Add sigar.ProcEnv for getting a process's environment

This PR adds the ability to retrieve the environment variables used
to start a process. It is implemented for Linux, OS X, and FreeBSD.
Neither Windows nor OpenBSD are implemented at this time.

Closes #61

CHANGELOG.md

@@ -12,6 +12,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 - Added support to `github.com/gosigar/sys/windows` for querying and enabling
   privileges in a process token.
 - Added utility code for interfacing with linux NETLINK_INET_DIAG. #60
+- Added `ProcArgs` for getting a process's environment variables. #61
 
 ### Changed
 - Changed several `OpenProcess` calls on Windows to request the lowest possible

README.md

@@ -29,6 +29,7 @@ The features vary by operating system.
 | LoadAverage     |   X   |    X   |         |    X    |    X    |
 | Mem             |   X   |    X   |    X    |    X    |    X    |
 | ProcArgs        |   X   |    X   |    X    |         |    X    |
+| ProcEnv         |   X   |    X   |         |         |    X    |
 | ProcExe         |   X   |    X   |         |         |    X    |
 | ProcFDUsage     |   X   |        |         |         |    X    |
 | ProcList        |   X   |    X   |    X    |         |    X    |

sigar_darwin.go

@@ -326,6 +326,18 @@ func (self *ProcArgs) Get(pid int) error {
 	return err
 }
 
+func (self *ProcEnv) Get(pid int) error {
+	if self.Vars == nil {
+		self.Vars = map[string]string{}
+	}
+
+	env := func(k, v string) {
+		self.Vars[k] = v
+	}
+
+	return kern_procargs(pid, nil, nil, env)
+}
+
 func (self *ProcExe) Get(pid int) error {
 	exe := func(arg string) {
 		self.Name = arg

sigar_interface.go

@@ -160,6 +160,10 @@ type ProcArgs struct {
 	List []string
 }
 
+type ProcEnv struct {
+	Vars map[string]string
+}
+
 type ProcExe struct {
 	Name string
 	Cwd  string

sigar_interface_test.go

@@ -128,6 +128,17 @@ func TestProcArgs(t *testing.T) {
 	}
 }
 
+func TestProcEnv(t *testing.T) {
+	env := &ProcEnv{}
+	if assert.NoError(t, skipNotImplemented(t, env.Get(os.Getpid()), "windows", "openbsd")) {
+		assert.True(t, len(env.Vars) > 0, "env is empty")
+
+		for k, v := range env.Vars {
+			assert.Equal(t, os.Getenv(k), v)
+		}
+	}
+}
+
 func TestProcExe(t *testing.T) {
 	exe := ProcExe{}
 	if assert.NoError(t, skipNotImplemented(t, exe.Get(os.Getppid()), "windows")) {

sigar_linux_common.go

@@ -305,6 +305,34 @@ func (self *ProcArgs) Get(pid int) error {
 	return nil
 }
 
+func (self *ProcEnv) Get(pid int) error {
+	contents, err := readProcFile(pid, "environ")
+	if err != nil {
+		return err
+	}
+
+	if self.Vars == nil {
+		self.Vars = map[string]string{}
+	}
+
+	pairs := bytes.Split(contents, []byte{0})
+	for _, kv := range pairs {
+		parts := bytes.SplitN(kv, []byte{'='}, 2)
+		if len(parts) != 2 {
+			continue
+		}
+
+		key := string(bytes.TrimSpace(parts[0]))
+		if key == "" {
+			continue
+		}
+
+		self.Vars[key] = string(bytes.TrimSpace(parts[1]))
+	}
+
+	return nil
+}
+
 func (self *ProcExe) Get(pid int) error {
 	fields := map[string]*string{
 		"exe":  &self.Name,

sigar_openbsd.go

@@ -357,6 +357,10 @@ func (self *ProcArgs) Get(pid int) error {
 	return nil
 }
 
+func (self *ProcEnv) Get(pid int) error {
+	return ErrNotImplemented{runtime.GOOS}
+}
+
 func (self *ProcState) Get(pid int) error {
 	return nil
 }

sigar_windows.go

@@ -67,6 +67,10 @@ func (self *FDUsage) Get() error {
 	return ErrNotImplemented{runtime.GOOS}
 }
 
+func (self *ProcEnv) Get(pid int) error {
+	return ErrNotImplemented{runtime.GOOS}
+}
+
 func (self *ProcExe) Get(pid int) error {
 	return ErrNotImplemented{runtime.GOOS}
 }