Luna/kernel/src/sys/open.cpp

#include "Log.h"
#include "fs/VFS.h"
#include "memory/MemoryManager.h"
#include "sys/Syscall.h"
#include "thread/Scheduler.h"

Result<u64> sys_open(Registers*, SyscallArgs args)
{
    u64 path_address = args[0];
    if (!MemoryManager::validate_userspace_string(path_address)) return err(EFAULT);

    const char* path = (const char*)path_address;
    int flags = (int)args[1];

    Thread* current = Scheduler::current();

    kinfoln("open: trying to open file %s, flags %d", path, flags);

    auto inode = TRY(VFS::resolve_path(path));

    int fd = TRY(current->allocate_fd(0));

    current->fd_table->fds[fd] = FileDescriptor { inode, 0, flags };

    kinfoln("open: allocated file descriptor %d for inode %zu", fd, inode->inode_number());

    return (u64)fd;
}

Result<u64> sys_close(Registers*, SyscallArgs args)
{
    int fd = (int)args[0];
    if (fd < 0 || fd >= FD_MAX) return err(EBADF);

    Thread* current = Scheduler::current();

    Option<FileDescriptor>& descriptor = current->fd_table->fds[fd];

    if (!descriptor.has_value()) return err(EBADF);

    kinfoln("close: closing file descriptor %d (was referencing inode %zu)", fd, descriptor->inode->inode_number());

    descriptor = {};

    return 0;
}