12 files changed, 161 insertions, 25 deletions
diff --git a/payload_generator/ext2_filesystem.cc b/payload_generator/ext2_filesystem.cc
index 9670e395..b7276d5f 100644
--- a/payload_generator/ext2_filesystem.cc
+++ b/payload_generator/ext2_filesystem.cc
@@ -111,6 +111,7 @@ unique_ptr<Ext2Filesystem> Ext2Filesystem::CreateFromFile(
   if (filename.empty())
     return nullptr;
   unique_ptr<Ext2Filesystem> result(new Ext2Filesystem());
+  result->filename_ = filename;
 
   errcode_t err = ext2fs_open(filename.c_str(),
                               0,  // flags (read only)
@@ -304,4 +305,39 @@ bool Ext2Filesystem::GetFiles(vector<File>* files) const {
   return true;
 }
 
+bool Ext2Filesystem::LoadSettings(chromeos::KeyValueStore* store) const {
+  // First search for the settings inode following symlinks if we find some.
+  ext2_ino_t ino_num = 0;
+  errcode_t err = ext2fs_namei_follow(
+      filsys_, EXT2_ROOT_INO /* root */, EXT2_ROOT_INO /* cwd */,
+      "/etc/update_engine.conf", &ino_num);
+  if (err != 0)
+    return false;
+
+  ext2_inode ino_data;
+  if (ext2fs_read_inode(filsys_, ino_num, &ino_data) != 0)
+    return false;
+
+  // Load the list of blocks and then the contents of the inodes.
+  vector<Extent> extents;
+  err = ext2fs_block_iterate2(filsys_, ino_num, BLOCK_FLAG_DATA_ONLY,
+                              nullptr,  // block_buf
+                              ProcessInodeAllBlocks,
+                              &extents);
+  if (err != 0)
+    return false;
+
+  chromeos::Blob blob;
+  uint64_t physical_size = BlocksInExtents(extents) * filsys_->blocksize;
+  // Sparse holes in the settings file are not supported.
+  if (EXT2_I_SIZE(&ino_data) > physical_size)
+    return false;
+  if (!utils::ReadExtents(filename_, extents, &blob, physical_size,
+                          filsys_->blocksize))
+    return false;
+
+  string text(blob.begin(), blob.begin() + EXT2_I_SIZE(&ino_data));
+  return store->LoadFromString(text);
+}
+
 }  // namespace chromeos_update_engine
diff --git a/payload_generator/ext2_filesystem.h b/payload_generator/ext2_filesystem.h
index c87849ca..66cb65f5 100644
--- a/payload_generator/ext2_filesystem.h
+++ b/payload_generator/ext2_filesystem.h
@@ -40,12 +40,17 @@ class Ext2Filesystem : public FilesystemInterface {
   //    and bitmap tables.
   bool GetFiles(std::vector<File>* files) const override;
 
+  bool LoadSettings(chromeos::KeyValueStore* store) const override;
+
  private:
   Ext2Filesystem() = default;
 
   // The ext2 main data structure holding the filesystem.
   ext2_filsys filsys_ = nullptr;
 
+  // The file where the filesystem is stored.
+  std::string filename_;
+
   DISALLOW_COPY_AND_ASSIGN(Ext2Filesystem);
 };
 
diff --git a/payload_generator/ext2_filesystem_unittest.cc b/payload_generator/ext2_filesystem_unittest.cc
index 122ba02c..d2ea2b30 100644
--- a/payload_generator/ext2_filesystem_unittest.cc
+++ b/payload_generator/ext2_filesystem_unittest.cc
@@ -177,4 +177,26 @@ TEST_F(Ext2FilesystemTest, ParseGeneratedImages) {
   }
 }
 
+TEST_F(Ext2FilesystemTest, LoadSettingsFailsTest) {
+  base::FilePath path = test_utils::GetBuildArtifactsPath().Append(
+      "gen/disk_ext2_1k.img");
+  unique_ptr<Ext2Filesystem> fs = Ext2Filesystem::CreateFromFile(path.value());
+
+  chromeos::KeyValueStore store;
+  // disk_ext2_1k.img doesn't have the /etc/update_engine.conf file.
+  EXPECT_FALSE(fs->LoadSettings(&store));
+}
+
+TEST_F(Ext2FilesystemTest, LoadSettingsWorksTest) {
+  base::FilePath path = test_utils::GetBuildArtifactsPath().Append(
+      "gen/disk_ext2_ue_settings.img");
+  unique_ptr<Ext2Filesystem> fs = Ext2Filesystem::CreateFromFile(path.value());
+
+  chromeos::KeyValueStore store;
+  EXPECT_TRUE(fs->LoadSettings(&store));
+  string minor_version;
+  EXPECT_TRUE(store.GetString("PAYLOAD_MINOR_VERSION", &minor_version));
+  EXPECT_EQ("1234", minor_version);
+}
+
 }  // namespace chromeos_update_engine
diff --git a/payload_generator/fake_filesystem.cc b/payload_generator/fake_filesystem.cc
index b474b26f..00911e12 100644
--- a/payload_generator/fake_filesystem.cc
+++ b/payload_generator/fake_filesystem.cc
@@ -38,4 +38,11 @@ void FakeFilesystem::AddFile(const std::string& filename,
   files_.push_back(file);
 }
 
