Add support for global env variable set over arduino-cli

Author: cmaglie

Diff for: executils/process.go

@@ -20,6 +20,7 @@ import (
 	"io"
 	"os"
 	"os/exec"
+	"sync"
 
 	"github.com/arduino/go-paths-helper"
 	"github.com/pkg/errors"
@@ -30,6 +31,28 @@ type Process struct {
 	cmd *exec.Cmd
 }
 
+var globalEnv struct {
+	env  []string
+	lock sync.Mutex
+}
+
+// SetProcessGlobalEnv set the environment variables that must be set for
+// all the processes started via executils
+func SetProcessGlobalEnv(env []string) {
+	globalEnv.lock.Lock()
+	globalEnv.env = env
+	globalEnv.lock.Unlock()
+}
+
+// GetProcessGlobalEnv return the environment variables that are set for
+// all the processes started via executils (it can be changed with executils.SetProcessGlobalEnv)
+func GetProcessGlobalEnv() []string {
+	globalEnv.lock.Lock()
+	defer globalEnv.lock.Unlock()
+	var res []string
+	return append(res, globalEnv.env...) // copy array
+}
+
 // NewProcess creates a command with the provided command line arguments.
 // The first argument is the path to the executable, the remainder are the
 // arguments to the command.
@@ -40,6 +63,7 @@ func NewProcess(args ...string) (*Process, error) {
 	p := &Process{
 		cmd: exec.Command(args[0], args[1:]...),
 	}
+	p.cmd.Env = GetProcessGlobalEnv()
 	TellCommandNotToSpawnShell(p.cmd)
 
 	// This is required because some tools detects if the program is running
@@ -140,7 +164,7 @@ func (p *Process) Run() error {
 
 // SetEnvironment set the enviroment for the running process. Each entry is of the form "key=value".
 func (p *Process) SetEnvironment(values []string) {
-	p.cmd.Env = values
+	p.cmd.Env = append(GetProcessGlobalEnv(), values...)
 }
 
 // RunWithinContext starts the specified command and waits for it to complete. If the given context