Port code to read cloned env

tools/cmd/ssh/main.go

@@ -3,8 +3,10 @@
 package ssh
 
 import (
+	"encoding/json"
 	"errors"
 	"fmt"
+	"io/fs"
 	"net/url"
 	"os"
 	"os/user"
@@ -12,6 +14,7 @@ import (
 
 	"kitty/tools/cli"
 	"kitty/tools/tty"
+	"kitty/tools/utils/shm"
 
 	"golang.org/x/exp/maps"
 	"golang.org/x/sys/unix"
@@ -43,11 +46,35 @@ func get_destination(hostname string) (username, hostname_for_match string) {
 	return
 }
 
-func add_cloned_env(val string) map[string]string {
+func read_data_from_shared_memory(shm_name string) ([]byte, error) {
-	return nil // TODO: Implement me
+	data, err := shm.ReadWithSizeAndUnlink(shm_name, func(f *os.File) error {
+		s, err := f.Stat()
+		if err != nil {
+			return fmt.Errorf("Failed to stat SHM file with error: %w", err)
+		}
+		if stat, ok := s.Sys().(unix.Stat_t); ok {
+			if os.Getuid() != int(stat.Uid) || os.Getgid() != int(stat.Gid) {
+				return fmt.Errorf("Incorrect owner on SHM file")
+			}
+		}
+		if s.Mode().Perm() != 0o600 {
+			return fmt.Errorf("Incorrect permissions on SHM file")
+		}
+		return nil
+	})
+	return data, err
 }
 
-func parse_kitten_args(found_extra_args []string, username, hostname_for_match string) (overrides []string, literal_env map[string]string) {
+func add_cloned_env(val string) (ans map[string]string, err error) {
+	data, err := read_data_from_shared_memory(val)
+	if err != nil {
+		return nil, err
+	}
+	err = json.Unmarshal(data, &ans)
+	return ans, err
+}
+
+func parse_kitten_args(found_extra_args []string, username, hostname_for_match string) (overrides []string, literal_env map[string]string, ferr error) {
 	literal_env = make(map[string]string)
 	overrides = make([]string, 0, 4)
 	for i, a := range found_extra_args {
@@ -56,8 +83,12 @@ func parse_kitten_args(found_extra_args []string, username, hostname_for_match s
 		}
 		if key, val, found := strings.Cut(a, "="); found {
 			if key == "clone_env" {
-				le := add_cloned_env(val)
+				le, err := add_cloned_env(val)
-				if le != nil {
+				if err != nil {
+					if !errors.Is(err, fs.ErrNotExist) {
+						return nil, nil, ferr
+					}
+				} else if le != nil {
 					literal_env = le
 				}
 			} else if key != "hostname" {
@@ -80,7 +111,10 @@ func run_ssh(ssh_args, server_args, found_extra_args []string) (rc int, err erro
 	insertion_point := len(cmd)
 	cmd = append(cmd, "--", hostname)
 	uname, hostname_for_match := get_destination(hostname)
-	overrides, literal_env := parse_kitten_args(found_extra_args, uname, hostname_for_match)
+	overrides, literal_env, err := parse_kitten_args(found_extra_args, uname, hostname_for_match)
+	if err != nil {
+		return 1, err
+	}
 	if insertion_point > 0 && overrides != nil && literal_env != nil {
 	}
 	// TODO: Implement me

tools/cmd/ssh/main_test.go

@@ -0,0 +1,39 @@
+// License: GPLv3 Copyright: 2023, Kovid Goyal, <kovid at kovidgoyal.net>
+
+package ssh
+
+import (
+	"encoding/binary"
+	"encoding/json"
+	"fmt"
+	"kitty/tools/utils/shm"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+)
+
+var _ = fmt.Print
+
+func TestCloneEnv(t *testing.T) {
+	env := map[string]string{"a": "1", "b": "2"}
+	data, err := json.Marshal(env)
+	if err != nil {
+		t.Fatal(err)
+	}
+	mmap, err := shm.CreateTemp("", 128)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer mmap.Unlink()
+	copy(mmap.Slice()[4:], data)
+	binary.BigEndian.PutUint32(mmap.Slice(), uint32(len(data)))
+	mmap.Close()
+	x, err := add_cloned_env(mmap.Name())
+	if err != nil {
+		t.Fatal(err)
+	}
+	diff := cmp.Diff(env, x)
+	if diff != "" {
+		t.Fatalf("Failed to deserialize env\n%s", diff)
+	}
+}