Restore applypatch/updater/edify for non-A/B OTA support

Google deleted this source from bootable/recovery outright (commit c7ebad5f,
"rm -rf non-AB code", 2024-04-05) — confirmed present at android-14, absent
at android-16.0.0_r4. The runtime side (install.cpp's SetUpNonAbUpdateCommands)
and build-side packaging (ota_from_target_files.py's GenerateNonAbOtaPackage)
both survived; only the source that builds the update-binary executable
itself was removed. Sourced from TeamWin's android_bootable_recovery
(android-14.1), the only living copy found, with install/ZipUtil.cpp,
get_args.cpp, and set_metadata.cpp intentionally left out (only wired into
TeamWin's modified install.cpp, which PawletOS isn't adopting — twrpinstall
carries its own independent copies).

Kept as its own repo, not folded into a recovery fork, so it's buildable
independent of whichever recovery UI ends up in use.

edify/Android.bp

@@ -0,0 +1,65 @@
+// Copyright (C) 2017 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.
+
+package {
+    default_applicable_licenses: ["external_update_binary_edify_license"],
+}
+
+// external_update_binary is a standalone repo (not nested inside
+// bootable/recovery), so this declares its own license module instead of
+// depending on bootable/recovery's internal "bootable_recovery_license" name.
+license {
+    name: "external_update_binary_edify_license",
+    visibility: [":__subpackages__"],
+    license_kinds: [
+        "SPDX-license-identifier-Apache-2.0",
+    ],
+    license_text: [
+        "//external/update_binary:NOTICE",
+    ],
+}
+
+cc_library_static {
+    name: "libedify",
+
+    host_supported: true,
+    vendor_available: true,
+    recovery_available: true,
+
+    srcs: [
+        "expr.cpp",
+        "lexer.ll",
+        "parser.yy",
+    ],
+
+    cflags: [
+        "-Wall",
+        "-Werror",
+        "-Wno-deprecated-register",
+        "-Wno-unused-parameter",
+    ],
+
+    export_include_dirs: [
+        "include",
+    ],
+
+    local_include_dirs: [
+        "include",
+    ],
+
+    static_libs: [
+        "libbase",
+        "libotautil",
+    ],
+}

edify/Android.mk

@@ -0,0 +1,58 @@
+# Copyright 2009 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.
+
+LOCAL_PATH := $(call my-dir)
+
+edify_src_files := \
+    lexer.ll \
+    parser.yy \
+    expr.cpp
+
+#
+# Build the host-side command line tool (host executable)
+#
+include $(CLEAR_VARS)
+
+LOCAL_SRC_FILES := \
+    $(edify_src_files) \
+    edify_parser.cpp
+
+LOCAL_CFLAGS := -Werror
+LOCAL_CPPFLAGS := -g -O0
+LOCAL_MODULE := edify_parser
+LOCAL_YACCFLAGS := -v
+LOCAL_CPPFLAGS += -Wno-unused-parameter
+LOCAL_CPPFLAGS += -Wno-deprecated-register
+LOCAL_CLANG := true
+LOCAL_C_INCLUDES += $(LOCAL_PATH)/..
+LOCAL_STATIC_LIBRARIES += libbase
+
+include $(BUILD_HOST_EXECUTABLE)
+
+#
+# Build the device-side library (static library)
+#
+include $(CLEAR_VARS)
+
+LOCAL_SRC_FILES := $(edify_src_files)
+
+LOCAL_CFLAGS := -Werror
+LOCAL_CPPFLAGS := -Wno-unused-parameter
+LOCAL_CPPFLAGS += -Wno-deprecated-register
+LOCAL_MODULE := libedify
+LOCAL_CLANG := true
+LOCAL_C_INCLUDES += $(LOCAL_PATH)/..
+LOCAL_STATIC_LIBRARIES += libbase
+
+include $(BUILD_STATIC_LIBRARY)

