build system: try to find a more precise EXTRAVERSION

The default EXTRAVERSION is .git.  Use some clues to determine a
more precise EXTRAVERSION:

- git describe

- A .frp_describe file embedded in the release tarball

- The name of the build directory:  tarballs of release tags from
  GitLab and GitHub include the version in the directory name.

2 files changed, 34 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
index a4031f6ec..9055b745e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -63,3 +63,8 @@ TAGS
 # user-supplied scripts
 #
 /embed
+
+#
+# release description for tarball
+#
+.frp_describe
diff --git a/Makefile b/Makefile
index 9dd359244..36d66d2d0 100644
--- a/Makefile
+++ b/Makefile
@@ -368,6 +368,35 @@ AFLAGS		:= $(AFLAGS)
 LDFLAGS         := $(LDFLAGS)
 LDLIBS          :=
 
+CONFIG_PLATFORM_MINGW32 ?=
+ifeq ($(CONFIG_PLATFORM_MINGW32),)
+CONFIG_PLATFORM_MINGW32 := $(shell grep ^CONFIG_PLATFORM_MINGW32= .config 2>/dev/null)
+CONFIG_PLATFORM_MINGW32 := $(subst CONFIG_PLATFORM_MINGW32=,,$(CONFIG_PLATFORM_MINGW32))
+CONFIG_PLATFORM_MINGW32 := $(subst ",,$(CONFIG_PLATFORM_MINGW32))
+#")
+endif
+
+# Try various methods to get a more specific EXTRAVERSION
+ifeq ($(CONFIG_PLATFORM_MINGW32),y)
+# Ask git
+extraversion = $(shell git describe --match FRP 2>/dev/null)
+ifeq ($(strip $(extraversion)),)
+# That didn't work, look for a .frp_describe file
+extraversion = $(shell cat .frp_describe 2>/dev/null | grep '^FRP-')
+ifeq ($(strip $(extraversion)),)
+# That didn't work either, look at current directory name
+e1 = $(shell basename `pwd` | grep '^busybox-w32-FRP-')
+ifneq ($(strip $(e1)),)
+extraversion = $(subst busybox-w32-,,$(e1))
+endif
+endif
+endif
+
+ifneq ($(strip $(extraversion)),)
+EXTRAVERSION = .$(subst FRP,git,$(extraversion))
+endif
+endif
+
 # Read KERNELRELEASE from .kernelrelease (if it exists)
 KERNELRELEASE = $(shell cat .kernelrelease 2> /dev/null)
 KERNELVERSION = $(VERSION).$(PATCHLEVEL).$(SUBLEVEL)$(EXTRAVERSION)