From 304a68c565d58ae52dd39cf6e2d6ef52cada7d19 Mon Sep 17 00:00:00 2001
From: Simon Ruderich <simon@ruderich.org>
Date: Wed, 14 Apr 2021 13:47:28 +0200
Subject: [PATCH] rpc: prepare to support more operating systems

---
 rpc/dial.go | 28 ++++++++++++++++++++++++----
 1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/rpc/dial.go b/rpc/dial.go
index db25cb7..680cb87 100644
--- a/rpc/dial.go
+++ b/rpc/dial.go
@@ -98,6 +98,25 @@ func (c *Conn) dialSSH(stdin io.Writer, stdout_ io.Reader) error {
 	path := fmt.Sprintf("/tmp/safcm-remote-%d", uid)
 
 	c.debugf("DialSSH: probing remote at %q", path)
+
+	// Compatibility for different operating systems
+	var compat string
+	switch goos {
+	case "linux":
+		compat = `
+dir_stat='drwxrwxrwt 0 0'
+file_stat="-rwx------ $(id -u) $(id -g)"
+compat_stat() {
+	stat -c '%A %u %g' "$1"
+}
+compat_sha512sum() {
+	sha512sum "$1"
+}
+`
+	default:
+		return fmt.Errorf("internal error: no support for %q", goos)
+	}
+
 	// Use a function so the shell cannot execute the input line-wise.
 	// This is important because we're also using stdin to send data to
 	// the script. If the shell executes the input line-wise then our
@@ -116,18 +135,19 @@ func (c *Conn) dialSSH(stdin io.Writer, stdout_ io.Reader) error {
 	// `test -e` is only used to prevent error messages if the file
 	// doesn't exist. It does not guard against any races.
 	_, err = fmt.Fprintf(stdin, `
+%s
 f() {
 	x=%q
 
 	dir="$(dirname "$x")"
-	if ! test "$(stat -c '%%A %%u %%g' "$dir")" = 'drwxrwxrwt 0 0'; then
+	if ! test "$(compat_stat "$dir")" = "$dir_stat"; then
 		echo "unsafe permissions on $dir, aborting" >&2
 		exit 1
 	fi
 
-	if test -e "$x" && test "$(stat -c '%%A %%u' "$x")" = "-rwx------ $(id -u)"; then
+	if test -e "$x" && test "$(compat_stat "$x")" = "$file_stat"; then
 		# Report checksum
-		sha512sum "$x"
+		compat_sha512sum "$x"
 	else
 		# Empty checksum to request upload
 		echo
@@ -155,7 +175,7 @@ f() {
 	exec "$x" sync
 }
 f
-`, path)
+`, compat, path)
 	if err != nil {
 		return err
 	}
-- 
2.44.1