+bool FakeFilesystem::LoadSettings(chromeos::KeyValueStore* store) const {
+  if (minor_version_ < 0)
+    return false;
+  store->SetString("PAYLOAD_MINOR_VERSION", std::to_string(minor_version_));
+  return true;
+}
+
 }  // namespace chromeos_update_engine
diff --git a/payload_generator/fake_filesystem.h b/payload_generator/fake_filesystem.h
index 10b66837..35b7756f 100644
--- a/payload_generator/fake_filesystem.h
+++ b/payload_generator/fake_filesystem.h
@@ -26,17 +26,25 @@ class FakeFilesystem : public FilesystemInterface {
   size_t GetBlockSize() const override;
   size_t GetBlockCount() const override;
   bool GetFiles(std::vector<File>* files) const override;
+  bool LoadSettings(chromeos::KeyValueStore* store) const override;
 
   // Fake methods.
 
   // Add a file to the list of fake files.
   void AddFile(const std::string& filename, const std::vector<Extent> extents);
 
+  // Sets the PAYLOAD_MINOR_VERSION key stored by LoadSettings(). Use a negative
+  // value to produce an error in LoadSettings().
+  void SetMinorVersion(int minor_version) {
+    minor_version_ = minor_version;
+  }
+
  private:
   FakeFilesystem() = default;
 
   uint64_t block_size_;
   uint64_t block_count_;
+  int minor_version_{-1};
 
   std::vector<File> files_;
 
diff --git a/payload_generator/filesystem_interface.h b/payload_generator/filesystem_interface.h
index 501a6be9..186eac43 100644
--- a/payload_generator/filesystem_interface.h
+++ b/payload_generator/filesystem_interface.h
@@ -20,6 +20,7 @@
 #include <vector>
 
 #include <base/macros.h>
+#include <chromeos/key_value_store.h>
 
 #include "update_engine/update_metadata.pb.h"
 
@@ -66,6 +67,10 @@ class FilesystemInterface {
   // Returns whether the function succeeded.
   virtual bool GetFiles(std::vector<File>* files) const = 0;
 
+  // Load the image settings stored in the filesystem in the
+  // /etc/update_engine.conf file. Returns whether the settings were found.
+  virtual bool LoadSettings(chromeos::KeyValueStore* store) const = 0;
+
  protected:
   FilesystemInterface() = default;
 
diff --git a/payload_generator/raw_filesystem.h b/payload_generator/raw_filesystem.h
index d8e1fe5f..bd664871 100644
--- a/payload_generator/raw_filesystem.h
+++ b/payload_generator/raw_filesystem.h
@@ -29,6 +29,10 @@ class RawFilesystem : public FilesystemInterface {
   // with the name passed during construction.
   bool GetFiles(std::vector<File>* files) const override;
 
+  bool LoadSettings(chromeos::KeyValueStore* store) const override {
+    return false;
+  }
+
  private:
   RawFilesystem() = default;
 
diff --git a/sample_images/disk_ext2_1k.txt b/sample_images/disk_ext2_1k.txt
index f13c080e..1494535c 100644
--- a/sample_images/disk_ext2_1k.txt
+++ b/sample_images/disk_ext2_1k.txt
@@ -1 +1 @@
-16777216 1024
+default 16777216 1024
diff --git a/sample_images/disk_ext2_4k.txt b/sample_images/disk_ext2_4k.txt
index d01d1054..cac718f7 100644
--- a/sample_images/disk_ext2_4k.txt
+++ b/sample_images/disk_ext2_4k.txt
@@ -1 +1 @@
-16777216 4096
+default 16777216 4096
diff --git a/sample_images/disk_ext2_ue_settings.txt b/sample_images/disk_ext2_ue_settings.txt
new file mode 100644
index 00000000..554f7dac
--- /dev/null
+++ b/sample_images/disk_ext2_ue_settings.txt
@@ -0,0 +1 @@
+ue_settings 16777216 4096
diff --git a/sample_images/generate_image.sh b/sample_images/generate_image.sh
index 0f0c3846..c4f132a0 100755
--- a/sample_images/generate_image.sh
+++ b/sample_images/generate_image.sh
@@ -17,29 +17,11 @@ cleanup() {
   rmdir "$1"
 }
 
