fix: strdup ObjC strings returned across CGo boundary

UTF8String pointers into NSString buffers become dangling once the
autorelease pool drains. Use strdup so callers own the memory, and
pair each call site in Go with C.free via defer.

Affected: getSystemInfo, getNSHomeDirectory, getNSCacheDirectory.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: 2 people

apps/finicky/src/util/directories.go

@@ -1,17 +1,21 @@
 package util
 
 /*
+#include <stdlib.h>
 #include "info.h"
 */
 import "C"
 import (
 	"fmt"
 	"strings"
+	"unsafe"
 )
 
 // UserHomeDir returns the user's home directory using NSHomeDirectory
 func UserHomeDir() (string, error) {
-	dir := C.GoString(C.getNSHomeDirectory())
+	cDir := C.getNSHomeDirectory()
+	defer C.free(unsafe.Pointer(cDir))
+	dir := C.GoString(cDir)
 	if dir == "" {
 		return "", fmt.Errorf("failed to get user home directory")
 	}
@@ -32,7 +36,12 @@ func ShortenPath(path string) string {
 
 // UserCacheDir returns the user's cache directory using NSSearchPathForDirectoriesInDomains
 func UserCacheDir() (string, error) {
-	dir := C.GoString(C.getNSCacheDirectory())
+	cDir := C.getNSCacheDirectory()
+	if cDir == nil {
+		return "", fmt.Errorf("failed to get user cache directory")
+	}
+	defer C.free(unsafe.Pointer(cDir))
+	dir := C.GoString(cDir)
 	if dir == "" {
 		return "", fmt.Errorf("failed to get user cache directory")
 	}

apps/finicky/src/util/info.go

@@ -39,6 +39,8 @@ func GetModifierKeys() map[string]bool {
 // GetSystemInfo returns system information
 func GetSystemInfo() map[string]string {
 	info := C.getSystemInfo()
+	defer C.free(unsafe.Pointer(info.localizedName))
+	defer C.free(unsafe.Pointer(info.name))
 	return map[string]string{
 		"localizedName": C.GoString(info.localizedName),
 		"name":          C.GoString(info.name),

apps/finicky/src/util/info.h

@@ -24,10 +24,10 @@ typedef struct {
 } PowerInfo;
 
 ModifierKeys getModifierKeys(void);
-SystemInfo getSystemInfo(void);
+SystemInfo getSystemInfo(void); /* caller must free localizedName and name */
 PowerInfo getPowerInfo(void);
 _Bool isAppRunning(const char* identifier);
-const char* getNSHomeDirectory(void);
-const char* getNSCacheDirectory(void);
+const char* getNSHomeDirectory(void);  /* caller must free */
+const char* getNSCacheDirectory(void); /* caller must free; may return NULL */
 
 #endif /* INFO_H */

apps/finicky/src/util/info.m

@@ -24,8 +24,8 @@ SystemInfo getSystemInfo() {
     NSString *nameStr = [currentHost name] ?: @"";
 
     SystemInfo info = {
-        .localizedName = [localizedNameStr UTF8String],
-        .name = [nameStr UTF8String]
+        .localizedName = strdup([localizedNameStr UTF8String]),
+        .name = strdup([nameStr UTF8String])
     };
     return info;
 }
@@ -119,14 +119,14 @@ _Bool isAppRunning(const char* identifier) {
 
 const char* getNSHomeDirectory(void) {
     NSString *homeDirString = NSHomeDirectory();
-    return [homeDirString UTF8String];
+    return strdup([homeDirString UTF8String]);
 }
 
 const char* getNSCacheDirectory(void) {
     NSArray *paths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, true);
     if (paths.count > 0) {
         NSString *cacheDirString = [paths objectAtIndex:0];
-        return [cacheDirString UTF8String];
+        return strdup([cacheDirString UTF8String]);
     }
     return NULL;
 }

apps/finicky/src/util/info_test.go

@@ -0,0 +1,61 @@
+//go:build darwin
+
+package util
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestGetSystemInfo(t *testing.T) {
+	info := GetSystemInfo()
+
+	if info["localizedName"] == "" {
+		t.Error("localizedName is empty")
+	}
+	if info["name"] == "" {
+		t.Error("name is empty")
+	}
+}
+
+func TestUserHomeDir(t *testing.T) {
+	dir, err := UserHomeDir()
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if !strings.HasPrefix(dir, "/") {
+		t.Errorf("expected absolute path, got %q", dir)
+	}
+}
+
+func TestUserCacheDir(t *testing.T) {
+	dir, err := UserCacheDir()
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if !strings.HasPrefix(dir, "/") {
+		t.Errorf("expected absolute path, got %q", dir)
+	}
+}
+
+func TestShortenPath(t *testing.T) {
+	home, err := UserHomeDir()
+	if err != nil {
+		t.Skip("could not get home dir")
+	}
+
+	cases := []struct {
+		input string
+		want  string
+	}{
+		{home, "~"},
+		{home + "/foo/bar", "~/foo/bar"},
+		{"/other/path", "/other/path"},
+		{"", ""},
+	}
+	for _, c := range cases {
+		if got := ShortenPath(c.input); got != c.want {
+			t.Errorf("ShortenPath(%q) = %q, want %q", c.input, got, c.want)
+		}
+	}
+}