1 //
2 // Copyright (C) 2012 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 "update_engine/payload_consumer/file_descriptor.h"
18
19 #include <fcntl.h>
20 #include <linux/fs.h>
21 #include <sys/ioctl.h>
22 #include <sys/stat.h>
23 #include <sys/types.h>
24
25 #include <base/posix/eintr_wrapper.h>
26
27 #include "update_engine/common/utils.h"
28
29 namespace chromeos_update_engine {
30
Open(const char * path,int flags,mode_t mode)31 bool EintrSafeFileDescriptor::Open(const char* path, int flags, mode_t mode) {
32 CHECK_EQ(fd_, -1);
33 return ((fd_ = HANDLE_EINTR(open(path, flags, mode))) >= 0);
34 }
35
Open(const char * path,int flags)36 bool EintrSafeFileDescriptor::Open(const char* path, int flags) {
37 CHECK_EQ(fd_, -1);
38 return ((fd_ = HANDLE_EINTR(open(path, flags))) >= 0);
39 }
40
Read(void * buf,size_t count)41 ssize_t EintrSafeFileDescriptor::Read(void* buf, size_t count) {
42 CHECK_GE(fd_, 0);
43 return HANDLE_EINTR(read(fd_, buf, count));
44 }
45
Write(const void * buf,size_t count)46 ssize_t EintrSafeFileDescriptor::Write(const void* buf, size_t count) {
47 CHECK_GE(fd_, 0);
48
49 // Attempt repeated writes, as long as some progress is being made.
50 char* char_buf = const_cast<char*>(reinterpret_cast<const char*>(buf));
51 ssize_t written = 0;
52 while (count > 0) {
53 ssize_t ret = HANDLE_EINTR(write(fd_, char_buf, count));
54
55 // Fail on either an error or no progress.
56 if (ret <= 0)
57 return (written ? written : ret);
58 written += ret;
59 count -= ret;
60 char_buf += ret;
61 }
62 return written;
63 }
64
Seek(off64_t offset,int whence)65 off64_t EintrSafeFileDescriptor::Seek(off64_t offset, int whence) {
66 CHECK_GE(fd_, 0);
67 return lseek64(fd_, offset, whence);
68 }
69
BlockDevSize()70 uint64_t EintrSafeFileDescriptor::BlockDevSize() {
71 if (fd_ < 0)
72 return 0;
73 struct stat stbuf;
74 if (fstat(fd_, &stbuf) < 0) {
75 PLOG(ERROR) << "Error stat-ing fd " << fd_;
76 return 0;
77 }
78 if (!S_ISBLK(stbuf.st_mode))
79 return 0;
80 off_t block_size = utils::BlockDevSize(fd_);
81 return block_size < 0 ? 0 : block_size;
82 }
83
BlkIoctl(int request,uint64_t start,uint64_t length,int * result)84 bool EintrSafeFileDescriptor::BlkIoctl(int request,
85 uint64_t start,
86 uint64_t length,
87 int* result) {
88 // If the ioctl BLKZEROOUT is not defined, just fail to perform any of these
89 // operations.
90 #ifndef BLKZEROOUT
91 return false;
92 #else // defined(BLKZEROOUT)
93 DCHECK(request == BLKDISCARD || request == BLKZEROOUT ||
94 request == BLKSECDISCARD);
95 // On some devices, the BLKDISCARD will actually read back as zeros, instead
96 // of "undefined" data. The BLKDISCARDZEROES ioctl tells whether that's the
97 // case, so we issue a BLKDISCARD in those cases to speed up the writes.
98 unsigned int arg;
99 if (request == BLKZEROOUT && ioctl(fd_, BLKDISCARDZEROES, &arg) == 0 && arg)
100 request = BLKDISCARD;
101
102 // Ensure the |fd_| is in O_DIRECT mode during this operation, so the write
103 // cache for this region is invalidated. This is required since otherwise
104 // reading back this region could consume stale data from the cache.
105 int flags = fcntl(fd_, F_GETFL, 0);
106 if (flags == -1) {
107 PLOG(WARNING) << "Couldn't get flags on fd " << fd_;
108 return false;
109 }
110 if ((flags & O_DIRECT) == 0 && fcntl(fd_, F_SETFL, flags | O_DIRECT) == -1) {
111 PLOG(WARNING) << "Couldn't set O_DIRECT on fd " << fd_;
112 return false;
113 }
114
115 uint64_t range[2] = {start, length};
116 *result = ioctl(fd_, request, range);
117
118 if ((flags & O_DIRECT) == 0 && fcntl(fd_, F_SETFL, flags) == -1) {
119 PLOG(WARNING) << "Couldn't remove O_DIRECT on fd " << fd_;
120 return false;
121 }
122 return true;
123 #endif // defined(BLKZEROOUT)
124 }
125
Flush()126 bool EintrSafeFileDescriptor::Flush() {
127 CHECK_GE(fd_, 0);
128 return true;
129 }
130
Close()131 bool EintrSafeFileDescriptor::Close() {
132 CHECK_GE(fd_, 0);
133 if (IGNORE_EINTR(close(fd_)))
134 return false;
135 fd_ = -1;
136 return true;
137 }
138
139 } // namespace chromeos_update_engine
140