/*
 * Copyright 2008-2010, Axel Dörfler, axeld@pinc-software.de.
 * Copyright 2011, Jérôme Duval, korli@users.berlios.de.
 * Copyright 2014 Haiku, Inc. All rights reserved.
 *
 * Distributed under the terms of the MIT License.
 *
 * Authors:
 *              Axel Dörfler, axeld@pinc-software.de
 *              Jérôme Duval, korli@users.berlios.de
 *              John Scipione, jscipione@gmail.com
 */


#include <dirent.h>
#include <unistd.h>
#include <util/kernel_cpp.h>
#include <string.h>

#include <new>

#include <AutoDeleter.h>
#include <fs_cache.h>
#include <fs_info.h>
#include <io_requests.h>
#include <NodeMonitor.h>
#include <StorageDefs.h>
#include <util/AutoLock.h>
#include <file_systems/fs_ops_support.h>

#include "DirectoryIterator.h"
#include "exfat.h"
#include "Inode.h"
#include "Utility.h"


//#define TRACE_EXFAT
#ifdef TRACE_EXFAT
#       define TRACE(x...) dprintf("\33[34mexfat:\33[0m " x)
#else
#       define TRACE(x...) ;
#endif
#define ERROR(x...) dprintf("\33[34mexfat:\33[0m " x)


#define EXFAT_IO_SIZE   65536


struct identify_cookie {
        exfat_super_block super_block;
        char name[B_FILE_NAME_LENGTH];
};


//!     exfat_io() callback hook
static status_t
iterative_io_get_vecs_hook(void* cookie, io_request* request, off_t offset,
        size_t size, struct file_io_vec* vecs, size_t* _count)
{
        Inode* inode = (Inode*)cookie;

        return file_map_translate(inode->Map(), offset, size, vecs, _count,
                inode->GetVolume()->BlockSize());
}


//!     exfat_io() callback hook
static status_t
iterative_io_finished_hook(void* cookie, io_request* request, status_t status,
        bool partialTransfer, size_t bytesTransferred)
{
        Inode* inode = (Inode*)cookie;
        rw_lock_read_unlock(inode->Lock());
        put_vnode(inode->GetVolume()->FSVolume(), inode->ID());
        return B_OK;
}


//      #pragma mark - Scanning


static float
exfat_identify_partition(int fd, partition_data* partition, void** _cookie)
{
        struct exfat_super_block superBlock;
        status_t status = Volume::Identify(fd, &superBlock);
        if (status != B_OK)
                return -1;

        identify_cookie* cookie = new (std::nothrow)identify_cookie;
        if (cookie == NULL)
                return -1;

        memcpy(&cookie->super_block, &superBlock, sizeof(exfat_super_block));
        memset(cookie->name, 0, sizeof(cookie->name));
                // zero out volume name

        uint32 rootDirCluster = superBlock.RootDirCluster();
        uint32 blockSize = 1 << superBlock.BlockShift();
        uint32 clusterSize = blockSize << superBlock.BlocksPerClusterShift();
        uint64 rootDirectoryOffset = EXFAT_SUPER_BLOCK_OFFSET
                + (uint64)superBlock.FirstDataBlock() * blockSize
                + (rootDirCluster - 2) * clusterSize;
        struct exfat_entry entry;
        size_t entrySize = sizeof(struct exfat_entry);
        for (uint32 i = 0; read_pos(fd, rootDirectoryOffset + i * entrySize,
                        &entry, entrySize) == (ssize_t)entrySize; i++) {
                if (entry.type == EXFAT_ENTRY_TYPE_NOT_IN_USE
                        || entry.type == EXFAT_ENTRY_TYPE_LABEL) {
                        if (get_volume_name(&entry, cookie->name, sizeof(cookie->name))
                                        != B_OK) {
                                delete cookie;
                                return -1;
                        }
                        break;
                }
        }

        if (cookie->name[0] == '\0') {
                off_t fileSystemSize = (off_t)superBlock.NumBlocks()
                        << superBlock.BlockShift();
                get_default_volume_name(fileSystemSize, cookie->name,
                        sizeof(cookie->name));
        }

