[PATCH] configure: actually disable 'git_update' mode with --disable-git-update

[Dan Streetman]

The --disable-git-update configure param sets git_update=no, but
some later checks only look for the .git dir. This changes the
--enable-git-update to set git_update=yes but also fail if it
does not find a .git dir. Then all the later checks for the .git
dir can just be changed to a check for $git_update = "yes".

Also update the Makefile to skip the 'git_update' checks if it has
been disabled.

This is needed because downstream packagers, e.g. Debian, Ubuntu, etc,
also keep the source code in git, but do not want to enable the
'git_update' mode; with the current code, that's not possible even
if the downstream package specifies --disable-git-update.

Signed-off-by: Dan Streetman <ddstreet@canonical.com>
---
Note this is a rebased resend of a previous email to qemu-trivial:
https://lists.nongnu.org/archive/html/qemu-trivial/2020-07/msg00180.html

 Makefile  | 15 +++++++++------
 configure | 21 +++++++++++++--------
 2 files changed, 22 insertions(+), 14 deletions(-)

diff --git a/Makefile b/Makefile
index c2120d8d48..42550ae086 100644
--- a/Makefile
+++ b/Makefile
@@ -25,6 +25,8 @@ git-submodule-update:
 
 .PHONY: git-submodule-update
 
+# If --disable-git-update specified, skip these git checks
+ifneq (no,$(GIT_UPDATE))
 git_module_status := $(shell \
   cd '$(SRC_PATH)' && \
   GIT="$(GIT)" ./scripts/git-submodule.sh status $(GIT_SUBMODULES); \
@@ -32,7 +34,12 @@ git_module_status := $(shell \
 )
 
 ifeq (1,$(git_module_status))
-ifeq (no,$(GIT_UPDATE))
+ifeq (yes,$(GIT_UPDATE))
+git-submodule-update:
+       $(call quiet-command, \
+          (cd $(SRC_PATH) && GIT="$(GIT)" ./scripts/git-submodule.sh update 
$(GIT_SUBMODULES)), \
+          "GIT","$(GIT_SUBMODULES)")
+else
 git-submodule-update:
        $(call quiet-command, \
             echo && \
@@ -41,11 +48,7 @@ git-submodule-update:
             echo "from the source directory checkout $(SRC_PATH)" && \
             echo && \
             exit 1)
-else
-git-submodule-update:
-       $(call quiet-command, \
-          (cd $(SRC_PATH) && GIT="$(GIT)" ./scripts/git-submodule.sh update 
$(GIT_SUBMODULES)), \
-          "GIT","$(GIT_SUBMODULES)")
+endif
 endif
 endif
 
diff --git a/configure b/configure
index 2acc4d1465..e7a241e971 100755
--- a/configure
+++ b/configure
@@ -318,7 +318,7 @@ then
     git_submodules="$git_submodules tests/fp/berkeley-testfloat-3"
     git_submodules="$git_submodules tests/fp/berkeley-softfloat-3"
 else
-    git_update=no
+    git_update=""
     git_submodules=""
 
     if ! test -f "$source_path/ui/keycodemapdb/README"
@@ -1598,7 +1598,12 @@ for opt do
   ;;
   --with-git=*) git="$optarg"
   ;;
-  --enable-git-update) git_update=yes
+  --enable-git-update)
+      git_update=yes
+      if test ! -e "$source_path/.git"; then
+          echo "ERROR: cannot --enable-git-update without .git"
+          exit 1
+      fi
   ;;
   --disable-git-update) git_update=no
   ;;
@@ -2011,7 +2016,7 @@ fi
 # Consult white-list to determine whether to enable werror
 # by default.  Only enable by default for git builds
 if test -z "$werror" ; then
-    if test -e "$source_path/.git" && \
+    if test "$git_update" = "yes" && \
         { test "$linux" = "yes" || test "$mingw32" = "yes"; }; then
         werror="yes"
     else
@@ -4412,10 +4417,10 @@ EOF
     fdt=system
   else
       # have GIT checkout, so activate dtc submodule
-      if test -e "${source_path}/.git" ; then
+      if test "$git_update" = "yes" ; then
           git_submodules="${git_submodules} dtc"
       fi
-      if test -d "${source_path}/dtc/libfdt" || test -e "${source_path}/.git" 
; then
+      if test -d "${source_path}/dtc/libfdt" || test "$git_update" = "yes" ; 
then
           fdt=git
           mkdir -p dtc
           if [ "$pwd_is_source_path" != "y" ] ; then
@@ -5385,7 +5390,7 @@ case "$capstone" in
   "" | yes)
     if $pkg_config capstone; then
       capstone=system
-    elif test -e "${source_path}/.git" && test $git_update = 'yes' ; then
+    elif test "$git_update" = "yes" ; then
       capstone=git
     elif test -e "${source_path}/capstone/Makefile" ; then
       capstone=internal
@@ -6414,7 +6419,7 @@ case "$slirp" in
   "" | yes)
     if $pkg_config slirp; then
       slirp=system
-    elif test -e "${source_path}/.git" && test $git_update = 'yes' ; then
+    elif test "$git_update" = "yes" ; then
       slirp=git
     elif test -e "${source_path}/slirp/Makefile" ; then
       slirp=internal
@@ -6776,7 +6781,7 @@ if test "$cpu" = "s390x" ; then
     roms="$roms s390-ccw"
     # SLOF is required for building the s390-ccw firmware on s390x,
     # since it is using the libnet code from SLOF for network booting.
-    if test -e "${source_path}/.git" ; then
+    if test "$git_update" = "yes" ; then
       git_submodules="${git_submodules} roms/SLOF"
     fi
   fi
-- 
2.25.1