// Copyright 2016 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <fuchsia/device/c/fidl.h>
#include <fuchsia/io/c/fidl.h>
#include <fuchsia/io/llcpp/fidl.h>
#include <lib/fdio/io.h>
#include <lib/fdio/namespace.h>
#include <lib/fdio/fd.h>
#include <lib/fdio/fdio.h>
#include <lib/fdio/directory.h>
#include <string.h>
#include <zircon/device/vfs.h>
#include <zircon/syscalls.h>

#include "private.h"

#define ZXDEBUG 0

// POLL_MASK and POLL_SHIFT intend to convert the lower five POLL events into
// ZX_USER_SIGNALs and vice-versa. Other events need to be manually converted to
// a zx_signals_t, if they are desired.
#define POLL_SHIFT  24
#define POLL_MASK   0x1F

static_assert(FDIO_CHUNK_SIZE >= PATH_MAX,
              "FDIO_CHUNK_SIZE must be large enough to contain paths");

static_assert(fuchsia_io_VMO_FLAG_READ == ZX_VM_PERM_READ,
              "Vmar / Vmo flags should be aligned");
static_assert(fuchsia_io_VMO_FLAG_WRITE == ZX_VM_PERM_WRITE,
              "Vmar / Vmo flags should be aligned");
static_assert(fuchsia_io_VMO_FLAG_EXEC == ZX_VM_PERM_EXECUTE,
              "Vmar / Vmo flags should be aligned");

static_assert(ZX_USER_SIGNAL_0 == (1 << POLL_SHIFT), "");
static_assert((POLLIN << POLL_SHIFT) == fuchsia_device_DEVICE_SIGNAL_READABLE, "");
static_assert((POLLPRI << POLL_SHIFT) == fuchsia_device_DEVICE_SIGNAL_OOB, "");
static_assert((POLLOUT << POLL_SHIFT) == fuchsia_device_DEVICE_SIGNAL_WRITABLE, "");
static_assert((POLLERR << POLL_SHIFT) == fuchsia_device_DEVICE_SIGNAL_ERROR, "");
static_assert((POLLHUP << POLL_SHIFT) == fuchsia_device_DEVICE_SIGNAL_HANGUP, "");

// The |mode| argument used for |fuchsia.io.Directory/Open| calls.
#define FDIO_CONNECT_MODE ((uint32_t)0755)

// Validates a |path| argument.
//
// Returns ZX_OK if |path| is non-null and less than |PATH_MAX| in length
// (excluding the null terminator). Upon success, the length of the path is
// returned via |out_length|.
//
// Otherwise, returns |ZX_ERR_INVALID_ARGS|.
static zx_status_t fdio_validate_path(const char* path, size_t* out_length) {
    if (path == nullptr) {
        return ZX_ERR_INVALID_ARGS;
    }
    size_t length = strnlen(path, PATH_MAX);
    if (length >= PATH_MAX) {
        return ZX_ERR_INVALID_ARGS;
    }
    *out_length = length;
    return ZX_OK;
}

__EXPORT
zx_status_t fdio_service_connect(const char* path, zx_handle_t h) {
    // TODO: fdio_validate_path?
    if (path == nullptr) {
        zx_handle_close(h);
        return ZX_ERR_INVALID_ARGS;
    }
    // Otherwise attempt to connect through the root namespace
    if (fdio_root_ns != nullptr) {
        return fdio_ns_connect(fdio_root_ns, path, ZX_FS_RIGHT_READABLE | ZX_FS_RIGHT_WRITABLE, h);
    }
    // Otherwise we fail
    zx_handle_close(h);
    return ZX_ERR_NOT_FOUND;
}

__EXPORT
zx_status_t fdio_service_connect_at(zx_handle_t dir, const char* path, zx_handle_t request_raw) {
    zx::channel request(request_raw);
    size_t length = 0u;
    zx_status_t status = fdio_validate_path(path, &length);
    if (status != ZX_OK) {
        return status;
    }

    if (dir == ZX_HANDLE_INVALID) {
        return ZX_ERR_UNAVAILABLE;
    }
    uint32_t flags = ZX_FS_RIGHT_READABLE | ZX_FS_RIGHT_WRITABLE;
    return fuchsia::io::Directory::Call::Open(zx::unowned_channel(dir),
                                              flags,
                                              FDIO_CONNECT_MODE,
                                              fidl::StringView(length, path),
                                              std::move(request));
}

__EXPORT
zx_status_t fdio_open(const char* path, uint32_t flags, zx_handle_t request) {
    // TODO: fdio_validate_path?
    if (path == nullptr) {
        zx_handle_close(request);
        return ZX_ERR_INVALID_ARGS;
    }
    // Otherwise attempt to connect through the root namespace
    if (fdio_root_ns != nullptr) {
        return fdio_ns_connect(fdio_root_ns, path, flags, request);
    }
    // Otherwise we fail
    zx_handle_close(request);
    return ZX_ERR_NOT_FOUND;
}

