Luna/kernel/src/fs/TmpFS.cpp

#define MODULE "tmpfs"

#include "fs/TmpFS.h"
#include "log/Log.h"
#include "std/errno.h"
#include "std/stdlib.h"
#include "std/string.h"

ssize_t TmpFSImpl::read(VFS::Node* node, size_t offset, size_t size, char* buffer)
{
    if (!node) return -1;
    if (!node->impl) return -1;
    return ((TmpFS*)node->impl)->read(node, offset, size, buffer);
}

ssize_t TmpFSImpl::write(VFS::Node* node, size_t offset, size_t size, char* buffer)
{
    if (!node) return -1;
    if (!node->impl) return -1;
    return ((TmpFS*)node->impl)->write(node, offset, size, buffer);
}

VFS::Node* TmpFSImpl::find(VFS::Node* node, const char* filename)
{
    if (!node) return 0;
    if (!node->impl) return 0;
    return ((TmpFS*)node->impl)->find(node, filename);
}

VFS::Node* TmpFSImpl::readdir(VFS::Node* node, long index)
{
    if (!node) return 0;
    if (!node->impl) return 0;
    return ((TmpFS*)node->impl)->readdir(node, index);
}

int TmpFSImpl::mkdir(VFS::Node* node, const char* filename, mode_t mode)
{
    if (!node) return -1;
    if (!node->impl) return -1;
    return ((TmpFS*)node->impl)->mkdir(node, filename, mode);
}

TmpFS* TmpFS::create(const char* name)
{
    return new TmpFS(name);
}

void TmpFS::release(TmpFS* fs)
{
    fs->purge();
    kfree(fs->m_dirs.buf);
    delete fs->root();
    delete fs;
}

extern uint64_t clock_now();

TmpFS::TmpFS(const char* name)
{
    m_root = new VFS::Node;
    m_root->atime = m_root->ctime = m_root->mtime = clock_now();
    m_root->impl = (uint64_t)this;
    m_root->inode = 0;
    m_root->gid = m_root->uid = 0;
    m_root->mode = 0755;
    m_root->length = 0;
    m_root->type = VFS_DIRECTORY;
    m_root->tty = 0;
    m_root->readdir_func = TmpFSImpl::readdir;
    m_root->find_func = TmpFSImpl::find;
    m_root->mkdir_func = TmpFSImpl::mkdir;
    m_root->flags = 0;
    strlcpy(m_root->name, name, sizeof(m_root->name));
    m_dirs.buf = (Directory*)krealloc(nullptr, sizeof(Directory));
    m_dirs.len = 1;
    m_dirs.buf[0] = {nullptr, 0, 1};
}

void TmpFS::purge()
{
    for (size_t i = 0; i < m_dirs.len; i++)
    {
        if (m_dirs.buf[i].valid && m_dirs.buf[i].len) kfree(m_dirs.buf[i].buf);
    }

    m_dirs.buf = (Directory*)krealloc(m_dirs.buf, sizeof(Directory)); // leave space for the root directory

    for (size_t i = 0; i < m_files.len; i++)
    {
        if (m_files.buf[i].valid && m_files.buf[i].len) kfree(m_files.buf[i].buf);
    }

    kfree(m_files.buf);
}

ssize_t TmpFS::read(VFS::Node* node, size_t offset, size_t size, char* buffer)
{
    if (!node) return -1;
    if (node->inode >= m_files.len) return -1;
    File& file = m_files.buf[node->inode];
    if (!file.valid) return -1;
    if (offset > file.len) return 0;
    if (offset + size > file.len) { size = file.len - offset; }
    memcpy(buffer, (void*)(file.buf + offset), size);
    return size;
}

ssize_t TmpFS::write(VFS::Node* node, size_t offset, size_t size, char* buffer)
{
    if (!node) return -1;
    if (node->inode >= m_files.len) return -1;
    File& file = m_files.buf[node->inode];
    if (!file.valid) return -1;
    if (offset + size > file.len)
    {
        char* newbuf = (char*)krealloc(file.buf, offset + size);
        if (!newbuf) { size = file.len - offset; }
        else
        {
            file.buf = newbuf;
            file.len = offset + size;
            node->length = file.len;
        }
    }
    memcpy((void*)(file.buf + offset), buffer, size);
    return size;
}

VFS::Node* TmpFS::find(VFS::Node* node, const char* filename)
{
    if (!node) return 0;
    if (node->inode >= m_dirs.len) return 0;
    Directory& dir = m_dirs.buf[node->inode];
    if (!dir.valid) return 0;
    for (size_t i = 0; i < dir.len; i++)
    {
        if (!strncmp(dir.buf[i].name, filename, sizeof(dir.buf[i].name))) { return &dir.buf[i]; }
    }
    return 0;
}

VFS::Node* TmpFS::readdir(VFS::Node* node, long index)
{
    if (!node) return 0;
    if (node->inode >= m_dirs.len) return 0;
    Directory& dir = m_dirs.buf[node->inode];
    if (!dir.valid) return 0;
    if (index >= (long)dir.len) return 0;
    return &dir.buf[index];
}

int TmpFS::mkdir(VFS::Node* node, const char* filename, mode_t mode)
{
    kinfoln("starting to create directory %s in %s", filename, node->name);

    if (!node) return 0;
    if (node->inode >= m_dirs.len) return 0;
    Directory& dir = m_dirs.buf[node->inode];
    if (!dir.valid) return 0;

    kinfoln("creating directory %s in %s", filename, node->name);

    size_t new_len = m_dirs.len + 1;
    Directory* new_buf = (Directory*)krealloc(m_dirs.buf, new_len);
    if (!new_buf) return -ENOMEM;

    m_dirs.len = new_len;
    m_dirs.buf = new_buf;

    uint64_t new_inode = m_dirs.len - 1;

    m_dirs.buf[new_inode].valid = 0;

    size_t new_dir_len = dir.len + 1;
    VFS::Node* new_dir_buf = (VFS::Node*)krealloc(dir.buf, new_dir_len);
    if (!new_dir_buf) return -ENOMEM;

    m_dirs.buf[new_inode].valid = 1;
    m_dirs.buf[new_inode].len = 0;
    m_dirs.buf[new_inode].buf = nullptr;

    dir.buf = new_dir_buf;
    dir.len = new_dir_len;

    node->mtime = clock_now();
    node->ctime = clock_now();
    node->length++;

    VFS::Node* new_node = &dir.buf[dir.len - 1];

    new_node->inode = new_inode;
    new_node->atime = new_node->ctime = new_node->mtime = clock_now();
    new_node->impl = (uint64_t)this;
    new_node->gid = new_node->uid = 0;
    new_node->mode = mode;
    new_node->length = 0;
    new_node->type = VFS_DIRECTORY;
    new_node->tty = 0;
    new_node->readdir_func = TmpFSImpl::readdir;
    new_node->find_func = TmpFSImpl::find;
    new_node->mkdir_func = TmpFSImpl::mkdir;
    new_node->flags = 0;
    strlcpy(new_node->name, filename, sizeof(new_node->name));

    return 0;
}