48 lines
1.0 KiB
Go
48 lines
1.0 KiB
Go
package sandbox
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import (
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"encoding/gob"
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"errors"
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"os"
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"strconv"
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)
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var (
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ErrNotSet = errors.New("environment variable not set")
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ErrInvalid = errors.New("bad file descriptor")
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)
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// Setup appends the read end of a pipe for setup params transmission and returns its fd.
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func Setup(extraFiles *[]*os.File) (int, *gob.Encoder, error) {
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if r, w, err := os.Pipe(); err != nil {
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return -1, nil, err
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} else {
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fd := 3 + len(*extraFiles)
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*extraFiles = append(*extraFiles, r)
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return fd, gob.NewEncoder(w), nil
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}
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}
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// Receive retrieves setup fd from the environment and receives params.
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func Receive(key string, e any, v **os.File) (func() error, error) {
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var setup *os.File
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if s, ok := os.LookupEnv(key); !ok {
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return nil, ErrNotSet
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} else {
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if fd, err := strconv.Atoi(s); err != nil {
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return nil, err
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} else {
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setup = os.NewFile(uintptr(fd), "setup")
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if setup == nil {
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return nil, ErrInvalid
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}
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if v != nil {
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*v = setup
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}
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}
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}
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return setup.Close, gob.NewDecoder(setup).Decode(e)
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}
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