1 /* 2 * Copyright (C) 2015 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 "file_magic.h" 18 19 #include <fcntl.h> 20 #include <sys/stat.h> 21 #include <sys/types.h> 22 23 #include <android-base/logging.h> 24 #include <android-base/stringprintf.h> 25 26 #include "base/unix_file/fd_file.h" 27 28 namespace art { 29 30 using android::base::StringPrintf; 31 32 File OpenAndReadMagic(const char* filename, uint32_t* magic, std::string* error_msg) { 33 CHECK(magic != nullptr); 34 File fd(filename, O_RDONLY, /* check_usage */ false); 35 if (fd.Fd() == -1) { 36 *error_msg = StringPrintf("Unable to open '%s' : %s", filename, strerror(errno)); 37 return File(); 38 } 39 if (!ReadMagicAndReset(fd.Fd(), magic, error_msg)) { 40 StringPrintf("Error in reading magic from file %s: %s", filename, error_msg->c_str()); 41 return File(); 42 } 43 return fd; 44 } 45 46 bool ReadMagicAndReset(int fd, uint32_t* magic, std::string* error_msg) { 47 int n = TEMP_FAILURE_RETRY(read(fd, magic, sizeof(*magic))); 48 if (n != sizeof(*magic)) { 49 *error_msg = StringPrintf("Failed to find magic"); 50 return false; 51 } 52 if (lseek(fd, 0, SEEK_SET) != 0) { 53 *error_msg = StringPrintf("Failed to seek to beginning of file : %s", strerror(errno)); 54 return false; 55 } 56 return true; 57 } 58 59 bool IsZipMagic(uint32_t magic) { 60 return (('P' == ((magic >> 0) & 0xff)) && 61 ('K' == ((magic >> 8) & 0xff))); 62 } 63 64 } // namespace art 65