        *_cookie = cookie;
        return 0.8f;
}


static status_t
exfat_scan_partition(int fd, partition_data* partition, void* _cookie)
{
        identify_cookie* cookie = (identify_cookie*)_cookie;

        partition->status = B_PARTITION_VALID;
        partition->flags |= B_PARTITION_FILE_SYSTEM;
        partition->content_size = cookie->super_block.NumBlocks()
                << cookie->super_block.BlockShift();
        partition->block_size = 1 << cookie->super_block.BlockShift();
        partition->content_name = strdup(cookie->name);

        return partition->content_name != NULL ? B_OK : B_NO_MEMORY;
}


static void
exfat_free_identify_partition_cookie(partition_data* partition, void* _cookie)
{
        delete (identify_cookie*)_cookie;
}


//      #pragma mark -


static status_t
exfat_mount(fs_volume* _volume, const char* device, uint32 flags,
        const char* args, ino_t* _rootID)
{
        Volume* volume = new(std::nothrow) Volume(_volume);
        if (volume == NULL)
                return B_NO_MEMORY;

        // TODO: this is a bit hacky: we can't use publish_vnode() to publish
        // the root node, or else its file cache cannot be created (we could
        // create it later, though). Therefore we're using get_vnode() in Mount(),
        // but that requires us to export our volume data before calling it.
        _volume->private_volume = volume;
        _volume->ops = &gExfatVolumeOps;

        status_t status = volume->Mount(device, flags);
        if (status != B_OK) {
                ERROR("Failed mounting the volume. Error: %s\n", strerror(status));
                delete volume;
                return status;
        }

        *_rootID = volume->RootNode()->ID();
        return B_OK;
}


static status_t
exfat_unmount(fs_volume *_volume)
{
        Volume* volume = (Volume *)_volume->private_volume;

        status_t status = volume->Unmount();
        delete volume;

        return status;
}


static status_t
exfat_read_fs_info(fs_volume* _volume, struct fs_info* info)
{
        Volume* volume = (Volume*)_volume->private_volume;

        // File system flags
        info->flags = B_FS_IS_PERSISTENT
                | (volume->IsReadOnly() ? B_FS_IS_READONLY : 0);
        info->io_size = EXFAT_IO_SIZE;
        info->block_size = volume->BlockSize();
        info->total_blocks = volume->SuperBlock().NumBlocks();
        info->free_blocks = 0; //volume->NumFreeBlocks();

        // Volume name
        strlcpy(info->volume_name, volume->Name(), sizeof(info->volume_name));

        // File system name
        strlcpy(info->fsh_name, "exfat", sizeof(info->fsh_name));

        return B_OK;
}


//      #pragma mark -


static status_t
exfat_get_vnode(fs_volume* _volume, ino_t id, fs_vnode* _node, int* _type,
        uint32* _flags, bool reenter)
{
        TRACE("get_vnode %" B_PRIdINO "\n", id);
        Volume* volume = (Volume*)_volume->private_volume;

        Inode* inode = new(std::nothrow) Inode(volume, id);
        if (inode == NULL)
                return B_NO_MEMORY;

        status_t status = inode->InitCheck();
        if (status != B_OK)
                delete inode;

        if (status == B_OK) {
                _node->private_node = inode;
                _node->ops = &gExfatVnodeOps;
                *_type = inode->Mode();
                *_flags = 0;
        } else
                ERROR("get_vnode: InitCheck() failed. Error: %s\n", strerror(status));

        return status;
}


static status_t
exfat_put_vnode(fs_volume* _volume, fs_vnode* _node, bool reenter)
{
        delete (Inode*)_node->private_node;
        return B_OK;
}


static bool
exfat_can_page(fs_volume* _volume, fs_vnode* _node, void* _cookie)
{
        return true;
}


static status_t
exfat_read_pages(fs_volume* _volume, fs_vnode* _node, void* _cookie,
        off_t pos, const iovec* vecs, size_t count, size_t* _numBytes)
{
        Volume* volume = (Volume*)_volume->private_volume;
        Inode* inode = (Inode*)_node->private_node;

        if (inode->FileCache() == NULL)
                return B_BAD_VALUE;

        rw_lock_read_lock(inode->Lock());

        uint32 vecIndex = 0;
        size_t vecOffset = 0;
        size_t bytesLeft = *_numBytes;
        status_t status;

        while (true) {
                file_io_vec fileVecs[8];
                size_t fileVecCount = 8;

                status = file_map_translate(inode->Map(), pos, bytesLeft, fileVecs,
                        &fileVecCount, 0);
                if (status != B_OK && status != B_BUFFER_OVERFLOW)
                        break;

                bool bufferOverflow = status == B_BUFFER_OVERFLOW;

                size_t bytes = bytesLeft;
                status = read_file_io_vec_pages(volume->Device(), fileVecs,
                        fileVecCount, vecs, count, &vecIndex, &vecOffset, &bytes);
                if (status != B_OK || !bufferOverflow)
                        break;

                pos += bytes;
                bytesLeft -= bytes;
        }

        rw_lock_read_unlock(inode->Lock());

        return status;
}


static status_t
exfat_io(fs_volume* _volume, fs_vnode* _node, void* _cookie,
        io_request* request)
{
        Volume* volume = (Volume*)_volume->private_volume;
        Inode* inode = (Inode*)_node->private_node;

