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mirror of https://github.com/rui314/mold.git synced 2024-11-11 16:58:12 +03:00
mold/linker_script.cc
Rui Ueyama f524122e6a wip
2021-03-29 14:36:55 +09:00

303 lines
7.8 KiB
C++

// On Linux, /usr/lib/x86_64-linux-gnu/libc.so is not actually
// a shared object file but an ASCII text file containing a linker
// script to include a "real" libc.so file. Therefore, we need to
// support a (very limited) subset of the linker script language.
#include "mold.h"
#include <cctype>
#include <iomanip>
static thread_local MemoryMappedFile *current_file;
static std::string_view get_line(std::string_view input, const char *pos) {
assert(input.data() <= pos);
assert(pos < input.data() + input.size());
i64 start = input.rfind('\n', pos - input.data());
if (start == input.npos)
start = 0;
else
start++;
i64 end = input.find('\n', pos - input.data());
if (end == input.npos)
end = input.size();
return input.substr(start, end - start);
}
class SyntaxError {
public:
SyntaxError(std::string_view errpos) {
std::string_view contents = current_file->get_contents();
std::string_view line = get_line(contents, errpos.data());
i64 lineno = 1;
for (i64 i = 0; contents.data() + i < line.data(); i++)
if (contents[i] == '\n')
lineno++;
i64 column = errpos.data() - line.data();
std::stringstream ss;
ss << current_file->name << ":" << lineno << ": ";
i64 indent = ss.tellp();
ss << line << "\n" << std::setw(indent + column) << " " << "^ ";
out << ss.str();
}
template <class T> SyntaxError &operator<<(T &&val) {
out << std::forward<T>(val);
return *this;
}
Fatal out;
};
static std::vector<std::string_view> tokenize(std::string_view input) {
std::vector<std::string_view> vec;
while (!input.empty()) {
if (isspace(input[0])) {
input = input.substr(1);
continue;
}
if (input.starts_with("/*")) {
i64 pos = input.find("*/", 2);
if (pos == std::string_view::npos)
SyntaxError(input) << "unclosed comment";
input = input.substr(pos + 2);
continue;
}
if (input[0] == '#') {
i64 pos = input.find("\n", 1);
if (pos == std::string_view::npos)
break;
input = input.substr(pos + 1);
continue;
}
if (input[0] == '"') {
i64 pos = input.find('"', 1);
if (pos == std::string_view::npos)
SyntaxError(input) << "unclosed string literal";
vec.push_back(input.substr(0, pos + 1));
input = input.substr(pos + 1);
continue;
}
i64 pos = input.find_first_not_of(
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
"0123456789_.$/\\~=+[]*?-!^:");
if (pos == 0)
pos = 1;
else if (pos == input.npos)
pos = input.size();
vec.push_back(input.substr(0, pos));
input = input.substr(pos);
}
return vec;
}
static std::span<std::string_view>
skip(std::span<std::string_view> tok, std::string_view str) {
if (tok.empty())
Fatal() << current_file->name << ": expected '" << str << "', but got EOF";
if (tok[0] != str)
SyntaxError(tok[0]) << "expected '" << str << "'";
return tok.subspan(1);
}
static std::string_view unquote(std::string_view s) {
if (s.size() > 0 && s[0] == '"') {
assert(s[s.size() - 1] == '"');
return s.substr(1, s.size() - 2);
}
return s;
}
static std::span<std::string_view>
read_output_format(std::span<std::string_view> tok) {
tok = skip(tok, "(");
while (!tok.empty() && tok[0] != ")")
tok = tok.subspan(1);
if (tok.empty())
Fatal() << current_file->name << ": expected ')', but got EOF";
return tok.subspan(1);
}
static MemoryMappedFile *resolve_path(Context &ctx, std::string_view tok) {
std::string str(unquote(tok));
if (str.starts_with("/"))
return MemoryMappedFile::must_open(ctx.arg.sysroot + str);
if (str.starts_with("-l"))
return find_library(ctx, str.substr(2));
if (std::string path = path_dirname(current_file->name) + "/";
