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//===-ELFAttrParserExtended.cpp-ELF Extended Attribute Information Printer-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM
// Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===------------------------------------------------------------------===//
#include "llvm/Support/ELFAttrParserExtended.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/ELFAttributes.h"
#include "llvm/Support/Errc.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/ScopedPrinter.h"
#include "llvm/Support/raw_ostream.h"
#include <cstdint>
using namespace llvm;
using namespace ELFAttrs;
std::optional<unsigned>
ELFExtendedAttrParser::getAttributeValue(unsigned Tag) const {
assert(
0 &&
"use getAttributeValue overloaded version accepting Stringref, unsigned");
return std::nullopt;
}
std::optional<unsigned>
ELFExtendedAttrParser::getAttributeValue(StringRef BuildAttrSubsectionName,
unsigned Tag) const {
for (const auto &SubSection : SubSectionVec) {
if (BuildAttrSubsectionName == SubSection.Name)
for (const auto &BAItem : SubSection.Content) {
if (Tag == BAItem.Tag)
return std::optional<unsigned>(BAItem.IntValue);
}
}
return std::nullopt;
}
std::optional<StringRef>
ELFExtendedAttrParser::getAttributeString(unsigned Tag) const {
assert(
0 &&
"use getAttributeValue overloaded version accepting Stringref, unsigned");
return std::nullopt;
}
std::optional<StringRef>
ELFExtendedAttrParser::getAttributeString(StringRef BuildAttrSubsectionName,
unsigned Tag) const {
for (const auto &SubSection : SubSectionVec) {
if (BuildAttrSubsectionName == SubSection.Name)
for (const auto &BAItem : SubSection.Content) {
if (Tag == BAItem.Tag)
return std::optional<StringRef>(BAItem.StringValue);
}
}
return std::nullopt;
}
StringRef
ELFExtendedAttrParser::getTagName(const StringRef &BuildAttrSubsectionName,
const unsigned Tag) {
for (const auto &Entry : TagsNamesMap) {
if (BuildAttrSubsectionName == Entry.SubsectionName)
if (Tag == Entry.Tag)
return Entry.TagName;
}
return "";
}
Error ELFExtendedAttrParser::parse(ArrayRef<uint8_t> Section,
llvm::endianness Endian) {
unsigned SectionNumber = 0;
De = DataExtractor(Section, Endian == llvm::endianness::little, 0);
// Early returns have specific errors. Consume the Error in Cursor.
struct ClearCursorError {
DataExtractor::Cursor &Cursor;
~ClearCursorError() { consumeError(Cursor.takeError()); }
} Clear{Cursor};
/*
ELF Extended Build Attributes Layout:
<format-version: ‘A’> --> Currently, there is only one version: 'A' (0x41)
[ <uint32: subsection-length> <NTBS: vendor-name> <bytes: vendor-data> ]
--> subsection-length: Offset from the start of this subsection to the
start of the next one.
--> vendor-name: Null-terminated byte string.
--> vendor-data expands to:
[ <uint8: optional> <uint8: parameter type> <attribute>* ]
--> optional: 0 = required, 1 = optional.
--> parameter type: 0 = ULEB128, 1 = NTBS.
--> attribute: <tag, value>* pair. Tag is ULEB128, value is of
<parameter type>.
*/
// Get format-version
uint8_t FormatVersion = De.getU8(Cursor);
if (!Cursor)
return Cursor.takeError();
if (ELFAttrs::Format_Version != FormatVersion)
return createStringError(errc::invalid_argument,
"unrecognized format-version: 0x" +
utohexstr(FormatVersion));
while (!De.eof(Cursor)) {
uint32_t ExtBASubsectionLength = De.getU32(Cursor);
if (!Cursor)
return Cursor.takeError();
// Minimal valid Extended Build Attributes subsection size is at
// least 8: length(4) name(at least a single char + null) optionality(1) and
// type(1)
// Extended Build Attributes subsection has to fit inside the section.
if (ExtBASubsectionLength < 8 ||
ExtBASubsectionLength > (Section.size() - Cursor.tell() + 4))
return createStringError(
errc::invalid_argument,
"invalid Extended Build Attributes subsection size at offset: " +
utohexstr(Cursor.tell() - 4));
StringRef VendorName = De.getCStrRef(Cursor);
if (!Cursor)
return Cursor.takeError();
uint8_t IsOptional = De.getU8(Cursor);
if (!Cursor)
return Cursor.takeError();
if (!(0 == IsOptional || 1 == IsOptional))
return createStringError(
errc::invalid_argument,
"\ninvalid Optionality at offset " + utohexstr(Cursor.tell() - 4) +
": " + utohexstr(IsOptional) + " (Options are 1|0)");
StringRef IsOptionalStr = IsOptional ? "optional" : "required";
uint8_t Type = De.getU8(Cursor);
if (!Cursor)
return Cursor.takeError();
if (!(0 == Type || 1 == Type))
return createStringError(errc::invalid_argument,
"\ninvalid Type at offset " +
utohexstr(Cursor.tell() - 4) + ": " +
utohexstr(Type) + " (Options are 1|0)");
StringRef TypeStr = Type ? "ntbs" : "uleb128";
BuildAttributeSubSection BASubSection;
BASubSection.Name = VendorName;
BASubSection.IsOptional = IsOptional;
BASubSection.ParameterType = Type;
if (Sw) {
Sw->startLine() << "Section " << ++SectionNumber << " {\n";
Sw->indent();
Sw->printNumber("SectionLength", ExtBASubsectionLength);
Sw->startLine() << "VendorName" << ": " << VendorName
<< " Optionality: " << IsOptionalStr
<< " Type: " << TypeStr << "\n";
Sw->startLine() << "Attributes {\n";
Sw->indent();
}
// Offset in Section
uint64_t OffsetInSection = Cursor.tell();
// Size: 4 bytes, Vendor Name: VendorName.size() + 1 (null termination),
// optionality: 1, type: 1
uint32_t BytesAllButAttributes = 4 + (VendorName.size() + 1) + 1 + 1;
while (Cursor.tell() <
(OffsetInSection + ExtBASubsectionLength - BytesAllButAttributes)) {
uint64_t Tag = De.getULEB128(Cursor);
if (!Cursor)
return Cursor.takeError();
StringRef TagName = getTagName(VendorName, Tag);
uint64_t ValueInt = 0;
std::string ValueStr = "";
if (Type) { // type==1 --> ntbs
ValueStr = De.getCStrRef(Cursor);
if (!Cursor)
return Cursor.takeError();
if (Sw)
Sw->printString("" != TagName ? TagName : utostr(Tag), ValueStr);
} else { // type==0 --> uleb128
ValueInt = De.getULEB128(Cursor);
if (!Cursor)
return Cursor.takeError();
if (Sw)
Sw->printNumber("" != TagName ? TagName : utostr(Tag), ValueInt);
}
// populate data structure
BuildAttributeItem BAItem(static_cast<BuildAttributeItem::Types>(Type),
Tag, ValueInt, ValueStr);
BASubSection.Content.push_back(BAItem);
}
if (Sw) {
// Close 'Attributes'
Sw->unindent();
Sw->startLine() << "}\n";
// Close 'Section'
Sw->unindent();
Sw->startLine() << "}\n";
}
// populate data structure
SubSectionVec.push_back(BASubSection);
}
return Cursor.takeError();
}
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