Alan Stokes | 068f6d4 | 2023-10-09 10:13:03 +0100 | [diff] [blame] | 1 | /* |
| 2 | * Copyright 2023 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | #include "apkmanifest.hpp" |
| 18 | |
| 19 | #include <android-base/logging.h> |
| 20 | #include <android-base/result.h> |
| 21 | #include <androidfw/AssetsProvider.h> |
| 22 | #include <androidfw/ResourceTypes.h> |
| 23 | #include <androidfw/StringPiece.h> |
| 24 | #include <androidfw/Util.h> |
| 25 | #include <stddef.h> |
| 26 | #include <stdint.h> |
| 27 | #include <utils/Errors.h> |
| 28 | |
| 29 | #include <cstdlib> |
| 30 | #include <limits> |
| 31 | #include <string> |
| 32 | #include <string_view> |
| 33 | |
| 34 | using android::Asset; |
| 35 | using android::AssetsProvider; |
| 36 | using android::OK; |
| 37 | using android::Res_value; |
| 38 | using android::ResXMLParser; |
| 39 | using android::ResXMLTree; |
| 40 | using android::statusToString; |
| 41 | using android::StringPiece16; |
| 42 | using android::base::Error; |
| 43 | using android::base::Result; |
| 44 | using android::util::Utf16ToUtf8; |
| 45 | using std::u16string_view; |
| 46 | using std::unique_ptr; |
| 47 | |
| 48 | struct ApkManifestInfo { |
| 49 | std::string package; |
| 50 | uint32_t version_code; |
| 51 | uint32_t version_code_major; |
| 52 | }; |
| 53 | |
| 54 | namespace { |
| 55 | // See https://developer.android.com/guide/topics/manifest/manifest-element |
| 56 | constexpr u16string_view MANIFEST_TAG_NAME{u"manifest"}; |
| 57 | constexpr u16string_view ANDROID_NAMESPACE_URL{u"http://schemas.android.com/apk/res/android"}; |
| 58 | constexpr u16string_view PACKAGE_ATTRIBUTE_NAME{u"package"}; |
| 59 | constexpr u16string_view VERSION_CODE_ATTRIBUTE_NAME{u"versionCode"}; |
| 60 | constexpr u16string_view VERSION_CODE_MAJOR_ATTRIBUTE_NAME{u"versionCodeMajor"}; |
| 61 | |
| 62 | // Read through the XML parse tree up to the <manifest> element. |
| 63 | Result<void> findManifestElement(ResXMLTree& tree) { |
| 64 | for (;;) { |
| 65 | ResXMLParser::event_code_t event = tree.next(); |
| 66 | switch (event) { |
| 67 | case ResXMLParser::END_DOCUMENT: |
| 68 | case ResXMLParser::END_TAG: |
| 69 | case ResXMLParser::TEXT: |
| 70 | default: |
| 71 | return Error() << "Unexpected XML parsing event: " << event; |
| 72 | case ResXMLParser::BAD_DOCUMENT: |
| 73 | return Error() << "Failed to parse XML: " << statusToString(tree.getError()); |
| 74 | case ResXMLParser::START_NAMESPACE: |
| 75 | case ResXMLParser::END_NAMESPACE: |
| 76 | // Not of interest, keep going. |
| 77 | break; |
| 78 | case ResXMLParser::START_TAG: |
| 79 | // The first tag in an AndroidManifest.xml should be <manifest> (no namespace). |
| 80 | // And that's actually the only tag we care about. |
| 81 | if (tree.getElementNamespaceID() >= 0) { |
| 82 | return Error() << "Root element has unexpected namespace."; |
| 83 | } |
| 84 | size_t nameLength = 0; |
| 85 | const char16_t* nameChars = tree.getElementName(&nameLength); |
| 86 | if (!nameChars) { |
| 87 | return Error() << "Missing tag name"; |
| 88 | } |
| 89 | if (u16string_view(nameChars, nameLength) != MANIFEST_TAG_NAME) { |
| 90 | return Error() << "Expected <manifest> as root element"; |
| 91 | } |
| 92 | return {}; |
| 93 | } |
| 94 | } |
| 95 | } |
| 96 | |
| 97 | // Return an attribute encoded as a string, converted to UTF-8. Note that all |
| 98 | // attributes are strings in the original XML, but the binary format encodes |
| 99 | // some as binary numbers etc. This function does not handle converting those |
| 100 | // encodings back to strings, so should only be used when it is known that a |
| 101 | // numeric value is not allowed. |
| 102 | Result<std::string> getStringOnlyAttribute(const ResXMLTree& tree, size_t index) { |
| 103 | size_t len; |
| 104 | const char16_t* value = tree.getAttributeStringValue(index, &len); |
| 105 | if (!value) { |
| 106 | return Error() << "Expected attribute to have string value"; |
| 107 | } |
| 108 | return Utf16ToUtf8(StringPiece16(value, len)); |
| 109 | } |
| 110 | |
| 111 | // Return the u32 value of an attribute. |
| 112 | Result<uint32_t> getU32Attribute(const ResXMLTree& tree, size_t index) { |
