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// +build !appengine
package maxminddb
import (
"os"
"runtime"
)
// Open takes a string path to a MaxMind DB file and returns a Reader
// structure or an error. The database file is opened using a memory map,
// except on Google App Engine where mmap is not supported; there the database
// is loaded into memory. Use the Close method on the Reader object to return
// the resources to the system.
func Open(file string) (*Reader, error) {
mapFile, err := os.Open(file)
if err != nil {
return nil, err
}
defer func() {
if rerr := mapFile.Close(); rerr != nil {
err = rerr
}
}()
stats, err := mapFile.Stat()
if err != nil {
return nil, err
}
fileSize := int(stats.Size())
mmap, err := mmap(int(mapFile.Fd()), fileSize)
if err != nil {
return nil, err
}
reader, err := FromBytes(mmap)
if err != nil {
if err2 := munmap(mmap); err2 != nil {
// failing to unmap the file is probably the more severe error
return nil, err2
}
return nil, err
}
reader.hasMappedFile = true
runtime.SetFinalizer(reader, (*Reader).Close)
return reader, err
}
// Close unmaps the database file from virtual memory and returns the
// resources to the system. If called on a Reader opened using FromBytes
// or Open on Google App Engine, this method does nothing.
func (r *Reader) Close() error {
var err error
if r.hasMappedFile {
runtime.SetFinalizer(r, nil)
r.hasMappedFile = false
err = munmap(r.buffer)
}
r.buffer = nil
return err
}