edify/README.md

@@ -0,0 +1,111 @@
+edify
+=====
+
+Update scripts (from donut onwards) are written in a new little
+scripting language ("edify") that is superficially somewhat similar to
+the old one ("amend").  This is a brief overview of the new language.
+
+- The entire script is a single expression.
+
+- All expressions are string-valued.
+
+- String literals appear in double quotes.  \n, \t, \", and \\ are
+  understood, as are hexadecimal escapes like \x4a.
+
+- String literals consisting of only letters, numbers, colons,
+  underscores, slashes, and periods don't need to be in double quotes.
+
+- The following words are reserved:
+
+       if    then    else   endif
+
+  They have special meaning when unquoted.  (In quotes, they are just
+  string literals.)
+
+- When used as a boolean, the empty string is "false" and all other
+  strings are "true".
+
+- All functions are actually macros (in the Lisp sense); the body of
+  the function can control which (if any) of the arguments are
+  evaluated.  This means that functions can act as control
+  structures.
+
+- Operators (like "&&" and "||") are just syntactic sugar for builtin
+  functions, so they can act as control structures as well.
+
+- ";" is a binary operator; evaluating it just means to first evaluate
+  the left side, then the right.  It can also appear after any
+  expression.
+
+- Comments start with "#" and run to the end of the line.
+
+
+
+Some examples:
+
+- There's no distinction between quoted and unquoted strings; the
+  quotes are only needed if you want characters like whitespace to
+  appear in the string.  The following expressions all evaluate to the
+  same string.
+
+     "a b"
+     a + " " + b
+     "a" + " " + "b"
+     "a\x20b"
+     a + "\x20b"
+     concat(a, " ", "b")
+     "concat"(a, " ", "b")
+
+  As shown in the last example, function names are just strings,
+  too.  They must be string *literals*, however.  This is not legal:
+
+     ("con" + "cat")(a, " ", b)         # syntax error!
+
+
+- The ifelse() builtin takes three arguments:  it evaluates exactly
+  one of the second and third, depending on whether the first one is
+  true.  There is also some syntactic sugar to make expressions that
+  look like if/else statements:
+
+     # these are all equivalent
+     ifelse(something(), "yes", "no")
+     if something() then yes else no endif
+     if something() then "yes" else "no" endif
+
+  The else part is optional.
+
+     if something() then "yes" endif    # if something() is false,
+                                        # evaluates to false
+
+     ifelse(condition(), "", abort())   # abort() only called if
+                                        # condition() is false
+
+  The last example is equivalent to:
+
+     assert(condition())
+
+
+- The && and || operators can be used similarly; they evaluate their
+  second argument only if it's needed to determine the truth of the
+  expression.  Their value is the value of the last-evaluated
+  argument:
+
+     file_exists("/data/system/bad") && delete("/data/system/bad")
+
+     file_exists("/data/system/missing") || create("/data/system/missing")
+
+     get_it() || "xxx"     # returns value of get_it() if that value is
+                           # true, otherwise returns "xxx"
+
+
+- The purpose of ";" is to simulate imperative statements, of course,
+  but the operator can be used anywhere.  Its value is the value of
+  its right side:
+
+     concat(a;b;c, d, e;f)     # evaluates to "cdf"
+
+  A more useful example might be something like:
+
+     ifelse(condition(),
+            (first_step(); second_step();),   # second ; is optional
+            alternative_procedure())