MemoryMappedFile *mb = MemoryMappedFile::open(path + str))
return mb;
if (MemoryMappedFile *mb = MemoryMappedFile::open(str))
return mb;
for (std::string_view dir : ctx.arg.library_paths) {
std::string root = dir.starts_with("/") ? ctx.arg.sysroot : "";
std::string path = root + std::string(dir) + "/" + str;
if (MemoryMappedFile *mb = MemoryMappedFile::open(path))
return mb;
}
SyntaxError(tok) << "library not found: " << str;
}
static std::span<std::string_view>
read_group(Context &ctx, std::span<std::string_view> tok) {
tok = skip(tok, "(");
while (!tok.empty() && tok[0] != ")") {
if (tok[0] == "AS_NEEDED") {
bool orig = ctx.as_needed;
ctx.as_needed = true;
tok = read_group(ctx, tok.subspan(1));
ctx.as_needed = orig;
continue;
}
MemoryMappedFile *mb = resolve_path(ctx, tok[0]);
read_file(ctx, mb);
tok = tok.subspan(1);
}
if (tok.empty())
Fatal() << current_file->name << ": expected ')', but got EOF";
return tok.subspan(1);
}
void parse_linker_script(Context &ctx, MemoryMappedFile *mb) {
current_file = mb;
std::vector<std::string_view> vec = tokenize(mb->get_contents());
std::span<std::string_view> tok = vec;
while (!tok.empty()) {
if (tok[0] == "OUTPUT_FORMAT")
tok = read_output_format(tok.subspan(1));
else if (tok[0] == "INPUT" || tok[0] == "GROUP")
tok = read_group(ctx, tok.subspan(1));
else
SyntaxError(tok[0]) << "unknown token";
}
}
static bool read_label(std::span<std::string_view> &tok,
std::string label) {
if (tok.size() >= 1 && tok[0] == label + ":") {
tok = tok.subspan(1);
return true;
}
if (tok.size() >= 2 && tok[0] == label && tok[1] == ":") {
tok = tok.subspan(2);
return true;
}
return false;
}
static void parse_version_script_commands(std::span<std::string_view> &tok,
i16 &ver, bool is_extern_cpp) {
bool is_global = true;
while (!tok.empty() && tok[0] != "}") {
if (read_label(tok, "global")) {
is_global = true;
continue;
}
if (read_label(tok, "local")) {
is_global = false;
continue;
}
if (tok[0] == "extern") {
tok = tok.subspan(1);
tok = skip(tok, "\"C++\"");
tok = skip(tok, "{");
parse_version_script_commands(tok, ver, true);
tok = skip(tok, "}");
tok = skip(tok, ";");
continue;
}
if (tok[0] == "*")
ctx.arg.default_version = (is_global ? ver : VER_NDX_LOCAL);
else
ctx.arg.version_patterns.push_back({tok[0], ver, is_extern_cpp});
tok = skip(tok.subspan(1), ";");
}
}
void parse_version_script(std::string path) {
current_file = MemoryMappedFile::must_open(path);
std::vector<std::string_view> vec = tokenize(current_file->get_contents());
std::span<std::string_view> tok = vec;
i16 next_ver = VER_NDX_LAST_RESERVED + 1;
while (!tok.empty()) {
i16 ver = VER_NDX_GLOBAL;
if (tok[0] != "{") {
ver = next_ver++;
ctx.arg.version_definitions.push_back(tok[0]);
tok = tok.subspan(1);
}
tok = skip(tok, "{");
parse_version_script_commands(tok, ver, false);
tok = skip(tok, "}");
if (!tok.empty() && tok[0] != ";")
tok = tok.subspan(1);
tok = skip(tok, ";");
}
if (!tok.empty())
SyntaxError(tok[0]) << "trailing garbage token";
}
void parse_dynamic_list(std::string path) {
current_file = MemoryMappedFile::must_open(path);
std::vector<std::string_view> vec = tokenize(current_file->get_contents());
std::span<std::string_view> tok = vec;
tok = skip(tok, "{");
i16 ver = VER_NDX_GLOBAL;
while (!tok.empty() && tok[0] != "}") {
if (read_label(tok, "global")) {
ver = VER_NDX_GLOBAL;
continue;
}
if (read_label(tok, "local")) {
ver = VER_NDX_LOCAL;
continue;
}
if (tok[0] == "*")
ctx.arg.default_version = ver;
else
ctx.arg.version_patterns.push_back({tok[0], ver, false});
tok = skip(tok.subspan(1), ";");
}
tok = skip(tok, "}");
tok = skip(tok, ";");
if (!tok.empty())
SyntaxError(tok[0]) << "trailing garbage token";
}