Support starting fuse from a block map

Factor out a new function from ApplyFromSdcard that installs a package
from a local path. Inside this function, we start the fuse and choose the
type of data provider depending on the path string. And similar to the
existing logic, we treat the package as a block map if the path starts
with a '@'.

This is part of the effort to install larger than 2GiB packages on ILP32
devices.

Bug: 127071893
Test: Build a 32 bit sailfish and create a 3GiB OTA package. Sideload
the package, uncrypt and install the package from sdcard.

Change-Id: I328ea34fa530731acbce7554bfc3059313ad6ece

3 files changed, 56 insertions, 26 deletions

diff --git a/install/Android.bp b/install/Android.bp
index 4696e501..89cc3f23 100644
--- a/install/Android.bp
+++ b/install/Android.bp
@@ -61,7 +61,7 @@ cc_library_static {
     srcs: [
         "adb_install.cpp",
         "asn1_decoder.cpp",
-        "fuse_sdcard_install.cpp",
+        "fuse_install.cpp",
         "install.cpp",
         "package.cpp",
         "verifier.cpp",
diff --git a/install/fuse_sdcard_install.cpp b/install/fuse_install.cpp
index 9fdb2f34..ffde4a34 100644
--- a/install/fuse_sdcard_install.cpp
+++ b/install/fuse_install.cpp
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-#include "install/fuse_sdcard_install.h"
+#include "install/fuse_install.h"
 
 #include <dirent.h>
 #include <signal.h>
@@ -27,6 +27,7 @@
 #include <algorithm>
 #include <functional>
 #include <memory>
+#include <string>
 #include <vector>
 
 #include <android-base/logging.h>
@@ -74,7 +75,8 @@ static std::string BrowseDirectory(const std::string& path, Device* device, Reco
       // Skip "." and ".." entries.
       if (name == "." || name == "..") continue;
       dirs.push_back(name + "/");
-    } else if (de->d_type == DT_REG && android::base::EndsWithIgnoreCase(name, ".zip")) {
+    } else if (de->d_type == DT_REG && (android::base::EndsWithIgnoreCase(name, ".zip") ||
+                                        android::base::EndsWithIgnoreCase(name, ".map"))) {
       entries.push_back(name);
     }
   }
@@ -119,42 +121,37 @@ static std::string BrowseDirectory(const std::string& path, Device* device, Reco
   // Unreachable.
 }
 
-static bool StartSdcardFuse(const std::string& path) {
-  auto file_data_reader = std::make_unique<FuseFileDataProvider>(path, 65536);
-
-  if (!file_data_reader->Valid()) {
+static bool StartInstallPackageFuse(std::string_view path) {
+  if (path.empty()) {
     return false;
   }
 
-  // The installation process expects to find the sdcard unmounted. Unmount it with MNT_DETACH so
-  // that our open file continues to work but new references see it as unmounted.
-  umount2("/sdcard", MNT_DETACH);
-
-  return run_fuse_sideload(std::move(file_data_reader)) == 0;
-}
+  constexpr auto FUSE_BLOCK_SIZE = 65536;
+  bool is_block_map = android::base::ConsumePrefix(&path, "@");
+  auto file_data_reader =
+      is_block_map ? FuseBlockDataProvider::CreateFromBlockMap(std::string(path), FUSE_BLOCK_SIZE)
+                   : FuseFileDataProvider::CreateFromFile(std::string(path), FUSE_BLOCK_SIZE);
 
-InstallResult ApplyFromSdcard(Device* device, RecoveryUI* ui) {
-  if (ensure_path_mounted(SDCARD_ROOT) != 0) {
-    LOG(ERROR) << "\n-- Couldn't mount " << SDCARD_ROOT << ".\n";
-    return INSTALL_ERROR;
+  if (!file_data_reader->Valid()) {
+    return false;
   }
 
-  std::string path = BrowseDirectory(SDCARD_ROOT, device, ui);
-  if (path.empty()) {
-    LOG(ERROR) << "\n-- No package file selected.\n";
-    ensure_path_unmounted(SDCARD_ROOT);
-    return INSTALL_ERROR;
+  if (android::base::StartsWith(path, SDCARD_ROOT)) {
+    // The installation process expects to find the sdcard unmounted. Unmount it with MNT_DETACH so
+    // that our open file continues to work but new references see it as unmounted.
+    umount2(SDCARD_ROOT, MNT_DETACH);
   }
 
-  ui->Print("\n-- Install %s ...\n", path.c_str());
-  SetSdcardUpdateBootloaderMessage();
+  return run_fuse_sideload(std::move(file_data_reader)) == 0;
+}
 
+InstallResult InstallWithFuseFromPath(std::string_view path, RecoveryUI* ui) {
   // We used to use fuse in a thread as opposed to a process. Since accessing
   // through fuse involves going from kernel to userspace to kernel, it leads
   // to deadlock when a page fault occurs. (Bug: 26313124)
   pid_t child;
   if ((child = fork()) == 0) {
-    bool status = StartSdcardFuse(path);
+    bool status = StartInstallPackageFuse(path);
 
     _exit(status ? EXIT_SUCCESS : EXIT_FAILURE);
   }
@@ -203,6 +200,32 @@ InstallResult ApplyFromSdcard(Device* device, RecoveryUI* ui) {
     LOG(ERROR) << "Error exit from the fuse process: " << WEXITSTATUS(status);
   }
 
+  return result;
+}
+
+InstallResult ApplyFromSdcard(Device* device) {
+  auto ui = device->GetUI();
+  if (ensure_path_mounted(SDCARD_ROOT) != 0) {
+    LOG(ERROR) << "\n-- Couldn't mount " << SDCARD_ROOT << ".\n";
+    return INSTALL_ERROR;
+  }
+
+  std::string path = BrowseDirectory(SDCARD_ROOT, device, ui);
+  if (path.empty()) {
+    LOG(ERROR) << "\n-- No package file selected.\n";
+    ensure_path_unmounted(SDCARD_ROOT);
+    return INSTALL_ERROR;
+  }
+
+  // Hint the install function to read from a block map file.
+  if (android::base::EndsWithIgnoreCase(path, ".map")) {
+    path = "@" + path;
+  }
+
+  ui->Print("\n-- Install %s ...\n", path.c_str());
+  SetSdcardUpdateBootloaderMessage();
+
+  auto result = InstallWithFuseFromPath(path, ui);
   ensure_path_unmounted(SDCARD_ROOT);
   return result;
 }
diff --git a/install/include/install/fuse_sdcard_install.h b/install/include/install/fuse_install.h
index e5bb01f0..63b116ae 100644
--- a/install/include/install/fuse_sdcard_install.h
+++ b/install/include/install/fuse_install.h
@@ -16,8 +16,15 @@
 
 #pragma once
 
+#include <string_view>
+
 #include "install/install.h"
 #include "recovery_ui/device.h"
 #include "recovery_ui/ui.h"
 
-InstallResult ApplyFromSdcard(Device* device, RecoveryUI* ui);
+// Starts FUSE with the package from |path| as the data source. And installs the package from
+// |FUSE_SIDELOAD_HOST_PATHNAME|. The |path| can point to the location of a package zip file or a
+// block map file with the prefix '@'; e.g. /sdcard/package.zip, @/cache/recovery/block.map.
+InstallResult InstallWithFuseFromPath(std::string_view path, RecoveryUI* ui);
+
+InstallResult ApplyFromSdcard(Device* device);