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