diff --git a/common.h b/common.h
index a948fb1..319af3d 100644
--- a/common.h
+++ b/common.h
@@ -17,15 +17,22 @@
 #ifndef RECOVERY_COMMON_H
 #define RECOVERY_COMMON_H
 
-#include <stdbool.h>
 #include <stdio.h>
 #include <stdarg.h>
 
 #define STRINGIFY(x) #x
 #define EXPAND(x) STRINGIFY(x)
 
+class RecoveryUI;
+
+extern RecoveryUI* ui;
 extern bool modified_flash;
-typedef struct fstab_rec Volume;
+
+// The current stage, e.g. "1/2".
+extern const char* stage;
+
+// The reason argument provided in "--reason=".
+extern const char* reason;
 
 // fopen a file, mounting volumes and making parent dirs as necessary.
 FILE* fopen_path(const char *path, const char *mode);
diff --git a/install.cpp b/install.cpp
index 0f9088a..3871271 100644
--- a/install.cpp
+++ b/install.cpp
@@ -43,8 +43,6 @@
 #include "ui.h"
 #include "verifier.h"
 
-extern RecoveryUI* ui;
-
 #define ASSUMED_UPDATE_BINARY_NAME  "META-INF/com/google/android/update-binary"
 #define PUBLIC_KEYS_FILE "/res/keys"
 static constexpr const char* METADATA_PATH = "META-INF/com/android/metadata";
diff --git a/install.h b/install.h
index 7f66a51..1ec01e8 100644
--- a/install.h
+++ b/install.h
@@ -20,10 +20,9 @@
 #include <string>
 #include <ziparchive/zip_archive.h>
 
-#include "common.h"
-
 enum { INSTALL_SUCCESS, INSTALL_ERROR, INSTALL_CORRUPT, INSTALL_NONE, INSTALL_SKIPPED,
         INSTALL_RETRY };
+
 // Install the package specified by root_path.  If INSTALL_SUCCESS is
 // returned and *wipe_cache is true on exit, caller should wipe the
 // cache partition.
diff --git a/print_sha1.h b/print_sha1.h
index c7c1f36..1f85895 100644
--- a/print_sha1.h
+++ b/print_sha1.h
@@ -20,7 +20,7 @@
 #include <stdint.h>
 #include <string>
 
-#include "openssl/sha.h"
+#include <openssl/sha.h>
 
 static std::string print_sha1(const uint8_t* sha1, size_t len) {
     const char* hex = "0123456789abcdef";
@@ -41,7 +41,7 @@
 }
 
 static std::string print_hex(const uint8_t* bytes, size_t len) {
-  return print_sha1(bytes, len);
+    return print_sha1(bytes, len);
 }
 
 #endif  // RECOVERY_PRINT_SHA1_H
diff --git a/recovery.cpp b/recovery.cpp
index bb7a15b..02d460e 100644
--- a/recovery.cpp
+++ b/recovery.cpp
@@ -70,8 +70,6 @@
 #include "screen_ui.h"
 #include "ui.h"
 
-struct selabel_handle *sehandle;
-
 static const struct option OPTIONS[] = {
   { "update_package", required_argument, NULL, 'u' },
   { "retry_count", required_argument, NULL, 'n' },
@@ -119,15 +117,18 @@
 // So we should check battery with a slightly lower limitation.
 static const int BATTERY_OK_PERCENTAGE = 20;
 static const int BATTERY_WITH_CHARGER_OK_PERCENTAGE = 15;
-constexpr const char* RECOVERY_WIPE = "/etc/recovery.wipe";
+static constexpr const char* RECOVERY_WIPE = "/etc/recovery.wipe";
+static constexpr const char* DEFAULT_LOCALE = "en_US";
 
-RecoveryUI* ui = NULL;
-static const char* locale = "en_US";
-char* stage = NULL;
-char* reason = NULL;
-bool modified_flash = false;
+static std::string locale;
 static bool has_cache = false;
 
