cgo 交叉编译

Posted on 2019-04-19 Edited on 2024-04-16 In Notes

缘起

Go 语言除了语法精炼、并发支持好外，还有一个优点就是可以调用 C 代码。可以直接在 Go 源代码里写 C 代码，也可以引 C 语言的外部库。这样在性能遇到瓶颈的地方可以重写，或者某些功能 Go 和第三方还缺失，但 C 语言有现成的库就可以直接用了。

官方 Cgo 这块目前有一篇博客和命令行文档。比如 sqlite 的 golang 驱动 go-sqlite3 就是基于 Cgo 的实现。编译本地版本，Go 本身已经支持得非常好，基本不需要额外设置，直接通过 go build 编译即可，但是要想编译其他平台的二进制版本，就需要跨平台的 $(CC), $(CXX) 支持。

方案

按照 Cgo 的编译思路，基本思路就是必须有一个跨平台的 C/C++ 编译器才可能实现交叉编译。

macOS

安装编译器

1 2	brew install FiloSottile/musl-cross/musl-cross brew install mingw-w64

编译

在 Make 文件中指定 $(CC),$(GCC) 为 musl-cross 提供的编译器，编译安装

注：此方案未验证，有兴趣的可以自行研究

docker

要想一次配置，到处运行，自然而然想到的就是 docker。基本思路就是通过 docker 配置好基础编译器，然后根据不同的项目挂载代码目录进行编译。karalabe/xgo 就做了类似的事情，非常满足我的需求。但是试用下来之后，发现几个问题：

不支持 go mod 模式
不能 (完整支持) 编译本地代码
不支持最新的 golang 版本
项目维护热度不足

无奈之下，只能自己 fork 下来定制了，自给自足。

修改如下：

重新发布了 docker 镜像到 dockerhub
移除了暂时用不上的 Android/iOS 版本支持，以减少 docker 镜像大小
修改 xgo CLI 完整支持本地代码编译，--pkg 为子目录 main.go 所在路径
修改基础镜像的 build.sh 支持相对路径以及 go mod 模式
尝试了下使用 gomobile 编译 Android/iOS 版本，但是不如现有方式方便，暂时放到分支上了，后期根据情况看是否合并到主分支
go mod 模式下自动挂载 $GOPATH 到容器中，减少编译时间

示例

安装修改版 xgo
1
go get -u github.com/gythialy/xgo

编写 Makefile

 MAINLDFLAGS="-X github.com/qlcchain/go-qlc/cmd/server/commands.Version=${SERVERVERSION} \
-X github.com/qlcchain/go-qlc/cmd/server/commands.GitRev=${GITREV} \
-X github.com/qlcchain/go-qlc/cmd/server/commands.BuildTime=${BUILDTIME} \
-X github.com/qlcchain/go-qlc/cmd/server/commands.Mode=MainNet"

 SERVERMAIN = cmd/server/main.go

 gqlc-server:
   xgo --dest=$(BUILDDIR) -v --tags="mainnet sqlite_userauth" --ldflags=$(MAINLDFLAGS) --out=$(SERVERBINARY)-v$(SERVERVERSION)-$(GITREV) \
   --targets="windows-6.0/*,darwin-10.10/amd64,linux/amd64,linux/386,linux/arm64,linux/mips64, linux/mips64le" \
   --pkg=$(SERVERMAIN) .

--dest: 编译好的二进制文件存放目录
--out: 二进制名字
--targets: 编译支持的平台
--pkg: main 函数不在根目录的情况，需要指定
.: 代码所在目录

完整 Makefile

.PHONY: all clean build build-test confidant confidant-test
.PHONY: gqlc-server gqlc-server-test
.PHONY: gqlc-client
.PHONY: deps

# Check for required command tools to build or stop immediately
EXECUTABLES = git go find pwd
K := $(foreach exec,$(EXECUTABLES),\
        $(if $(shell which $(exec)),some string,$(error "No $(exec) in PATH)))

