mirror of
https://github.com/rui314/mold.git
synced 2024-09-21 09:57:18 +03:00
121 lines
3.5 KiB
C++
121 lines
3.5 KiB
C++
// This file implements the same functionality as elf/output-file.cc.
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// We have two different implemetntations for ELF and Mach-O because
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// we implemented a special optimization for ELF or Linux.
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//
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// On Linux, it is faster to write to an existing file than creating a
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// new file and writing to it. So, we overwrite an existing executable
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// if exists.
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//
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// On macOS, it looks like the system does not assume that an executable
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// is mutated once it is created. Due to some code signing mechanism or
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// something, we always have to create a fresh file.
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#include "mold.h"
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#include <fcntl.h>
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#include <sys/mman.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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namespace mold::macho {
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template <typename E>
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class MemoryMappedOutputFile : public OutputFile<E> {
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public:
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MemoryMappedOutputFile(Context<E> &ctx, std::string path, i64 filesize, i64 perm)
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: OutputFile<E>(path, filesize, true) {
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std::string dir(path_dirname(path));
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output_tmpfile = (char *)save_string(ctx, dir + "/.mold-XXXXXX").data();
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i64 fd = mkstemp(output_tmpfile);
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if (fd == -1)
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Fatal(ctx) << "cannot open " << output_tmpfile << ": " << errno_string();
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if (ftruncate(fd, filesize))
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Fatal(ctx) << "ftruncate failed";
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if (fchmod(fd, perm) == -1)
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Fatal(ctx) << "fchmod failed";
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this->buf = (u8 *)mmap(nullptr, filesize, PROT_READ | PROT_WRITE,
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MAP_SHARED, fd, 0);
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if (this->buf == MAP_FAILED)
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Fatal(ctx) << path << ": mmap failed: " << errno_string();
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::close(fd);
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}
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void close(Context<E> &ctx) override {
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Timer t(ctx, "close_file");
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munmap(this->buf, this->filesize);
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if (rename(output_tmpfile, this->path.c_str()) == -1)
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Fatal(ctx) << this->path << ": rename failed: " << errno_string();
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output_tmpfile = nullptr;
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}
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};
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template <typename E>
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class MallocOutputFile : public OutputFile<E> {
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public:
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MallocOutputFile(Context<E> &ctx, std::string path, i64 filesize, i64 perm)
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: OutputFile<E>(path, filesize, false), perm(perm) {
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this->buf = (u8 *)mmap(NULL, filesize, PROT_READ | PROT_WRITE,
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MAP_SHARED | MAP_ANONYMOUS, -1, 0);
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if (this->buf == MAP_FAILED)
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Fatal(ctx) << "mmap failed: " << errno_string();
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}
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void close(Context<E> &ctx) override {
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Timer t(ctx, "close_file");
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if (this->path == "-") {
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fwrite(this->buf, this->filesize, 1, stdout);
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fclose(stdout);
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return;
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}
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i64 fd = ::open(this->path.c_str(), O_RDWR | O_CREAT, perm);
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if (fd == -1)
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Fatal(ctx) << "cannot open " << this->path << ": " << errno_string();
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FILE *fp = fdopen(fd, "w");
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fwrite(this->buf, this->filesize, 1, fp);
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fclose(fp);
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}
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private:
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i64 perm;
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};
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template <typename E>
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std::unique_ptr<OutputFile<E>>
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OutputFile<E>::open(Context<E> &ctx, std::string path, i64 filesize, i64 perm) {
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Timer t(ctx, "open_file");
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if (path.starts_with('/') && !ctx.arg.chroot.empty())
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path = ctx.arg.chroot + "/" + path_clean(path);
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bool is_special = false;
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if (path == "-") {
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is_special = true;
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} else {
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struct stat st;
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if (stat(path.c_str(), &st) == 0 && (st.st_mode & S_IFMT) != S_IFREG)
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is_special = true;
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}
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std::unique_ptr<OutputFile> file;
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if (is_special)
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file = std::make_unique<MallocOutputFile<E>>(ctx, path, filesize, perm);
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else
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file = std::make_unique<MemoryMappedOutputFile<E>>(ctx, path, filesize, perm);
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return file;
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}
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#define INSTANTIATE(E) \
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template class OutputFile<E>
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INSTANTIATE(ARM64);
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INSTANTIATE(X86_64);
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} // namespace mold::macho
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