kernel: share directory streams across seeks and reads

This commit is contained in:
nmzik
2026-09-10 14:32:42 +04:00
parent 23e7df21b1
commit d2fa86579b
2 changed files with 228 additions and 132 deletions
+109 -132
View File
@@ -28,7 +28,8 @@ namespace Libs::LibKernel::FileSystem {
LIB_NAME("libkernel", "libkernel");
constexpr int DESCRIPTOR_MIN = 3;
constexpr int DESCRIPTOR_MIN = 3;
constexpr uint64_t DIR_BLOCK_SIZE = 512;
enum class SpecialFile {
None,
@@ -68,7 +69,7 @@ struct File {
std::atomic_bool sync_writes;
SpecialFile special;
Common::Mutex mutex;
std::vector<Common::File::DirEntry> dents;
std::vector<uint8_t> dirents;
uint64_t dents_offset;
};
@@ -119,6 +120,51 @@ static uint64_t AlignUp(uint64_t value, uint64_t alignment) {
return (alignment != 0 ? (value + alignment - 1) & ~(alignment - 1) : value);
}
static std::vector<uint8_t> PackDirents(const std::vector<Common::File::DirEntry>& entries) {
std::vector<uint8_t> dirents;
uint64_t offset = 0;
uint64_t last_reclen_offset = 0;
for (const auto& entry: entries) {
const auto& name = entry.name;
EXIT_NOT_IMPLEMENTED(name.size() > 255);
const auto reclen = AlignUp(8 + name.size() + 1, 4);
if (offset + reclen > dirents.size()) {
if (!dirents.empty()) {
auto* last_reclen =
reinterpret_cast<uint16_t*>(dirents.data() + last_reclen_offset);
*last_reclen += static_cast<uint16_t>(dirents.size() - offset);
}
offset = dirents.size();
dirents.resize(offset + DIR_BLOCK_SIZE);
}
*reinterpret_cast<uint32_t*>(dirents.data() + offset) =
Common::hash(name.data(), static_cast<uint32_t>(name.size()));
*reinterpret_cast<uint16_t*>(dirents.data() + offset + 4) = static_cast<uint16_t>(reclen);
dirents[offset + 6] = entry.is_file ? 8 : 4;
dirents[offset + 7] = static_cast<uint8_t>(name.size());
memcpy(dirents.data() + offset + 8, name.c_str(), name.size() + 1);
last_reclen_offset = offset + 4;
offset += reclen;
}
if (!dirents.empty()) {
auto* last_reclen = reinterpret_cast<uint16_t*>(dirents.data() + last_reclen_offset);
*last_reclen += static_cast<uint16_t>(dirents.size() - offset);
}
return dirents;
}
static uint64_t ReadDirectory(File* file, void* buf, uint64_t count) {
const auto remaining =
file->dents_offset < file->dirents.size() ? file->dirents.size() - file->dents_offset : 0;
const auto bytes = std::min(count, remaining);
if (bytes != 0) {
Memory::InvalidateMemory(reinterpret_cast<uint64_t>(buf), bytes);
memcpy(buf, file->dirents.data() + file->dents_offset, bytes);
file->dents_offset += bytes;
}
return bytes;
}
static int PosixToKernel(int posix_errno) {
return KERNEL_ERROR_UNKNOWN + posix_errno;
}
@@ -433,15 +479,16 @@ int KYTY_SYSV_ABI KernelOpen(const char* path, int flags, uint16_t mode) {
EXIT_NOT_IMPLEMENTED(!directory && rw_mode != Common::File::Mode::Read);
EXIT_NOT_IMPLEMENTED(!directory && (trunc || creat));
file->dents = Common::File::GetDirEntries(file->real_name);
const auto entries = Common::File::GetDirEntries(file->real_name);
file->dirents = PackDirents(entries);
file->dents_offset = 0;
file->directory = true;
LOGF_COLOR(Log::Color::Green, "\tOpen dir: %s, entries = %" PRIu32 ", [ok]\n",
Common::PathToString(file->real_name).c_str(),
static_cast<uint32_t>(file->dents.size()));
static_cast<uint32_t>(entries.size()));
for (const auto& f: file->dents) {
for (const auto& f: entries) {
LOGF("\t\t%s %s\n", f.is_file ? "[file]" : "[dir ]", f.name.c_str());
}
} else {
@@ -538,11 +585,18 @@ int64_t KYTY_SYSV_ABI KernelRead(int d, void* buf, size_t nbytes) {
return KERNEL_ERROR_EBADF;
}