# server
SERVERVERSION ?= 1.2.6.6
SERVERBINARY = gqlc
SERVERTESTBINARY = gqlct
SERVERMAIN = cmd/server/main.go

# client
CLIENTVERSION ?= 1.2.6.6
CLIENTBINARY = gqlcc
CLIENTMAIN = cmd/client/main.go

BUILDDIR = build
GITREV = $(shell git rev-parse --short HEAD)
BUILDTIME = $(shell date +'%Y-%m-%d_%T')
TARGET=windows-6.0/*,darwin-10.10/amd64,linux/amd64
TARGET_CONFIDANT=linux/arm-7

MAINLDFLAGS="-X github.com/qlcchain/go-qlc/cmd/server/commands.Version=${SERVERVERSION} \
  -X github.com/qlcchain/go-qlc/cmd/server/commands.GitRev=${GITREV} \
  -X github.com/qlcchain/go-qlc/cmd/server/commands.BuildTime=${BUILDTIME} \
  -X github.com/qlcchain/go-qlc/cmd/server/commands.Mode=MainNet"

TESTLDFLAGS="-X github.com/qlcchain/go-qlc/cmd/server/commands.Version=${SERVERVERSION} \
  -X github.com/qlcchain/go-qlc/cmd/server/commands.GitRev=${GITREV} \
  -X github.com/qlcchain/go-qlc/cmd/server/commands.BuildTime=${BUILDTIME} \
  -X github.com/qlcchain/go-qlc/cmd/server/commands.Mode=TestNet"

CLIENTLDFLAGS="-X github.com/qlcchain/go-qlc/cmd/client/commands.Version=${CLIENTVERSION} \
  -X github.com/qlcchain/go-qlc/cmd/client/commands.GitRev=${GITREV} \
  -X github.com/qlcchain/go-qlc/cmd/client/commands.BuildTime=${BUILDTIME}" \

deps:
  go get -u golang.org/x/lint/golint
  go get -u github.com/gythialy/xgo
  go get -u github.com/git-chglog/git-chglog/cmd/git-chglog

confidant:
  CGO_ENABLED=1 CC=/opt/gcc-linaro-5.3.1-2016.05-x86_64_arm-linux-gnueabihf/bin/arm-linux-gnueabihf-gcc GOARCH=arm GOARM=7 \
  GO111MODULE=on go build -tags "confidant" -ldflags $(MAINLDFLAGS) -v -i -o $(shell pwd)/$(BUILDDIR)/$(SERVERBINARY) $(shell pwd)/$(SERVERMAIN)
  @echo "Build $(SERVERBINARY) done."
  @echo "Run \"$(shell pwd)/$(BUILDDIR)/$(SERVERBINARY)\" to start $(SERVERBINARY)."
  CGO_ENABLED=1 CC=/home/lichao/ppr_cross/gcc-linaro-5.3.1-2016.05-x86_64_arm-linux-gnueabihf/bin/arm-linux-gnueabihf-gcc GOARCH=arm GOARM=7 \
  GO111MODULE=on go build -ldflags $(CLIENTLDFLAGS) -v -i -o $(shell pwd)/$(BUILDDIR)/$(CLIENTBINARY) $(shell pwd)/$(CLIENTMAIN)
  @echo "Build $(CLIENTBINARY) done."
  @echo "Run \"$(shell pwd)/$(BUILDDIR)/$(CLIENTBINARY)\" to start $(CLIENTBINARY)."

confidant-test:
  CGO_ENABLED=1 CC=/opt/gcc-linaro-5.3.1-2016.05-x86_64_arm-linux-gnueabihf/bin/arm-linux-gnueabihf-gcc GOARCH=arm GOARM=7 \
  GO111MODULE=on go build -tags "confidant testnet" -ldflags $(MAINLDFLAGS) -v -i -o $(shell pwd)/$(BUILDDIR)/$(SERVERBINARY) $(shell pwd)/$(SERVERMAIN)
  @echo "Build $(SERVERBINARY) done."
  @echo "Run \"$(shell pwd)/$(BUILDDIR)/$(SERVERBINARY)\" to start $(SERVERBINARY)."
  CGO_ENABLED=1 CC=/home/lichao/ppr_cross/gcc-linaro-5.3.1-2016.05-x86_64_arm-linux-gnueabihf/bin/arm-linux-gnueabihf-gcc GOARCH=arm GOARM=7 \
  GO111MODULE=on go build -ldflags $(CLIENTLDFLAGS) -v -i -o $(shell pwd)/$(BUILDDIR)/$(CLIENTBINARY) $(shell pwd)/$(CLIENTMAIN)
  @echo "Build $(CLIENTBINARY) done."
  @echo "Run \"$(shell pwd)/$(BUILDDIR)/$(CLIENTBINARY)\" to start $(CLIENTBINARY)."

