; then
             echo cleaning up submodules...
             git submodule foreach 'git clean -dfqx && git reset --hard'
         fi

bootstrap

@@ -1,6 +1,6 @@
 #! /bin/sh
 # Print a version string.
-scriptversion=2013-05-08.20; # UTC
+scriptversion=2013-07-03.20; # UTC
 
 # Bootstrap this package from checked-out sources.
 
@@ -551,7 +551,7 @@ fi
 echo "$0: Bootstrapping from checked-out $package sources..."
 
 # See if we can use gnulib's git-merge-changelog merge driver.
-if test -d .git && (git --version) >/dev/null 2>/dev/null ; then
+if $use_git && test -d .git && (git --version) >/dev/null 2>/dev/null ; then
   if git config merge.merge-changelog.driver >/dev/null ; then
     :
   elif (git-merge-changelog --version) >/dev/null 2>/dev/null ; then
@@ -574,13 +574,17 @@ git_modules_config () {
   test -f .gitmodules && git config --file .gitmodules "$@"
 }
 
-gnulib_path=$(git_modules_config submodule.gnulib.path)
+if $use_git; then
-test -z "$gnulib_path" && gnulib_path=gnulib
+  gnulib_path=$(git_modules_config submodule.gnulib.path)
+  test -z "$gnulib_path" && gnulib_path=gnulib
+fi
 
-# Get gnulib files.
+# Get gnulib files.  Populate $GNULIB_SRCDIR, possibly updating a
+# submodule, for use in the rest of the script.
 
 case ${GNULIB_SRCDIR--} in
 -)
+  # Note that $use_git is necessarily true in this case.
   if git_modules_config submodule.gnulib.url >/dev/null; then
     echo "$0: getting gnulib files..."
     git submodule init || exit $?
@@ -601,8 +605,8 @@ case ${GNULIB_SRCDIR--} in
   GNULIB_SRCDIR=$gnulib_path
   ;;
 *)
-  # Use GNULIB_SRCDIR as a reference.
+  # Use GNULIB_SRCDIR directly or as a reference.
-  if test -d "$GNULIB_SRCDIR"/.git && \
+  if $use_git && test -d "$GNULIB_SRCDIR"/.git && \
         git_modules_config submodule.gnulib.url >/dev/null; then
     echo "$0: getting gnulib files..."
     if git submodule -h|grep -- --reference > /dev/null; then
@@ -628,6 +632,9 @@ case ${GNULIB_SRCDIR--} in
   ;;
 esac
 
+# $GNULIB_SRCDIR now points to the version of gnulib to use, and
+# we no longer need to use git or $gnulib_path below here.
+
 if $bootstrap_sync; then
   cmp -s "$0" "$GNULIB_SRCDIR/build-aux/bootstrap" || {
     echo "$0: updating bootstrap and restarting..."

cfg.mk

@@ -828,6 +828,7 @@ ifeq (0,$(MAKELEVEL))
       test -d .git || { echo 0; exit; };				\
       test -f po/Makevars || { echo 1; exit; };				\
       test -f AUTHORS || { echo 1; exit; };				\
+      test "no-git" = "$$(cat $(_curr_status))" && { echo 0; exit; };	\
       actual=$$(git submodule status | $(_submodule_hash);		\
 		git hash-object bootstrap.conf;				\
 		git ls-tree -d HEAD gnulib/local | awk '{print $$3}';	\

docs/compiling.html.in

@@ -65,8 +65,36 @@
       checkout it is necessary to generate the configure script and Makefile.in
       templates using the <code>autogen.sh</code> command. By default when
       the <code>configure</code> script is run from within a GIT checkout, it
-      will turn on -Werror for builds. This can be disabled with --disable-werror,
+      will turn on -Werror for builds. This can be disabled with
-      but this is not recommended. To build &amp; install libvirt to your home
+      --disable-werror, but this is not recommended.
+    </p>
+    <p>
+      Libvirt takes advantage of
+      the <a href="http://www.gnu.org/software/gnulib/">gnulib</a>
+      project to provide portability to a number of platforms.  This
+      is normally done dynamically via a git submodule in
+      the <code>.gnulib</code> subdirectory, which is auto-updated as
+      needed when you do incremental builds.  Setting the environment
+      variable <code>GNULIB_SRCDIR</code> to a local directory
+      containing a git checkout of gnulib will let you reduce local
+      disk space requirements and network download time, regardless of
+      which actual commit you have in that reference directory.
+    </p>
+    <p>
+      However, if you are developing on a platform where git is not
+      available, or are behind a firewall that does not allow for git
+      to easily obtain the gnulib submodule, it is possible to instead
+      use a static mode of operation where you are then responsible
+      for updating the git submodule yourself.  In this mode, you must
+      track the exact gnulib commit needed by libvirt (usually not the
+      latest gnulib.git) via alternative means, such as a shared NFS
+      drive or manual download, and run this any time libvirt.git
+      updates the commit stored in the .gnulib submodule:</p>
+    <pre>
+      $ GNULIB_SRCDIR=/path/to/gnulib ./autogen.sh --no-git
+    </pre>
+
+    <p>To build &amp; install libvirt to your home
       directory the following commands can be run:
     </p>
 

docs/hacking.html.in

@@ -35,7 +35,9 @@
   git checkout -t origin -b workbranch
   Hack, committing any changes along the way
 </pre>
-        <p>Then, when you want to post your patches:</p>
+        <p>More hints on compiling can be
+        found <a href="compiling.html">here</a>.  When you want to
+        post your patches:</p>
 <pre>
   git pull --rebase
   (fix any conflicts)