edify/expr.cpp

@@ -0,0 +1,425 @@
+/*
+ * Copyright (C) 2009 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 "edify/expr.h"
+
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <memory>
+#include <string>
+#include <unordered_map>
+#include <vector>
+
+#include <android-base/parseint.h>
+#include <android-base/stringprintf.h>
+#include <android-base/strings.h>
+
+#include "otautil/error_code.h"
+
+// Functions should:
+//
+//    - return a malloc()'d string
+//    - if Evaluate() on any argument returns nullptr, return nullptr.
+
+static bool BooleanString(const std::string& s) {
+    return !s.empty();
+}
+
+bool Evaluate(State* state, const std::unique_ptr<Expr>& expr, std::string* result) {
+    if (result == nullptr) {
+        return false;
+    }
+
+    std::unique_ptr<Value> v(expr->fn(expr->name.c_str(), state, expr->argv));
+    if (!v) {
+        return false;
+    }
+    if (v->type != Value::Type::STRING) {
+      ErrorAbort(state, kArgsParsingFailure, "expecting string, got value type %d", v->type);
+      return false;
+    }
+
+    *result = v->data;
+    return true;
+}
+
+Value* EvaluateValue(State* state, const std::unique_ptr<Expr>& expr) {
+    return expr->fn(expr->name.c_str(), state, expr->argv);
+}
+
+Value* StringValue(const char* str) {
+    if (str == nullptr) {
+        return nullptr;
+    }
+    return new Value(Value::Type::STRING, str);
+}
+
+Value* StringValue(const std::string& str) {
+    return StringValue(str.c_str());
+}
+
+Value* ConcatFn(const char* name, State* state, const std::vector<std::unique_ptr<Expr>>& argv) {
+    if (argv.empty()) {
+        return StringValue("");
+    }
+    std::string result;
+    for (size_t i = 0; i < argv.size(); ++i) {
+        std::string str;
+        if (!Evaluate(state, argv[i], &str)) {
+            return nullptr;
+        }
+        result += str;
+    }
+
+    return StringValue(result);
+}
+
+Value* IfElseFn(const char* name, State* state, const std::vector<std::unique_ptr<Expr>>& argv) {
+    if (argv.size() != 2 && argv.size() != 3) {
+        state->errmsg = "ifelse expects 2 or 3 arguments";
+        return nullptr;
+    }
+
+    std::string cond;
+    if (!Evaluate(state, argv[0], &cond)) {
+        return nullptr;
+    }
+
+    if (!cond.empty()) {
+        return EvaluateValue(state, argv[1]);
+    } else if (argv.size() == 3) {
+        return EvaluateValue(state, argv[2]);
+    }
+
+    return StringValue("");
+}
+
+Value* AbortFn(const char* name, State* state, const std::vector<std::unique_ptr<Expr>>& argv) {
+    std::string msg;
+    if (!argv.empty() && Evaluate(state, argv[0], &msg)) {
+      state->errmsg += msg;
+    } else {
+      state->errmsg += "called abort()";
+    }
+    return nullptr;
+}
+
+Value* AssertFn(const char* name, State* state, const std::vector<std::unique_ptr<Expr>>& argv) {
+    for (size_t i = 0; i < argv.size(); ++i) {
+        std::string result;
+        if (!Evaluate(state, argv[i], &result)) {
+            return nullptr;
+        }
+        if (result.empty()) {
+            int len = argv[i]->end - argv[i]->start;
+            state->errmsg = "assert failed: " + state->script.substr(argv[i]->start, len);
+            return nullptr;
+        }
+    }
+    return StringValue("");
+}
+
+Value* SleepFn(const char* name, State* state, const std::vector<std::unique_ptr<Expr>>& argv) {
+    std::string val;
+    if (!Evaluate(state, argv[0], &val)) {
+        return nullptr;
+    }
+
+    int v;
+    if (!android::base::ParseInt(val.c_str(), &v, 0)) {
+        return nullptr;
+    }
+    sleep(v);
+
+    return StringValue(val);
+}
+
+Value* StdoutFn(const char* name, State* state, const std::vector<std::unique_ptr<Expr>>& argv) {
+    for (size_t i = 0; i < argv.size(); ++i) {
+        std::string v;
+        if (!Evaluate(state, argv[i], &v)) {
+            return nullptr;
+        }
+        fputs(v.c_str(), stdout);
+    }
+    return StringValue("");
+}
+
+Value* LogicalAndFn(const char* name, State* state,
+                    const std::vector<std::unique_ptr<Expr>>& argv) {