#ifndef EXFAT_SHELL
        if (io_request_is_write(request) && volume->IsReadOnly()) {
                notify_io_request(request, B_READ_ONLY_DEVICE);
                return B_READ_ONLY_DEVICE;
        }
#endif

        if (inode->FileCache() == NULL) {
#ifndef EXFAT_SHELL
                notify_io_request(request, B_BAD_VALUE);
#endif
                return B_BAD_VALUE;
        }

        // We lock the node here and will unlock it in the "finished" hook.
        rw_lock_read_lock(inode->Lock());

        acquire_vnode(_volume, inode->ID());

        return do_iterative_fd_io(volume->Device(), request,
                iterative_io_get_vecs_hook, iterative_io_finished_hook, inode);
}


static status_t
exfat_get_file_map(fs_volume* _volume, fs_vnode* _node, off_t offset,
        size_t size, struct file_io_vec* vecs, size_t* _count)
{
        TRACE("exfat_get_file_map()\n");
        Inode* inode = (Inode*)_node->private_node;
        size_t index = 0, max = *_count;

        while (true) {
                off_t blockOffset;
                off_t blockLength;
                status_t status = inode->FindBlock(offset, blockOffset, &blockLength);
                if (status != B_OK)
                        return status;

                if (index > 0 && (vecs[index - 1].offset
                                == blockOffset - vecs[index - 1].length)) {
                        vecs[index - 1].length += blockLength;
                } else {
                        if (index >= max) {
                                // we're out of file_io_vecs; let's bail out
                                *_count = index;
                                return B_BUFFER_OVERFLOW;
                        }

                        vecs[index].offset = blockOffset;
                        vecs[index].length = blockLength;
                        index++;
                }

                offset += blockLength;
                size -= blockLength;

                if ((off_t)size <= vecs[index - 1].length || offset >= inode->Size()) {
                        // We're done!
                        *_count = index;
                        TRACE("exfat_get_file_map for inode %" B_PRIdINO"\n", inode->ID());
                        return B_OK;
                }
        }

        // can never get here
        return B_ERROR;
}


//      #pragma mark -


static status_t
exfat_lookup(fs_volume* _volume, fs_vnode* _directory, const char* name,
        ino_t* _vnodeID)
{
        TRACE("exfat_lookup: name address: %p (%s)\n", name, name);
        Volume* volume = (Volume*)_volume->private_volume;
        Inode* directory = (Inode*)_directory->private_node;

        // check access permissions
        status_t status = directory->CheckPermissions(X_OK);
        if (status < B_OK)
                return status;

        status = DirectoryIterator(directory).Lookup(name, strlen(name), _vnodeID);
        if (status != B_OK) {
                ERROR("exfat_lookup: name %s (%s)\n", name, strerror(status));
                if (status == B_ENTRY_NOT_FOUND)
                        entry_cache_add_missing(volume->ID(), directory->ID(), name);
                return status;
        }

        TRACE("exfat_lookup: ID %" B_PRIdINO "\n", *_vnodeID);
        entry_cache_add(volume->ID(), directory->ID(), name, *_vnodeID);

        return get_vnode(volume->FSVolume(), *_vnodeID, NULL);
}


static status_t
exfat_ioctl(fs_volume* _volume, fs_vnode* _node, void* _cookie, uint32 cmd,
        void* buffer, size_t bufferLength)
{
        TRACE("ioctl: %" B_PRIu32 "\n", cmd);

