LocalFile.cc

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#include "systemfuncs.hh"
#include "unistdp.hh"
#include <sys/types.h>
#include <sys/stat.h>
#if HAVE_MMAP
#include <sys/mman.h>
#endif
#if defined _WIN32
#include <io.h>
#include <iostream>
#endif
#include "LocalFile.hh"
#include "FileException.hh"
#include "FileNotFoundException.hh"
#include "narrow.hh"
#include "one_of.hh"
 
#include <bit>
#include <cstring> // for strchr, strerror
#include <cerrno>
#include <cassert>
#include <memory>
 
namespace openmsx {
 
LocalFile::LocalFile(std::string filename_, File::OpenMode mode)
        : filename(std::move(filename_))
{
        if (mode == File::OpenMode::SAVE_PERSISTENT) {
                if (auto pos = filename.find_last_of('/'); pos != std::string::npos) {
                        FileOperations::mkdirp(filename.substr(0, pos));
                }
        }
 
        const std::string& name = FileOperations::getNativePath(filename);
        if (mode == one_of(File::OpenMode::SAVE_PERSISTENT, File::OpenMode::TRUNCATE)) {
                // open file read/write truncated
                file = FileOperations::openFile(name, "wb+");
        } else if (mode == File::OpenMode::CREATE) {
                // open file read/write
                file = FileOperations::openFile(name, "rb+");
                if (!file) {
                        // create if it didn't exist yet
                        file = FileOperations::openFile(name, "wb+");
                }
        } else {
                // open file read/write
                file = FileOperations::openFile(name, "rb+");
                if (!file) {
                        // if that fails try read only
                        file = FileOperations::openFile(name, "rb");
                        readOnly = true;
                }
        }
        if (!file) {
                int err = errno;
                if (err == ENOENT) {
                        throw FileNotFoundException(
                                "File \"", filename, "\" not found");
                } else {
                        throw FileException(
                                "Error opening file \"", filename, "\": ",
                                strerror(err));
                }
        }
        (void)getSize(); // query filesize, but ignore result
}
 
LocalFile::LocalFile(std::string filename_, const char* mode)
        : filename(std::move(filename_))
{
        assert(strchr(mode, 'b'));
        const std::string name = FileOperations::getNativePath(filename);
        file = FileOperations::openFile(name, mode);
        if (!file) {
                throw FileException("Error opening file \"", filename, '"');
        }
        (void)getSize(); // query filesize, but ignore result
}
 
LocalFile::~LocalFile()
{
        munmap();
}
 
void LocalFile::preCacheFile()
{
        cache.emplace(FileOperations::getNativePath(filename));
}
 
void LocalFile::read(std::span<uint8_t> buffer)
{
        if (fread(buffer.data(), 1, buffer.size(), file.get()) != buffer.size()) {
                if (ferror(file.get())) {
                        throw FileException("Error reading file");
                }
                if (feof(file.get())) {
                        throw FileException("Read beyond end of file");
                }
        }
}
 
void LocalFile::write(std::span<const uint8_t> buffer)
{
        if (fwrite(buffer.data(), 1, buffer.size(), file.get()) != buffer.size()) {
                if (ferror(file.get())) {
                        throw FileException("Error writing file");
                }
        }
}
 
#if defined _WIN32
std::span<const uint8_t> LocalFile::mmap()
{
        size_t size = getSize();
        if (size == 0) return {static_cast<uint8_t*>(nullptr), size};
 
        if (!mmem) {
                int fd = _fileno(file.get());
                if (fd == -1) {
                        throw FileException("_fileno failed");
                }
                auto hFile = reinterpret_cast<HANDLE>(_get_osfhandle(fd)); // No need to close
                if (hFile == INVALID_HANDLE_VALUE) {
                        throw FileException("_get_osfhandle failed");
                }
                assert(!hMmap);
                hMmap = CreateFileMapping(hFile, nullptr, PAGE_WRITECOPY, 0, 0, nullptr);
                if (!hMmap) {
                        throw FileException(
                                "CreateFileMapping failed: ", GetLastError());
                }
                mmem = static_cast<uint8_t*>(MapViewOfFile(hMmap, FILE_MAP_COPY, 0, 0, 0));
                if (!mmem) {
                        DWORD gle = GetLastError();
                        CloseHandle(hMmap);
                        hMmap = nullptr;
                        throw FileException("MapViewOfFile failed: ", gle);
                }
        }
        return {mmem, size};
}
 
