1 //===- FileHeaderReader.cpp - XRay File Header Reader --------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 #include "llvm/XRay/FileHeaderReader.h" 9 10 namespace llvm { 11 namespace xray { 12 13 // Populates the FileHeader reference by reading the first 32 bytes of the file. 14 Expected<XRayFileHeader> readBinaryFormatHeader(DataExtractor &HeaderExtractor, 15 uint32_t &OffsetPtr) { 16 // FIXME: Maybe deduce whether the data is little or big-endian using some 17 // magic bytes in the beginning of the file? 18 19 // First 32 bytes of the file will always be the header. We assume a certain 20 // format here: 21 // 22 // (2) uint16 : version 23 // (2) uint16 : type 24 // (4) uint32 : bitfield 25 // (8) uint64 : cycle frequency 26 // (16) - : padding 27 XRayFileHeader FileHeader; 28 auto PreReadOffset = OffsetPtr; 29 FileHeader.Version = HeaderExtractor.getU16(&OffsetPtr); 30 if (OffsetPtr == PreReadOffset) 31 return createStringError( 32 std::make_error_code(std::errc::invalid_argument), 33 "Failed reading version from file header at offset %d.", OffsetPtr); 34 35 PreReadOffset = OffsetPtr; 36 FileHeader.Type = HeaderExtractor.getU16(&OffsetPtr); 37 if (OffsetPtr == PreReadOffset) 38 return createStringError( 39 std::make_error_code(std::errc::invalid_argument), 40 "Failed reading file type from file header at offset %d.", OffsetPtr); 41 42 PreReadOffset = OffsetPtr; 43 uint32_t Bitfield = HeaderExtractor.getU32(&OffsetPtr); 44 if (OffsetPtr == PreReadOffset) 45 return createStringError( 46 std::make_error_code(std::errc::invalid_argument), 47 "Failed reading flag bits from file header at offset %d.", OffsetPtr); 48 49 FileHeader.ConstantTSC = Bitfield & 1uL; 50 FileHeader.NonstopTSC = Bitfield & 1uL << 1; 51 PreReadOffset = OffsetPtr; 52 FileHeader.CycleFrequency = HeaderExtractor.getU64(&OffsetPtr); 53 if (OffsetPtr == PreReadOffset) 54 return createStringError( 55 std::make_error_code(std::errc::invalid_argument), 56 "Failed reading cycle frequency from file header at offset %d.", 57 OffsetPtr); 58 59 std::memcpy(&FileHeader.FreeFormData, 60 HeaderExtractor.getData().bytes_begin() + OffsetPtr, 16); 61 62 // Manually advance the offset pointer 16 bytes, after getting a raw memcpy 63 // from the underlying data. 64 OffsetPtr += 16; 65 return std::move(FileHeader); 66 } 67 68 } // namespace xray 69 } // namespace llvm 70