+    std::string left;
+    if (!Evaluate(state, argv[0], &left)) {
+        return nullptr;
+    }
+    if (BooleanString(left)) {
+        return EvaluateValue(state, argv[1]);
+    } else {
+        return StringValue("");
+    }
+}
+
+Value* LogicalOrFn(const char* name, State* state,
+                   const std::vector<std::unique_ptr<Expr>>& argv) {
+    std::string left;
+    if (!Evaluate(state, argv[0], &left)) {
+        return nullptr;
+    }
+    if (!BooleanString(left)) {
+        return EvaluateValue(state, argv[1]);
+    } else {
+        return StringValue(left);
+    }
+}
+
+Value* LogicalNotFn(const char* name, State* state,
+                    const std::vector<std::unique_ptr<Expr>>& argv) {
+    std::string val;
+    if (!Evaluate(state, argv[0], &val)) {
+        return nullptr;
+    }
+
+    return StringValue(BooleanString(val) ? "" : "t");
+}
+
+Value* SubstringFn(const char* name, State* state,
+                   const std::vector<std::unique_ptr<Expr>>& argv) {
+    std::string needle;
+    if (!Evaluate(state, argv[0], &needle)) {
+        return nullptr;
+    }
+
+    std::string haystack;
+    if (!Evaluate(state, argv[1], &haystack)) {
+        return nullptr;
+    }
+
+    std::string result = (haystack.find(needle) != std::string::npos) ? "t" : "";
+    return StringValue(result);
+}
+
+Value* EqualityFn(const char* name, State* state, const std::vector<std::unique_ptr<Expr>>& argv) {
+    std::string left;
+    if (!Evaluate(state, argv[0], &left)) {
+        return nullptr;
+    }
+    std::string right;
+    if (!Evaluate(state, argv[1], &right)) {
+        return nullptr;
+    }
+
+    const char* result = (left == right) ? "t" : "";
+    return StringValue(result);
+}
+
+Value* InequalityFn(const char* name, State* state,
+                    const std::vector<std::unique_ptr<Expr>>& argv) {
+    std::string left;
+    if (!Evaluate(state, argv[0], &left)) {
+        return nullptr;
+    }
+    std::string right;
+    if (!Evaluate(state, argv[1], &right)) {
+        return nullptr;
+    }
+
+    const char* result = (left != right) ? "t" : "";
+    return StringValue(result);
+}
+
+Value* SequenceFn(const char* name, State* state, const std::vector<std::unique_ptr<Expr>>& argv) {
+    std::unique_ptr<Value> left(EvaluateValue(state, argv[0]));
+    if (!left) {
+        return nullptr;
+    }
+    return EvaluateValue(state, argv[1]);
+}
+
+Value* LessThanIntFn(const char* name, State* state,
+                     const std::vector<std::unique_ptr<Expr>>& argv) {
+    if (argv.size() != 2) {
+        state->errmsg = "less_than_int expects 2 arguments";
+        return nullptr;
+    }
+
+    std::vector<std::string> args;
+    if (!ReadArgs(state, argv, &args)) {
+        return nullptr;
+    }
+
+    // Parse up to at least long long or 64-bit integers.
+    int64_t l_int;
+    if (!android::base::ParseInt(args[0].c_str(), &l_int)) {
+        state->errmsg = "failed to parse int in " + args[0];
+        return nullptr;
+    }
+
+    int64_t r_int;
+    if (!android::base::ParseInt(args[1].c_str(), &r_int)) {
+        state->errmsg = "failed to parse int in " + args[1];
+        return nullptr;
+    }
+
+    return StringValue(l_int < r_int ? "t" : "");
+}
+
+Value* GreaterThanIntFn(const char* name, State* state,
+                        const std::vector<std::unique_ptr<Expr>>& argv) {
+    if (argv.size() != 2) {
+        state->errmsg = "greater_than_int expects 2 arguments";
+        return nullptr;
+    }
+
+    std::vector<std::string> args;
+    if (!ReadArgs(state, argv, &args)) {
+        return nullptr;
+    }
+
+    // Parse up to at least long long or 64-bit integers.
+    int64_t l_int;
+    if (!android::base::ParseInt(args[0].c_str(), &l_int)) {
+        state->errmsg = "failed to parse int in " + args[0];
+        return nullptr;
+    }
+
+    int64_t r_int;
+    if (!android::base::ParseInt(args[1].c_str(), &r_int)) {
+        state->errmsg = "failed to parse int in " + args[1];
+        return nullptr;
+    }
+
