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      1 /*
      2  * Copyright (C) 2010 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 "os.h"
     18 
     19 #include <sys/types.h>
     20 #include <sys/stat.h>
     21 #include <fcntl.h>
     22 #include <cstddef>
     23 #include <memory>
     24 
     25 #include "base/logging.h"
     26 #include "base/unix_file/fd_file.h"
     27 
     28 namespace art {
     29 
     30 File* OS::OpenFileForReading(const char* name) {
     31   return OpenFileWithFlags(name, O_RDONLY);
     32 }
     33 
     34 File* OS::OpenFileReadWrite(const char* name) {
     35   return OpenFileWithFlags(name, O_RDWR);
     36 }
     37 
     38 static File* CreateEmptyFile(const char* name, int extra_flags) {
     39   // In case the file exists, unlink it so we get a new file. This is necessary as the previous
     40   // file may be in use and must not be changed.
     41   unlink(name);
     42 
     43   return OS::OpenFileWithFlags(name, O_CREAT | extra_flags);
     44 }
     45 
     46 File* OS::CreateEmptyFile(const char* name) {
     47   return art::CreateEmptyFile(name, O_RDWR | O_TRUNC);
     48 }
     49 
     50 File* OS::CreateEmptyFileWriteOnly(const char* name) {
     51   return art::CreateEmptyFile(name, O_WRONLY | O_TRUNC | O_NOFOLLOW | O_CLOEXEC);
     52 }
     53 
     54 File* OS::OpenFileWithFlags(const char* name, int flags) {
     55   CHECK(name != nullptr);
     56   std::unique_ptr<File> file(new File);
     57   if (!file->Open(name, flags, 0666)) {
     58     return nullptr;
     59   }
     60   return file.release();
     61 }
     62 
     63 bool OS::FileExists(const char* name) {
     64   struct stat st;
     65   if (stat(name, &st) == 0) {
     66     return S_ISREG(st.st_mode);  // TODO: Deal with symlinks?
     67   } else {
     68     return false;
     69   }
     70 }
     71 
     72 bool OS::DirectoryExists(const char* name) {
     73   struct stat st;
     74   if (stat(name, &st) == 0) {
     75     return S_ISDIR(st.st_mode);  // TODO: Deal with symlinks?
     76   } else {
     77     return false;
     78   }
     79 }
     80 
     81 }  // namespace art
     82