# The module cache copy of a FIPS snapshot is used only if the module
# cache records the module zip hash from GOROOT/lib/fips140/fips140.sum
# for it, the way downloaded modules are checked against go.sum.
# Otherwise it is discarded and the snapshot is unpacked again.
#
# This detects a cache entry that was not unpacked from the bundled
# snapshot (or whose hash record is missing). Like go.sum, it does not
# protect the module cache from being modified in place: the replaced
# source file below stands in for stale contents, not an attacker.

env snap=v1.26.0
env GOFIPS140=$snap
env GOMODCACHE=$WORK/modcache
env GOFLAGS=-modcacherw

# Go+BoringCrypto conflicts with GOFIPS140.
[GOEXPERIMENT:boringcrypto] skip

env ziphash=$GOMODCACHE/cache/download/golang.org/fips140/@v/$snap.ziphash
env srcfile=$GOMODCACHE/golang.org/fips140@$snap/fips140/$snap/sha256/sha256.go

# unpacking the snapshot records its module zip hash in the module cache
go list -f '{{.DefaultGODEBUG}}'
stdout fips140=on
exists $ziphash
exists $srcfile
grep '^h1:dtoPX1ALGGp4rMLzyh6oqIkYRXnXxRkpPWu56l5DFpM=$' $ziphash
cp $ziphash good.ziphash

# a recorded hash that does not match fips140.sum
# discards the cached copy and unpacks the snapshot again
cp bad.ziphash $ziphash
rm $srcfile
cp stale/sha256.go $srcfile
go list -f '{{.DefaultGODEBUG}}'
stdout fips140=on
exists $srcfile
! grep stale $srcfile
cmp $ziphash good.ziphash

# so does a missing hash
rm $ziphash
rm $srcfile
cp stale/sha256.go $srcfile
go list -f '{{.DefaultGODEBUG}}'
stdout fips140=on
exists $srcfile
! grep stale $srcfile
cmp $ziphash good.ziphash

-- go.mod --
module m
-- x.go --
package main
import _ "crypto/sha256"
func main() {
}
-- bad.ziphash --
h1:AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=
-- stale/sha256.go --
package sha256 // stale