Generalize unxz

native/src/init/selinux.cpp

@@ -2,7 +2,7 @@
 
 #include <magisk.hpp>
 #include <sepolicy.hpp>
-#include <base.hpp>
+#include <embed.hpp>
 
 #include "init.hpp"
 
@@ -38,6 +38,16 @@ void MagiskInit::patch_sepolicy(const char *in, const char *out) {
     }
 }
 
+static void dump_preload() {
+    int fd = xopen("/dev/preload.so", O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC, 0644);
+    if (fd < 0)
+        return;
+    fd_channel ch(fd);
+    if (!unxz(ch, byte_view(init_ld_xz, sizeof(init_ld_xz))))
+        return;
+    close(fd);
+}
+
 #define MOCK_COMPAT    SELINUXMOCK "/compatible"
 #define MOCK_LOAD      SELINUXMOCK "/load"
 #define MOCK_ENFORCE   SELINUXMOCK "/enforce"
@@ -50,7 +60,7 @@ bool MagiskInit::hijack_sepolicy() {
         // This meant that instead of going through convoluted methods trying to alter
         // and block init's control flow, we can just LD_PRELOAD and replace the
         // security_load_policy function with our own implementation.
-        dump_preload("/dev/preload.so", 0644);
+        dump_preload();
         setenv("LD_PRELOAD", "/dev/preload.so", 1);
     }