| // Licensed to the Apache Software Foundation (ASF) under one |
| // or more contributor license agreements. See the NOTICE file |
| // distributed with this work for additional information |
| // regarding copyright ownership. The ASF licenses this file |
| // to you under the Apache License, Version 2.0 (the |
| // "License"); you may not use this file except in compliance |
| // with the License. You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, |
| // software distributed under the License is distributed on an |
| // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| // KIND, either express or implied. See the License for the |
| // specific language governing permissions and limitations |
| // under the License. |
| |
| #include "exec/read-write-util.h" |
| |
| #include "common/names.h" |
| |
| using namespace impala; |
| |
| namespace { |
| |
| // Returns MAX_ZLONG_LEN + 1 if the encoded int is more than MAX_ZLONG_LEN bytes long, |
| // otherwise returns the length of the encoded int. Reads MAX_ZLONG_LEN bytes in 'buf'. |
| int FindZIntegerLength(uint8_t* buf) { |
| uint64_t x = *reinterpret_cast<uint64_t*>(buf); |
| for (int i = 0; i < sizeof(x); ++i) { |
| if ((x & (0x80LL << (i * 8))) == 0) return i + 1; |
| } |
| uint16_t y = *reinterpret_cast<uint16_t*>(buf + 8); |
| if ((y & 0x80) == 0) return 9; |
| if ((y & 0x8000) == 0) return 10; |
| return 11; |
| } |
| |
| // Slow path for ReadZInteger() that checks for out-of-bounds on every byte |
| template <int MAX_LEN, typename ZResultType> |
| ZResultType ReadZIntegerSlow(uint8_t** buf, uint8_t* buf_end) { |
| uint64_t zlong = 0; |
| int shift = 0; |
| bool more = true; |
| for (int i = 0; more && i < MAX_LEN; ++i) { |
| if (UNLIKELY(*buf >= buf_end)) return ZResultType::error(); |
| DCHECK_LE(shift, 64); |
| zlong |= static_cast<uint64_t>(**buf & 0x7f) << shift; |
| shift += 7; |
| more = (**buf & 0x80) != 0; |
| ++(*buf); |
| } |
| // Invalid int that's longer than maximum |
| if (UNLIKELY(more)) return ZResultType::error(); |
| return ZResultType((zlong >> 1) ^ -(zlong & 1)); |
| } |
| |
| } |
| |
| // This function is not inlined because it can potentially cause LLVM to crash (see |
| // http://llvm.org/bugs/show_bug.cgi?id=19315), and inlining does not appear to have any |
| // performance impact. |
| template <int MAX_LEN, typename ZResultType> |
| ZResultType ReadWriteUtil::ReadZInteger(uint8_t** buf, uint8_t* buf_end) { |
| DCHECK(MAX_LEN == MAX_ZINT_LEN || MAX_LEN == MAX_ZLONG_LEN); |
| |
| // Use MAX_ZLONG_LEN rather than MAX_LEN since FindZIntegerLength() always assumes at |
| // least MAX_ZLONG_LEN bytes in buffer. |
| if (UNLIKELY(buf_end - *buf < MAX_ZLONG_LEN)) { |
| return ReadZIntegerSlow<MAX_LEN, ZResultType>(buf, buf_end); |
| } |
| // Once we get here, we don't need to worry about going off end of buffer. |
| int num_bytes = FindZIntegerLength(*buf); |
| if (UNLIKELY(num_bytes > MAX_LEN)) return ZResultType::error(); |
| |
| uint64_t zlong = 0; |
| int shift = 0; |
| for (int i = 0; i < num_bytes; ++i) { |
| zlong |= static_cast<uint64_t>(**buf & 0x7f) << shift; |
| shift += 7; |
| ++(*buf); |
| } |
| return ZResultType((zlong >> 1) ^ -(zlong & 1)); |
| } |
| |
| // Instantiate the template for long and int. |
| template ReadWriteUtil::ZLongResult |
| ReadWriteUtil::ReadZInteger<ReadWriteUtil::MAX_ZLONG_LEN, ReadWriteUtil::ZLongResult>( |
| uint8_t** buf, uint8_t* buf_end); |
| template ReadWriteUtil::ZIntResult |
| ReadWriteUtil::ReadZInteger<ReadWriteUtil::MAX_ZINT_LEN, ReadWriteUtil::ZIntResult>( |
| uint8_t** buf, uint8_t* buf_end); |
| |
| int ReadWriteUtil::PutZInt(int32_t integer, uint8_t* buf) { |
| // Move the sign bit to the first bit. |
| uint32_t uinteger = (static_cast<uint32_t>(integer) << 1) ^ (integer >> 31); |
| const int mask = 0x7f; |
| const int cont = 0x80; |
| buf[0] = uinteger & mask; |
| int len = 1; |
| while ((uinteger >>= 7) != 0) { |
| // Set the continuation bit. |
| buf[len - 1] |= cont; |
| buf[len] = uinteger & mask; |
| ++len; |
| } |
| |
| return len; |
| } |
| |
| int ReadWriteUtil::PutZLong(int64_t longint, uint8_t* buf) { |
| // Move the sign bit to the first bit. |
| uint64_t ulongint = (static_cast<uint64_t>(longint) << 1) ^ (longint >> 63); |
| const int mask = 0x7f; |
| const int cont = 0x80; |
| buf[0] = ulongint & mask; |
| int len = 1; |
| while ((ulongint >>= 7) != 0) { |
| // Set the continuation bit. |
| buf[len - 1] |= cont; |
| buf[len] = ulongint & mask; |
| ++len; |
| } |
| |
| return len; |
| } |
| |
| string ReadWriteUtil::HexDump(const uint8_t* buf, int64_t length) { |
| stringstream ss; |
| ss << std::hex; |
| for (int i = 0; i < length; ++i) { |
| ss << static_cast<int>(buf[i]) << " "; |
| } |
| return ss.str(); |
| } |
| |
| string ReadWriteUtil::HexDump(const char* buf, int64_t length) { |
| return HexDump(reinterpret_cast<const uint8_t*>(buf), length); |
| } |