__EXPORT
zx_status_t fdio_open_at(zx_handle_t dir, const char* path, uint32_t flags,
                         zx_handle_t raw_request) {
    zx::channel request(raw_request);
    size_t length = 0u;
    zx_status_t status = fdio_validate_path(path, &length);
    if (status != ZX_OK) {
        return status;
    }

    if (flags & ZX_FS_FLAG_DESCRIBE) {
        return ZX_ERR_INVALID_ARGS;
    }

    return fuchsia::io::Directory::Call::Open(zx::unowned_channel(dir),
                                              flags,
                                              FDIO_CONNECT_MODE,
                                              fidl::StringView(length, path),
                                              std::move(request));
}

__EXPORT
zx_handle_t fdio_service_clone(zx_handle_t handle) {
    if (handle == ZX_HANDLE_INVALID) {
        return ZX_HANDLE_INVALID;
    }
    zx::channel clone, request;
    zx_status_t status = zx::channel::create(0, &clone, &request);
    if (status != ZX_OK) {
        return ZX_HANDLE_INVALID;
    }
    uint32_t flags = ZX_FS_FLAG_CLONE_SAME_RIGHTS;
    status = fuchsia::io::Node::Call::Clone(zx::unowned_channel(handle), flags, std::move(request));
    if (status != ZX_OK) {
        return ZX_HANDLE_INVALID;
    }
    return clone.release();
}

__EXPORT
zx_status_t fdio_service_clone_to(zx_handle_t handle, zx_handle_t request_raw) {
    zx::channel request(request_raw);
    if (!request.is_valid()) {
        return ZX_ERR_INVALID_ARGS;
    }
    uint32_t flags = ZX_FS_FLAG_CLONE_SAME_RIGHTS;
    return fuchsia::io::Node::Call::Clone(zx::unowned_channel(handle), flags, std::move(request));
}

// Creates an |fdio_t| from a Zircon socket object.
//
// Examines |socket| and determines whether to create a pipe, stream socket, or
// datagram socket.
//
// Always consumes |socket|.
static zx_status_t fdio_from_socket(zx_handle_t socket, fdio_t** out_io) {
    zx_info_socket_t info;
    memset(&info, 0, sizeof(info));
    zx_status_t status = zx_object_get_info(socket,
                                            ZX_INFO_SOCKET,
                                            &info,
                                            sizeof(info),
                                            nullptr,
                                            nullptr);
    if (status != ZX_OK) {
        zx_handle_close(socket);
        return status;
    }
    fdio_t* io = nullptr;
    if ((info.options & ZX_SOCKET_HAS_CONTROL) != 0) {
        // If the socket has a control plane, then the socket is either
        // a stream or a datagram socket.
        if ((info.options & ZX_SOCKET_DATAGRAM) != 0) {
            io = fdio_socket_create_datagram(socket, IOFLAG_SOCKET_CONNECTED);
        } else {
            io = fdio_socket_create_stream(socket, IOFLAG_SOCKET_CONNECTED);
        }
    } else {
        // Without a control plane, the socket is a pipe.
        io = fdio_pipe_create(socket);
    }
    if (!io) {
        return ZX_ERR_NO_RESOURCES;
    }
    *out_io = io;
    return ZX_OK;
}

// Create an |fdio_t| from a |handle| and an |info|.
//
// Uses |info| to determine what kind of |fdio_t| to create.
//
// Upon success, |out_io| receives ownership of all handles.
//
// Upon failure, consumes all handles.
static zx_status_t fdio_from_node_info(zx_handle_t raw_handle,
                                       fuchsia::io::NodeInfo info,
                                       fdio_t** out_io) {
    zx::handle handle(raw_handle);
    fdio_t* io = nullptr;
    zx_status_t status = ZX_OK;
    if (!handle.is_valid()) {
        return ZX_ERR_INVALID_ARGS;
    }

