[PATCH] build: export GIT_CEILING_DIRECTORIES for package builds

[Jeffery To]

A package may run git as part of its build process, and if the package
source code is not from a git checkout, then git may traverse up the
directory tree to find buildroot's repository directory (.git).

For instance, Poetry Core, a Python build backend, will read the
contents of .gitignore for paths to exclude when creating a Python
package. If it finds buildroot's .gitignore file, then Poetry Core will
exclude all of the package's files[1].

This exports GIT_CEILING_DIRECTORIES for both package and host builds so
that git will not traverse beyond $(BUILD_DIR)/$(BUILD_DIR_HOST).

[1]: https://github.com/python-poetry/poetry/issues/5547

Signed-off-by: Jeffery To <jeffery.to at gmail.com>
---
 include/host-build.mk | 1 +
 include/package.mk    | 1 +
 2 files changed, 2 insertions(+)

diff --git a/include/host-build.mk b/include/host-build.mk
index b7fb0a737f14..7485f91e422e 100644
--- a/include/host-build.mk
+++ b/include/host-build.mk
@@ -131,6 +131,7 @@ define Host/Exports/Default
   $(1) : export STAGING_PREFIX=$$(HOST_BUILD_PREFIX)
   $(1) : export PKG_CONFIG_PATH=$$(STAGING_DIR_HOST)/lib/pkgconfig:$$(HOST_BUILD_PREFIX)/lib/pkgconfig
   $(1) : export PKG_CONFIG_LIBDIR=$$(HOST_BUILD_PREFIX)/lib/pkgconfig
+  $(1) : export GIT_CEILING_DIRECTORIES=$$(BUILD_DIR_HOST)
   $(if $(HOST_CONFIG_SITE),$(1) : export CONFIG_SITE:=$(HOST_CONFIG_SITE))
   $(if $(IS_PACKAGE_BUILD),$(1) : export PATH=$$(TARGET_PATH_PKG))
 endef
diff --git a/include/package.mk b/include/package.mk
index f03cb15f05d5..c391d320aa2c 100644
--- a/include/package.mk
+++ b/include/package.mk
@@ -194,6 +194,7 @@ define Build/Exports/Default
   $(1) : export CONFIG_SITE:=$$(CONFIG_SITE)
   $(1) : export PKG_CONFIG_PATH:=$$(PKG_CONFIG_PATH)
   $(1) : export PKG_CONFIG_LIBDIR:=$$(PKG_CONFIG_PATH)
+  $(1) : export GIT_CEILING_DIRECTORIES:=$$(BUILD_DIR)
 endef
 Build/Exports=$(Build/Exports/Default)
 
-- 
2.39.2