        /*Volume* volume = (Volume*)_volume->private_volume;*/
        return B_DEV_INVALID_IOCTL;
}


static status_t
exfat_read_stat(fs_volume* _volume, fs_vnode* _node, struct stat* stat)
{
        Inode* inode = (Inode*)_node->private_node;

        stat->st_dev = inode->GetVolume()->ID();
        stat->st_ino = inode->ID();
        stat->st_nlink = 1;
        stat->st_blksize = EXFAT_IO_SIZE;

        stat->st_uid = inode->UserID();
        stat->st_gid = inode->GroupID();
        stat->st_mode = inode->Mode();
        stat->st_type = 0;

        inode->GetAccessTime(stat->st_atim);
        inode->GetModificationTime(stat->st_mtim);
        inode->GetChangeTime(stat->st_ctim);
        inode->GetCreationTime(stat->st_crtim);

        stat->st_size = inode->Size();
        stat->st_blocks = (inode->Size() + DEV_BSIZE - 1) / DEV_BSIZE;

        return B_OK;
}


static status_t
exfat_open(fs_volume* /*_volume*/, fs_vnode* _node, int openMode,
        void** _cookie)
{
        Inode* inode = (Inode*)_node->private_node;

        // opening a directory read-only is allowed, although you can't read
        // any data from it.
        if (inode->IsDirectory() && (openMode & O_RWMASK) != 0)
                return B_IS_A_DIRECTORY;

        status_t status = inode->CheckPermissions(open_mode_to_access(openMode));
        if (status != B_OK)
                return status;

        // Prepare the cookie
        file_cookie* cookie = new(std::nothrow) file_cookie;
        if (cookie == NULL)
                return B_NO_MEMORY;
        ObjectDeleter<file_cookie> cookieDeleter(cookie);

        cookie->open_mode = openMode & EXFAT_OPEN_MODE_USER_MASK;
        cookie->last_size = inode->Size();
        cookie->last_notification = system_time();

        if ((openMode & O_NOCACHE) != 0 && inode->FileCache() != NULL) {
                // Disable the file cache, if requested?
                status = file_cache_disable(inode->FileCache());
                if (status != B_OK)
                        return status;
        }

        cookieDeleter.Detach();
        *_cookie = cookie;

        return B_OK;
}


static status_t
exfat_read(fs_volume* _volume, fs_vnode* _node, void* _cookie, off_t pos,
        void* buffer, size_t* _length)
{
        Inode* inode = (Inode*)_node->private_node;

        if (!inode->IsFile()) {
                *_length = 0;
                return inode->IsDirectory() ? B_IS_A_DIRECTORY : B_BAD_VALUE;
        }

        return inode->ReadAt(pos, (uint8*)buffer, _length);
}


static status_t
exfat_close(fs_volume *_volume, fs_vnode *_node, void *_cookie)
{
        return B_OK;
}


static status_t
exfat_free_cookie(fs_volume* _volume, fs_vnode* _node, void* _cookie)
{
        file_cookie* cookie = (file_cookie*)_cookie;
        Volume* volume = (Volume*)_volume->private_volume;
        Inode* inode = (Inode*)_node->private_node;

        if (inode->Size() != cookie->last_size)
                notify_stat_changed(volume->ID(), -1, inode->ID(), B_STAT_SIZE);

        delete cookie;
        return B_OK;
}


static status_t
exfat_access(fs_volume* _volume, fs_vnode* _node, int accessMode)
{
        Inode* inode = (Inode*)_node->private_node;
        return inode->CheckPermissions(accessMode);
}


static status_t
exfat_read_link(fs_volume *_volume, fs_vnode *_node, char *buffer,
        size_t *_bufferSize)
{
        Inode* inode = (Inode*)_node->private_node;

        if (!inode->IsSymLink())
                return B_BAD_VALUE;

        status_t result = inode->ReadAt(0, reinterpret_cast<uint8*>(buffer),
                _bufferSize);
        if (result != B_OK)
                return result;

        *_bufferSize = inode->Size();

        return B_OK;
}


//      #pragma mark - Directory functions


static status_t
exfat_open_dir(fs_volume* /*_volume*/, fs_vnode* _node, void** _cookie)
{
        Inode* inode = (Inode*)_node->private_node;
        status_t status = inode->CheckPermissions(R_OK);
        if (status < B_OK)
                return status;

        if (!inode->IsDirectory())
                return B_NOT_A_DIRECTORY;

        DirectoryIterator* iterator = new(std::nothrow) DirectoryIterator(inode);
        if (iterator == NULL || iterator->InitCheck() != B_OK) {
                delete iterator;
                return B_NO_MEMORY;
        }