+    return StringValue(l_int > r_int ? "t" : "");
+}
+
+Value* Literal(const char* name, State* state, const std::vector<std::unique_ptr<Expr>>& argv) {
+    return StringValue(name);
+}
+
+// -----------------------------------------------------------------
+//   the function table
+// -----------------------------------------------------------------
+
+static std::unordered_map<std::string, Function> fn_table;
+
+void RegisterFunction(const std::string& name, Function fn) {
+    fn_table[name] = fn;
+}
+
+Function FindFunction(const std::string& name) {
+    if (fn_table.find(name) == fn_table.end()) {
+        return nullptr;
+    } else {
+        return fn_table[name];
+    }
+}
+
+void RegisterBuiltins() {
+    RegisterFunction("ifelse", IfElseFn);
+    RegisterFunction("abort", AbortFn);
+    RegisterFunction("assert", AssertFn);
+    RegisterFunction("concat", ConcatFn);
+    RegisterFunction("is_substring", SubstringFn);
+    RegisterFunction("stdout", StdoutFn);
+    RegisterFunction("sleep", SleepFn);
+
+    RegisterFunction("less_than_int", LessThanIntFn);
+    RegisterFunction("greater_than_int", GreaterThanIntFn);
+}
+
+
+// -----------------------------------------------------------------
+//   convenience methods for functions
+// -----------------------------------------------------------------
+
+// Evaluate the expressions in argv, and put the results of strings in args. If any expression
+// evaluates to nullptr, return false. Return true on success.
+bool ReadArgs(State* state, const std::vector<std::unique_ptr<Expr>>& argv,
+              std::vector<std::string>* args) {
+    return ReadArgs(state, argv, args, 0, argv.size());
+}
+
+bool ReadArgs(State* state, const std::vector<std::unique_ptr<Expr>>& argv,
+              std::vector<std::string>* args, size_t start, size_t len) {
+    if (args == nullptr) {
+        return false;
+    }
+    if (start + len > argv.size()) {
+        return false;
+    }
+    for (size_t i = start; i < start + len; ++i) {
+        std::string var;
+        if (!Evaluate(state, argv[i], &var)) {
+            args->clear();
+            return false;
+        }
+        args->push_back(var);
+    }
+    return true;
+}
+
+// Evaluate the expressions in argv, and put the results of Value* in args. If any expression
+// evaluate to nullptr, return false. Return true on success.
+bool ReadValueArgs(State* state, const std::vector<std::unique_ptr<Expr>>& argv,
+                   std::vector<std::unique_ptr<Value>>* args) {
+    return ReadValueArgs(state, argv, args, 0, argv.size());
+}
+
+bool ReadValueArgs(State* state, const std::vector<std::unique_ptr<Expr>>& argv,
+                   std::vector<std::unique_ptr<Value>>* args, size_t start, size_t len) {
+    if (args == nullptr) {
+        return false;
+    }
+    if (len == 0 || start + len > argv.size()) {
+        return false;
+    }
+    for (size_t i = start; i < start + len; ++i) {
+        std::unique_ptr<Value> v(EvaluateValue(state, argv[i]));
+        if (!v) {
+            args->clear();
+            return false;
+        }
+        args->push_back(std::move(v));
+    }
+    return true;
+}
+
+// Use printf-style arguments to compose an error message to put into
+// *state.  Returns nullptr.
+Value* ErrorAbort(State* state, const char* format, ...) {
+    va_list ap;
+    va_start(ap, format);
+    android::base::StringAppendV(&state->errmsg, format, ap);
+    va_end(ap);
+    return nullptr;
+}
+
+Value* ErrorAbort(State* state, CauseCode cause_code, const char* format, ...) {
+  std::string err_message;
+  va_list ap;
+  va_start(ap, format);
+  android::base::StringAppendV(&err_message, format, ap);
+  va_end(ap);
+  // Ensure that there's exactly one line break at the end of the error message.
+  state->errmsg = android::base::Trim(err_message) + "\n";
+  state->cause_code = cause_code;
+  return nullptr;
+}
+
+State::State(const std::string& script, UpdaterInterface* interface)
+    : script(script), updater(interface), error_code(kNoError), cause_code(kNoCause) {}

