blob: d75ebb0ed4ddfa90fa450e6770b0f7e02f8611b1 [file] [log] [blame]
//===- LinkerScript.cpp ---------------------------------------------------===//
//
// The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains the parser/evaluator of the linker script.
// It does not construct an AST but consume linker script directives directly.
// Results are written to Driver or Config object.
//
//===----------------------------------------------------------------------===//
#include "LinkerScript.h"
#include "Config.h"
#include "Driver.h"
#include "InputSection.h"
#include "SymbolTable.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/StringSaver.h"
using namespace llvm;
using namespace llvm::object;
using namespace lld;
using namespace lld::elf;
LinkerScript *elf::Script;
template <class ELFT>
SectionRule *LinkerScript::find(InputSectionBase<ELFT> *S) {
for (SectionRule &R : Sections)
if (R.match(S))
return &R;
return nullptr;
}
template <class ELFT>
StringRef LinkerScript::getOutputSection(InputSectionBase<ELFT> *S) {
SectionRule *R = find(S);
return R ? R->Dest : "";
}
template <class ELFT>
bool LinkerScript::isDiscarded(InputSectionBase<ELFT> *S) {
return getOutputSection(S) == "/DISCARD/";
}
template <class ELFT> bool LinkerScript::shouldKeep(InputSectionBase<ELFT> *S) {
SectionRule *R = find(S);
return R && R->Keep;
}
ArrayRef<uint8_t> LinkerScript::getFiller(StringRef Name) {
auto I = Filler.find(Name);
if (I == Filler.end())
return {};
return I->second;
}
// A compartor to sort output sections. Returns -1 or 1 if both
// A and B are mentioned in linker scripts. Otherwise, returns 0
// to use the default rule which is implemented in Writer.cpp.
int LinkerScript::compareSections(StringRef A, StringRef B) {
auto E = SectionOrder.end();
auto I = std::find(SectionOrder.begin(), E, A);
auto J = std::find(SectionOrder.begin(), E, B);
if (I == E || J == E)
return 0;
return I < J ? -1 : 1;
}
// Returns true if S matches T. S can contain glob meta-characters.
// The asterisk ('*') matches zero or more characacters, and the question
// mark ('?') matches one character.
static bool matchStr(StringRef S, StringRef T) {
for (;;) {
if (S.empty())
return T.empty();
if (S[0] == '*') {
S = S.substr(1);
if (S.empty())
// Fast path. If a pattern is '*', it matches anything.
return true;
for (size_t I = 0, E = T.size(); I < E; ++I)
if (matchStr(S, T.substr(I)))
return true;
return false;
}
if (T.empty() || (S[0] != T[0] && S[0] != '?'))
return false;
S = S.substr(1);
T = T.substr(1);
}
}
template <class ELFT> bool SectionRule::match(InputSectionBase<ELFT> *S) {
return matchStr(SectionPattern, S->getSectionName());
}
class elf::ScriptParser {
typedef void (ScriptParser::*Handler)();
public:
ScriptParser(BumpPtrAllocator *A, StringRef S, bool B)
: Saver(*A), Tokens(tokenize(S)), IsUnderSysroot(B) {}
void run();
private:
void setError(const Twine &Msg);
static std::vector<StringRef> tokenize(StringRef S);
static StringRef skipSpace(StringRef S);
bool atEOF();
StringRef next();
StringRef peek();
bool skip(StringRef Tok);
void expect(StringRef Expect);
void addFile(StringRef Path);
void readAsNeeded();
void readEntry();
void readExtern();
void readGroup();
void readInclude();
void readNothing() {}
void readOutput();
void readOutputArch();
void readOutputFormat();
void readSearchDir();
void readSections();
void readOutputSectionDescription();
void readSectionPatterns(StringRef OutSec, bool Keep);
std::vector<uint8_t> parseHex(StringRef S);
StringSaver Saver;
std::vector<StringRef> Tokens;
const static StringMap<Handler> Cmd;
size_t Pos = 0;
bool IsUnderSysroot;
bool Error = false;
};
const StringMap<elf::ScriptParser::Handler> elf::ScriptParser::Cmd = {
{"ENTRY", &ScriptParser::readEntry},
{"EXTERN", &ScriptParser::readExtern},
{"GROUP", &ScriptParser::readGroup},
{"INCLUDE", &ScriptParser::readInclude},
{"INPUT", &ScriptParser::readGroup},
{"OUTPUT", &ScriptParser::readOutput},
{"OUTPUT_ARCH", &ScriptParser::readOutputArch},
{"OUTPUT_FORMAT", &ScriptParser::readOutputFormat},
{"SEARCH_DIR", &ScriptParser::readSearchDir},
{"SECTIONS", &ScriptParser::readSections},
{";", &ScriptParser::readNothing}};
void ScriptParser::run() {
while (!atEOF()) {
StringRef Tok = next();
if (Handler Fn = Cmd.lookup(Tok))
(this->*Fn)();
else
setError("unknown directive: " + Tok);
}
}
// We don't want to record cascading errors. Keep only the first one.