EXIT_NOT_IMPLEMENTED(file->directory);
EXIT_IF(!file->opened);
EXIT_NOT_IMPLEMENTED(nbytes > UINT_MAX);
if (nbytes > INT_MAX) {
return KERNEL_ERROR_EINVAL;
}
if (file->directory) {
Common::LockGuard lock(file->mutex);
const auto bytes = ReadDirectory(file, buf, nbytes);
LOGF("\tRead %" PRIu64 " directory bytes from: %s\n", bytes,
Common::PathToString(file->real_name).c_str());
return static_cast<int64_t>(bytes);
}
if (file->special == SpecialFile::Random) {
FillRandomBuffer(buf, nbytes);
@@ -761,7 +815,7 @@ int64_t KYTY_SYSV_ABI KernelLseek(int d, int64_t offset, int whence) {
PRINT_NAME();
if (d < DESCRIPTOR_MIN) {
return KERNEL_ERROR_EPERM;
return KERNEL_ERROR_EBADF;
}
auto* file = g_files->GetFile(d);
@@ -770,8 +824,6 @@ int64_t KYTY_SYSV_ABI KernelLseek(int d, int64_t offset, int whence) {
return KERNEL_ERROR_EBADF;
}
EXIT_NOT_IMPLEMENTED(file->directory);
EXIT_IF(!file->opened);
if (file->special != SpecialFile::None) {
@@ -780,38 +832,47 @@ int64_t KYTY_SYSV_ABI KernelLseek(int d, int64_t offset, int whence) {
Common::LockGuard lock(file->mutex);
bool is_invalid = file->f.IsInvalid();
if (whence == 1) {
offset = static_cast<int64_t>(file->f.Tell()) + offset;
whence = 0;
}
if (whence == 2) {
offset = static_cast<int64_t>(file->f.Size()) + offset;
whence = 0;
}
EXIT_NOT_IMPLEMENTED(whence != 0);
if (offset < 0) {
return KERNEL_ERROR_EINVAL;
}
file->f.Seek(offset);
auto pos = static_cast<int64_t>(file->f.Tell());
EXIT_IF(pos != offset);
if (is_invalid) {
if (!file->directory && file->f.IsInvalid()) {
LOGF("\tfile is invalid\n");
return KERNEL_ERROR_EIO;
}
LOGF("\tLseek (pos = %" PRId64 ") to: %s\n", offset,
uint64_t base = 0;
switch (whence) {
case 0: break;
case 1: base = file->directory ? file->dents_offset : file->f.Tell(); break;
case 2: base = file->directory ? file->dirents.size() : file->f.Size(); break;
default: return KERNEL_ERROR_EINVAL;
}
uint64_t position = 0;
if (offset >= 0) {
if (base > static_cast<uint64_t>(INT64_MAX - offset)) {
return KERNEL_ERROR_EOVERFLOW;
}
position = base + static_cast<uint64_t>(offset);
} else {
const auto distance = uint64_t {0} - static_cast<uint64_t>(offset);
if (base < distance) {
return KERNEL_ERROR_EINVAL;
}
position = base - distance;
if (position > INT64_MAX) {
return KERNEL_ERROR_EOVERFLOW;
}
}
if (file->directory) {
file->dents_offset = position;
} else {
file->f.Seek(position);
EXIT_IF(file->f.Tell() != position);
}
LOGF("\tLseek (pos = %" PRIu64 ") to: %s\n", position,
Common::PathToString(file->real_name).c_str());
return pos;
return static_cast<int64_t>(position);
}
int KYTY_SYSV_ABI KernelStat(const char* path, FileStat* sb) {
@@ -842,9 +903,10 @@ int KYTY_SYSV_ABI KernelStat(const char* path, FileStat* sb) {
auto wt = at;
if (is_dir) {
stat.st_size = 0;
stat.st_size =
static_cast<int64_t>(PackDirents(Common::File::GetDirEntries(real_file_name)).size());
stat.st_blksize = 512;
stat.st_blocks = 0;
stat.st_blocks = stat.st_size / 512;
} else {
stat.st_size = static_cast<int64_t>(Common::File::Size(real_file_name));
stat.st_blksize = 512;
@@ -920,9 +982,9 @@ int KYTY_SYSV_ABI KernelFstat(int d, FileStat* sb) {
stat.st_blksize = 512;
stat.st_blocks = (stat.st_size + 511) / 512;
} else {
stat.st_size = 0;
stat.st_size = static_cast<int64_t>(file->dirents.size());
stat.st_blksize = 512;
stat.st_blocks = 0;
stat.st_blocks = stat.st_size / 512;
}
SecToTimespec(&stat.st_atim, at.ToUnix());
@@ -1057,14 +1119,15 @@ int KYTY_SYSV_ABI KernelGetdirentries(int fd, char* buf, int nbytes, int64_t* ba