edify/include/edify/expr.h

@@ -0,0 +1,159 @@
+/*
+ * Copyright (C) 2009 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 _EXPRESSION_H
+#define _EXPRESSION_H
+
+#include <unistd.h>
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "edify/updater_interface.h"
+
+// Forward declaration to avoid including "otautil/error_code.h".
+enum ErrorCode : int;
+enum CauseCode : int;
+
+struct State {
+  State(const std::string& script, UpdaterInterface* cookie);
+
+  // The source of the original script.
+  const std::string& script;
+
+  // A pointer to app-specific data; the libedify doesn't use this value.
+  UpdaterInterface* updater;
+
+  // The error message (if any) returned if the evaluation aborts.
+  // Should be empty initially, will be either empty or a string that
+  // Evaluate() returns.
+  std::string errmsg;
+
+  // error code indicates the type of failure (e.g. failure to update system image)
+  // during the OTA process.
+  ErrorCode error_code;
+
+  // cause code provides more detailed reason of an OTA failure (e.g. fsync error)
+  // in addition to the error code.
+  CauseCode cause_code;
+
+  bool is_retry = false;
+};
+
+struct Value {
+  enum class Type {
+    STRING = 1,
+    BLOB = 2,
+  };
+
+  Value(Type type, std::string str) : type(type), data(std::move(str)) {}
+
+  Type type;
+  std::string data;
+};
+
+struct Expr;
+
+using Function = Value* (*)(const char* name, State* state,
+                            const std::vector<std::unique_ptr<Expr>>& argv);
+
+struct Expr {
+  Function fn;
+  std::string name;
+  std::vector<std::unique_ptr<Expr>> argv;
+  int start, end;
+
+  Expr(Function fn, const std::string& name, int start, int end) :
+    fn(fn),
+    name(name),
+    start(start),
+    end(end) {}
+};
+
+// Evaluate the input expr, return the resulting Value.
+Value* EvaluateValue(State* state, const std::unique_ptr<Expr>& expr);
+
+// Evaluate the input expr, assert that it is a string, and update the result parameter. This
+// function returns true if the evaluation succeeds. This is a convenience function for older
+// functions that want to deal only with strings.
+bool Evaluate(State* state, const std::unique_ptr<Expr>& expr, std::string* result);
+
+// Glue to make an Expr out of a literal.
+Value* Literal(const char* name, State* state, const std::vector<std::unique_ptr<Expr>>& argv);
+
+// Functions corresponding to various syntactic sugar operators.
+// ("concat" is also available as a builtin function, to concatenate
+// more than two strings.)
+Value* ConcatFn(const char* name, State* state, const std::vector<std::unique_ptr<Expr>>& argv);
+Value* LogicalAndFn(const char* name, State* state, const std::vector<std::unique_ptr<Expr>>& argv);
+Value* LogicalOrFn(const char* name, State* state, const std::vector<std::unique_ptr<Expr>>& argv);
+Value* LogicalNotFn(const char* name, State* state, const std::vector<std::unique_ptr<Expr>>& argv);
+Value* SubstringFn(const char* name, State* state, const std::vector<std::unique_ptr<Expr>>& argv);
+Value* EqualityFn(const char* name, State* state, const std::vector<std::unique_ptr<Expr>>& argv);
+Value* InequalityFn(const char* name, State* state, const std::vector<std::unique_ptr<Expr>>& argv);
+Value* SequenceFn(const char* name, State* state, const std::vector<std::unique_ptr<Expr>>& argv);
+
+// Global builtins, registered by RegisterBuiltins().
+Value* IfElseFn(const char* name, State* state, const std::vector<std::unique_ptr<Expr>>& argv);
+Value* AssertFn(const char* name, State* state, const std::vector<std::unique_ptr<Expr>>& argv);
+Value* AbortFn(const char* name, State* state, const std::vector<std::unique_ptr<Expr>>& argv);
+
+// Register a new function.  The same Function may be registered under
+// multiple names, but a given name should only be used once.
+void RegisterFunction(const std::string& name, Function fn);
+
+// Register all the builtins.
+void RegisterBuiltins();
+
+// Find the Function for a given name; return NULL if no such function
+// exists.
+Function FindFunction(const std::string& name);
+
+// --- convenience functions for use in functions ---
+
+// Evaluate the expressions in argv, and put the results of strings in args. If any expression
+// evaluates to nullptr, return false. Return true on success.
+bool ReadArgs(State* state, const std::vector<std::unique_ptr<Expr>>& argv,
+              std::vector<std::string>* args);
+bool ReadArgs(State* state, const std::vector<std::unique_ptr<Expr>>& argv,
+              std::vector<std::string>* args, size_t start, size_t len);
+
+// Evaluate the expressions in argv, and put the results of Value* in args. If any
+// expression evaluate to nullptr, return false. Return true on success.
+bool ReadValueArgs(State* state, const std::vector<std::unique_ptr<Expr>>& argv,
+                   std::vector<std::unique_ptr<Value>>* args);
+bool ReadValueArgs(State* state, const std::vector<std::unique_ptr<Expr>>& argv,
+                   std::vector<std::unique_ptr<Value>>* args, size_t start, size_t len);
+
+// Use printf-style arguments to compose an error message to put into
+// *state.  Returns NULL.
+Value* ErrorAbort(State* state, const char* format, ...)
+    __attribute__((format(printf, 2, 3), deprecated));
+
+// ErrorAbort has an optional (but recommended) argument 'cause_code'. If the cause code
+// is set, it will be logged into last_install and provides reason of OTA failures.
+Value* ErrorAbort(State* state, CauseCode cause_code, const char* format, ...)
+    __attribute__((format(printf, 3, 4)));
+
+// Copying the string into a Value.
+Value* StringValue(const char* str);
+
+Value* StringValue(const std::string& str);
+
+int ParseString(const std::string& str, std::unique_ptr<Expr>* root, int* error_count);
+
+#endif  // _EXPRESSION_H

