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Created December 19, 2013 20:14
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  1. @ernesto-jimenez ernesto-jimenez revised this gist Dec 19, 2013. 1 changed file with 5 additions and 1 deletion.
    6 changes: 5 additions & 1 deletion _README.md
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    Original file line number Diff line number Diff line change
    @@ -19,4 +19,8 @@ This example is cross compiling the https://github.com/ernesto-jimenez/emit_urls

    1. Cross compile the binary: ```GOARM=5 GOOS=linux GOARCH=arm CGOENABLED=1 ../bin/go build -tags android -o main-arm $GOPATH/src/github.com/ernesto-jimenez/emit_urls/main.go```
    2. Push binary to the Android device with adb: ```adb push main-arm /data/local/tmp/```
    3. Run program in the device: ```adb shell ./data/local/tmp/main-arm http://rediris.es```
    3. Run program in the device: ```adb shell ./data/local/tmp/main-arm http://rediris.es```

    ## Credits

    This is based on the following patch from @minux https://codereview.appspot.com/6454055
  2. @ernesto-jimenez ernesto-jimenez created this gist Dec 19, 2013.
    22 changes: 22 additions & 0 deletions _README.md
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    @@ -0,0 +1,22 @@
    # Patch to cross compile to android with net/http support

    ## Installation instructions

    We need to patch Go's source code to allow cgo when cross-compiling and make Android-specific changes since it sometimes differs from linux (e.g.: it doesn't use /etc/resolv.conf for DNS config)

    1. Clone the go source: ```hg clone -u release https://code.google.com/p/go```
    2. Enter the go source directory: ```cd go```
    3. Apply the patch in this gist: ```patch -p1 < /path/to/patch/go_android.patch```
    4. Enter the go/src directory: ```cd src```
    5. Generate binaries for Android cross-compile: ```GOOS=linux GOARCH=arm ./make.bash```
    6. Install standard packages for android: ```GOOS=linux GOARCH=arm CGOENABLED=1 ../bin/go install -tags android -a -v std```

    ## Example program for Android and running in the device

    Requirements: an android device with remote debugging enabled, ```adb``` to build the binary. This doesn't require the device to be rooted.

    This example is cross compiling the https://github.com/ernesto-jimenez/emit_urls project.

    1. Cross compile the binary: ```GOARM=5 GOOS=linux GOARCH=arm CGOENABLED=1 ../bin/go build -tags android -o main-arm $GOPATH/src/github.com/ernesto-jimenez/emit_urls/main.go```
    2. Push binary to the Android device with adb: ```adb push main-arm /data/local/tmp/```
    3. Run program in the device: ```adb shell ./data/local/tmp/main-arm http://rediris.es```
    142 changes: 142 additions & 0 deletions go_android.patch
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    Original file line number Diff line number Diff line change
    @@ -0,0 +1,142 @@
    diff -r 87dea3f5ebe7 src/cmd/go/build.go
    --- a/src/cmd/go/build.go Fri Nov 29 08:32:31 2013 +1100
    +++ b/src/cmd/go/build.go Thu Dec 19 17:34:24 2013 +0100
    @@ -1928,9 +1928,9 @@
    )

    func (b *builder) cgo(p *Package, cgoExe, obj string, gccfiles []string, gxxfiles []string) (outGo, outObj []string, err error) {
    - if goos != toolGOOS {
    - return nil, nil, errors.New("cannot use cgo when compiling for a different operating system")
    - }
    + //if goos != toolGOOS {
    + //return nil, nil, errors.New("cannot use cgo when compiling for a different operating system")
    + //}

