kernel: retain POSIX file descriptor close-on-exec flags

src/kernel/fileSystem.cpp

@@ -70,6 +70,7 @@ struct File {
 	std::atomic_bool                    writable;
 	std::atomic_bool                    append;
 	std::atomic_bool                    sync_writes;
+	std::atomic_bool                    close_on_exec;
 	SpecialFile                         special;
 	Common::Mutex                       mutex;
 	std::vector<uint8_t>                dirents;
@@ -449,11 +450,12 @@ int KYTY_SYSV_ABI KernelOpen(const char* path, int flags, uint16_t mode) {
 
 	EXIT_IF(file == nullptr || file->opened || file->directory);
 
-	file->name        = path;
-	file->readable    = rw_mode != Common::File::Mode::Write;
-	file->writable    = rw_mode != Common::File::Mode::Read;
-	file->append      = append;
-	file->sync_writes = fsync || sync || dsync;
+	file->name          = path;
+	file->readable      = rw_mode != Common::File::Mode::Write;
+	file->writable      = rw_mode != Common::File::Mode::Read;
+	file->append        = append;
+	file->sync_writes   = fsync || sync || dsync;
+	file->close_on_exec = (static_cast<uint32_t>(flags) & 0x00100000u) != 0;
 
 	if (!directory && IsRandomDevice(file->name)) {
 		file->real_name = file->name;
@@ -585,6 +587,27 @@ int KYTY_SYSV_ABI KernelClose(int d) {
 	return OK;
 }
 
+int KYTY_SYSV_ABI KernelFcntl(int d, int command, int arg) {
+	PRINT_NAME();
+
+	if (d < DESCRIPTOR_MIN) {
+		return KERNEL_ERROR_EBADF;
+	}
+
+	auto* file = g_files->GetFile(d);
+	if (file == nullptr || !file->opened) {
+		return KERNEL_ERROR_EBADF;
+	}
+
+	switch (command) {
+		case 1: return file->close_on_exec.load(std::memory_order_relaxed); // F_GETFD
+		case 2: // F_SETFD, FD_CLOEXEC
+			file->close_on_exec.store((arg & 1) != 0, std::memory_order_relaxed);
+			return OK;
+		default: return KERNEL_ERROR_EINVAL;
+	}
+}
+
 int64_t KYTY_SYSV_ABI KernelRead(int d, void* buf, size_t nbytes) {
 	PRINT_NAME();
 

src/kernel/fileSystem.h

@@ -59,6 +59,7 @@ std::filesystem::path GetRealFilename(const std::string& mounted_file_name);
 
 int KYTY_SYSV_ABI     KernelOpen(const char* path, int flags, uint16_t mode);
 int KYTY_SYSV_ABI     KernelClose(int d);
+int KYTY_SYSV_ABI     KernelFcntl(int d, int command, int arg);
 int64_t KYTY_SYSV_ABI KernelRead(int d, void* buf, size_t nbytes);
 int64_t KYTY_SYSV_ABI KernelPread(int d, void* buf, size_t nbytes, int64_t offset);
 int64_t KYTY_SYSV_ABI KernelPreadv(int d, const KernelIovec* iov, int iovcnt, int64_t offset);

src/libs/libKernel.cpp

@@ -1974,6 +1974,12 @@ int64_t KYTY_SYSV_ABI fstat(int d, LibKernel::FileSystem::FileStat* sb) {
 	return POSIX_N_CALL(LibKernel::FileSystem::KernelFstat(d, sb));
 }
 
+int KYTY_SYSV_ABI fcntl(int d, int command, int arg) {
+	PRINT_NAME();
+
+	return POSIX_N_CALL(LibKernel::FileSystem::KernelFcntl(d, command, arg));
+}
+
 int KYTY_SYSV_ABI ftruncate(int d, int64_t length) {
 	PRINT_NAME();
 
@@ -2163,6 +2169,7 @@ LIB_DEFINE(InitLibKernel_1_Posix) {
 	LIB_FUNC("E6ao34wPw+U", stat);
 	LIB_FUNC("JGMio+21L4c", mkdir);
 	LIB_FUNC("ih4CD9-gghM", Posix::ftruncate);
+	LIB_FUNC("8nY19bKoiZk", Posix::fcntl);
 	LIB_FUNC("pDuPEf3m4fI", Posix::sem_init);
 	LIB_FUNC("cDW233RAwWo", Posix::sem_destroy);
 	LIB_FUNC("YCV5dGGBcCo", Posix::sem_wait);