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 "unix_file/fd_file.h"
27
28 namespace art {
29
30 using android::base::StringPrintf;
31
OpenAndReadMagic(const char * filename,uint32_t * magic,std::string * error_msg)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
ReadMagicAndReset(int fd,uint32_t * magic,std::string * error_msg)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
IsZipMagic(uint32_t magic)59 bool IsZipMagic(uint32_t magic) {
60 return (('P' == ((magic >> 0) & 0xff)) &&
61 ('K' == ((magic >> 8) & 0xff)));
62 }
63
64 } // namespace art
65