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package hooks
import (
"bytes"
"fmt"
"os"
"path/filepath"
)
// Given a set of hook directories, returns whether a hook with the given name exists in any of them.
func Exists(hookDirs []string, hookName string) bool {
for _, hookDir := range hookDirs {
_, err := os.Stat(filepath.Join(hookDir, hookName))
if err == nil {
return true
}
}
return false
}
// Installs a hook in the hooks directory. If the file already exists, it is
// not overwritten unless it contains the string "#!acmetool-managed!#" in its
// first 4096 bytes.
func Replace(hookDirs []string, name, data string) error {
if len(hookDirs) == 0 {
hookDirs = DefaultPaths
}
if len(hookDirs) == 0 {
return fmt.Errorf("no hooks directory configured")
}
// Find the directory in the filesystem which has the most parent components
// of it already created.
hookDirectory, err := preferredHookDir(hookDirs)
if err != nil {
return err
}
filename := filepath.Join(hookDirectory, name)
isManaged, err := isManagedFile(filename)
if os.IsNotExist(err) || (err == nil && isManaged) {
return writeHook(filename, data)
}
return err
}
func preferredHookDir(hookDirs []string) (hookDirectory string, err error) {
bestLA := 255
for _, dir := range hookDirs {
var la int
la, err = levelsAbsent(dir)
if err != nil {
return
}
if la < bestLA {
hookDirectory = dir
bestLA = la
}
}
if hookDirectory == "" {
hookDirectory = hookDirs[0]
}
return
}
func levelsAbsent(dir string) (int, error) {
for i := 0; dir != "." && dir != "/"; i++ {
_, err := os.Stat(dir)
if err == nil {
return i, nil
}
dir = filepath.Join(dir, "..")
}
return 255, fmt.Errorf("cannot find a level which exists")
}
func writeHook(filename, data string) error {
err := os.MkdirAll(filepath.Dir(filename), 0755)
if err != nil {
return err
}
f, err := os.OpenFile(filename, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0755)
if err != nil {
return nil
}
defer f.Close()
f.Write([]byte(data))
return nil
}
func isManagedFile(filename string) (bool, error) {
f, err := os.Open(filename)
if err != nil {
return false, err
}
defer f.Close()
b := make([]byte, 4096)
n, _ := f.Read(b)
b = b[0:n]
return bytes.Index(b, []byte("#!acmetool-managed!#")) >= 0, nil
}
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