spec: Automatically apply all patches with git

With this change, any patch declared in libvirt.spec with Patch[0-9]* is
automatically applied in %prep. Unlike with the standard %patch[0-9]*,
patches are applied with "git am" to avoid some unexpected results.
However, as a result of this, all patches must be in the right format
for "git am" to be able to apply them; they should ideally be generated
from git using "git format-patch".
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

cfg.mk

@@ -1084,7 +1084,7 @@ exclude_file_name_regexp--sc_prohibit_strdup = \
   ^(docs/|examples/|src/util/virstring\.c|tests/virnetserverclientmock.c$$)
 
 exclude_file_name_regexp--sc_prohibit_close = \
-  (\.p[yl]$$|^docs/|^(src/util/virfile\.c|src/libvirt-stream\.c|tests/vir(cgroup|pci)mock\.c)$$)
+  (\.p[yl]$$|\.spec\.in$$|^docs/|^(src/util/virfile\.c|src/libvirt-stream\.c|tests/vir(cgroup|pci)mock\.c)$$)
 
 exclude_file_name_regexp--sc_prohibit_empty_lines_at_EOF = \
   (^tests/(qemuhelp|nodeinfo|virpcitest)data/|\.diff$$)

libvirt.spec.in

@@ -425,6 +425,7 @@ BuildRequires: gettext-devel
 BuildRequires: libtool
 BuildRequires: /usr/bin/pod2man
 %endif
+BuildRequires: git
 BuildRequires: perl
 BuildRequires: python
 %if %{with_systemd}
@@ -1198,6 +1199,41 @@ driver
 %prep
 %setup -q
 
+# Patches have to be stored in a temporary file because RPM has
+# a limit on the length of the result of any macro expansion;
+# if the string is longer, it's silently cropped
+%{lua:
+    tmp = os.tmpname();
+    f = io.open(tmp, "w+");
+    count = 0;
+    for i, p in ipairs(patches) do
+        f:write(p.."\n");
+        count = count + 1;
+    end;
+    f:close();
+    print("PATCHCOUNT="..count.."\n")
+    print("PATCHLIST="..tmp.."\n")
+}
+
+git init -q
+git config user.name rpm-build
+git config user.email rpm-build
+git config gc.auto 0
+git add .
+git commit -q -a --author 'rpm-build <rpm-build>' \
+           -m '%{name}-%{version} base'
+
+COUNT=$(grep '\.patch$' $PATCHLIST | wc -l)
+if [ $COUNT -ne $PATCHCOUNT ]; then
+    echo "Found $COUNT patches in $PATCHLIST, expected $PATCHCOUNT"
+    exit 1
+fi
+if [ $COUNT -gt 0 ]; then
+    xargs git am <$PATCHLIST || exit 1
+fi
+echo "Applied $COUNT patches"
+rm -f $PATCHLIST
+
 %build
 %if ! %{with_xen}
     %define _without_xen --without-xen