Add a singleton CacheLocation to replace the hard coded locations

This class allows us to set the following locations dynamically:
cache_temp_source, last_command_file, stash_directory_base.

In the updater's main function, we reset the values of these variables
to their default locations in /cache; while we can set them to temp
files in unit tests or host simulation.

Test: unit tests pass
Change-Id: I528652650caa41373617ab055d41b1f1a4ec0f87

applypatch/applypatch.cpp

@@ -40,10 +40,9 @@
 
 #include "edify/expr.h"
 #include "otafault/ota_io.h"
+#include "otautil/cache_location.h"
 #include "otautil/print_sha1.h"
 
-std::string cache_temp_source = "/cache/saved.file";
-
 static int LoadPartitionContents(const std::string& filename, FileContents* file);
 static size_t FileSink(const unsigned char* data, size_t len, int fd);
 static int GenerateTarget(const FileContents& source_file, const std::unique_ptr<Value>& patch,
@@ -404,7 +403,7 @@ int applypatch_check(const char* filename, const std::vector<std::string>& patch
     // If the source file is missing or corrupted, it might be because we were killed in the middle
     // of patching it.  A copy of it should have been made in cache_temp_source.  If that file
     // exists and matches the sha1 we're looking for, the check still passes.
-    if (LoadFileContents(cache_temp_source.c_str(), &file) != 0) {
+    if (LoadFileContents(CacheLocation::location().cache_temp_source().c_str(), &file) != 0) {
       printf("failed to load cache file\n");
       return 1;
     }
@@ -526,7 +525,7 @@ int applypatch(const char* source_filename, const char* target_filename,
   printf("source file is bad; trying copy\n");
 
   FileContents copy_file;
-  if (LoadFileContents(cache_temp_source.c_str(), &copy_file) < 0) {
+  if (LoadFileContents(CacheLocation::location().cache_temp_source().c_str(), &copy_file) < 0) {
     printf("failed to read copy file\n");
     return 1;
   }
@@ -621,7 +620,7 @@ static int GenerateTarget(const FileContents& source_file, const std::unique_ptr
     printf("not enough free space on /cache\n");
     return 1;
   }
-  if (SaveFileContents(cache_temp_source.c_str(), &source_file) < 0) {
+  if (SaveFileContents(CacheLocation::location().cache_temp_source().c_str(), &source_file) < 0) {
     printf("failed to back up source file\n");
     return 1;
   }
@@ -667,7 +666,7 @@ static int GenerateTarget(const FileContents& source_file, const std::unique_ptr
   }
 
   // Delete the backup copy of the source.
-  unlink(cache_temp_source.c_str());
+  unlink(CacheLocation::location().cache_temp_source().c_str());
 
   // Success!
   return 0;

applypatch/freecache.cpp

@@ -33,6 +33,7 @@
 #include <android-base/stringprintf.h>
 
 #include "applypatch/applypatch.h"
+#include "otautil/cache_location.h"
 
 static int EliminateOpenFiles(std::set<std::string>* files) {
   std::unique_ptr<DIR, decltype(&closedir)> d(opendir("/proc"), closedir);
@@ -92,7 +93,7 @@ static std::set<std::string> FindExpendableFiles() {
 
       // We can't delete cache_temp_source; if it's there we might have restarted during
       // installation and could be depending on it to be there.
-      if (path == cache_temp_source) {
+      if (path == CacheLocation::location().cache_temp_source()) {
         continue;
       }
 

applypatch/include/applypatch/applypatch.h

@@ -34,12 +34,6 @@ struct FileContents {
   std::vector<unsigned char> data;
 };
 
-// When there isn't enough room on the target filesystem to hold the patched version of the file,
-// we copy the original here and delete it to free up space.  If the expected source file doesn't
-// exist, or is corrupted, we look to see if the cached file contains the bits we want and use it as
-// the source instead.  The default location for the cached source is "/cache/saved.file".
-extern std::string cache_temp_source;
-
 using SinkFn = std::function<size_t(const unsigned char*, size_t)>;
 
 // applypatch.cpp

otautil/Android.bp

@@ -21,6 +21,7 @@ cc_library_static {
         "SysUtil.cpp",
         "DirUtil.cpp",
         "ThermalUtil.cpp",
+        "cache_location.cpp",
         "rangeset.cpp",
     ],
 

otautil/cache_location.cpp

@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "otautil/cache_location.h"
+
+constexpr const char kDefaultCacheTempSource[] = "/cache/saved.file";
+constexpr const char kDefaultLastCommandFile[] = "/cache/recovery/last_command";
+constexpr const char kDefaultStashDirectoryBase[] = "/cache/recovery";
+
+CacheLocation& CacheLocation::location() {
+  static CacheLocation cache_location;
+  return cache_location;
+}
+
+void CacheLocation::ResetLocations() {
+  cache_temp_source_ = kDefaultCacheTempSource;
+  last_command_file_ = kDefaultLastCommandFile;
+  stash_directory_base_ = kDefaultStashDirectoryBase;
+}

