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| 1 // Copyright (c) 2009 The Chromium OS Authors. All rights reserved. |
| 2 // Use of this source code is governed by a BSD-style license that can be |
| 3 // found in the LICENSE file. |
| 4 |
| 5 #include "update_engine/extent_writer.h" |
| 6 #include <errno.h> |
| 7 #include <unistd.h> |
| 8 #include <algorithm> |
| 9 |
| 10 using std::min; |
| 11 |
| 12 namespace chromeos_update_engine { |
| 13 |
| 14 namespace { |
| 15 // Returns true on success. |
| 16 bool WriteAll(int fd, const void *buf, size_t count) { |
| 17 const char* c_buf = reinterpret_cast<const char*>(buf); |
| 18 ssize_t bytes_written = 0; |
| 19 while (bytes_written < static_cast<ssize_t>(count)) { |
| 20 ssize_t rc = write(fd, c_buf + bytes_written, count - bytes_written); |
| 21 TEST_AND_RETURN_FALSE_ERRNO(rc >= 0); |
| 22 bytes_written += rc; |
| 23 } |
| 24 return true; |
| 25 } |
| 26 } |
| 27 |
| 28 bool DirectExtentWriter::Write(const void* bytes, size_t count) { |
| 29 if (count == 0) |
| 30 return true; |
| 31 const char* c_bytes = reinterpret_cast<const char*>(bytes); |
| 32 size_t bytes_written = 0; |
| 33 while (count - bytes_written > 0) { |
| 34 TEST_AND_RETURN_FALSE(next_extent_index_ < extents_.size()); |
| 35 uint64 bytes_remaining_next_extent = |
| 36 extents_[next_extent_index_].num_blocks() * block_size_ - |
| 37 extent_bytes_written_; |
| 38 CHECK_NE(bytes_remaining_next_extent, 0); |
| 39 size_t bytes_to_write = |
| 40 static_cast<size_t>(min(static_cast<uint64>(count - bytes_written), |
| 41 bytes_remaining_next_extent)); |
| 42 TEST_AND_RETURN_FALSE(bytes_to_write > 0); |
| 43 |
| 44 if (extents_[next_extent_index_].start_block() != kSparseHole) { |
| 45 const off64_t offset = |
| 46 extents_[next_extent_index_].start_block() * block_size_ + |
| 47 extent_bytes_written_; |
| 48 TEST_AND_RETURN_FALSE_ERRNO(lseek64(fd_, offset, SEEK_SET) != |
| 49 static_cast<off64_t>(-1)); |
| 50 TEST_AND_RETURN_FALSE( |
| 51 WriteAll(fd_, c_bytes + bytes_written, bytes_to_write)); |
| 52 } |
| 53 bytes_written += bytes_to_write; |
| 54 extent_bytes_written_ += bytes_to_write; |
| 55 if (bytes_remaining_next_extent == bytes_to_write) { |
| 56 // We filled this extent |
| 57 CHECK_EQ(extent_bytes_written_, |
| 58 extents_[next_extent_index_].num_blocks() * block_size_); |
| 59 // move to next extent |
| 60 extent_bytes_written_ = 0; |
| 61 next_extent_index_++; |
| 62 } |
| 63 } |
| 64 return true; |
| 65 } |
| 66 |
| 67 } // namespace chromeos_update_engine |
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