Reland: Add getprop to toolbox

Add a non-toybox version of getprop, so that we can interface with the
new C++ PropertyInfoAreaFile class to return property context
information.

Bug: 36001741
Test: Compared toolbox getprop results with toybox getprop
Change-Id: I4e90aa5b843cb5cfcbe85f05f23ae8e22729b26e

3 files changed, 133 insertions, 0 deletions

diff --git a/toolbox/Android.bp b/toolbox/Android.bp
index 02365c600..9f7fc3bd6 100644
--- a/toolbox/Android.bp
+++ b/toolbox/Android.bp
@@ -44,9 +44,11 @@ genrule {
 cc_defaults {
     name: "toolbox_binary_defaults",
     defaults: ["toolbox_defaults"],
+    cpp_std: "experimental",
     srcs: [
         "toolbox.c",
         "getevent.c",
+        "getprop.cpp",
         "newfs_msdos.c",
     ],
     generated_headers: [
@@ -54,12 +56,15 @@ cc_defaults {
     ],
     whole_static_libs: ["libtoolbox_dd"],
     shared_libs: [
+        "libbase",
         "libcutils",
     ],
+    static_libs: ["libpropertyinfoparser"],
 
     symlinks: [
         "dd",
         "getevent",
+        "getprop",
         "newfs_msdos",
     ],
 }
diff --git a/toolbox/getprop.cpp b/toolbox/getprop.cpp
new file mode 100644
index 000000000..611e2448b
--- /dev/null
+++ b/toolbox/getprop.cpp
@@ -0,0 +1,127 @@
+//
+// 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.
+//
+
+#include <getopt.h>
+#include <sys/system_properties.h>
+
+#include <iostream>
+#include <string>
+#include <vector>
+
+#include <android-base/properties.h>
+#include <property_info_parser/property_info_parser.h>
+
+using android::base::GetProperty;
+using android::properties::PropertyInfoAreaFile;
+
+PropertyInfoAreaFile property_info_file;
+
+void PrintAllProperties(bool print_property_context) {
+    std::vector<std::pair<std::string, std::string>> properties;
+    __system_property_foreach(
+        [](const prop_info* pi, void* cookie) {
+            __system_property_read_callback(
+                pi,
+                [](void* cookie, const char* name, const char* value, unsigned) {
+                    auto properties =
+                        reinterpret_cast<std::vector<std::pair<std::string, std::string>>*>(cookie);
+                    properties->emplace_back(name, value);
+                },
+                cookie);
+        },
+        &properties);
+
+    std::sort(properties.begin(), properties.end());
+
+    if (print_property_context) {
+        for (auto& [name, value] : properties) {
+            const char* context = nullptr;
+            property_info_file->GetPropertyInfo(name.c_str(), &context, nullptr);
+            value = context;
+        }
+    }
+
+    for (const auto& [name, value] : properties) {
+        std::cout << "[" << name << "]: [" << value << "]" << std::endl;
+    }
+}
+
+void PrintProperty(const char* name, const char* default_value, bool print_property_context) {
+    if (print_property_context) {
+        const char* context = nullptr;
+        property_info_file->GetPropertyInfo(name, &context, nullptr);
+        std::cout << context << std::endl;
+    } else {
+        std::cout << GetProperty(name, default_value) << std::endl;
+    }
+}
+
+extern "C" int getprop_main(int argc, char** argv) {
+    bool print_property_context = false;
+
+    while (true) {
+        static const struct option long_options[] = {
+            {"help", no_argument, nullptr, 'h'},
+            {nullptr, 0, nullptr, 0},
+        };
+
+        int arg = getopt_long(argc, argv, "Z", long_options, nullptr);
+
+        if (arg == -1) {
+            break;
+        }
+
+        switch (arg) {
+            case 'h':
+                std::cout << "usage: getprop [-Z] [NAME [DEFAULT]]\n\n"
+                             "Gets an Android system property, or lists them all.\n"
+                             "Use -Z to return the property context instead of the property value\n"
+                          << std::endl;
+                return 0;
+            case 'Z':
+                print_property_context = true;
+                break;
+            case '?':
+                return -1;
+            default:
+                std::cerr << "getprop: getopt returned invalid result: " << arg << std::endl;
+                return -1;
+        }
+    }
+
+    if (print_property_context) {
+        property_info_file.LoadDefaultPath();
+        if (!property_info_file) {
+            std::cerr << "Unable to load property info file" << std::endl;
+            return -1;
+        }
+    }
+
+    if (optind >= argc) {
+        PrintAllProperties(print_property_context);
+        return 0;
+    }
+
+    if (optind < argc - 2) {
+        std::cerr << "getprop: Max 2 arguments (see \"getprop --help\")" << std::endl;
+        return -1;
+    }
+
+    PrintProperty(argv[optind], (optind == argc - 1) ? "" : argv[optind + 1],
+                  print_property_context);
+
+    return 0;
+}
diff --git a/toolbox/tools.h b/toolbox/tools.h
index 9134af367..505f5281b 100644
--- a/toolbox/tools.h
+++ b/toolbox/tools.h
@@ -1,4 +1,5 @@
 TOOL(dd)
 TOOL(getevent)
+TOOL(getprop)
 TOOL(newfs_msdos)
 TOOL(toolbox)