Luna/kernel/src/thread/Task.cpp

#define MODULE "sched"

#include "thread/Task.h"
#include "log/Log.h"
#include "memory/VMM.h"
#include "std/assert.h"
#include "std/errno.h"
#include "std/string.h"

void Task::restore_context(Context* context)
{
    memcpy(context, &regs, sizeof(Context));
}

void Task::save_context(Context* context)
{
    memcpy(&regs, context, sizeof(Context));
}

void Task::save_floating()
{
    floating_saved = true;
    asm volatile("fxsave (%0)" : : "r"((char*)floating_region));
}

void Task::restore_floating()
{
    if (!floating_saved) return;
    asm volatile("fxrstor (%0)" : : "r"((char*)floating_region));
}

bool Task::is_user_task()
{
    return user_task;
}

int Task::alloc_fd()
{
    int fd;
    for (fd = 0; fd < TASK_MAX_FDS; fd++)
    {
        if (!files[fd].is_open()) break;
    }

    if (fd == TASK_MAX_FDS) { return -1; }

    return fd;
}

int Task::alloc_fd_greater_than_or_equal(int base_fd)
{
    int fd;
    if (base_fd >= TASK_MAX_FDS) return -1;
    for (fd = base_fd; fd < TASK_MAX_FDS; fd++)
    {
        if (!files[fd].is_open()) break;
    }

    if (fd == TASK_MAX_FDS) { return -1; }

    return fd;
}

void Task::switch_to_address_space()
{
    VMM::switch_to_user_address_space(address_space);
    VMM::apply_address_space();
}

bool Task::has_died()
{
    return state == Exited;
}

void Task::resume_read()
{
    regs.rax = files[blocking_read_info.fd].read(blocking_read_info.size, blocking_read_info.buf);
}

bool Task::is_read_still_blocking()
{
    return VFS::would_block(files[blocking_read_info.fd].node());
}

void Task::resume()
{
    VMM::switch_back_to_kernel_address_space();
    VMM::apply_address_space();
    VMM::switch_to_previous_user_address_space();
    switch (block_reason)
    {
    case BlockReason::None: ASSERT(false);
    case BlockReason::Reading: resume_read(); break;
    case BlockReason::Waiting: resume_wait(); break;

    default: ASSERT(false);
    }
    VMM::apply_address_space();
    block_reason = BlockReason::None;
    state = Running;
}

bool Task::is_still_blocking()
{
    switch (block_reason)
    {
    case BlockReason::None: ASSERT(false);
    case BlockReason::Reading: return is_read_still_blocking();
    case BlockReason::Waiting: return is_wait_still_blocking();

    default: ASSERT(false);
    }
}

Descriptor* Task::descriptor_from_fd(int fd, int& error)
{
    if (fd < 0 || fd >= TASK_MAX_FDS)
    {
        error = EBADF;
        return nullptr;
    }
    if (!files[fd].is_open())
    {
        error = EBADF;
        return nullptr;
    }
    return &files[fd];
}

bool Task::is_superuser()
{
    return euid == 0 || egid == 0;
}