otautil/include/otautil/cache_location.h

@@ -0,0 +1,72 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _OTAUTIL_OTAUTIL_CACHE_LOCATION_H_
+#define _OTAUTIL_OTAUTIL_CACHE_LOCATION_H_
+
+#include <string>
+
+#include "android-base/macros.h"
+
+// A singleton class to maintain the update related locations. The locations should be only set
+// once at the start of the program.
+class CacheLocation {
+ public:
+  static CacheLocation& location();
+
+  // Reset the locations to their default values.
+  void ResetLocations();
+
+  // getter and setter functions.
+  std::string cache_temp_source() const {
+    return cache_temp_source_;
+  }
+  void set_cache_temp_source(const std::string& temp_source) {
+    cache_temp_source_ = temp_source;
+  }
+
+  std::string last_command_file() const {
+    return last_command_file_;
+  }
+  void set_last_command_file(const std::string& last_command) {
+    last_command_file_ = last_command;
+  }
+
+  std::string stash_directory_base() const {
+    return stash_directory_base_;
+  }
+  void set_stash_directory_base(const std::string& base) {
+    stash_directory_base_ = base;
+  }
+
+ private:
+  CacheLocation() {}
+  DISALLOW_COPY_AND_ASSIGN(CacheLocation);
+
+  // When there isn't enough room on the target filesystem to hold the patched version of the file,
+  // we copy the original here and delete it to free up space.  If the expected source file doesn't
+  // exist, or is corrupted, we look to see if the cached file contains the bits we want and use it
+  // as the source instead.  The default location for the cached source is "/cache/saved.file".
+  std::string cache_temp_source_;
+
+  // Location to save the last command that stashes blocks.
+  std::string last_command_file_;
+
+  // The base directory to write stashes during update.
+  std::string stash_directory_base_;
+};
+
+#endif  // _OTAUTIL_OTAUTIL_CACHE_LOCATION_H_

tests/component/applypatch_test.cpp

@@ -35,6 +35,7 @@
 #include "applypatch/applypatch.h"
 #include "applypatch/applypatch_modes.h"
 #include "common/test_constants.h"
+#include "otautil/cache_location.h"
 #include "otautil/print_sha1.h"
 
 static void sha1sum(const std::string& fname, std::string* sha1, size_t* fsize = nullptr) {
@@ -93,14 +94,14 @@ class ApplyPatchCacheTest : public ApplyPatchTest {
  protected:
   void SetUp() override {
     ApplyPatchTest::SetUp();
-    cache_temp_source = old_file;
+    CacheLocation::location().set_cache_temp_source(old_file);
   }
 };
 
 class ApplyPatchModesTest : public ::testing::Test {
  protected:
   void SetUp() override {
-    cache_temp_source = cache_source.path;
+    CacheLocation::location().set_cache_temp_source(cache_source.path);
   }
 
   TemporaryFile cache_source;

tests/component/updater_test.cpp

@@ -41,6 +41,7 @@
 #include "common/test_constants.h"
 #include "edify/expr.h"
 #include "otautil/SysUtil.h"
+#include "otautil/cache_location.h"
 #include "otautil/error_code.h"
 #include "otautil/print_sha1.h"
 #include "updater/blockimg.h"
@@ -104,7 +105,16 @@ class UpdaterTest : public ::testing::Test {
     RegisterBuiltins();
     RegisterInstallFunctions();
     RegisterBlockImageFunctions();
+
+    // Mock the location of last_command_file.
+    CacheLocation::location().set_cache_temp_source(temp_saved_source_.path);
+    CacheLocation::location().set_last_command_file(temp_last_command_.path);
+    CacheLocation::location().set_stash_directory_base(temp_stash_base_.path);
   }
+
+  TemporaryFile temp_saved_source_;
+  TemporaryFile temp_last_command_;
+  TemporaryDir temp_stash_base_;
 };
 
 TEST_F(UpdaterTest, getprop) {
@@ -542,7 +552,7 @@ TEST_F(UpdaterTest, block_image_update_fail) {
   expect("", script.c_str(), kNoCause, &updater_info);
   // Updater generates the stash name based on the input file name.
   std::string name_digest = get_sha1(update_file.path);
-  std::string stash_base = "/cache/recovery/" + name_digest;
+  std::string stash_base = std::string(temp_stash_base_.path) + "/" + name_digest;
   ASSERT_EQ(0, access(stash_base.c_str(), F_OK));
   ASSERT_EQ(-1, access((stash_base + src_hash).c_str(), F_OK));
   ASSERT_EQ(0, rmdir(stash_base.c_str()));
@@ -709,8 +719,7 @@ TEST_F(UpdaterTest, brotli_new_data) {
 }
 