        *_cookie = iterator;
        return B_OK;
}


static status_t
exfat_read_dir(fs_volume *_volume, fs_vnode *_node, void *_cookie,
        struct dirent *dirent, size_t bufferSize, uint32 *_num)
{
        TRACE("exfat_read_dir\n");
        DirectoryIterator* iterator = (DirectoryIterator*)_cookie;
        Volume* volume = (Volume*)_volume->private_volume;

        uint32 maxCount = *_num;
        uint32 count = 0;

        while (count < maxCount && bufferSize > sizeof(struct dirent)) {
                ino_t id;
                size_t length = bufferSize - offsetof(struct dirent, d_name);

                status_t status = iterator->GetNext(dirent->d_name, &length, &id);
                if (status == B_ENTRY_NOT_FOUND)
                        break;

                if (status == B_BUFFER_OVERFLOW) {
                        // the remaining name buffer length was too small
                        if (count == 0)
                                return B_BUFFER_OVERFLOW;
                        break;
                }

                if (status != B_OK)
                        return status;

                dirent->d_dev = volume->ID();
                dirent->d_ino = id;

                dirent = next_dirent(dirent, length, bufferSize);
                count++;
        }

        *_num = count;
        TRACE("exfat_read_dir end\n");
        return B_OK;
}


static status_t
exfat_rewind_dir(fs_volume * /*_volume*/, fs_vnode * /*node*/, void *_cookie)
{
        DirectoryIterator* iterator = (DirectoryIterator*)_cookie;

        return iterator->Rewind();
}


static status_t
exfat_close_dir(fs_volume * /*_volume*/, fs_vnode * /*node*/, void * /*_cookie*/)
{
        return B_OK;
}


static status_t
exfat_free_dir_cookie(fs_volume *_volume, fs_vnode *_node, void *_cookie)
{
        delete (DirectoryIterator*)_cookie;
        return B_OK;
}


fs_volume_ops gExfatVolumeOps = {
        &exfat_unmount,
        &exfat_read_fs_info,
        NULL,   // write_fs_info()
        NULL,   // fs_sync,
        &exfat_get_vnode,
};


fs_vnode_ops gExfatVnodeOps = {
        /* vnode operations */
        &exfat_lookup,
        NULL,
        &exfat_put_vnode,
        NULL,   // exfat_remove_vnode,

        /* VM file access */
        &exfat_can_page,
        &exfat_read_pages,
        NULL,   // exfat_write_pages,

        NULL,   // io()
        NULL,   // cancel_io()

        &exfat_get_file_map,

        &exfat_ioctl,
        NULL,
        NULL,   // fs_select
        NULL,   // fs_deselect
        NULL,   // fs_fsync,

        &exfat_read_link,
        NULL,   // fs_create_symlink,

        NULL,   // fs_link,
        NULL,   // fs_unlink,
        NULL,   // fs_rename,

        &exfat_access,
        &exfat_read_stat,
        NULL,   // fs_write_stat,
        NULL,   // fs_preallocate

        /* file operations */
        NULL,   // fs_create,
        &exfat_open,
        &exfat_close,
        &exfat_free_cookie,
        &exfat_read,
        NULL,   //      fs_write,

        /* directory operations */
        NULL,   // fs_create_dir,
        NULL,   // fs_remove_dir,
        &exfat_open_dir,
        &exfat_close_dir,
        &exfat_free_dir_cookie,
        &exfat_read_dir,
        &exfat_rewind_dir,

        /* attribute directory operations */
        NULL,   // fs_open_attr_dir,
        NULL,   // fs_close_attr_dir,
        NULL,   // fs_free_attr_dir_cookie,
        NULL,   // fs_read_attr_dir,
        NULL,   // fs_rewind_attr_dir,

        /* attribute operations */
        NULL,   // fs_create_attr,
        NULL,   // fs_open_attr,
        NULL,   // fs_close_attr,
        NULL,   // fs_free_attr_cookie,
        NULL,   // fs_read_attr,
        NULL,   // fs_write_attr,
        NULL,   // fs_read_attr_stat,
        NULL,   // fs_write_attr_stat,
        NULL,   // fs_rename_attr,
        NULL,   // fs_remove_attr,
};


static file_system_module_info sExfatFileSystem = {
        {
                "file_systems/exfat" B_CURRENT_FS_API_VERSION,
                0,
                NULL,
        },

        "exfat",                                                // short_name
        "ExFAT File System",                    // pretty_name
        0,                                                              // DDM flags

        // scanning
        exfat_identify_partition,
        exfat_scan_partition,
        exfat_free_identify_partition_cookie,
        NULL,   // free_partition_content_cookie()

        &exfat_mount,

        NULL,
};


module_info *modules[] = {
        (module_info *)&sExfatFileSystem,
        NULL,
};