void LocalFile::munmap()
{
        if (mmem) {
                // TODO: make this a valid failure path
                // When pages are dirty, UnmapViewOfFile is a save operation,
                // and that can fail. However, munmap is called from
                // the destructor, for which there is no expectation
                // that it will fail. So this area needs some work.
                // It is NOT an option to throw an exception (not even
                // FatalError).
                if (!UnmapViewOfFile(mmem)) {
                        std::cerr << "UnmapViewOfFile failed: "
                                  << GetLastError()
                                  << '\n';
                }
                mmem = nullptr;
        }
        if (hMmap) {
                CloseHandle(hMmap);
                hMmap = nullptr;
        }
}
 
#elif HAVE_MMAP
std::span<const uint8_t> LocalFile::mmap()
{
        size_t size = getSize();
        if (size == 0) return {static_cast<uint8_t*>(nullptr), size};
 
        if (!mmem) {
                mmem = static_cast<uint8_t*>(
                          ::mmap(nullptr, size, PROT_READ | PROT_WRITE,
                                 MAP_PRIVATE, fileno(file.get()), 0));
                // MAP_FAILED is #define'd using an old-style cast, we
                // have to redefine it ourselves to avoid a warning
                auto* MY_MAP_FAILED = std::bit_cast<void*>(intptr_t(-1));
                if (mmem == MY_MAP_FAILED) {
                        throw FileException("Error mmapping file");
                }
        }
        return {mmem, size};
}
 
void LocalFile::munmap()
{
        if (mmem) {
                try {
                        ::munmap(mmem, getSize());
                } catch (FileException&) {
                        // In theory getSize() could throw. Does that ever
                        // happen in practice?
                }
                mmem = nullptr;
        }
}
#endif
 
size_t LocalFile::getSize()
{
#if defined _WIN32
        // Normal fstat compiles but doesn't seem to be working the same
        // as on POSIX, regarding size support.
        struct _stat64 st;
        int ret = _fstat64(fileno(file.get()), &st);
#else
        struct stat st;
        int ret = fstat(fileno(file.get()), &st);
        if (ret && (errno == EOVERFLOW)) {
                // on 32-bit systems, the fstat() call returns a EOVERFLOW
                // error in case the file is bigger than (1<<31)-1 bytes
                throw FileException("Files >= 2GB are not supported on "
                                    "32-bit platforms: ", getURL());
        }
#endif
        if (ret) {
                throw FileException("Cannot get file size");
        }
        return st.st_size;
}
 
void LocalFile::seek(size_t pos)
{
#if defined _WIN32
        int ret = _fseeki64(file.get(), pos, SEEK_SET);
#else
        int ret = fseek(file.get(), narrow_cast<long>(pos), SEEK_SET);
#endif
        if (ret != 0) {
                throw FileException("Error seeking file");
        }
}
 
size_t LocalFile::getPos()
{
        return ftell(file.get());
}
 
#if HAVE_FTRUNCATE
void LocalFile::truncate(size_t size)
{
        int fd = fileno(file.get());
        if (ftruncate(fd, narrow_cast<off_t>(size))) {
                throw FileException("Error truncating file");
        }
}
#endif
 
void LocalFile::flush()
{
        fflush(file.get());
}
 
const std::string& LocalFile::getURL() const
{
        return filename;
}
 
std::string LocalFile::getLocalReference()
{
        return filename;
}
 
bool LocalFile::isReadOnly() const
{
        return readOnly;
}
 
time_t LocalFile::getModificationDate()
{
#if defined _WIN32
        // Normal fstat compiles but doesn't seem to be working the same
        // as on POSIX, regarding size support.
        struct _stat64 st;
        int ret = _fstat64(fileno(file.get()), &st);
#else
        struct stat st;
        int ret = fstat(fileno(file.get()), &st);
#endif
        if (ret) {
                throw FileException("Cannot stat file");
        }
        return st.st_mtime;
}
 
} // namespace openmsx