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 #ifndef ART_COMPILER_LINKER_ERROR_DELAYING_OUTPUT_STREAM_H_ 18 #define ART_COMPILER_LINKER_ERROR_DELAYING_OUTPUT_STREAM_H_ 19 20 #include "output_stream.h" 21 22 #include "base/logging.h" 23 24 namespace art { 25 26 // OutputStream wrapper that delays reporting an error until Flush(). 27 class ErrorDelayingOutputStream FINAL : public OutputStream { 28 public: ErrorDelayingOutputStream(OutputStream * output)29 explicit ErrorDelayingOutputStream(OutputStream* output) 30 : OutputStream(output->GetLocation()), 31 output_(output), 32 output_good_(true), 33 output_offset_(0) { } 34 35 // This function always succeeds to simplify code. 36 // Use Good() to check the actual status of the output stream. WriteFully(const void * buffer,size_t byte_count)37 bool WriteFully(const void* buffer, size_t byte_count) OVERRIDE { 38 if (output_good_) { 39 if (!output_->WriteFully(buffer, byte_count)) { 40 PLOG(ERROR) << "Failed to write " << byte_count 41 << " bytes to " << GetLocation() << " at offset " << output_offset_; 42 output_good_ = false; 43 } 44 } 45 output_offset_ += byte_count; 46 return true; 47 } 48 49 // This function always succeeds to simplify code. 50 // Use Good() to check the actual status of the output stream. Seek(off_t offset,Whence whence)51 off_t Seek(off_t offset, Whence whence) OVERRIDE { 52 // We keep shadow copy of the offset so that we return 53 // the expected value even if the output stream failed. 54 off_t new_offset; 55 switch (whence) { 56 case kSeekSet: 57 new_offset = offset; 58 break; 59 case kSeekCurrent: 60 new_offset = output_offset_ + offset; 61 break; 62 default: 63 LOG(FATAL) << "Unsupported seek type: " << whence; 64 UNREACHABLE(); 65 } 66 if (output_good_) { 67 off_t actual_offset = output_->Seek(offset, whence); 68 if (actual_offset == static_cast<off_t>(-1)) { 69 PLOG(ERROR) << "Failed to seek in " << GetLocation() << ". Offset=" << offset 70 << " whence=" << whence << " new_offset=" << new_offset; 71 output_good_ = false; 72 } 73 DCHECK_EQ(actual_offset, new_offset); 74 } 75 output_offset_ = new_offset; 76 return new_offset; 77 } 78 79 // Flush the output and return whether all operations have succeeded. 80 // Do nothing if we already have a pending error. Flush()81 bool Flush() OVERRIDE { 82 if (output_good_) { 83 output_good_ = output_->Flush(); 84 } 85 return output_good_; 86 } 87 88 // Check (without flushing) whether all operations have succeeded so far. Good()89 bool Good() const { 90 return output_good_; 91 } 92 93 private: 94 OutputStream* output_; 95 bool output_good_; // True if all writes to output succeeded. 96 off_t output_offset_; // Keep track of the current position in the stream. 97 }; 98 99 } // namespace art 100 101 #endif // ART_COMPILER_LINKER_ERROR_DELAYING_OUTPUT_STREAM_H_ 102