+RecoveryUI* ui = nullptr;
+bool modified_flash = false;
+const char* stage = nullptr;
+const char* reason = nullptr;
+struct selabel_handle* sehandle;
+
 /*
  * The recovery tool communicates with the main system through /cache files.
  *   /cache/recovery/command - INPUT - command line for tool, one arg per line
@@ -206,6 +207,9 @@
 // close a file, log an error if the error indicator is set
 static void check_and_fclose(FILE *fp, const char *name) {
     fflush(fp);
+    if (fsync(fileno(fp)) == -1) {
+        PLOG(ERROR) << "Failed to fsync " << name;
+    }
     if (ferror(fp)) {
         PLOG(ERROR) << "Error in " << name;
     }
@@ -486,24 +490,18 @@
 // clear the recovery command and prepare to boot a (hopefully working) system,
 // copy our log file to cache as well (for the system to read). This function is
 // idempotent: call it as many times as you like.
-static void
-finish_recovery() {
+static void finish_recovery() {
     // Save the locale to cache, so if recovery is next started up
     // without a --locale argument (eg, directly from the bootloader)
     // it will use the last-known locale.
-    if (locale != NULL) {
-        size_t len = strlen(locale);
-        __pmsg_write(LOCALE_FILE, locale, len);
-        if (has_cache) {
-            LOG(INFO) << "Saving locale \"" << locale << "\"";
-            FILE* fp = fopen_path(LOCALE_FILE, "w");
-            if (fp != NULL) {
-                fwrite(locale, 1, len, fp);
-                fflush(fp);
-                fsync(fileno(fp));
-                check_and_fclose(fp, LOCALE_FILE);
-            }
+    if (!locale.empty() && has_cache) {
+        LOG(INFO) << "Saving locale \"" << locale << "\"";
+
+        FILE* fp = fopen_path(LOCALE_FILE, "w");
+        if (!android::base::WriteStringToFd(locale, fileno(fp))) {
+            PLOG(ERROR) << "Failed to save locale to " << LOCALE_FILE;
         }
+        check_and_fclose(fp, LOCALE_FILE);
     }
 
     copy_logs();
@@ -1253,40 +1251,32 @@
     printf("%s=%s\n", key, name);
 }
 
-static void
-load_locale_from_cache() {
-    FILE* fp = fopen_path(LOCALE_FILE, "r");
-    char buffer[80];
-    if (fp != NULL) {
-        fgets(buffer, sizeof(buffer), fp);
-        int j = 0;
-        unsigned int i;
-        for (i = 0; i < sizeof(buffer) && buffer[i]; ++i) {
-            if (!isspace(buffer[i])) {
-                buffer[j++] = buffer[i];
-            }
-        }
-        buffer[j] = 0;
-        locale = strdup(buffer);
-        check_and_fclose(fp, LOCALE_FILE);
+static std::string load_locale_from_cache() {
+    if (ensure_path_mounted(LOCALE_FILE) != 0) {
+        LOG(ERROR) << "Can't mount " << LOCALE_FILE;
+        return "";
     }
+
+    std::string content;
+    if (!android::base::ReadFileToString(LOCALE_FILE, &content)) {
+        PLOG(ERROR) << "Can't read " << LOCALE_FILE;
+        return "";
+    }
+
+    return android::base::Trim(content);
 }
 
-static RecoveryUI* gCurrentUI = NULL;
-
-void
-ui_print(const char* format, ...) {
-    char buffer[256];
-
+void ui_print(const char* format, ...) {
+    std::string buffer;
     va_list ap;
     va_start(ap, format);
-    vsnprintf(buffer, sizeof(buffer), format, ap);
+    android::base::StringAppendV(&buffer, format, ap);
     va_end(ap);
 
-    if (gCurrentUI != NULL) {
-        gCurrentUI->Print("%s", buffer);
+    if (ui != nullptr) {
+        ui->Print("%s", buffer.c_str());
     } else {
-        fputs(buffer, stdout);
+        fputs(buffer.c_str(), stdout);
     }
 }
 
@@ -1295,8 +1285,8 @@
 void UiLogger(android::base::LogId id, android::base::LogSeverity severity,
                const char* tag, const char* file, unsigned int line,
                const char* message) {
-    if (severity >= android::base::ERROR && gCurrentUI != NULL) {
-        gCurrentUI->Print("E:%s\n", message);
+    if (severity >= android::base::ERROR && ui != nullptr) {
+        ui->Print("E:%s\n", message);
     } else {
         fprintf(stdout, "%c:%s\n", log_characters[severity], message);
     }
@@ -1392,7 +1382,7 @@
     };
     std::string log_content = android::base::Join(log_buffer, "\n");
     if (!android::base::WriteStringToFile(log_content, TEMPORARY_INSTALL_FILE)) {
-      PLOG(ERROR) << "failed to write " << TEMPORARY_INSTALL_FILE;
+        PLOG(ERROR) << "failed to write " << TEMPORARY_INSTALL_FILE;
     }
 