edify/include/edify/updater_interface.h

@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2019 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.
+ */
+
+#pragma once
+
+#include <stdint.h>
+
+#include <string>
+#include <string_view>
+
+struct ZipArchive;
+typedef ZipArchive* ZipArchiveHandle;
+
+class UpdaterRuntimeInterface;
+
+class UpdaterInterface {
+ public:
+  virtual ~UpdaterInterface() = default;
+
+  // Writes the message to command pipe, adds a new line in the end.
+  virtual void WriteToCommandPipe(const std::string_view message, bool flush = false) const = 0;
+
+  // Sends over the message to recovery to print it on the screen.
+  virtual void UiPrint(const std::string_view message) const = 0;
+
+  // Given the name of the block device, returns |name| for updates on the device; or the file path
+  // to the fake block device for simulations.
+  virtual std::string FindBlockDeviceName(const std::string_view name) const = 0;
+
+  virtual UpdaterRuntimeInterface* GetRuntime() const = 0;
+  virtual ZipArchiveHandle GetPackageHandle() const = 0;
+  virtual std::string GetResult() const = 0;
+  virtual uint8_t* GetMappedPackageAddress() const = 0;
+  virtual size_t GetMappedPackageLength() const = 0;
+};

edify/include/edify/updater_runtime_interface.h

@@ -0,0 +1,77 @@
+/*
+ * Copyright (C) 2019 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.
+ */
+
+#pragma once
+
+#include <string>
+#include <string_view>
+#include <vector>
+
+// This class serves as the base to updater runtime. It wraps the runtime dependent functions; and
+// updates on device and host simulations can have different implementations. e.g. block devices
+// during host simulation merely a temporary file. With this class, the caller side in registered
+// updater's functions will stay the same for both update and simulation.
+class UpdaterRuntimeInterface {
+ public:
+  virtual ~UpdaterRuntimeInterface() = default;
+
+  // Returns true if it's a runtime instance for simulation.
+  virtual bool IsSimulator() const = 0;
+
+  // Returns the value of system property |key|. If the property doesn't exist, returns
+  // |default_value|.
+  virtual std::string GetProperty(const std::string_view key,
+                                  const std::string_view default_value) const = 0;
+
+  // Given the name of the block device, returns |name| for updates on the device; or the file path
+  // to the fake block device for simulations.
+  virtual std::string FindBlockDeviceName(const std::string_view name) const = 0;
+
+  // Mounts the |location| on |mount_point|. Returns 0 on success.
+  virtual int Mount(const std::string_view location, const std::string_view mount_point,
+                    const std::string_view fs_type, const std::string_view mount_options) = 0;
+
+  // Returns true if |mount_point| is mounted.
+  virtual bool IsMounted(const std::string_view mount_point) const = 0;
+
+  // Unmounts the |mount_point|. Returns a pair of results with the first value indicating
+  // if the |mount_point| is mounted, and the second value indicating the result of umount(2).
+  virtual std::pair<bool, int> Unmount(const std::string_view mount_point) = 0;
+
+  // Reads |filename| and puts its value to |content|.
+  virtual bool ReadFileToString(const std::string_view filename, std::string* content) const = 0;
+
+  // Updates the content of |filename| with |content|.
+  virtual bool WriteStringToFile(const std::string_view content,
+                                 const std::string_view filename) const = 0;
+
+  // Wipes the first |len| bytes of block device in |filename|.
+  virtual int WipeBlockDevice(const std::string_view filename, size_t len) const = 0;
+
+  // Starts a child process and runs the program with |args|. Uses vfork(2) if |is_vfork| is true.
+  virtual int RunProgram(const std::vector<std::string>& args, bool is_vfork) const = 0;
+
+  // Runs tune2fs with arguments |args|.
+  virtual int Tune2Fs(const std::vector<std::string>& args) const = 0;
+
+  // Dynamic partition related functions.
+  virtual bool MapPartitionOnDeviceMapper(const std::string& partition_name, std::string* path) = 0;
+  virtual bool UnmapPartitionOnDeviceMapper(const std::string& partition_name) = 0;
+  virtual bool UpdateDynamicPartitions(const std::string_view op_list_value) = 0;
+
+  // On devices supports A/B, add current slot suffix to arg. Otherwise, return |arg| as is.
+  virtual std::string AddSlotSuffix(const std::string_view arg) const = 0;
+};

edify/lexer.ll

@@ -0,0 +1,112 @@
+%{
+/*
+ * Copyright (C) 2009 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 <string.h>
+#include <string>
+
+#include "edify/expr.h"
+#include "yydefs.h"
+#include "parser.h"
+
+int gLine = 1;
+int gColumn = 1;
+int gPos = 0;
+
+std::string string_buffer;
+
+#define ADVANCE do {yylloc.start=gPos; yylloc.end=gPos+yyleng; \
+                    gColumn+=yyleng; gPos+=yyleng;} while(0)
+
+%}
+
+%x STR
+
+%option noinput
+%option nounput
+%option noyywrap
+
+%%
+
+
+\" {
+    BEGIN(STR);
+    string_buffer.clear();
+    yylloc.start = gPos;
+    ++gColumn;
+    ++gPos;
+}
+
+<STR>{
+  \" {
+      ++gColumn;
+      ++gPos;
+      BEGIN(INITIAL);
+      yylval.str = strdup(string_buffer.c_str());
+      yylloc.end = gPos;
+      return STRING;
+  }
+
+  \\n   { gColumn += yyleng; gPos += yyleng; string_buffer.push_back('\n'); }
+  \\t   { gColumn += yyleng; gPos += yyleng; string_buffer.push_back('\t'); }
+  \\\"  { gColumn += yyleng; gPos += yyleng; string_buffer.push_back('\"'); }
+  \\\\  { gColumn += yyleng; gPos += yyleng; string_buffer.push_back('\\'); }
+
+  \\x[0-9a-fA-F]{2} {
+      gColumn += yyleng;
+      gPos += yyleng;
+      int val;
+      sscanf(yytext+2, "%x", &val);
+      string_buffer.push_back(static_cast<char>(val));
+  }
+
+  \n {
+      ++gLine;
+      ++gPos;
+      gColumn = 1;
+      string_buffer.push_back(yytext[0]);
+  }
+
+  . {
+      ++gColumn;
+      ++gPos;
+      string_buffer.push_back(yytext[0]);
+  }
+}
+
+if                ADVANCE; return IF;
+then              ADVANCE; return THEN;
+else              ADVANCE; return ELSE;
+endif             ADVANCE; return ENDIF;
+
+[a-zA-Z0-9_:/.]+ {
+  ADVANCE;
+  yylval.str = strdup(yytext);
+  return STRING;
+}
+
+\&\&              ADVANCE; return AND;
+\|\|              ADVANCE; return OR;
+==                ADVANCE; return EQ;
+!=                ADVANCE; return NE;
+
+[+(),!;]          ADVANCE; return yytext[0];
+
+[ \t]+            ADVANCE;
+
+(#.*)?\n          gPos += yyleng; ++gLine; gColumn = 1;
+
+.                 return BAD;

