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//===- 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 Symtab or Config object.
//
//===----------------------------------------------------------------------===//
#include "Config.h"
#include "Driver.h"
#include "SymbolTable.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/StringSaver.h"
using namespace llvm;
using namespace lld;
using namespace lld::elf2;
namespace {
class LinkerScript {
public:
LinkerScript(BumpPtrAllocator *A, StringRef S)
: Saver(*A), Tokens(tokenize(S)) {}
void run();
private:
static std::vector<StringRef> tokenize(StringRef S);
static StringRef skipSpace(StringRef S);
StringRef next();
bool atEOF() { return Tokens.size() == Pos; }
void expect(StringRef Expect);
void addFile(StringRef Path);
void readAsNeeded();
void readEntry();
void readGroup();
void readInclude();
void readOutput();
void readOutputFormat();
void readSearchDir();
StringSaver Saver;
std::vector<StringRef> Tokens;
size_t Pos = 0;
};
}
void LinkerScript::run() {
while (!atEOF()) {
StringRef Tok = next();
if (Tok == "ENTRY") {
readEntry();
} else if (Tok == "GROUP" || Tok == "INPUT") {
readGroup();
} else if (Tok == "INCLUDE") {
readInclude();
} else if (Tok == "OUTPUT") {
readOutput();
} else if (Tok == "OUTPUT_FORMAT") {
readOutputFormat();
} else if (Tok == "SEARCH_DIR") {
readSearchDir();
} else {
error("unknown directive: " + Tok);
}
}
}
// Split S into linker script tokens.
std::vector<StringRef> LinkerScript::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");
Ret.push_back(S.substr(1, E));
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 LinkerScript::skipSpace(StringRef S) {
for (;;) {
if (S.startswith("/*")) {
size_t E = S.find("*/", 2);
if (E == StringRef::npos)
error("unclosed comment in a linker script");
S = S.substr(E + 2);
continue;
}
size_t Size = S.size();
S = S.ltrim();
if (S.size() == Size)
return S;
}
}
StringRef LinkerScript::next() {
if (Pos == Tokens.size())
error("unexpected EOF");
return Tokens[Pos++];
}
void LinkerScript::expect(StringRef Expect) {
StringRef Tok = next();
if (Tok != Expect)
error(Expect + " expected, but got " + Tok);
}
void LinkerScript::addFile(StringRef S) {
if (S.startswith("/")) {
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->addFile(searchLibrary(S.substr(2)));
} else {
std::string Path = findFromSearchPaths(S);
if (Path.empty())
error("Unable to find " + S);
Driver->addFile(Saver.save(Path));
}
}
void LinkerScript::readAsNeeded() {
expect("(");
bool Orig = Config->AsNeeded;
Config->AsNeeded = true;
for (;;) {
StringRef Tok = next();
if (Tok == ")")
break;
addFile(Tok);
}
Config->AsNeeded = Orig;
}
void LinkerScript::readEntry() {
// -e <symbol> takes predecence over ENTRY(<symbol>).
expect("(");
StringRef Tok = next();
if (Config->Entry.empty())
Config->Entry = Tok;
expect(")");
}
void LinkerScript::readGroup() {
expect("(");
for (;;) {
StringRef Tok = next();
if (Tok == ")")
return;
if (Tok == "AS_NEEDED") {
readAsNeeded();
continue;
}
addFile(Tok);
}
}
void LinkerScript::readInclude() {
StringRef Tok = next();
auto MBOrErr = MemoryBuffer::getFile(Tok);
error(MBOrErr, "cannot open " + Tok);
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 LinkerScript::readOutput() {
// -o <file> takes predecence over OUTPUT(<file>).
expect("(");
StringRef Tok = next();
if (Config->OutputFile.empty())
Config->OutputFile = Tok;
expect(")");
}
void LinkerScript::readOutputFormat() {
// Error checking only for now.
expect("(");
next();
expect(")");
}
void LinkerScript::readSearchDir() {
expect("(");
Config->SearchPaths.push_back(next());
expect(")");
}
// Entry point. The other functions or classes are private to this file.
void lld::elf2::readLinkerScript(BumpPtrAllocator *A, MemoryBufferRef MB) {
LinkerScript(A, MB.getBuffer()).run();
}
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