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to reflect the new license. We understand that people may be surprised that we're moving the header entirely to discuss the new license. We checked this carefully with the Foundation's lawyer and we believe this is the correct approach. Essentially, all code in the project is now made available by the LLVM project under our new license, so you will see that the license headers include that license only. Some of our contributors have contributed code under our old license, and accordingly, we have retained a copy of our old license notice in the top-level files in each project and repository. llvm-svn: 351636
70 lines
2.6 KiB
C++
70 lines
2.6 KiB
C++
//===- FileHeaderReader.cpp - XRay File Header Reader --------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/XRay/FileHeaderReader.h"
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namespace llvm {
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namespace xray {
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// Populates the FileHeader reference by reading the first 32 bytes of the file.
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Expected<XRayFileHeader> readBinaryFormatHeader(DataExtractor &HeaderExtractor,
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uint32_t &OffsetPtr) {
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// FIXME: Maybe deduce whether the data is little or big-endian using some
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// magic bytes in the beginning of the file?
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// First 32 bytes of the file will always be the header. We assume a certain
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// format here:
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//
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// (2) uint16 : version
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// (2) uint16 : type
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// (4) uint32 : bitfield
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// (8) uint64 : cycle frequency
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// (16) - : padding
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XRayFileHeader FileHeader;
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auto PreReadOffset = OffsetPtr;
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FileHeader.Version = HeaderExtractor.getU16(&OffsetPtr);
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if (OffsetPtr == PreReadOffset)
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return createStringError(
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std::make_error_code(std::errc::invalid_argument),
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"Failed reading version from file header at offset %d.", OffsetPtr);
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PreReadOffset = OffsetPtr;
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FileHeader.Type = HeaderExtractor.getU16(&OffsetPtr);
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if (OffsetPtr == PreReadOffset)
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return createStringError(
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std::make_error_code(std::errc::invalid_argument),
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"Failed reading file type from file header at offset %d.", OffsetPtr);
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PreReadOffset = OffsetPtr;
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uint32_t Bitfield = HeaderExtractor.getU32(&OffsetPtr);
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if (OffsetPtr == PreReadOffset)
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return createStringError(
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std::make_error_code(std::errc::invalid_argument),
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"Failed reading flag bits from file header at offset %d.", OffsetPtr);
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FileHeader.ConstantTSC = Bitfield & 1uL;
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FileHeader.NonstopTSC = Bitfield & 1uL << 1;
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PreReadOffset = OffsetPtr;
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FileHeader.CycleFrequency = HeaderExtractor.getU64(&OffsetPtr);
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if (OffsetPtr == PreReadOffset)
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return createStringError(
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std::make_error_code(std::errc::invalid_argument),
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"Failed reading cycle frequency from file header at offset %d.",
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OffsetPtr);
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std::memcpy(&FileHeader.FreeFormData,
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HeaderExtractor.getData().bytes_begin() + OffsetPtr, 16);
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// Manually advance the offset pointer 16 bytes, after getting a raw memcpy
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// from the underlying data.
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OffsetPtr += 16;
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return std::move(FileHeader);
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}
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} // namespace xray
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} // namespace llvm
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