| 113 | auto type = tree.getAttributeDataType(index); |
| 114 | switch (type) { |
| 115 | case Res_value::TYPE_INT_DEC: |
| 116 | case Res_value::TYPE_INT_HEX: |
| 117 | // This is how we'd expect the version to be encoded - and we don't |
| 118 | // care what base it was originally in. |
| 119 | return tree.getAttributeData(index); |
| 120 | case Res_value::TYPE_STRING: { |
| 121 | // If the original string is encoded, then we need to convert it. |
| 122 | auto str = OR_RETURN(getStringOnlyAttribute(tree, index)); |
| 123 | char* str_end = nullptr; |
| 124 | // Note that by specifying base 0 we allow for octal, hex, or |
| 125 | // decimal representations here. |
| 126 | unsigned long value = std::strtoul(str.c_str(), &str_end, 0); |
| 127 | if (str_end != str.c_str() + str.size() || |
| 128 | value > std::numeric_limits<uint32_t>::max()) { |
| 129 | return Error() << "Invalid numeric value"; |
| 130 | } |
| 131 | return static_cast<uint32_t>(value); |
| 132 | } |
| 133 | default: |
| 134 | return Error() << "Expected numeric value, got type " << type; |
| 135 | } |
| 136 | } |
| 137 | |
| 138 | // Parse the binary manifest and extract the information we care about. |
| 139 | // Everything we're interested in should be an attribute on the <manifest> tag. |
| 140 | // We don't care what order they come in, absent attributes will be treated as |
| 141 | // the default value, and any unknown attributes (including ones not in the |
| 142 | // expected namespace) will be ignored. |
| 143 | Result<unique_ptr<ApkManifestInfo>> parseManifest(const void* manifest, size_t size) { |
| 144 | ResXMLTree tree; |
| 145 | auto status = tree.setTo(manifest, size); |
| 146 | if (status != OK) { |
| 147 | return Error() << "Failed to create XML Tree: " << statusToString(status); |
| 148 | } |
| 149 | |
| 150 | OR_RETURN(findManifestElement(tree)); |
| 151 | |
| 152 | unique_ptr<ApkManifestInfo> info{new ApkManifestInfo{}}; |
| 153 | |
| 154 | size_t count = tree.getAttributeCount(); |
| 155 | for (size_t i = 0; i < count; ++i) { |
| 156 | size_t len; |
| 157 | const char16_t* chars; |
| 158 | |
| 159 | chars = tree.getAttributeNamespace(i, &len); |
| 160 | auto namespaceUrl = chars ? u16string_view(chars, len) : u16string_view(); |
| 161 | |
| 162 | chars = tree.getAttributeName(i, &len); |
| 163 | auto attributeName = chars ? u16string_view(chars, len) : u16string_view(); |
| 164 | |
| 165 | if (namespaceUrl.empty()) { |
| 166 | if (attributeName == PACKAGE_ATTRIBUTE_NAME) { |
| 167 | auto result = getStringOnlyAttribute(tree, i); |
| 168 | if (!result.ok()) return Error() << "Package name: " << result.error(); |
| 169 | info->package = *result; |
| 170 | } |
| 171 | } else if (namespaceUrl == ANDROID_NAMESPACE_URL) { |
| 172 | if (attributeName == VERSION_CODE_ATTRIBUTE_NAME) { |
| 173 | auto result = getU32Attribute(tree, i); |
| 174 | if (!result.ok()) return Error() << "Version code: " << result.error(); |
| 175 | info->version_code = *result; |
| 176 | } else if (attributeName == VERSION_CODE_MAJOR_ATTRIBUTE_NAME) { |
| 177 | auto result = getU32Attribute(tree, i); |
| 178 | if (!result.ok()) return Error() << "Version code major: " << result.error(); |
| 179 | info->version_code_major = *result; |
| 180 | } |
| 181 | } |
| 182 | } |
| 183 | |
| 184 | return info; |
| 185 | } |
| 186 | } // namespace |
| 187 | |
| 188 | const ApkManifestInfo* extractManifestInfo(const void* manifest, size_t size) { |
| 189 | auto result = parseManifest(manifest, size); |
| 190 | if (!result.ok()) { |
| 191 | LOG(ERROR) << "Failed to parse APK manifest:" << result.error().message(); |
| 192 | return nullptr; |
| 193 | } |
| 194 | return result->release(); |
| 195 | } |
| 196 | |
| 197 | void freeManifestInfo(const ApkManifestInfo* info) { |
| 198 | delete info; |
| 199 | } |
| 200 | |
| 201 | const char* getPackageName(const ApkManifestInfo* info) { |
| 202 | return info->package.c_str(); |
| 203 | } |
| 204 | |
| 205 | uint64_t getVersionCode(const ApkManifestInfo* info) { |
| 206 | return info->version_code | (static_cast<uint64_t>(info->version_code_major) << 32); |
| 207 | } |