Initial commit

This commit is contained in:
Ria Bhatia
2017-12-04 13:32:57 -06:00
committed by Erik St. Martin
commit 0075e5b0f3
9056 changed files with 2523100 additions and 0 deletions

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## 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.

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// +build freebsd
package reexec
import (
"os/exec"
)
// Self returns the path to the current process's binary.
// Uses os.Args[0].
func Self() string {
return naiveSelf()
}
// Command returns *exec.Cmd which have Path as current binary.
// For example if current binary is "docker" at "/usr/bin/", then cmd.Path will
// be set to "/usr/bin/docker".
func Command(args ...string) *exec.Cmd {
return &exec.Cmd{
Path: Self(),
Args: args,
}
}

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// +build linux
package reexec
import (
"os/exec"
"syscall"
)
// Self returns the path to the current process's binary.
// Returns "/proc/self/exe".
func Self() string {
return "/proc/self/exe"
}
// Command returns *exec.Cmd which have Path as current binary. Also it setting
// SysProcAttr.Pdeathsig to SIGTERM.
// This will use the in-memory version (/proc/self/exe) of the current binary,
// it is thus safe to delete or replace the on-disk binary (os.Args[0]).
func Command(args ...string) *exec.Cmd {
return &exec.Cmd{
Path: Self(),
Args: args,
SysProcAttr: &syscall.SysProcAttr{
Pdeathsig: syscall.SIGTERM,
},
}
}

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// +build !linux,!windows,!freebsd
package reexec
import (
"os/exec"
)
// Command is unsupported on operating systems apart from Linux and Windows.
func Command(args ...string) *exec.Cmd {
return nil
}

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// +build windows
package reexec
import (
"os/exec"
)
// Self returns the path to the current process's binary.
// Uses os.Args[0].
func Self() string {
return naiveSelf()
}
// Command returns *exec.Cmd which have Path as current binary.
// For example if current binary is "docker.exe" at "C:\", then cmd.Path will
// be set to "C:\docker.exe".
func Command(args ...string) *exec.Cmd {
return &exec.Cmd{
Path: Self(),
Args: args,
}
}

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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
}
func naiveSelf() string {
name := os.Args[0]
if filepath.Base(name) == name {
if lp, err := exec.LookPath(name); err == nil {
return lp
}
}
// handle conversion of relative paths to absolute
if absName, err := filepath.Abs(name); err == nil {
return absName
}
// if we couldn't get absolute name, return original
// (NOTE: Go only errors on Abs() if os.Getwd fails)
return name
}