     // Also write the info into last_log.
@@ -1495,18 +1485,24 @@
         }
     }
 
-    if (locale == nullptr && has_cache) {
-        load_locale_from_cache();
+    if (locale.empty()) {
+        if (has_cache) {
+            locale = load_locale_from_cache();
+        }
+
+        if (locale.empty()) {
+            locale = DEFAULT_LOCALE;
+        }
     }
-    printf("locale is [%s]\n", locale);
+
+    printf("locale is [%s]\n", locale.c_str());
     printf("stage is [%s]\n", stage);
     printf("reason is [%s]\n", reason);
 
     Device* device = make_device();
     ui = device->GetUI();
-    gCurrentUI = ui;
 
-    ui->SetLocale(locale);
+    ui->SetLocale(locale.c_str());
     ui->Init();
     // Set background string to "installing security update" for security update,
     // otherwise set it to "installing system update".
@@ -1521,7 +1517,7 @@
     if (show_text) ui->ShowText(true);
 
     struct selinux_opt seopts[] = {
-      { SELABEL_OPT_PATH, "/file_contexts" }
+        { SELABEL_OPT_PATH, "/file_contexts" }
     };
 
     sehandle = selabel_open(SELABEL_CTX_FILE, seopts, 1);
@@ -1693,7 +1689,7 @@
             break;
     }
     while (true) {
-      pause();
+        pause();
     }
     // Should be unreachable.
     return EXIT_SUCCESS;
diff --git a/roots.h b/roots.h
index a14b7d9..542f03b 100644
--- a/roots.h
+++ b/roots.h
@@ -17,7 +17,7 @@
 #ifndef RECOVERY_ROOTS_H_
 #define RECOVERY_ROOTS_H_
 
-#include "common.h"
+typedef struct fstab_rec Volume;
 
 // Load and parse volume data from /etc/recovery.fstab.
 void load_volume_table();
diff --git a/tests/component/updater_test.cpp b/tests/component/updater_test.cpp
index a859f11..337769e 100644
--- a/tests/component/updater_test.cpp
+++ b/tests/component/updater_test.cpp
@@ -16,7 +16,9 @@
 
 #include <string>
 
+#include <android-base/file.h>
 #include <android-base/properties.h>
+#include <android-base/test_utils.h>
 #include <gtest/gtest.h>
 
