Make more uniform GO build options.

Avoid building any of the GO stuff:

   make GOLANG=no ...

Build with a specific build of GO:

   make GO=~/sdk/go1.16rc1/bin/go ...

Also, now golang/go#43149 is resolved in the
go1.16rc1 build (it does not work in the go1.16beta1 but we don't support
that one any more), remove the forced CGO use for the go/psx-signals build.

Signed-off-by: Andrew G. Morgan <[email protected]>

Author: AndrewGMorgan

Make.Rules

@@ -103,16 +103,21 @@ PAM_CAP ?= $(shell if [ -f /usr/include/security/pam_modules.h ]; then echo $(SH
 PTHREADS ?= yes
 
 ifeq ($(PTHREADS),yes)
-GO := go
-GOLANG := $(shell if [ -n "$(shell $(GO) version 2>/dev/null)" ]; then echo yes ; else echo no ; fi)
+GO ?= go
+GOLANG ?= $(shell if [ -n "$(shell $(GO) version 2>/dev/null)" ]; then echo yes ; else echo no ; fi)
 ifeq ($(GOLANG),yes)
-GOROOT := $(shell $(GO) env GOROOT)
-GOCGO := $(shell if [ "$(shell $(GO) env CGO_ENABLED)" = 1 ]; then echo yes ; else echo no ; fi)
-GOOSARCH := $(shell $(GO) env GOHOSTOS)_$(shell $(GO) env GOHOSTARCH)
+GOROOT ?= $(shell $(GO) env GOROOT)
+GOCGO ?= $(shell if [ "$(shell $(GO) env CGO_ENABLED)" = 1 ]; then echo yes ; else echo no ; fi)
+GOOSARCH ?= $(shell $(GO) env GOHOSTOS)_$(shell $(GO) env GOHOSTARCH)
+CGO_REQUIRED=$(shell $(topdir)/go/cgo-required.sh $(GO))
+ifeq ($(CGO_REQUIRED),1)
+# Strictly speaking go1.15 doesn't need this, but 1.16 is when the
+# real golang support arrives for non-cgo support, so drop the last
+# vestige of legacy workarounds then.
+CGO_LDFLAGS_ALLOW := -Wl,-?-wrap[=,][^-.@][^,]*
+endif
 CGO_CFLAGS := -I$(topdir)/libcap/include
 CGO_LDFLAGS := -L$(topdir)/libcap
-CGO_LDFLAGS_ALLOW := -Wl,-?-wrap[=,][^-.@][^,]*
-CGO_REQUIRED=$(shell $(topdir)/go/cgo-required.sh)
 endif
 endif
 

go/.gitignore

@@ -3,6 +3,7 @@ compare-cap
 try-launching
 try-launching-cgo
 psx-signals
+psx-signals-cgo
 b210613
 mknames
 web

go/Makefile

@@ -76,12 +76,11 @@ ifeq ($(CGO_REQUIRED),0)
 	GO111MODULE=off CGO_ENABLED="1" CGO_LDFLAGS_ALLOW="$(CGO_LDFLAGS_ALLOW)" GOPATH=$(GOPATH) $(GO) build -o $@-cgo $<
 endif
 
-# Bug reported issues:
-#   https://bugzilla.kernel.org/show_bug.cgi?id=210533 (cgo - fixed)
-#   https://github.com/golang/go/issues/43149 (nocgo - not fixed yet)
-# When the latter is fixed we can replace CGO_ENABLED=1 with ="$(CGO_REQUIRED)"
-psx-signals: psx-signals.go  $(PSXGOPACKAGE)
-	GO111MODULE=off CGO_ENABLED=1 CGO_LDFLAGS_ALLOW="$(CGO_LDFLAGS_ALLOW)" CGO_CFLAGS="$(CGO_CFLAGS)" CGO_LDFLAGS="$(CGO_LDFLAGS)" GOPATH=$(GOPATH) $(GO) build $<
+psx-signals: psx-signals.go $(PSXGOPACKAGE)
+	GO111MODULE=off CGO_ENABLED="$(CGO_REQUIRED)" CGO_LDFLAGS_ALLOW="$(CGO_LDFLAGS_ALLOW)" CGO_CFLAGS="$(CGO_CFLAGS)" CGO_LDFLAGS="$(CGO_LDFLAGS)" GOPATH=$(GOPATH) $(GO) build $<
+ifeq ($(CGO_REQUIRED),0)
+	GO111MODULE=off CGO_ENABLED="1" CGO_LDFLAGS_ALLOW="$(CGO_LDFLAGS_ALLOW)" CGO_CFLAGS="$(CGO_CFLAGS)" CGO_LDFLAGS="$(CGO_LDFLAGS)" GOPATH=$(GOPATH) $(GO) build -o $@-cgo $<
+endif
 
 b210613: b210613.go $(CAPGOPACKAGE)
 	GO111MODULE=off CGO_ENABLED="$(CGO_REQUIRED)" CGO_LDFLAGS_ALLOW="$(CGO_LDFLAGS_ALLOW)" CGO_CFLAGS="$(CGO_CFLAGS)" CGO_LDFLAGS="$(CGO_LDFLAGS)" GOPATH=$(GOPATH) $(GO) build $<
@@ -91,6 +90,9 @@ test: all
 	GO111MODULE=off CGO_ENABLED="$(CGO_REQUIRED)" CGO_LDFLAGS_ALLOW="$(CGO_LDFLAGS_ALLOW)" GOPATH="$(GOPATH)" $(GO) test $(IMPORTDIR)/cap
 	LD_LIBRARY_PATH=../libcap ./compare-cap
 	./psx-signals
+ifeq ($(CGO_REQUIRED),0)
+	./psx-signals-cgo
+endif
 	./setid --caps=false
 	./gowns -- -c "echo gowns runs"
 
@@ -122,5 +124,5 @@ clean:
 	rm -f web setid gowns
 	rm -f compare-cap try-launching try-launching-cgo
 	rm -f $(topdir)/cap/*~ $(topdir)/psx/*~
-	rm -f psx-signals b210613
+	rm -f b210613 psx-signals psx-signals-cgo
 	rm -fr pkg src

go/cgo-required.sh

@@ -4,8 +4,13 @@
 # available to the working go runtime or not. If it isn't we always
 # have to use libcap/psx to get POSIX semantics for syscalls that
 # change security state.
+if [ -n "$1" ]; then
+    export GO="${1}"
+else
+    export GO=go
+fi
 
-if [ -z "$(go doc syscall 2>/dev/null|grep AllThreadsSyscall)" ]; then
+if [ -z "$(${GO} doc syscall 2>/dev/null|grep AllThreadsSyscall)" ]; then
     echo "1"
 else
     echo "0"