Makefile: build fuchsia go binaries using the sdk

This commit removes a dependency on fuchsia's tools/devshell/contrib/go,
which was removed recently[0].

Now to build go binaries for fuchsia we are not relying on the
fuchsia.git repo at all. The code just needs a copy of the fuchsia
//third_party/go repository, the fuchsia sdk and a copy of clang.

Users should download the sdk and clang beforehand (see documentation
for links), and then run (with the correct environment variables):

```
$ make TARGETOS=fuchsia TARGETARCH=amd64 \
    SOURCEDIR=$HOME/fuchsia \
    FX_SDK_PATH=${HOME}/sdk/fuchsia-sdk \
    CLANG_PATH=${HOME}/sdk/clang \
    fuchsia_go
```

After that, they will be able to build the syzkaller go binaries by
doing:

```
$ make TARGETOS=fuchsia TARGETARCH=amd64 \
    SOURCEDIR=$HOME/fuchsia \
    FX_SDK_PATH=${HOME}/sdk/fuchsia-sdk \
    CLANG_PATH=${HOME}/sdk/clang
```

This commits adds two scripts to tools/fuchsia, one for building go in
fuchsia (just calls the ./make.all script in fuchsia's go repo), and one
that replaces the devshell/contrib/go script.

Given that go is unsupported in fuchsia, this change might break at any
point.

[0]: https://fuchsia-review.googlesource.com/c/fuchsia/+/291631

2 files changed, 58 insertions, 0 deletions

diff --git a/tools/fuchsia/build-go.sh b/tools/fuchsia/build-go.sh
new file mode 100755
index 000000000..49ce0f418
--- /dev/null
+++ b/tools/fuchsia/build-go.sh
@@ -0,0 +1,32 @@
+#!/bin/bash
+
+# This script can be used to compile Go for fuchsia.
+# You need to have a fuchsia checkout defined in the FX_SRC_PATH variable,
+# The fuchsia sdk in the FX_SDK_PATH variable, and a CLANG compatible with
+# fuchsia in CLANG_PATH.
+
+if [[ -z ${FX_SDK_PATH} ]]; then
+  echo "FX_SDK_PATH variable not set"
+  exit 1
+fi
+
+if [[ -z ${FX_SRC_PATH} ]]; then
+  echo "FX_SRC_PATH variable not set"
+  exit 1
+fi
+
+if [[ -z ${CLANG_PATH} ]]; then
+  echo "CLANG_PATH variable not set"
+  exit 1
+fi
+
+cd "${FX_SRC_PATH}/third_party/go/src"
+
+FUCHSIA_SHARED_LIBS=${FX_SDK_PATH}/arch/x64/lib \
+  CLANG_PREFIX=${CLANG_PATH}/bin \
+  FDIO_INCLUDE=${FX_SDK_PATH}/pkg/fdio/include \
+  ZIRCON_SYSROOT=${FX_SDK_PATH}/arch/x64/sysroot \
+  CC=${FX_SRC_PATH}/third_party/go/misc/fuchsia/clangwrap.sh \
+  CGO_ENABLED=1 \
+  GOOS=fuchsia \
+  ./make.bash
diff --git a/tools/fuchsia/go b/tools/fuchsia/go
new file mode 100755
index 000000000..bff63d190
--- /dev/null
+++ b/tools/fuchsia/go
@@ -0,0 +1,26 @@
+#!/bin/bash
+
+if [[ -z ${FX_SDK_PATH} ]]; then
+  echo "FX_SDK_PATH variable not set"
+  exit 1
+fi
+
+if [[ -z ${FX_SRC_PATH} ]]; then
+  echo "FX_SRC_PATH variable not set"
+  exit 1
+fi
+
+if [[ -z ${CLANG_PATH} ]]; then
+  echo "CLANG_PATH variable not set"
+  exit 1
+fi
+
+FUCHSIA_SHARED_LIBS="${FX_SDK_PATH}/arch/x64/lib" \
+  CLANG_PREFIX="${CLANG_PATH}/bin" \
+  FDIO_INCLUDE="${FX_SDK_PATH}/pkg/fdio/include" \
+  ZIRCON_SYSROOT="${FX_SDK_PATH}/arch/x64/sysroot" \
+  CC="${FX_SRC_PATH}/third_party/go/misc/fuchsia/clangwrap.sh" \
+  CGO_ENABLED=1 \
+  GOOS=fuchsia \
+  GOROOT="${FX_SRC_PATH}/third_party/go" \
+  "${FX_SRC_PATH}/third_party/go/bin/go" "$@"