apex: mount up apex files into /sbin for library access
This patch uses the loop device to mount files under
/sbin/ from /system/apex in order for the device to
use libraries or other files store inside these files.
Each apex file is mounted over a loop device into a
directory correpsonding to the apex filename under
/sbin/.
Once apex mounting is completed, TWRP will set a
property twrp.apex.loaded to true so that init
can use them as a LD_LIBARY_PATH source.
Change-Id: I69f14a969123ac9cf1afc85b6cf76836cb092fb2
Change-Id: Ica6a7d8e479bcaec8bec4483b5e8d2b45ee105fb
diff --git a/twrpApex.cpp b/twrpApex.cpp
new file mode 100755
index 0000000..33ec4dc
--- /dev/null
+++ b/twrpApex.cpp
@@ -0,0 +1,135 @@
+#include "twrpApex.hpp"
+
+namespace fs = std::filesystem;
+
+bool twrpApex::loadApexImages() {
+ std::vector<std::string> apexFiles;
+ if (access(APEX_DIR, F_OK) != 0) {
+ LOGERR("Unable to open %s\n", APEX_DIR);
+ return false;
+ }
+ for (const auto& entry : fs::directory_iterator(APEX_DIR)) {
+ if (entry.is_regular_file()) {
+ apexFiles.push_back(entry.path().string());
+ }
+ }
+
+ if (!createLoopBackDevices(apexFiles.size())) {
+ LOGERR("unable to create loop devices to mount apex files\n");
+ return false;
+ }
+
+ size_t apexFileCount = 0;
+ for (auto&& apexFile : apexFiles) {
+ std::string fileToMount = unzipImage(apexFile);
+ loadApexImage(fileToMount, apexFileCount++);
+ }
+ return true;
+}
+
+std::string twrpApex::unzipImage(std::string file) {
+ ZipArchiveHandle handle;
+ int32_t ret = OpenArchive(file.c_str(), &handle);
+ if (ret != 0) {
+ LOGERR("unable to open zip archive %s\n", file.c_str());
+ CloseArchive(handle);
+ return nullptr;
+ }
+
+ ZipEntry entry;
+ ZipString zip_string(APEX_PAYLOAD);
+ ret = FindEntry(handle, zip_string, &entry);
+ if (ret != 0) {
+ LOGERR("unable to find %s in zip\n", APEX_PAYLOAD);
+ CloseArchive(handle);
+ return nullptr;
+ }
+
+ std::string baseFile = basename(file.c_str());
+ std::string path = "/sbin/" + baseFile;
+ int fd = open(path.c_str(), O_WRONLY|O_CREAT|O_TRUNC, 0666);
+ ret = ExtractEntryToFile(handle, &entry, fd);
+ if (ret != 0) {
+ LOGERR("unable to extract %s\n", path.c_str());
+ close(fd);
+ CloseArchive(handle);
+ return nullptr;
+ }
+
+ close(fd);
+ CloseArchive(handle);
+ return path;
+}
+
+bool twrpApex::createLoopBackDevices(size_t count) {
+ size_t existing_loop_device_count = 0;
+
+ for (const auto& entry : fs::directory_iterator(LOOP_BLOCK_DEVICE_DIR)) {
+ if (entry.is_block_file() && entry.path().string().find("loop") != std::string::npos) {
+ existing_loop_device_count++;
+ }
+ }
+
+ if (existing_loop_device_count < count) {
+ size_t devices_to_create = count - existing_loop_device_count;
+ for (size_t i = existing_loop_device_count; i < (devices_to_create + existing_loop_device_count); ++i) {
+ std::string loop_device = LOOP_BLOCK_DEVICE_DIR;
+ loop_device = loop_device + "loop" + std::to_string(i);
+ int ret = mknod(loop_device.c_str(), S_IFBLK | S_IRUSR | S_IWUSR , makedev(7, i));
+ if (ret != 0) {
+ LOGERR("unable to create loop device: %s\n", loop_device.c_str());
+ return false;
+ }
+ }
+ }
+ return true;
+}
+
+bool twrpApex::loadApexImage(std::string fileToMount, size_t loop_device_number) {
+ struct loop_info64 info;
+
+ int fd = open(fileToMount.c_str(), O_RDONLY);
+ if (fd < 0) {
+ LOGERR("unable to open apex file: %s\n", fileToMount.c_str());
+ return false;
+ }
+
+ std::string loop_device = "/dev/block/loop" + std::to_string(loop_device_number);
+ int loop_fd = open(loop_device.c_str(), O_RDONLY);
+ if (loop_fd < 0) {
+ LOGERR("unable to open loop device: %s\n", loop_device.c_str());
+ close(fd);
+ return false;
+ }
+
+ if (ioctl(loop_fd, LOOP_SET_FD, fd) < 0) {
+ LOGERR("failed to mount %s to loop device %s\n", fileToMount.c_str(), loop_device.c_str());
+ close(fd);
+ close(loop_fd);
+ return false;
+ }
+
+ close(fd);
+
+ memset(&info, 0, sizeof(struct loop_info64));
+ if (ioctl(loop_fd, LOOP_SET_STATUS64, &info)) {
+ LOGERR("failed to mount loop: %s: %s\n", fileToMount.c_str(), strerror(errno));
+ close(loop_fd);
+ return false;
+ }
+ close(loop_fd);
+ std::string bind_mount = fileToMount + "-mount";
+ int ret = mkdir(bind_mount.c_str(), 0666);
+ if (ret != 0) {
+ LOGERR("unable to create mount directory: %s\n", bind_mount.c_str());
+ return false;
+ }
+
+ ret = mount(loop_device.c_str(), bind_mount.c_str(), "ext4", MS_RDONLY, nullptr);
+ if (ret != 0) {
+ LOGERR("unable to mount loop device %s to %s\n", loop_device.c_str(), bind_mount.c_str());
+ return false;
+ }
+
+ return true;
+}