73 lines
1.6 KiB
Go
73 lines
1.6 KiB
Go
package nixfig
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import (
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"bytes"
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"encoding/json"
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"errors"
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"fmt"
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"os"
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"os/exec"
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)
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var (
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// Nix is the command to call for nix
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Nix string
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ErrNixNotFound = errors.New("nix was not found or set. You can set it either with `nixfig.Nix` or the `NIXFIG_NIX` environment variable")
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)
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func init() {
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nixPath, _ := exec.LookPath("nix")
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Nix = nixPath
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if envPath, ok := os.LookupEnv("NIXFIG_NIX"); ok {
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Nix = envPath
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}
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}
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// Unmarshal unmarshals a nix expression as JSON into a struct
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func Unmarshal(data []byte, v any) error {
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if Nix == "" {
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return ErrNixNotFound
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}
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var stdout, stderr bytes.Buffer
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cmd := exec.Command(Nix, "eval", "--json", "--expr", string(data))
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cmd.Stdout = &stdout
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cmd.Stderr = &stderr
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if err := cmd.Run(); err != nil {
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return fmt.Errorf("could not run %q: %w", Nix, err)
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}
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if stderr.Len() > 0 {
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return errors.New(stderr.String())
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}
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if err := json.Unmarshal(stdout.Bytes(), v); err != nil {
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return fmt.Errorf("could not unmarshal nix config as JSON: %w", err)
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}
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return nil
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}
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// Marshal marshals a struct into a nix expression
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func Marshal(v any) ([]byte, error) {
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if Nix == "" {
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return nil, ErrNixNotFound
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}
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data, err := json.Marshal(v)
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if err != nil {
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return nil, fmt.Errorf("could not marshal JSON: %w", err)
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}
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var stdout, stderr bytes.Buffer
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cmd := exec.Command(Nix, "eval", "--expr", fmt.Sprintf(`(builtins.fromJSON %q)`, string(data)))
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cmd.Stdout = &stdout
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cmd.Stderr = &stderr
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if err := cmd.Run(); err != nil {
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return nil, fmt.Errorf("could not run %q: %w", Nix, err)
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}
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if stderr.Len() > 0 {
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return nil, errors.New(stderr.String())
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}
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return stdout.Bytes(), nil
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}
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