 TEST_F(UpdaterTest, last_command_update) {
-  TemporaryFile temp_file;
-  last_command_file = temp_file.path;
+  std::string last_command_file = CacheLocation::location().last_command_file();
 
   std::string block1 = std::string(4096, '1');
   std::string block2 = std::string(4096, '2');
@@ -797,8 +806,7 @@ TEST_F(UpdaterTest, last_command_update) {
 }
 
 TEST_F(UpdaterTest, last_command_update_unresumable) {
-  TemporaryFile temp_file;
-  last_command_file = temp_file.path;
+  std::string last_command_file = CacheLocation::location().last_command_file();
 
   std::string block1 = std::string(4096, '1');
   std::string block2 = std::string(4096, '2');
@@ -853,8 +861,7 @@ TEST_F(UpdaterTest, last_command_update_unresumable) {
 }
 
 TEST_F(UpdaterTest, last_command_verify) {
-  TemporaryFile temp_file;
-  last_command_file = temp_file.path;
+  std::string last_command_file = CacheLocation::location().last_command_file();
 
   std::string block1 = std::string(4096, '1');
   std::string block2 = std::string(4096, '2');

updater/blockimg.cpp

@@ -53,6 +53,7 @@
 
 #include "edify/expr.h"
 #include "otafault/ota_io.h"
+#include "otautil/cache_location.h"
 #include "otautil/error_code.h"
 #include "otautil/print_sha1.h"
 #include "otautil/rangeset.h"
@@ -65,17 +66,15 @@
 #define DEBUG_ERASE  0
 
 static constexpr size_t BLOCKSIZE = 4096;
-static constexpr const char* STASH_DIRECTORY_BASE = "/cache/recovery";
 static constexpr mode_t STASH_DIRECTORY_MODE = 0700;
 static constexpr mode_t STASH_FILE_MODE = 0600;
 
-std::string last_command_file = "/cache/recovery/last_command";
-
 static CauseCode failure_type = kNoCause;
 static bool is_retry = false;
 static std::unordered_map<std::string, RangeSet> stash_map;
 
 static void DeleteLastCommandFile() {
+  std::string last_command_file = CacheLocation::location().last_command_file();
   if (unlink(last_command_file.c_str()) == -1 && errno != ENOENT) {
     PLOG(ERROR) << "Failed to unlink: " << last_command_file;
   }
@@ -84,6 +83,7 @@ static void DeleteLastCommandFile() {
 // Parse the last command index of the last update and save the result to |last_command_index|.
 // Return true if we successfully read the index.
 static bool ParseLastCommandFile(int* last_command_index) {
+  std::string last_command_file = CacheLocation::location().last_command_file();
   android::base::unique_fd fd(TEMP_FAILURE_RETRY(open(last_command_file.c_str(), O_RDONLY)));
   if (fd == -1) {
     if (errno != ENOENT) {
@@ -119,6 +119,7 @@ static bool ParseLastCommandFile(int* last_command_index) {
 // Update the last command index in the last_command_file if the current command writes to the
 // stash either explicitly or implicitly.
 static bool UpdateLastCommandIndex(int command_index, const std::string& command_string) {
+  std::string last_command_file = CacheLocation::location().last_command_file();
   std::string last_command_tmp = last_command_file + ".tmp";
   std::string content = std::to_string(command_index) + "\n" + command_string;
   android::base::unique_fd wfd(
@@ -676,7 +677,7 @@ static std::string GetStashFileName(const std::string& base, const std::string&
         return "";
     }
 
-    std::string fn(STASH_DIRECTORY_BASE);
+    std::string fn(CacheLocation::location().stash_directory_base());
     fn += "/" + base + "/" + id + postfix;
 
     return fn;

updater/include/updater/blockimg.h

@@ -19,7 +19,6 @@
 
 #include <string>
 
-extern std::string last_command_file;
 void RegisterBlockImageFunctions();
 
 #endif

updater/updater.cpp

@@ -34,6 +34,7 @@
 #include "otafault/config.h"
 #include "otautil/DirUtil.h"
 #include "otautil/SysUtil.h"
+#include "otautil/cache_location.h"
 #include "otautil/error_code.h"
 #include "updater/blockimg.h"
 #include "updater/install.h"
@@ -168,6 +169,10 @@ int main(int argc, char** argv) {
   }
   ota_io_init(za, state.is_retry);
 
+  // Initialize the cache_temp_source, last_command_file and stash_directory_base to their default
+  // locations.
+  CacheLocation::location().ResetLocations();
+
   std::string result;
   bool status = Evaluate(&state, root, &result);