build:
  GO111MODULE=on go build -ldflags $(MAINLDFLAGS) -v -i -o $(shell pwd)/$(BUILDDIR)/$(SERVERBINARY) $(shell pwd)/$(SERVERMAIN)
  @echo "Build $(SERVERBINARY) done."
  @echo "Run \"$(shell pwd)/$(BUILDDIR)/$(SERVERBINARY)\" to start $(SERVERBINARY)."
  GO111MODULE=on go build -ldflags $(CLIENTLDFLAGS) -v -i -o $(shell pwd)/$(BUILDDIR)/$(CLIENTBINARY) $(shell pwd)/$(CLIENTMAIN)
  @echo "Build $(CLIENTBINARY) done."
  @echo "Run \"$(shell pwd)/$(BUILDDIR)/$(CLIENTBINARY)\" to start $(CLIENTBINARY)."

build-test:
  GO111MODULE=on go build -tags "testnet" -ldflags $(TESTLDFLAGS) -v -i -o $(shell pwd)/$(BUILDDIR)/$(SERVERBINARY) $(shell pwd)/$(SERVERMAIN)
  @echo "Build test server done."
  @echo "Run \"$(BUILDDIR)/$(SERVERBINARY)\" to start $(SERVERBINARY)."
  GO111MODULE=on go build -ldflags $(CLIENTLDFLAGS) -v -i -o $(shell pwd)/$(BUILDDIR)/$(CLIENTBINARY) $(shell pwd)/$(CLIENTMAIN)
  @echo "Build test client done."
  @echo "Run \"$(BUILDDIR)/$(CLIENTBINARY)\" to start $(CLIENTBINARY)."

all: gqlc-server gqlc-server-test gqlc-client

clean:
  rm -rf $(shell pwd)/$(BUILDDIR)/

gqlc-server:
  xgo --dest=$(BUILDDIR) --ldflags=$(MAINLDFLAGS) --out=$(SERVERBINARY)-v$(SERVERVERSION)-$(GITREV) \
    --targets=$(TARGET) --pkg=$(SERVERMAIN) .
  xgo --dest=$(BUILDDIR) --tags="confidant" --ldflags=$(MAINLDFLAGS) --out=$(SERVERBINARY)-confidant-v$(SERVERVERSION)-$(GITREV) \
  --targets=$(TARGET_CONFIDANT) --pkg=$(SERVERMAIN) .

gqlc-server-test:
  xgo --dest=$(BUILDDIR) --tags="testnet" --ldflags=$(TESTLDFLAGS) --out=$(SERVERTESTBINARY)-v$(SERVERVERSION)-$(GITREV) \
  --targets=$(TARGET) --pkg=$(SERVERMAIN) .
  xgo --dest=$(BUILDDIR) --tags="confidant testnet" --ldflags=$(TESTLDFLAGS) --out=$(SERVERTESTBINARY)-confidant-v$(SERVERVERSION)-$(GITREV) \
  --targets=$(TARGET_CONFIDANT) --pkg=$(SERVERMAIN) .

gqlc-client:
  xgo --dest=$(BUILDDIR) --ldflags=$(CLIENTLDFLAGS) --out=$(CLIENTBINARY)-v$(CLIENTVERSION)-$(GITREV) \
  --targets="windows-6.0/amd64,darwin-10.10/amd64,linux/amd64" \
  --pkg=$(CLIENTMAIN) .

编译
1
make clean gqlc-server

结语

虽然通过 docker 的方式暂时解决了 cgo 的跨平台编译，但是还是挺折腾的，编译速度也不是特别理想。希望后期 Go 官方能有更完整的交叉的编译方案。

参考链接

EASY WINDOWS AND LINUX CROSS-COMPILERS FOR MACOS
richfelker/musl-cross-make
karalabe/xgo

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