-# generate_fs <filename> <size> [block_size] [block_groups]
-generate_fs() {
-  local filename="$1"
-  local size="$2"
-  local block_size="${3:-4096}"
-  local block_groups="${4:-}"
-
-  local mkfs_opts=( -q -F -b "${block_size}" -L "ROOT-TEST" -t ext2 )
-  if [[ -n "${block_groups}" ]]; then
-    mkfs_opts+=( -G "${block_groups}" )
-  fi
-
-  local mntdir=$(mktemp --tmpdir -d generate_ext2.XXXXXX)
-  trap 'cleanup "${mntdir}"; rm -f "${filename}"' INT TERM EXIT
-
-  # Cleanup old image.
-  if [[ -e "${filename}" ]]; then
-    rm -f "${filename}"
-  fi
-  truncate --size="${size}" "${filename}"
-
-  mkfs.ext2 "${mkfs_opts[@]}" "${filename}"
-  sudo mount "${filename}" "${mntdir}" -o loop
+# add_files_default <mntdir> <block_size>
+# Add several test files to the image mounted in <mntdir>.
+add_files_default() {
+  local mntdir="$1"
+  local block_size="$2"
 
   ### Generate the files used in unittest with descriptive names.
   sudo touch "${mntdir}"/empty-file
@@ -93,6 +75,71 @@ generate_fs() {
     "empty space data but it won't be all zeros." |
     sudo dd of="${mntdir}"/removed conv=fsync status=none
   sudo rm "${mntdir}"/removed
+}
+
+# add_files_ue_settings <mntdir> <block_size>
+# Add the update_engine.conf settings file. This file contains the
+add_files_ue_settings() {
+  local mntdir="$1"
+
+  sudo mkdir -p "${mntdir}"/etc >/dev/null
+  sudo tee "${mntdir}"/etc/update_engine.conf >/dev/null <<EOF
+PAYLOAD_MINOR_VERSION=1234
+EOF
+  # Example of a real lsb-release file released on link stable.
+  sudo tee "${mntdir}"/etc/lsb-release >/dev/null <<EOF
+CHROMEOS_AUSERVER=https://tools.google.com/service/update2
+CHROMEOS_BOARD_APPID={F26D159B-52A3-491A-AE25-B23670A66B32}
+CHROMEOS_CANARY_APPID={90F229CE-83E2-4FAF-8479-E368A34938B1}
+CHROMEOS_DEVSERVER=
+CHROMEOS_RELEASE_APPID={F26D159B-52A3-491A-AE25-B23670A66B32}
+CHROMEOS_RELEASE_BOARD=link-signed-mp-v4keys
+CHROMEOS_RELEASE_BRANCH_NUMBER=63
+CHROMEOS_RELEASE_BUILD_NUMBER=6946
+CHROMEOS_RELEASE_BUILD_TYPE=Official Build
+CHROMEOS_RELEASE_CHROME_MILESTONE=43
+CHROMEOS_RELEASE_DESCRIPTION=6946.63.0 (Official Build) stable-channel link
+CHROMEOS_RELEASE_NAME=Chrome OS
+CHROMEOS_RELEASE_PATCH_NUMBER=0
+CHROMEOS_RELEASE_TRACK=stable-channel
+CHROMEOS_RELEASE_VERSION=6946.63.0
+GOOGLE_RELEASE=6946.63.0
+EOF
+}
+
+# generate_fs <filename> <kind> <size> [block_size] [block_groups]
+generate_fs() {
+  local filename="$1"
+  local kind="$2"
+  local size="$3"
+  local block_size="${4:-4096}"
+  local block_groups="${5:-}"
+
+  local mkfs_opts=( -q -F -b "${block_size}" -L "ROOT-TEST" -t ext2 )
+  if [[ -n "${block_groups}" ]]; then
+    mkfs_opts+=( -G "${block_groups}" )
+  fi
+
+  local mntdir=$(mktemp --tmpdir -d generate_ext2.XXXXXX)
+  trap 'cleanup "${mntdir}"; rm -f "${filename}"' INT TERM EXIT
+
+  # Cleanup old image.
+  if [[ -e "${filename}" ]]; then
+    rm -f "${filename}"
+  fi
+  truncate --size="${size}" "${filename}"
+
+  mkfs.ext2 "${mkfs_opts[@]}" "${filename}"
+  sudo mount "${filename}" "${mntdir}" -o loop
+
+  case "${kind}" in
+    ue_settings)
+      add_files_ue_settings "${mntdir}" "${block_size}"
+      ;;
+    default)
+      add_files_default "${mntdir}" "${block_size}"
+      ;;
+  esac
 
   cleanup "${mntdir}"
   trap - INT TERM EXIT
diff --git a/update_engine.gyp b/update_engine.gyp
index 9294f661..6df8e7e5 100644
--- a/update_engine.gyp
+++ b/update_engine.gyp
@@ -332,6 +332,7 @@
           'sources': [
             'sample_images/disk_ext2_1k.txt',
             'sample_images/disk_ext2_4k.txt',
+            'sample_images/disk_ext2_ue_settings.txt',
           ],
           'includes': ['generate_image.gypi'],
         },