ricochet-go/core/config.go

171 lines
4.0 KiB
Go

package core
import (
"encoding/json"
"io/ioutil"
"log"
"os"
"sync"
)
// XXX This is partially but not fully compatible with Ricochet's JSON
// configs. It might be better to be explicitly not compatible, but have
// an automatic import function.
type Config struct {
filePath string
root ConfigRoot
mutex sync.RWMutex
}
type ConfigRoot struct {
Contacts map[string]ConfigContact
Identity ConfigIdentity
// Not used by the permanent instance in Config
writable bool
config *Config
}
type ConfigContact struct {
Hostname string
LastConnected string `json:",omitempty"`
Nickname string
WhenCreated string
Request ConfigContactRequest `json:",omitempty"`
}
type ConfigContactRequest struct {
Pending bool
MyNickname string
Message string
WhenDelivered string `json:",omitempty"`
WhenRejected string `json:",omitempty"`
RemoteError string `json:",omitempty"`
}
type ConfigIdentity struct {
DataDirectory string `json:",omitempty"`
ServiceKey string
}
func LoadConfig(filePath string) (*Config, error) {
config := &Config{
filePath: filePath,
}
data, err := ioutil.ReadFile(config.filePath)
if err != nil {
log.Printf("Config read error from %s: %v", config.filePath, err)
return nil, err
}
if err := json.Unmarshal(data, &config.root); err != nil {
log.Printf("Config parse error: %v", err)
return nil, err
}
return config, nil
}
// Return a read-only snapshot of the current configuration. This object
// _must not_ be stored, and you must call Close() when finished with it.
// This function may block.
func (c *Config) OpenRead() *ConfigRoot {
c.mutex.RLock()
root := c.root
root.writable = false
root.config = c
return &root
}
// Return a writable snapshot of the current configuration. This object
// _must not_ be stored, and you must call Save() or Discard() when
// finished with it. This function may block.
func (c *Config) OpenWrite() *ConfigRoot {
c.mutex.Lock()
root := c.root
root.writable = true
root.config = c
return &root
}
func (root *ConfigRoot) Close() {
if root.writable {
log.Panic("Close called on writable config object; use Save or Discard")
}
if root.config == nil {
log.Panic("Close called on closed config object")
}
root.config.mutex.RUnlock()
root.config = nil
}
// Save saves the state to the Config object, and attempts to write to
// disk. An error is returned if the write fails, but changes to the
// object are not discarded on error. XXX This is bad API
func (root *ConfigRoot) Save() error {
if !root.writable {
log.Panic("Save called on read-only config object")
}
if root.config == nil {
log.Panic("Save called on closed config object")
}
c := root.config
root.writable = false
root.config = nil
c.root = *root
err := c.save()
c.mutex.Unlock()
return err
}
// Discard cannot be relied on to restore the state exactly as it was,
// because of potentially shared slice or map objects, but does not do
// an immediate save to disk. XXX This is bad API
func (root *ConfigRoot) Discard() {
if !root.writable {
log.Panic("Discard called on read-only config object")
}
if root.config == nil {
log.Panic("Discard called on closed config object")
}
c := root.config
root.config = nil
c.mutex.Unlock()
}
func (c *Config) save() error {
data, err := json.MarshalIndent(c.root, "", " ")
if err != nil {
log.Printf("Config encoding error: %v", err)
return err
}
// Make a pathetic attempt at atomic file write by writing into a
// temporary file and renaming over the original; this is probably
// imperfect as-implemented, but better than truncating and writing
// directly.
tempPath := c.filePath + ".new"
file, err := os.OpenFile(tempPath, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0600)
if err != nil {
log.Printf("Config save error: %v", err)
return err
}
if _, err := file.Write(data); err != nil {
log.Printf("Config write error: %v", err)
file.Close()
return err
}
file.Close()
if err := os.Rename(tempPath, c.filePath); err != nil {
log.Printf("Config replace error: %v", err)
return err
}
return nil
}