void ScriptParser::setError(const Twine &Msg) {
if (Error)
return;
error(Msg);
Error = true;
}
// Split S into linker script tokens.
std::vector<StringRef> ScriptParser::tokenize(StringRef S) {
std::vector<StringRef> Ret;
for (;;) {
S = skipSpace(S);
if (S.empty())
return Ret;
// Quoted token
if (S.startswith("\"")) {
size_t E = S.find("\"", 1);
if (E == StringRef::npos) {
error("unclosed quote");
return {};
}
Ret.push_back(S.substr(1, E - 1));
S = S.substr(E + 1);
continue;
}
// Unquoted token
size_t Pos = S.find_first_not_of(
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
"0123456789_.$/\\~=+[]*?-:");
// A character that cannot start a word (which is usually a
// punctuation) forms a single character token.
if (Pos == 0)
Pos = 1;
Ret.push_back(S.substr(0, Pos));
S = S.substr(Pos);
}
}
// Skip leading whitespace characters or /**/-style comments.
StringRef ScriptParser::skipSpace(StringRef S) {
for (;;) {
if (S.startswith("/*")) {
size_t E = S.find("*/", 2);
if (E == StringRef::npos) {
error("unclosed comment in a linker script");
return "";
}
S = S.substr(E + 2);
continue;
}
size_t Size = S.size();
S = S.ltrim();
if (S.size() == Size)
return S;
}
}
// An errneous token is handled as if it were the last token before EOF.
bool ScriptParser::atEOF() { return Error || Tokens.size() == Pos; }
StringRef ScriptParser::next() {
if (Error)
return "";
if (atEOF()) {
setError("unexpected EOF");
return "";
}
return Tokens[Pos++];
}
StringRef ScriptParser::peek() {
StringRef Tok = next();
if (Error)
return "";
--Pos;
return Tok;
}
bool ScriptParser::skip(StringRef Tok) {
if (Error)
return false;
if (atEOF()) {
setError("unexpected EOF");
return false;
}
if (Tok != Tokens[Pos])
return false;
++Pos;
return true;
}
void ScriptParser::expect(StringRef Expect) {
if (Error)
return;
StringRef Tok = next();
if (Tok != Expect)
setError(Expect + " expected, but got " + Tok);
}
void ScriptParser::addFile(StringRef S) {
if (IsUnderSysroot && S.startswith("/")) {
SmallString<128> Path;
(Config->Sysroot + S).toStringRef(Path);
if (sys::fs::exists(Path)) {
Driver->addFile(Saver.save(Path.str()));
return;
}
}
if (sys::path::is_absolute(S)) {
Driver->addFile(S);
} else if (S.startswith("=")) {
if (Config->Sysroot.empty())
Driver->addFile(S.substr(1));
else
Driver->addFile(Saver.save(Config->Sysroot + "/" + S.substr(1)));
} else if (S.startswith("-l")) {
Driver->addLibrary(S.substr(2));
} else if (sys::fs::exists(S)) {
Driver->addFile(S);
} else {
std::string Path = findFromSearchPaths(S);
if (Path.empty())
setError("unable to find " + S);
else
Driver->addFile(Saver.save(Path));
}
}
void ScriptParser::readAsNeeded() {
expect("(");
bool Orig = Config->AsNeeded;
Config->AsNeeded = true;
while (!Error) {
StringRef Tok = next();
if (Tok == ")")
break;
addFile(Tok);
}
Config->AsNeeded = Orig;
}
void ScriptParser::readEntry() {
// -e <symbol> takes predecence over ENTRY(<symbol>).
