From 46275b90c27865ee4fb9f243cd2e7002de8516f9 Mon Sep 17 00:00:00 2001
From: topjohnwu <topjohnwu@gmail.com>
Date: Thu, 21 Sep 2023 05:47:21 -0700
Subject: [PATCH] Generalize unxz

---
 native/src/init/init.cpp    | 20 ++++----------------
 native/src/init/init.hpp    |  4 ++--
 native/src/init/rootdir.cpp |  9 ++++++---
 native/src/init/selinux.cpp | 14 ++++++++++++--
 4 files changed, 24 insertions(+), 23 deletions(-)

diff --git a/native/src/init/init.cpp b/native/src/init/init.cpp
index 9b6ad4721..65a21b9a3 100644
--- a/native/src/init/init.cpp
+++ b/native/src/init/init.cpp
@@ -12,12 +12,13 @@
 
 using namespace std;
 
-bool unxz(int fd, const uint8_t *buf, size_t size) {
+bool unxz(out_stream &strm, rust::Slice<const uint8_t> bytes) {
     uint8_t out[8192];
     xz_crc32_init();
+    size_t size = bytes.size();
     struct xz_dec *dec = xz_dec_init(XZ_DYNALLOC, 1 << 26);
     struct xz_buf b = {
-        .in = buf,
+        .in = bytes.data(),
         .in_pos = 0,
         .in_size = size,
         .out = out,
@@ -29,20 +30,11 @@ bool unxz(int fd, const uint8_t *buf, size_t size) {
         ret = xz_dec_run(dec, &b);
         if (ret != XZ_OK && ret != XZ_STREAM_END)
             return false;
-        write(fd, out, b.out_pos);
+        strm.write(out, b.out_pos);
         b.out_pos = 0;
     } while (b.in_pos != size);
     return true;
-}
 
-static int dump_bin(const uint8_t *buf, size_t sz, const char *path, mode_t mode) {
-    int fd = xopen(path, O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC, mode);
-    if (fd < 0)
-        return 1;
-    if (!unxz(fd, buf, sz))
-        return 1;
-    close(fd);
-    return 0;
 }
 
 void restore_ramdisk_init() {
@@ -59,10 +51,6 @@ void restore_ramdisk_init() {
     }
 }
 
-int dump_preload(const char *path, mode_t mode) {
-    return dump_bin(init_ld_xz, sizeof(init_ld_xz), path, mode);
-}
-
 class RecoveryInit : public BaseInit {
 public:
     using BaseInit::BaseInit;
diff --git a/native/src/init/init.hpp b/native/src/init/init.hpp
index 96592421e..e5c5e2d01 100644
--- a/native/src/init/init.hpp
+++ b/native/src/init/init.hpp
@@ -1,4 +1,5 @@
 #include <base.hpp>
+#include <stream.hpp>
 
 #include "init-rs.hpp"
 
@@ -26,12 +27,11 @@ struct BootConfig {
 extern std::vector<std::string> mount_list;
 
 int magisk_proxy_main(int argc, char *argv[]);
-bool unxz(int fd, const uint8_t *buf, size_t size);
+bool unxz(out_stream &strm, rust::Slice<const uint8_t> bytes);
 void load_kernel_info(BootConfig *config);
 bool check_two_stage();
 const char *backup_init();
 void restore_ramdisk_init();
-int dump_preload(const char *path, mode_t mode);
 
 /***************
  * Base classes
diff --git a/native/src/init/rootdir.cpp b/native/src/init/rootdir.cpp
index 9b2d3d649..ac058f587 100644
--- a/native/src/init/rootdir.cpp
+++ b/native/src/init/rootdir.cpp
@@ -167,14 +167,16 @@ static void extract_files(bool sbin) {
         mmap_data magisk(m32);
         unlink(m32);
         int fd = xopen("magisk32", O_WRONLY | O_CREAT, 0755);
-        unxz(fd, magisk.buf(), magisk.sz());
+        fd_channel ch(fd);
+        unxz(ch, magisk);
         close(fd);
     }
     if (access(m64, F_OK) == 0) {
         mmap_data magisk(m64);
         unlink(m64);
         int fd = xopen("magisk64", O_WRONLY | O_CREAT, 0755);
-        unxz(fd, magisk.buf(), magisk.sz());
+        fd_channel ch(fd);
+        unxz(ch, magisk);
         close(fd);
         xsymlink("./magisk64", "magisk");
     } else {
@@ -184,7 +186,8 @@ static void extract_files(bool sbin) {
         mmap_data stub(stub_xz);
         unlink(stub_xz);
         int fd = xopen("stub.apk", O_WRONLY | O_CREAT, 0);
-        unxz(fd, stub.buf(), stub.sz());
+        fd_channel ch(fd);
+        unxz(ch, stub);
         close(fd);
     }
 }
diff --git a/native/src/init/selinux.cpp b/native/src/init/selinux.cpp
index 4ddb92350..2eff10411 100644
--- a/native/src/init/selinux.cpp
+++ b/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);
     }