 #include "edify/expr.h"
@@ -97,3 +99,84 @@
     // sha1_check() expects at least one argument.
     expect(nullptr, "sha1_check()", kArgsParsingFailure);
 }
+
+TEST_F(UpdaterTest, file_getprop) {
+    // file_getprop() expects two arguments.
+    expect(nullptr, "file_getprop()", kArgsParsingFailure);
+    expect(nullptr, "file_getprop(\"arg1\")", kArgsParsingFailure);
+    expect(nullptr, "file_getprop(\"arg1\", \"arg2\", \"arg3\")", kArgsParsingFailure);
+
+    // File doesn't exist.
+    expect(nullptr, "file_getprop(\"/doesntexist\", \"key1\")", kFileGetPropFailure);
+
+    // Reject too large files (current limit = 65536).
+    TemporaryFile temp_file1;
+    std::string buffer(65540, '\0');
+    ASSERT_TRUE(android::base::WriteStringToFile(buffer, temp_file1.path));
+
+    // Read some keys.
+    TemporaryFile temp_file2;
+    std::string content("ro.product.name=tardis\n"
+                        "# comment\n\n\n"
+                        "ro.product.model\n"
+                        "ro.product.board =  magic \n");
+    ASSERT_TRUE(android::base::WriteStringToFile(content, temp_file2.path));
+
+    std::string script1("file_getprop(\"" + std::string(temp_file2.path) +
+                       "\", \"ro.product.name\")");
+    expect("tardis", script1.c_str(), kNoCause);
+
+    std::string script2("file_getprop(\"" + std::string(temp_file2.path) +
+                       "\", \"ro.product.board\")");
+    expect("magic", script2.c_str(), kNoCause);
+
+    // No match.
+    std::string script3("file_getprop(\"" + std::string(temp_file2.path) +
+                       "\", \"ro.product.wrong\")");
+    expect("", script3.c_str(), kNoCause);
+
+    std::string script4("file_getprop(\"" + std::string(temp_file2.path) +
+                       "\", \"ro.product.name=\")");
+    expect("", script4.c_str(), kNoCause);
+
+    std::string script5("file_getprop(\"" + std::string(temp_file2.path) +
+                       "\", \"ro.product.nam\")");
+    expect("", script5.c_str(), kNoCause);
+
+    std::string script6("file_getprop(\"" + std::string(temp_file2.path) +
+                       "\", \"ro.product.model\")");
+    expect("", script6.c_str(), kNoCause);
+}
+
+TEST_F(UpdaterTest, delete) {
+    // Delete none.
+    expect("0", "delete()", kNoCause);
+    expect("0", "delete(\"/doesntexist\")", kNoCause);
+    expect("0", "delete(\"/doesntexist1\", \"/doesntexist2\")", kNoCause);
+    expect("0", "delete(\"/doesntexist1\", \"/doesntexist2\", \"/doesntexist3\")", kNoCause);
+
+    // Delete one file.
+    TemporaryFile temp_file1;
+    ASSERT_TRUE(android::base::WriteStringToFile("abc", temp_file1.path));
+    std::string script1("delete(\"" + std::string(temp_file1.path) + "\")");
+    expect("1", script1.c_str(), kNoCause);
+
+    // Delete two files.
+    TemporaryFile temp_file2;
+    ASSERT_TRUE(android::base::WriteStringToFile("abc", temp_file2.path));
+    TemporaryFile temp_file3;
+    ASSERT_TRUE(android::base::WriteStringToFile("abc", temp_file3.path));
+    std::string script2("delete(\"" + std::string(temp_file2.path) + "\", \"" +
+                        std::string(temp_file3.path) + "\")");
+    expect("2", script2.c_str(), kNoCause);
+
+    // Delete already deleted files.
+    expect("0", script2.c_str(), kNoCause);
+
+    // Delete one out of three.
+    TemporaryFile temp_file4;
+    ASSERT_TRUE(android::base::WriteStringToFile("abc", temp_file4.path));
+    std::string script3("delete(\"/doesntexist1\", \"" + std::string(temp_file4.path) +
+                        "\", \"/doesntexist2\")");
+    expect("1", script3.c_str(), kNoCause);
+}
diff --git a/updater/install.cpp b/updater/install.cpp
index efc96c4..25f6a91 100644
--- a/updater/install.cpp
+++ b/updater/install.cpp
@@ -66,7 +66,7 @@
 
 // Send over the buffer to recovery though the command pipe.
 static void uiPrint(State* state, const std::string& buffer) {
-    UpdaterInfo* ui = reinterpret_cast<UpdaterInfo*>(state->cookie);
+    UpdaterInfo* ui = static_cast<UpdaterInfo*>(state->cookie);
 
     // "line1\nline2\n" will be split into 3 tokens: "line1", "line2" and "".
     // So skip sending empty strings to UI.
@@ -117,6 +117,7 @@
 }
 
 // mount(fs_type, partition_type, location, mount_point)
+// mount(fs_type, partition_type, location, mount_point, mount_options)
 //
 //    fs_type="ext4"   partition_type="EMMC"    location=device
 Value* MountFn(const char* name, State* state, int argc, Expr* argv[]) {
@@ -252,7 +253,6 @@
     return WEXITSTATUS(status);
 }
 