    cgoCPPFLAGS := stringList(envList("CGO_CPPFLAGS"), p.CgoCPPFLAGS)
    cgoCFLAGS := stringList(envList("CGO_CFLAGS"), p.CgoCFLAGS)
    diff -r 87dea3f5ebe7 src/pkg/net/dnsconfig_android.go
    --- /dev/null Thu Jan 01 00:00:00 1970 +0000
    +++ b/src/pkg/net/dnsconfig_android.go Thu Dec 19 17:34:24 2013 +0100
    @@ -0,0 +1,53 @@
    +// Copyright 2009 The Go Authors. All rights reserved.
    +// Use of this source code is governed by a BSD-style
    +// license that can be found in the LICENSE file.
    +
    +// +build android,linux
    +
    +package net
    +
    +import (
    + "fmt"
    + "os/exec"
    +)
    +
    +type dnsConfig struct {
    + servers []string // servers to use
    + search []string // suffixes to append to local name
    + ndots int // number of dots in name to trigger absolute lookup
    + timeout int // seconds before giving up on packet
    + attempts int // lost packets before giving up on server
    + rotate bool // round robin among servers
    +}
    +
    +// Using getprop since Android doesn't have resolv.conf
    +func dnsReadConfig() (*dnsConfig, error) {
    + conf := new(dnsConfig)
    + conf.servers = make([]string, 3)[0:0] // small, but the standard limit
    + conf.search = make([]string, 0)
    + conf.ndots = 1
    + conf.timeout = 5
    + conf.attempts = 2
    + conf.rotate = false
    + var ip string
    +
    + for i := 1; i <= 4; i++ {
    + out, err := exec.Command("/system/bin/getprop", fmt.Sprintf("net.dns%v", i)).Output()
    + m := len(out)
    + if err != nil {
    + continue
    + }
    + if m < 2 {
    + continue
    + }
    + ip = string(out[:m-1])
    +
    + a := conf.servers
    + n := len(a)
    + a = a[0 : n+1]
    + a[n] = ip
    + conf.servers = a
    + }
    +
    + return conf, nil
    +}
    diff -r 87dea3f5ebe7 src/pkg/net/dnsconfig_unix.go
    --- a/src/pkg/net/dnsconfig_unix.go Fri Nov 29 08:32:31 2013 +1100
    +++ b/src/pkg/net/dnsconfig_unix.go Thu Dec 19 17:34:24 2013 +0100
    @@ -2,7 +2,7 @@
    // Use of this source code is governed by a BSD-style
    // license that can be found in the LICENSE file.

    -// +build darwin dragonfly freebsd linux netbsd openbsd
    +// +build darwin dragonfly freebsd !android,linux netbsd openbsd

    // Read system DNS config from /etc/resolv.conf

    diff -r 87dea3f5ebe7 src/pkg/os/file_android.go
    --- /dev/null Thu Jan 01 00:00:00 1970 +0000
    +++ b/src/pkg/os/file_android.go Thu Dec 19 17:34:24 2013 +0100
    @@ -0,0 +1,17 @@
    +// Copyright 2012 The Go Authors. All rights reserved.
    +// Use of this source code is governed by a BSD-style
    +// license that can be found in the LICENSE file.
    +
    +// +build android,linux
    +
    +package os
    +
    +// TempDir returns the default directory to use for temporary files.
    +func TempDir() string {
    + dir := Getenv("TMPDIR")
    + if dir == "" {
    + dir = "/data/local/tmp"
    + }
    + return dir
    +}
    +
    diff -r 87dea3f5ebe7 src/pkg/os/file_non_android.go
    --- /dev/null Thu Jan 01 00:00:00 1970 +0000
    +++ b/src/pkg/os/file_non_android.go Thu Dec 19 17:34:24 2013 +0100
    @@ -0,0 +1,17 @@
    +// Copyright 2012 The Go Authors. All rights reserved.
    +// Use of this source code is governed by a BSD-style
    +// license that can be found in the LICENSE file.
    +
    +// +build darwin freebsd !android,linux netbsd openbsd
    +
    +package os
    +
    +// TempDir returns the default directory to use for temporary files.
    +func TempDir() string {
    + dir := Getenv("TMPDIR")
    + if dir == "" {
    + dir = "/tmp"
    + }
    + return dir
    +}
    +
    diff -r 87dea3f5ebe7 src/pkg/os/file_unix.go
    --- a/src/pkg/os/file_unix.go Fri Nov 29 08:32:31 2013 +1100
    +++ b/src/pkg/os/file_unix.go Thu Dec 19 17:34:24 2013 +0100
    @@ -279,11 +279,3 @@
    return name
    }

    -// TempDir returns the default directory to use for temporary files.
    -func TempDir() string {
    - dir := Getenv("TMPDIR")
    - if dir == "" {
    - dir = "/tmp"
    - }
    - return dir
    -}