    switch (info.which()) {
    case fuchsia::io::NodeInfo::Tag::kDirectory:
        io = fdio_dir_create(handle.release());
        break;
    case fuchsia::io::NodeInfo::Tag::kService:
        io = fdio_remote_create(handle.release(), 0);
        break;
    case fuchsia::io::NodeInfo::Tag::kFile:
        io = fdio_file_create(handle.release(), info.mutable_file().event.release());
        break;
    case fuchsia::io::NodeInfo::Tag::kDevice:
        io = fdio_remote_create(handle.release(), info.mutable_device().event.release());
        break;
    case fuchsia::io::NodeInfo::Tag::kTty:
        io = fdio_remote_create(handle.release(), info.mutable_tty().event.release());
        break;
    case fuchsia::io::NodeInfo::Tag::kVmofile: {
        uint64_t seek = 0u;
        zx_status_t io_status = fuchsia_io_FileSeek(
            handle.get(), 0, fuchsia_io_SeekOrigin_START, &status, &seek);
        if (io_status != ZX_OK) {
            status = io_status;
        }
        if (status != ZX_OK) {
            return status;
        }
        io = fdio_vmofile_create(handle.release(),
                                 info.mutable_vmofile().vmo.release(),
                                 info.vmofile().offset,
                                 info.vmofile().length,
                                 seek);
        break;
    }
    case fuchsia::io::NodeInfo::Tag::kPipe: {
        return fdio_from_socket(info.mutable_pipe().socket.release(), out_io);
    }
    default:
        return ZX_ERR_NOT_SUPPORTED;
    }

    if (io == nullptr) {
        return ZX_ERR_NO_RESOURCES;
    }

    *out_io = io;
    return ZX_OK;
}

// Creates an |fdio_t| from a Zircon channel object.
//
// The |channel| must implement the |fuchsia.io.Node| protocol. Uses the
// |Describe| method from the |fuchsia.io.Node| protocol to determine the type
// of |fdio_t| object to create.
//
// Always consumes |channel|.
static zx_status_t fdio_from_channel(zx_handle_t channel, fdio_t** out_io) {
    fuchsia::io::NodeInfo info;
    zx_status_t status = fuchsia::io::Node::Call::Describe(zx::unowned_channel(channel), &info);
    if (status != ZX_OK) {
        zx_handle_close(channel);
        return status;
    }
    return fdio_from_node_info(channel, std::move(info), out_io);
}

__EXPORT
zx_status_t fdio_create(zx_handle_t handle, fdio_t** out_io) {
    zx_info_handle_basic_t info;
    zx_status_t status = zx_object_get_info(handle, ZX_INFO_HANDLE_BASIC, &info,
                                            sizeof(info), nullptr, nullptr);
    if (status != ZX_OK)
        return status;
    fdio_t* io = nullptr;
    switch (info.type) {
        case ZX_OBJ_TYPE_CHANNEL:
            return fdio_from_channel(handle, out_io);
        case ZX_OBJ_TYPE_SOCKET:
            return fdio_from_socket(handle, out_io);
        case ZX_OBJ_TYPE_VMO:
            io = fdio_vmo_create(handle, 0u);
            break;
        case ZX_OBJ_TYPE_LOG:
            io = fdio_logger_create(handle);
            break;
        default: {
            zx_handle_close(handle);
            return ZX_ERR_INVALID_ARGS;
        }
    }
    if (io == nullptr) {
        return ZX_ERR_NO_MEMORY;
    }
    *out_io = io;
    return ZX_OK;
}

zx_status_t fdio_remote_open_at(zx_handle_t dir, const char* path, uint32_t flags,
                                uint32_t mode, fdio_t** out_io) {
    size_t length = 0u;
    zx_status_t status = fdio_validate_path(path, &length);
    if (status != ZX_OK) {
        return status;
    }

    zx::channel handle, request;
    status = zx::channel::create(0, &handle, &request);
    if (status != ZX_OK) {
        return status;
    }

    status = fuchsia::io::Directory::Call::Open(zx::unowned_channel(dir),
                                                flags,
                                                mode,
                                                fidl::StringView(length, path),
                                                std::move(request));
    if (status != ZX_OK) {
        return status;
    }

    if (flags & ZX_FS_FLAG_DESCRIBE) {
        fuchsia::io::NodeInfo node_info;
        zx_status_t on_open_status = ZX_OK;
        status = fuchsia::io::Directory::Call::HandleEvents(zx::unowned_channel(handle),
                                                            fuchsia::io::Directory::EventHandlers {
            .on_open = [&node_info, &on_open_status](zx_status_t status,
                                                     fuchsia::io::NodeInfo* info) {
                on_open_status = status;
                if (info) {
                    node_info = std::move(*info);
                }
                return ZX_OK;
            },
            .unknown = [] {
                return ZX_ERR_IO;
            }
        });

        if (status == ZX_ERR_PEER_CLOSED) {
            return status;
        } else if (status != ZX_OK) {
            return ZX_ERR_IO;
        } else if (on_open_status != ZX_OK) {
            return on_open_status;
        }
        return fdio_from_node_info(handle.release(), std::move(node_info), out_io);
    }

    fdio_t* io = fdio_remote_create(handle.release(), 0);
    if (io == nullptr) {
        return ZX_ERR_NO_RESOURCES;
    }
    *out_io = io;
    return ZX_OK;
}