return KERNEL_ERROR_EBADF;
}
constexpr uint64_t DIR_BLOCK_SIZE = 512;
constexpr uint64_t DIRENT_META_SIZE = 8;
if (!file->directory || nbytes < static_cast<int>(DIR_BLOCK_SIZE)) {
return KERNEL_ERROR_EINVAL;
}
EXIT_IF(!file->opened);
Common::LockGuard lock(file->mutex);
if (file->dents_offset > file->dirents.size() || file->dents_offset % DIR_BLOCK_SIZE != 0) {
return KERNEL_ERROR_EINVAL;
}
LOGF("\t dir = %s\n"
"\t nbytes = %d\n"
@@ -1074,94 +1137,8 @@ int KYTY_SYSV_ABI KernelGetdirentries(int fd, char* buf, int nbytes, int64_t* ba
if (basep != nullptr) {
*basep = static_cast<int64_t>(file->dents_offset);
}
std::vector<uint8_t> dirents;
dirents.reserve(
std::max<size_t>(static_cast<size_t>(DIR_BLOCK_SIZE), file->dents.size() * 64u));
uint64_t next_ceiling = 0;
uint64_t dirent_offset = 0;
int64_t last_reclen_offset = -1;
for (const auto& entry: file->dents) {
const auto& str = entry.name;
auto str_size = str.size();
EXIT_NOT_IMPLEMENTED(str_size > 255);
uint64_t reclen = AlignUp(DIRENT_META_SIZE + str_size + 1, 4);
if (dirent_offset + reclen > next_ceiling) {
if (last_reclen_offset >= 0) {
auto* last_reclen =
reinterpret_cast<uint16_t*>(dirents.data() + last_reclen_offset);
*last_reclen = static_cast<uint16_t>(*last_reclen + (next_ceiling - dirent_offset));
}
dirent_offset = next_ceiling;
next_ceiling += DIR_BLOCK_SIZE;
dirents.resize(next_ceiling);
std::fill(dirents.begin() + static_cast<std::ptrdiff_t>(dirent_offset), dirents.end(),
0);
}
*reinterpret_cast<uint32_t*>(dirents.data() + dirent_offset + 0) =
Common::hash(str.data(), static_cast<uint32_t>(str.size()));
*reinterpret_cast<uint16_t*>(dirents.data() + dirent_offset + 4) =
static_cast<uint16_t>(reclen);
*reinterpret_cast<uint8_t*>(dirents.data() + dirent_offset + 6) = (entry.is_file ? 8 : 4);
*reinterpret_cast<uint8_t*>(dirents.data() + dirent_offset + 7) =
static_cast<uint8_t>(str_size);
memcpy(dirents.data() + dirent_offset + 8, str.data(), str_size);
dirents[dirent_offset + 8 + str_size] = '\0';
last_reclen_offset = static_cast<int64_t>(dirent_offset + 4);
dirent_offset += reclen;
LOGF("\t name = %s\n", str.data());
}
if (last_reclen_offset >= 0) {
auto* last_reclen = reinterpret_cast<uint16_t*>(dirents.data() + last_reclen_offset);
*last_reclen = static_cast<uint16_t>(*last_reclen + (next_ceiling - dirent_offset));
}
const uint64_t directory_size = next_ceiling;
if (file->dents_offset >= directory_size) {
return 0;
}
uint64_t bytes_written = 0;
uint64_t working_offset = file->dents_offset;
uint64_t dirent_buffer_offset = 0;
uint64_t aligned_count = AlignDown(static_cast<uint64_t>(nbytes), DIR_BLOCK_SIZE);
while (dirent_buffer_offset < dirents.size()) {
const auto* normal_dirent = dirents.data() + dirent_buffer_offset;
uint16_t reclen = *reinterpret_cast<const uint16_t*>(normal_dirent + 4);
uint8_t namlen = *(normal_dirent + 7);
if (namlen == 0 || reclen == 0) {
break;
}
if (working_offset >= reclen) {
dirent_buffer_offset += reclen;
working_offset -= reclen;
continue;
}
if (bytes_written + reclen > aligned_count) {
break;
}
const auto bytes_to_copy = reclen - working_offset;
memcpy(buf + bytes_written, normal_dirent + working_offset, bytes_to_copy);
bytes_written += bytes_to_copy;
dirent_buffer_offset += reclen;
working_offset = 0;
}
file->dents_offset += bytes_written;
return static_cast<int64_t>(bytes_written);
return static_cast<int>(
ReadDirectory(file, buf, AlignDown(static_cast<uint64_t>(nbytes), DIR_BLOCK_SIZE)));
}
int KYTY_SYSV_ABI KernelGetdents(int fd, char* buf, int nbytes) {