syscall: x/tools broken on FreeBSD by FreeBSD 12 support CL

[dmitshur]

The x/tools subrepo seems to be broken after CL 138595. /cc @paulzhol

2018/10/10 14:30:05 goimports: scanning directory /tmp/workdir/go/src: open /tmp/workdir/go/src/cmd/compile/internal/ssa/testdata : no such file or directory
2018/10/10 14:30:05 goimports: scanning directory /tmp/workdir/go/src: open /tmp/workdir/go/src/runtime/msan	: no such file or directory
2018/10/10 14:30:05 goimports: scanning directory /tmp/workdir/go/src: open /tmp/workdir/go/src/math/randamd6�E�: no such file or directory
--- FAIL: TestFindImportInternal (0.00s)
    fix_test.go:1443: findImportGoPath("race", Acquire ...) = "", false; want "internal/race", false
2018/10/10 14:30:05 goimports: scanning directory /tmp/workdir/go/src: open /tmp/workdir/go/src/runtime/testdata.go: no such file or directory
2018/10/10 14:30:05 goimports: scanning directory /tmp/workdir/go/src: open /tmp/workdir/go/src/runtime/testdata.go: no such file or directory
2018/10/10 14:30:05 goimports: scanning directory /tmp/workdir/go/src: open /tmp/workdir/go/src/runtime/msan	: no such file or directory
2018/10/10 14:30:05 goimports: scanning directory /tmp/workdir/go/src: open /tmp/workdir/go/src/runtime/internaldefs3_liCH�: no such file or directory
2018/10/10 14:30:05 goimports: scanning directory /tmp/workdir/go/src: open /tmp/workdir/go/src/math/randamd6�E�: no such file or directory
2018/10/10 14:30:05 goimports: scanning directory /tmp/workdir/go/src: open /tmp/workdir/go/src/cmd/compile/internal/ssa/testdata : no such file or directory
2018/10/10 14:30:05 goimports: scanning directory /tmp/workdir/go/src: open /tmp/workdir/go/src/runtime/testdata.go: no such file or directory
2018/10/10 14:30:05 goimports: scanning directory /tmp/workdir/go/src: open /tmp/workdir/go/src/cmd/compile/internal/ssa/testdata : no such file or directory
2018/10/10 14:30:05 goimports: scanning directory /tmp/workdir/go/src: open /tmp/workdir/go/src/runtime/testdata.go: no such file or directory
2018/10/10 14:30:05 goimports: scanning directory /tmp/workdir/go/src: open /tmp/workdir/go/src/runtime/internaldefs3_liCH�: no such file or directory
FAIL
FAIL	golang.org/x/tools/imports	0.468s

See https://build.golang.org/?repo=golang.org%2fx%2ftools#short and https://go-review.googlesource.com/c/go/+/138595#message-71a4da926fb9669d319aa4b34fd9d548de32dc23.

/cc @bradfitz @bcmills @heschik

[bradfitz]

Looks like the null termination is broken when converting the FreeBSD 12 structs to the FreeBSD 11 structs.

I guess we're lacking test coverage of some system call(s) in std.

[paulzhol]

convertFromDirents11 seems to be broken but only occasionally. I'm investigating
Unsurprisingly that test works on FreeBSD 12.

[gopherbot]

Change https://golang.org/cl/141297 mentions this issue: syscall: fix FreeBSD convertFromDirents11

[gopherbot]

Change https://golang.org/cl/141801 mentions this issue: internal/fastwalk: don't cross Dirent.Reclen boundry while looking for NULL in parseDirEnt