Support reading compressed files through exec

pkg/analyze/analyze.go

@@ -2,6 +2,7 @@ package analyze
 
 import (
 	"fmt"
+	"io"
 	"log"
 	"net/netip"
 	"os"
@@ -143,11 +144,13 @@ func (a *Analyzer) RunLoop(iter fileiter.Iterator) error {
 }
 
 func (a *Analyzer) AnalyzeFile(filename string) error {
-	f, err := os.Open(filename)
+	f, err := OpenFile(filename)
 	if err != nil {
 		return err
 	}
-	defer f.Close()
+	if closer, ok := f.(io.Closer); ok {
+		defer closer.Close()
+	}
 	return a.RunLoop(fileiter.NewWithScanner(f))
 }
 

pkg/analyze/file.go

@@ -3,13 +3,59 @@ package analyze
 import (
 	"io"
 	"os"
+	"os/exec"
+	"path/filepath"
 
 	"github.com/nxadm/tail"
 	"github.com/taoky/ayano/pkg/fileiter"
 )
 
 const oneMiB = 1024 * 1024
 
+func filterByCommand(r io.Reader, args []string) (io.ReadCloser, error) {
+	cmd := exec.Command(args[0], args[1:]...)
+	cmd.Stdin = r
+	stdout, err := cmd.StdoutPipe()
+	if err != nil {
+		return nil, err
+	}
+	if err := cmd.Start(); err != nil {
+		return nil, err
+	}
+	go func() {
+		cmd.Wait()
+		if closer, ok := r.(io.Closer); ok {
+			closer.Close()
+		}
+	}()
+	return stdout, err
+}
+
+type filterFunc func(r io.Reader) (io.Reader, error)
+
+var fileTypes = map[string]filterFunc{
+	".gz": func(r io.Reader) (io.Reader, error) {
+		return filterByCommand(r, []string{"gzip", "-cd"})
+	},
+	".xz": func(r io.Reader) (io.Reader, error) {
+		return filterByCommand(r, []string{"xz", "-cd", "-T", "0"})
+	},
+	".zst": func(r io.Reader) (io.Reader, error) {
+		return filterByCommand(r, []string{"zstd", "-cd", "-T0"})
+	},
+}
+
+func OpenFile(filename string) (io.Reader, error) {
+	f, err := os.Open(filename)
+	if err != nil {
+		return nil, err
+	}
+	if filter, ok := fileTypes[filepath.Ext(filename)]; ok {
+		return filter(f)
+	}
+	return f, nil
+}
+
 func (a *Analyzer) OpenTailIterator(filename string) (fileiter.Iterator, error) {
 	var seekInfo *tail.SeekInfo
 	if a.Config.Whole {