internal/env: relocate from app

This package is much cleaner to stub independently, and makes no sense to lump into app.

Signed-off-by: Ophestra <cat@gensokyo.uk>

2 files changed, 184 insertions, 0 deletions

diff --git a/internal/env/env.go b/internal/env/env.go
new file mode 100644
index 00000000..ebb816d6
--- /dev/null
+++ b/internal/env/env.go
@@ -0,0 +1,66 @@
+// Package env provides the [Paths] struct for efficiently building paths from the environment.
+package env
+
+import (
+	"log"
+	"os"
+	"strconv"
+
+	"hakurei.app/container/check"
+	"hakurei.app/hst"
+)
+
+// Paths holds paths copied from the environment and is used to create [hst.Paths].
+type Paths struct {
+	// TempDir is returned by [os.TempDir].
+	TempDir *check.Absolute
+	// RuntimePath is copied from $XDG_RUNTIME_DIR.
+	RuntimePath *check.Absolute
+}
+
+// Copy expands [Paths] into [hst.Paths].
+func (env *Paths) Copy(v *hst.Paths, userid int) {
+	if env == nil || env.TempDir == nil || v == nil {
+		panic("attempting to use an invalid Paths")
+	}
+
+	v.TempDir = env.TempDir
+	v.SharePath = env.TempDir.Append("hakurei." + strconv.Itoa(userid))
+
+	if env.RuntimePath == nil {
+		// fall back to path in share since hakurei has no hard XDG dependency
+		v.RunDirPath = v.SharePath.Append("run")
+		v.RuntimePath = v.RunDirPath.Append("compat")
+	} else {
+		v.RuntimePath = env.RuntimePath
+		v.RunDirPath = env.RuntimePath.Append("hakurei")
+	}
+}
+
+// CopyPaths returns a populated [Paths].
+func CopyPaths() *Paths { return CopyPathsFunc(log.Fatalf, os.TempDir, os.Getenv) }
+
+// CopyPathsFunc returns a populated [Paths],
+// using the provided [log.Fatalf], [os.TempDir], [os.Getenv] functions.
+func CopyPathsFunc(
+	fatalf func(format string, v ...any),
+	tempdir func() string,
+	getenv func(key string) string,
+) *Paths {
+	const xdgRuntimeDir = "XDG_RUNTIME_DIR"
+
+	var env Paths
+
+	if tempDir, err := check.NewAbs(tempdir()); err != nil {
+		fatalf("invalid TMPDIR: %v", err)
+		panic("unreachable")
+	} else {
+		env.TempDir = tempDir
+	}
+
+	if a, err := check.NewAbs(getenv(xdgRuntimeDir)); err == nil {
+		env.RuntimePath = a
+	}
+
+	return &env
+}
diff --git a/internal/env/env_test.go b/internal/env/env_test.go
new file mode 100644
index 00000000..8a07d6b5
--- /dev/null
+++ b/internal/env/env_test.go
@@ -0,0 +1,118 @@
+package env_test
+
+import (
+	"fmt"
+	"reflect"
+	"testing"
+
+	"hakurei.app/container"
+	"hakurei.app/container/check"
+	"hakurei.app/container/fhs"
+	"hakurei.app/container/stub"
+	"hakurei.app/hst"
+	"hakurei.app/internal/env"
+)
+
+func TestPaths(t *testing.T) {
+	t.Parallel()
+
+	testCases := []struct {
+		name string
+		env  *env.Paths
+		want hst.Paths
+
+		wantPanic string
+	}{
+		{"nil", nil, hst.Paths{}, "attempting to use an invalid Paths"},
+		{"zero", new(env.Paths), hst.Paths{}, "attempting to use an invalid Paths"},
+
+		{"nil tempdir", &env.Paths{
+			RuntimePath: fhs.AbsTmp,
+		}, hst.Paths{}, "attempting to use an invalid Paths"},
+
+		{"nil runtime", &env.Paths{
+			TempDir: fhs.AbsTmp,
+		}, hst.Paths{
+			TempDir:     fhs.AbsTmp,
+			SharePath:   fhs.AbsTmp.Append("hakurei.3735928559"),
+			RuntimePath: fhs.AbsTmp.Append("hakurei.3735928559/run/compat"),
+			RunDirPath:  fhs.AbsTmp.Append("hakurei.3735928559/run"),
+		}, ""},
+
+		{"full", &env.Paths{
+			TempDir:     fhs.AbsTmp,
+			RuntimePath: fhs.AbsRunUser.Append("1000"),
+		}, hst.Paths{
+			TempDir:     fhs.AbsTmp,
+			SharePath:   fhs.AbsTmp.Append("hakurei.3735928559"),
+			RuntimePath: fhs.AbsRunUser.Append("1000"),
+			RunDirPath:  fhs.AbsRunUser.Append("1000/hakurei"),
+		}, ""},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			if tc.wantPanic != "" {
+				defer func() {
+					if r := recover(); r != tc.wantPanic {
+						t.Errorf("Copy: panic = %#v, want %q", r, tc.wantPanic)
+					}
+				}()
+			}
+
+			var sc hst.Paths
+			tc.env.Copy(&sc, 0xdeadbeef)
+			if !reflect.DeepEqual(&sc, &tc.want) {
+				t.Errorf("Copy: %#v, want %#v", sc, tc.want)
+			}
+		})
+	}
+}
+
+func TestCopyPaths(t *testing.T) {
+	t.Parallel()
+
+	testCases := []struct {
+		name  string
+		env   map[string]string
+		tmp   string
+		fatal string
+		want  env.Paths
+	}{
+		{"invalid tempdir", nil, "\x00",
+			"invalid TMPDIR: path \"\\x00\" is not absolute", env.Paths{}},
+		{"empty environment", make(map[string]string), container.Nonexistent,
+			"", env.Paths{TempDir: check.MustAbs(container.Nonexistent)}},
+		{"invalid XDG_RUNTIME_DIR", map[string]string{"XDG_RUNTIME_DIR": "\x00"}, container.Nonexistent,
+			"", env.Paths{TempDir: check.MustAbs(container.Nonexistent)}},
+		{"full", map[string]string{"XDG_RUNTIME_DIR": "/\x00"}, container.Nonexistent,
+			"", env.Paths{TempDir: check.MustAbs(container.Nonexistent), RuntimePath: check.MustAbs("/\x00")}},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			if tc.fatal != "" {
+				defer stub.HandleExit(t)
+			}
+
+			got := env.CopyPathsFunc(func(format string, v ...any) {
+				if tc.fatal == "" {
+					t.Fatalf("unexpected call to fatalf: format = %q, v = %#v", format, v)
+				}
+
+				if got := fmt.Sprintf(format, v...); got != tc.fatal {
+					t.Fatalf("fatalf: %q, want %q", got, tc.fatal)
+				}
+				panic(stub.PanicExit)
+			}, func() string { return tc.tmp }, func(key string) string { return tc.env[key] })
+
+			if tc.fatal != "" {
+				t.Fatalf("copyPaths: expected fatal %q", tc.fatal)
+			}
+
+			if !reflect.DeepEqual(got, &tc.want) {
+				t.Errorf("copyPaths: %#v, want %#v", got, &tc.want)
+			}
+		})
+	}
+}