From 2495e17b6c2d4323b0c989b8ef27248f29eb9548 Mon Sep 17 00:00:00 2001
From: Luke Shumaker <lukeshu@lukeshu.com>
Date: Fri, 15 Feb 2019 22:04:54 -0500
Subject: write fi-sponge

---
 README.md           |   2 +
 fi-sponge/sponge.go | 108 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 110 insertions(+)
 create mode 100644 fi-sponge/sponge.go

diff --git a/README.md b/README.md
index 4760806..0dfd357 100644
--- a/README.md
+++ b/README.md
@@ -13,6 +13,8 @@ streams:
    mentioned in it.
  - `fi-prune-empty`: Prunes a fast-import stream, removing empty
    commits and empty merges.
+ - `fi-sponge`: Soaks up a fast-import stream, and re-emits it,
+   potentially with different flags.
 
 There are also a few special-purpose commands for working with
 fast-import streams of the Arch Build System:
diff --git a/fi-sponge/sponge.go b/fi-sponge/sponge.go
new file mode 100644
index 0000000..1d42143
--- /dev/null
+++ b/fi-sponge/sponge.go
@@ -0,0 +1,108 @@
+// Copyright 2019  Luke Shumaker <lukeshu@parabola.nu>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+// Command fi-sponge soaks up a fast-import stream, and re-emits it,
+// potentially with different flags.
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+	"syscall"
+)
+
+func usage() {
+	fmt.Printf("Usage: git fast-export | %s [FAST-IMPORT-FLAGS] -- [FAST-EXPORT-FLAGS] | git fast-import\n", os.Args[0])
+}
+
+func main() {
+	var split int
+	for i := range os.Args {
+		switch os.Args[i] {
+		case "--":
+			split = i
+		case "-h", "--help":
+			usage()
+			os.Exit(0)
+		}
+	}
+	if split == 0 {
+		fmt.Fprintf(os.Stderr, "%s: must give a '--' argument\n", os.Args[0])
+		fmt.Fprintf(os.Stderr, "Try '%s --help' for more information\n", os.Args[0])
+		os.Exit(2)
+	}
+	inargs := os.Args[1:split]
+	outargs := os.Args[split+1:]
+	err := sponge(inargs, outargs)
+	if err != nil {
+		if ee, ok := err.(*exec.ExitError); ok {
+			ws := ee.ProcessState.Sys().(syscall.WaitStatus)
+			switch {
+			case ws.Exited():
+				os.Exit(ws.ExitStatus())
+			case ws.Signaled():
+				os.Exit(128 + int(ws.Signal()))
+			}
+		} else {
+			fmt.Fprintf(os.Stderr, "%s: error: %v\n", os.Args[0], err)
+			os.Exit(255)
+		}
+	}
+}
+
+func sponge(inargs, outargs []string) error {
+	tmpdir, err := ioutil.TempDir("", filepath.Base(os.Args[0])+".")
+	if err != nil {
+		return err
+	}
+	defer os.RemoveAll(tmpdir)
+
+	cmd := exec.Command("git", "init", ".")
+	cmd.Dir = tmpdir
+	cmd.Stdout = os.Stderr
+	cmd.Stderr = os.Stderr
+	if err := cmd.Run(); err != nil {
+		return err
+	}
+
+	cmd = exec.Command("git", append([]string{"fast-import", "--cat-blob-fd=0"}, inargs...)...)
+	cmd.Stdin = os.Stdin
+	cmd.Stdout = os.Stderr
+	cmd.Stderr = os.Stderr
+	if err := cmd.Run(); err != nil {
+		return err
+	}
+
+	cmd = exec.Command("git", "for-each-ref", "--format=%(refname)")
+	cmd.Stderr = os.Stderr
+	b, err := cmd.Output()
+	if err != nil {
+		return err
+	}
+	refs := strings.Split(strings.TrimSuffix(string(b), "\n"), "\n")
+
+	cmd = exec.Command("git", append(append([]string{"fast-export"}, outargs...), refs...)...)
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	if err := cmd.Run(); err != nil {
+		return err
+	}
+
+	return nil
+}
-- 
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