edify/parser.yy

@@ -0,0 +1,145 @@
+%{
+/*
+ * Copyright (C) 2009 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 <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include <android-base/macros.h>
+
+#include "edify/expr.h"
+#include "yydefs.h"
+#include "parser.h"
+
+extern int gLine;
+extern int gColumn;
+
+void yyerror(std::unique_ptr<Expr>* root, int* error_count, const char* s);
+int yyparse(std::unique_ptr<Expr>* root, int* error_count);
+
+struct yy_buffer_state;
+void yy_switch_to_buffer(struct yy_buffer_state* new_buffer);
+struct yy_buffer_state* yy_scan_string(const char* yystr);
+
+// Convenience function for building expressions with a fixed number
+// of arguments.
+static Expr* Build(Function fn, YYLTYPE loc, size_t count, ...) {
+    va_list v;
+    va_start(v, count);
+    Expr* e = new Expr(fn, "(operator)", loc.start, loc.end);
+    for (size_t i = 0; i < count; ++i) {
+        e->argv.emplace_back(va_arg(v, Expr*));
+    }
+    va_end(v);
+    return e;
+}
+
+%}
+
+%locations
+
+%union {
+    char* str;
+    Expr* expr;
+    std::vector<std::unique_ptr<Expr>>* args;
+}
+
+%token AND OR SUBSTR SUPERSTR EQ NE IF THEN ELSE ENDIF
+%token <str> STRING BAD
+%type <expr> expr
+%type <args> arglist
+
+%destructor { delete $$; } expr
+%destructor { delete $$; } arglist
+
+%parse-param {std::unique_ptr<Expr>* root}
+%parse-param {int* error_count}
+%define parse.error verbose
+
+/* declarations in increasing order of precedence */
+%left ';'
+%left ','
+%left OR
+%left AND
+%left EQ NE
+%left '+'
+%right '!'
+
+%%
+
+input:  expr           { root->reset($1); }
+;
+
+expr:  STRING {
+    $$ = new Expr(Literal, $1, @$.start, @$.end);
+}
+|  '(' expr ')'                      { $$ = $2; $$->start=@$.start; $$->end=@$.end; }
+|  expr ';'                          { $$ = $1; $$->start=@1.start; $$->end=@1.end; }
+|  expr ';' expr                     { $$ = Build(SequenceFn, @$, 2, $1, $3); }
+|  error ';' expr                    { $$ = $3; $$->start=@$.start; $$->end=@$.end; }
+|  expr '+' expr                     { $$ = Build(ConcatFn, @$, 2, $1, $3); }
+|  expr EQ expr                      { $$ = Build(EqualityFn, @$, 2, $1, $3); }
+|  expr NE expr                      { $$ = Build(InequalityFn, @$, 2, $1, $3); }
+|  expr AND expr                     { $$ = Build(LogicalAndFn, @$, 2, $1, $3); }
+|  expr OR expr                      { $$ = Build(LogicalOrFn, @$, 2, $1, $3); }
+|  '!' expr                          { $$ = Build(LogicalNotFn, @$, 1, $2); }
+|  IF expr THEN expr ENDIF           { $$ = Build(IfElseFn, @$, 2, $2, $4); }
+|  IF expr THEN expr ELSE expr ENDIF { $$ = Build(IfElseFn, @$, 3, $2, $4, $6); }
+| STRING '(' arglist ')' {
+    Function fn = FindFunction($1);
+    if (fn == nullptr) {
+        std::string msg = "unknown function \"" + std::string($1) + "\"";
+        yyerror(root, error_count, msg.c_str());
+        YYERROR;
+    }
+    $$ = new Expr(fn, $1, @$.start, @$.end);
+    $$->argv = std::move(*$3);
+}
+;
+
+arglist:    /* empty */ {
+    $$ = new std::vector<std::unique_ptr<Expr>>;
+}
+| expr {
+    $$ = new std::vector<std::unique_ptr<Expr>>;
+    $$->emplace_back($1);
+}
+| arglist ',' expr {
+    UNUSED($1);
+    $$->push_back(std::unique_ptr<Expr>($3));
+}
+;
+
+%%
+
+void yyerror(std::unique_ptr<Expr>* root, int* error_count, const char* s) {
+  if (strlen(s) == 0) {
+    s = "syntax error";
+  }
+  printf("line %d col %d: %s\n", gLine, gColumn, s);
+  ++*error_count;
+}
+
+int ParseString(const std::string& str, std::unique_ptr<Expr>* root, int* error_count) {
+  yy_switch_to_buffer(yy_scan_string(str.c_str()));
+  return yyparse(root, error_count);
+}

edify/yydefs.h

@@ -0,0 +1,38 @@
+/*
+ * Copyright (C) 2009 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 _YYDEFS_H_
+#define _YYDEFS_H_
+
+#define YYLTYPE YYLTYPE
+typedef struct {
+    int start, end;
+} YYLTYPE;
+
+#define YYLLOC_DEFAULT(Current, Rhs, N) \
+    do { \
+        if (N) { \
+            (Current).start = YYRHSLOC(Rhs, 1).start; \
+            (Current).end = YYRHSLOC(Rhs, N).end; \
+        } else { \
+            (Current).start = YYRHSLOC(Rhs, 0).start; \
+            (Current).end = YYRHSLOC(Rhs, 0).end; \
+        } \
+    } while (0)
+
+int yylex();
+
+#endif