expect("(");
StringRef Tok = next();
if (Config->Entry.empty())
Config->Entry = Tok;
expect(")");
}
void ScriptParser::readExtern() {
expect("(");
while (!Error) {
StringRef Tok = next();
if (Tok == ")")
return;
Config->Undefined.push_back(Tok);
}
}
void ScriptParser::readGroup() {
expect("(");
while (!Error) {
StringRef Tok = next();
if (Tok == ")")
return;
if (Tok == "AS_NEEDED") {
readAsNeeded();
continue;
}
addFile(Tok);
}
}
void ScriptParser::readInclude() {
StringRef Tok = next();
auto MBOrErr = MemoryBuffer::getFile(Tok);
if (!MBOrErr) {
setError("cannot open " + Tok);
return;
}
std::unique_ptr<MemoryBuffer> &MB = *MBOrErr;
StringRef S = Saver.save(MB->getMemBufferRef().getBuffer());
std::vector<StringRef> V = tokenize(S);
Tokens.insert(Tokens.begin() + Pos, V.begin(), V.end());
}
void ScriptParser::readOutput() {
// -o <file> takes predecence over OUTPUT(<file>).
expect("(");
StringRef Tok = next();
if (Config->OutputFile.empty())
Config->OutputFile = Tok;
expect(")");
}
void ScriptParser::readOutputArch() {
// Error checking only for now.
expect("(");
next();
expect(")");
}
void ScriptParser::readOutputFormat() {
// Error checking only for now.
expect("(");
next();
StringRef Tok = next();
if (Tok == ")")
return;
if (Tok != ",") {
setError("unexpected token: " + Tok);
return;
}
next();
expect(",");
next();
expect(")");
}
void ScriptParser::readSearchDir() {
expect("(");
Config->SearchPaths.push_back(next());
expect(")");
}
void ScriptParser::readSections() {
expect("{");
while (!Error && !skip("}"))
readOutputSectionDescription();
}
void ScriptParser::readSectionPatterns(StringRef OutSec, bool Keep) {
expect("(");
while (!Error && !skip(")"))
Script->Sections.emplace_back(OutSec, next(), Keep);
}
std::vector<uint8_t> ScriptParser::parseHex(StringRef S) {
std::vector<uint8_t> Hex;
while (!S.empty()) {
StringRef B = S.substr(0, 2);
S = S.substr(2);
uint8_t H;
if (B.getAsInteger(16, H)) {
setError("not a hexadecimal value: " + B);
return {};
}
Hex.push_back(H);
}
return Hex;
}
void ScriptParser::readOutputSectionDescription() {
StringRef OutSec = next();
Script->SectionOrder.push_back(OutSec);
expect(":");
expect("{");
while (!Error && !skip("}")) {
StringRef Tok = next();
if (Tok == "*") {
readSectionPatterns(OutSec, false);
} else if (Tok == "KEEP") {
expect("(");
next(); // Skip *
readSectionPatterns(OutSec, true);
expect(")");
} else {
setError("unknown command " + Tok);
}
}
StringRef Tok = peek();
if (Tok.startswith("=")) {
if (!Tok.startswith("=0x")) {
setError("filler should be a hexadecimal value");
return;
}
Tok = Tok.substr(3);
Script->Filler[OutSec] = parseHex(Tok);
next();
}
}
static bool isUnderSysroot(StringRef Path) {
if (Config->Sysroot == "")
return false;
for (; !Path.empty(); Path = sys::path::parent_path(Path))
if (sys::fs::equivalent(Config->Sysroot, Path))
return true;
return false;
}
// Entry point. The other functions or classes are private to this file.
void LinkerScript::read(MemoryBufferRef MB) {
StringRef Path = MB.getBufferIdentifier();
ScriptParser(&Alloc, MB.getBuffer(), isUnderSysroot(Path)).run();
}
template StringRef LinkerScript::getOutputSection(InputSectionBase<ELF32LE> *);
template StringRef LinkerScript::getOutputSection(InputSectionBase<ELF32BE> *);
template StringRef LinkerScript::getOutputSection(InputSectionBase<ELF64LE> *);
template StringRef LinkerScript::getOutputSection(InputSectionBase<ELF64BE> *);
template bool LinkerScript::isDiscarded(InputSectionBase<ELF32LE> *);
template bool LinkerScript::isDiscarded(InputSectionBase<ELF32BE> *);
template bool LinkerScript::isDiscarded(InputSectionBase<ELF64LE> *);
template bool LinkerScript::isDiscarded(InputSectionBase<ELF64BE> *);
template bool LinkerScript::shouldKeep(InputSectionBase<ELF32LE> *);
template bool LinkerScript::shouldKeep(InputSectionBase<ELF32BE> *);
template bool LinkerScript::shouldKeep(InputSectionBase<ELF64LE> *);
template bool LinkerScript::shouldKeep(InputSectionBase<ELF64BE> *);