forked from hairyhenderson/gomplate
/
plugins.go
117 lines (102 loc) · 2.45 KB
/
plugins.go
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package gomplate
import (
"bytes"
"context"
"fmt"
"io"
"os"
"os/exec"
"os/signal"
"path/filepath"
"runtime"
"text/template"
"time"
"github.com/duffpl/gomplate/v3/conv"
"github.com/duffpl/gomplate/v3/internal/config"
)
func bindPlugins(ctx context.Context, cfg *config.Config, funcMap template.FuncMap) error {
for k, v := range cfg.Plugins {
plugin := &plugin{
ctx: ctx,
name: k,
path: v,
timeout: cfg.PluginTimeout,
stderr: cfg.Stderr,
}
if _, ok := funcMap[plugin.name]; ok {
return fmt.Errorf("function %q is already bound, and can not be overridden", plugin.name)
}
funcMap[plugin.name] = plugin.run
}
return nil
}
// plugin represents a custom function that binds to an external process to be executed
type plugin struct {
ctx context.Context
stderr io.Writer
name, path string
timeout time.Duration
}
// builds a command that's appropriate for running scripts
// nolint: gosec
func (p *plugin) buildCommand(a []string) (name string, args []string) {
switch filepath.Ext(p.path) {
case ".ps1":
a = append([]string{"-File", p.path}, a...)
return findPowershell(), a
case ".cmd", ".bat":
a = append([]string{"/c", p.path}, a...)
return "cmd.exe", a
default:
return p.path, a
}
}
// finds the appropriate powershell command for the platform - prefers
// PowerShell Core (`pwsh`), but on Windows if it's not found falls back to
// Windows PowerShell (`powershell`).
func findPowershell() string {
if runtime.GOOS != "windows" {
return "pwsh"
}
_, err := exec.LookPath("pwsh")
if err != nil {
return "powershell"
}
return "pwsh"
}
func (p *plugin) run(args ...interface{}) (interface{}, error) {
a := conv.ToStrings(args...)
name, a := p.buildCommand(a)
ctx, cancel := context.WithTimeout(p.ctx, p.timeout)
defer cancel()
c := exec.CommandContext(ctx, name, a...)
c.Stdin = nil
c.Stderr = p.stderr
outBuf := &bytes.Buffer{}
c.Stdout = outBuf
start := time.Now()
err := c.Start()
if err != nil {
return nil, err
}
// make sure all signals are propagated
sigs := make(chan os.Signal, 1)
signal.Notify(sigs)
go func() {
select {
case sig := <-sigs:
// Pass signals to the sub-process
if c.Process != nil {
// nolint: gosec
_ = c.Process.Signal(sig)
}
case <-ctx.Done():
}
}()
err = c.Wait()
elapsed := time.Since(start)
if ctx.Err() != nil {
err = fmt.Errorf("plugin timed out after %v: %w", elapsed, ctx.Err())
}
return outBuf.String(), err
}