nix-amer/internal/instruction/copy.go

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package instruction
import (
"os"
"strings"
)
type copy struct {
raw string
Src string
Dst string
}
func (d *copy) Raw() string { return strings.Join([]string{"copy", d.raw}, " ") }
func (d *copy) Build(_args string) error {
// 1. extract action (sub command)
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split := strings.Fields(_args)
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// 2. check syntax
if len(split) != 2 {
return ErrInvalidSyntax
}
d.Src = strings.Trim(split[0], " \t")
d.Dst = strings.Trim(split[1], " \t")
d.raw = _args
return nil
}
func (d copy) Exec(ctx ExecutionContext) ([]byte, error) {
// 1. fail if source file not found
if _, err := os.Stat(d.Src); os.IsNotExist(err) {
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return nil, &FileError{"cannot find file", d.Src, err}
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}
// 2. execute script
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if err := ctx.Executor.Command("cp", "-r", d.Src, d.Dst).Run(); err != nil {
return nil, &FileError{"cannot copy to", d.Dst, err}
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}
return nil, nil
}
func (d copy) DryRun(ctx ExecutionContext) ([]byte, error) {
// 1. fail if source file not found
if _, err := os.Stat(d.Src); os.IsNotExist(err) {
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return nil, &FileError{"cannot find file", d.Src, err}
}
// 2. if destination to create : try to create (then remove)
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fi, err := os.Stat(d.Dst)
if os.IsNotExist(err) {
file, err2 := os.OpenFile(d.Dst, os.O_APPEND|os.O_WRONLY|os.O_CREATE, os.FileMode(0777))
if err2 != nil {
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return nil, &FileError{"cannot copy to", d.Dst, err2}
}
file.Close()
if err2 := os.Remove(d.Dst); err2 != nil {
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return nil, &FileError{"cannot remove dry-run file", d.Dst, err2}
}
return nil, nil
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} else if fi != nil && fi.IsDir() {
return nil, nil // no error if dir
}
// 3. if destination exists : check write permission
file, err := os.OpenFile(d.Dst, os.O_APPEND|os.O_WRONLY, 0600)
if err != nil {
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return nil, &FileError{"cannot copy to", d.Dst, err}
}
file.Close()
return nil, nil
}