-
 // format(fs_type, partition_type, location, fs_size, mount_point)
 //
 //    fs_type="ext4"   partition_type="EMMC"    location=device    fs_size=<bytes> mount_point=<location>
@@ -301,14 +301,13 @@
     if (fs_type == "ext4") {
         int status = make_ext4fs(location.c_str(), size, mount_point.c_str(), sehandle);
         if (status != 0) {
-            printf("%s: make_ext4fs failed (%d) on %s",
-                    name, status, location.c_str());
+            printf("%s: make_ext4fs failed (%d) on %s", name, status, location.c_str());
             return StringValue("");
         }
         return StringValue(location);
     } else if (fs_type == "f2fs") {
         if (size < 0) {
-            printf("fs_size can't be negative for f2fs: %s", fs_size.c_str());
+            printf("%s: fs_size can't be negative for f2fs: %s", name, fs_size.c_str());
             return StringValue("");
         }
         std::string num_sectors = std::to_string(size / 512);
@@ -318,8 +317,7 @@
                 num_sectors.c_str(), nullptr};
         int status = exec_cmd(f2fs_path, (char* const*)f2fs_argv);
         if (status != 0) {
-            printf("%s: mkfs.f2fs failed (%d) on %s",
-                    name, status, location.c_str());
+            printf("%s: mkfs.f2fs failed (%d) on %s", name, status, location.c_str());
             return StringValue("");
         }
         return StringValue(location);
@@ -365,8 +363,14 @@
     return StringValue(dst_name);
 }
 
+// delete([filename, ...])
+//   Deletes all the filenames listed. Returns the number of files successfully deleted.
+//
+// delete_recursive([dirname, ...])
+//   Recursively deletes dirnames and all their contents. Returns the number of directories
+//   successfully deleted.
 Value* DeleteFn(const char* name, State* state, int argc, Expr* argv[]) {
-    std::vector<std::string> paths;
+    std::vector<std::string> paths(argc);
     for (int i = 0; i < argc; ++i) {
         if (!Evaluate(state, argv[i], &paths[i])) {
             return nullptr;
@@ -382,7 +386,7 @@
         }
     }
 
-    return StringValue(android::base::StringPrintf("%d", success));
+    return StringValue(std::to_string(success));
 }
 
 
@@ -860,9 +864,13 @@
 // file_getprop(file, key)
 //
 //   interprets 'file' as a getprop-style file (key=value pairs, one
-//   per line. # comment lines,blank lines, lines without '=' ignored),
+//   per line. # comment lines, blank lines, lines without '=' ignored),
 //   and returns the value for 'key' (or "" if it isn't defined).
 Value* FileGetPropFn(const char* name, State* state, int argc, Expr* argv[]) {
+    if (argc != 2) {
+        return ErrorAbort(state, kArgsParsingFailure, "%s() expects 2 args, got %d", name, argc);
+    }
+
     std::vector<std::string> args;
     if (!ReadArgs(state, 2, argv, &args)) {
         return ErrorAbort(state, kArgsParsingFailure, "%s() Failed to parse the argument(s)", name);
@@ -876,11 +884,10 @@
                           filename.c_str(), strerror(errno));
     }
 
-#define MAX_FILE_GETPROP_SIZE    65536
-
+    constexpr off_t MAX_FILE_GETPROP_SIZE = 65536;
     if (st.st_size > MAX_FILE_GETPROP_SIZE) {
-        return ErrorAbort(state, kFileGetPropFailure, "%s too large for %s (max %d)",
-                          filename.c_str(), name, MAX_FILE_GETPROP_SIZE);
+        return ErrorAbort(state, kFileGetPropFailure, "%s too large for %s (max %lld)",
+                          filename.c_str(), name, static_cast<long long>(MAX_FILE_GETPROP_SIZE));
     }
 
     std::string buffer(st.st_size, '\0');
@@ -913,7 +920,7 @@
         }
 
         // trim whitespace between key and '='
-        std::string str = android::base::Trim(line.substr(0, equal_pos - 1));
+        std::string str = android::base::Trim(line.substr(0, equal_pos));
 
         // not the key we're looking for
         if (key != str) continue;
diff --git a/verifier.cpp b/verifier.cpp
index 82cdd3b..44098f7 100644
--- a/verifier.cpp
+++ b/verifier.cpp
@@ -14,9 +14,11 @@
  * limitations under the License.
  */
 
+#include "verifier.h"
+
 #include <errno.h>
-#include <malloc.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 
 #include <algorithm>
@@ -31,9 +33,6 @@
 #include "common.h"
 #include "print_sha1.h"
 #include "ui.h"
-#include "verifier.h"
-
-extern RecoveryUI* ui;
 
 static constexpr size_t MiB = 1024 * 1024;