From d98455f7411557d7b555896ed3febeb370033648 Mon Sep 17 00:00:00 2001
From: unclejack <unclejacksons@gmail.com>
Date: Thu, 30 Oct 2014 14:48:30 +0200
Subject: [PATCH] pkg/reexec: move reexec code to a new package

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)

Conflicts:
	integration/runtime_test.go
		fixed imports
---
 reexec/MAINTAINERS |  1 +
 reexec/README.md   |  5 +++++
 reexec/reexec.go   | 45 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 51 insertions(+)
 create mode 100644 reexec/MAINTAINERS
 create mode 100644 reexec/README.md
 create mode 100644 reexec/reexec.go

diff --git a/reexec/MAINTAINERS b/reexec/MAINTAINERS
new file mode 100644
index 0000000..e48a0c7
--- /dev/null
+++ b/reexec/MAINTAINERS
@@ -0,0 +1 @@
+Michael Crosby <michael@docker.com> (@crosbymichael)
diff --git a/reexec/README.md b/reexec/README.md
new file mode 100644
index 0000000..45592ce
--- /dev/null
+++ b/reexec/README.md
@@ -0,0 +1,5 @@
+## reexec
+
+The `reexec` package facilitates the busybox style reexec of the docker binary that we require because 
+of the forking limitations of using Go.  Handlers can be registered with a name and the argv 0 of 
+the exec of the binary will be used to find and execute custom init paths.
diff --git a/reexec/reexec.go b/reexec/reexec.go
new file mode 100644
index 0000000..136b905
--- /dev/null
+++ b/reexec/reexec.go
@@ -0,0 +1,45 @@
+package reexec
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+)
+
+var registeredInitializers = make(map[string]func())
+
+// Register adds an initialization func under the specified name
+func Register(name string, initializer func()) {
+	if _, exists := registeredInitializers[name]; exists {
+		panic(fmt.Sprintf("reexec func already registred under name %q", name))
+	}
+
+	registeredInitializers[name] = initializer
+}
+
+// Init is called as the first part of the exec process and returns true if an
+// initialization function was called.
+func Init() bool {
+	initializer, exists := registeredInitializers[os.Args[0]]
+	if exists {
+		initializer()
+
+		return true
+	}
+
+	return false
+}
+
+// Self returns the path to the current processes binary
+func Self() string {
+	name := os.Args[0]
+
+	if filepath.Base(name) == name {
+		if lp, err := exec.LookPath(name); err == nil {
+			name = lp
+		}
+	}
+
+	return name
+}