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      1 /*
      2  * Copyright (C) 2016 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 "SymbolDatabase.h"
     18 
     19 #include <err.h>
     20 #include <stdio.h>
     21 #include <stdlib.h>
     22 
     23 #include <fstream>
     24 #include <streambuf>
     25 #include <string>
     26 #include <unordered_set>
     27 
     28 #include <llvm/ADT/SmallVector.h>
     29 #include <llvm/ADT/StringRef.h>
     30 #include <llvm/Object/Binary.h>
     31 #include <llvm/Object/ELFObjectFile.h>
     32 
     33 #include "versioner.h"
     34 
     35 using namespace llvm;
     36 using namespace llvm::object;
     37 
     38 std::unordered_set<std::string> getSymbols(const std::string& filename) {
     39   std::unordered_set<std::string> result;
     40   auto binaryOrError = createBinary(filename);
     41   if (!binaryOrError) {
     42     errx(1, "failed to open library at %s: %s\n", filename.c_str(),
     43          llvm::toString(binaryOrError.takeError()).c_str());
     44   }
     45 
     46   ELFObjectFileBase* elf = dyn_cast_or_null<ELFObjectFileBase>(binaryOrError.get().getBinary());
     47   if (!elf) {
     48     errx(1, "failed to parse %s as ELF", filename.c_str());
     49   }
     50 
     51   for (const ELFSymbolRef symbol : elf->getDynamicSymbolIterators()) {
     52     Expected<StringRef> symbolNameOrError = symbol.getName();
     53 
     54     if (!symbolNameOrError) {
     55       errx(1, "failed to get symbol name for symbol in %s: %s", filename.c_str(),
     56            llvm::toString(symbolNameOrError.takeError()).c_str());
     57     }
     58 
     59     result.insert(symbolNameOrError.get().str());
     60   }
     61 
     62   return result;
     63 }
     64 
     65 // The NDK platforms are built by copying the platform directories on top of
     66 // each other to build each successive API version. Thus, we need to walk
     67 // backwards to find each desired file.
     68 static std::string readPlatformFile(const CompilationType& type, llvm::StringRef platform_dir,
     69                                     const std::string& filename, bool required) {
     70   int api_level = type.api_level;
     71   std::ifstream stream;
     72   while (api_level >= arch_min_api[type.arch]) {
     73     if (supported_levels.count(api_level) == 0) {
     74       --api_level;
     75       continue;
     76     }
     77 
     78     std::string path = std::string(platform_dir) + "/android-" + std::to_string(api_level) +
     79                        "/arch-" + to_string(type.arch) + "/symbols/" + filename;
     80 
     81     stream = std::ifstream(path);
     82     if (stream) {
     83       return std::string(std::istreambuf_iterator<char>(stream), std::istreambuf_iterator<char>());
     84     }
     85 
     86     --api_level;
     87   }
     88 
     89   if (required) {
     90     errx(1, "failed to find platform file '%s' for %s", filename.c_str(), to_string(type).c_str());
     91   }
     92 
     93   return std::string();
     94 }
     95 
     96 static std::map<std::string, NdkSymbolType> parsePlatform(const CompilationType& type,
     97                                                           const std::string& platform_dir) {
     98   std::map<std::string, NdkSymbolType> result;
     99   std::map<std::string, bool /*required*/> wanted_files = {
    100     { "libc.so.functions.txt", true },
    101     { "libc.so.variables.txt", false },
    102     { "libdl.so.functions.txt", false },
    103     { "libm.so.functions.txt", false },
    104     { "libm.so.variables.txt", false },
    105   };
    106 
    107   for (const auto& pair : wanted_files) {
    108     llvm::StringRef file = pair.first;
    109     bool required = pair.second;
    110     NdkSymbolType symbol_type;
    111     if (file.endswith(".functions.txt")) {
    112       symbol_type = NdkSymbolType::function;
    113     } else if (file.endswith(".variables.txt")) {
    114       symbol_type = NdkSymbolType::variable;
    115     } else {
    116       errx(1, "internal error: unexpected platform filename '%s'\n", file.str().c_str());
    117     }
    118 
    119     std::string platform_file = readPlatformFile(type, platform_dir, file, required);
    120     if (platform_file.empty()) {
    121       continue;
    122     }
    123 
    124     llvm::SmallVector<llvm::StringRef, 0> symbols;
    125     llvm::StringRef(platform_file).split(symbols, "\n");
    126 
    127     for (llvm::StringRef symbol_name : symbols) {
    128       if (symbol_name.empty()) {
    129         continue;
    130       }
    131 
    132       if (result.count(symbol_name) != 0) {
    133         if (strict) {
    134           printf("duplicated symbol '%s' in '%s'\n", symbol_name.str().c_str(), file.str().c_str());
    135         }
    136       }
    137 
    138       result[symbol_name] = symbol_type;
    139     }
    140   }
    141 
    142   return result;
    143 }
    144 
    145 NdkSymbolDatabase parsePlatforms(const std::set<CompilationType>& types,
    146                                  const std::string& platform_dir) {
    147   std::map<std::string, std::map<CompilationType, NdkSymbolType>> result;
    148   for (const CompilationType& type : types) {
    149     std::map<std::string, NdkSymbolType> symbols = parsePlatform(type, platform_dir);
    150     for (const auto& it : symbols) {
    151       result[it.first][type] = it.second;
    152     }
    153   }
    154 
    155   return result;
    156 }
    157