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/*
This file is part of libextractor.
(C) 2012 Vidyut Samanta and Christian Grothoff
libextractor is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published
by the Free Software Foundation; either version 3, or (at your
option) any later version.
libextractor is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with libextractor; see the file COPYING. If not, write to the
Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.
*/
/**
* @file main/extractor_ipc.h
* @brief IPC with plugin (OS-independent API)
* @author Christian Grothoff
*/
#ifndef EXTRACTOR_IPC_H
#define EXTRACTOR_IPC_H
#include "extractor_datasource.h"
/**
* How long do we allow an individual meta data object to be?
* Used to guard against (broken) plugns causing us to use
* excessive amounts of memory.
*/
#define MAX_META_DATA 32 * 1024 * 1024
/**
* Maximum length of a shared memory object name
*/
#define MAX_SHM_NAME 255
/**
* Sent from LE to a plugin to initialize it (open shm,
* reset position counters etc).
*/
#define MESSAGE_INIT_STATE 0x01
/**
* Sent from LE to a plugin to tell it that shm contents
* were updated. Only used for OPMODE_COMPRESS.
*/
#define MESSAGE_UPDATED_SHM 0x02
/**
* Sent from plugin to LE to tell LE that plugin is done
* analyzing current file and will send no more data.
*/
#define MESSAGE_DONE 0x03
/**
* Sent from plugin to LE to tell LE that plugin needs
* to read a different part of the source file.
*/
#define MESSAGE_SEEK 0x04
/**
* Sent from plugin to LE to tell LE about metadata discovered.
*/
#define MESSAGE_META 0x05
/**
* Sent from LE to plugin to make plugin discard its state (unmap
* and close shm).
*/
#define MESSAGE_DISCARD_STATE 0x06
/**
* Definition of an IPC communication channel with
* some plugin.
*/
struct EXTRACTOR_Channel;
/**
* Definition of a shared memory area.
*/
struct EXTRACTOR_SharedMemory;
/**
* Header used for our IPC replies. A header
* with all fields being zero is used to indicate
* the end of the stream.
*/
struct IpcHeader
{
/**
* Type of the meta data.
*/
enum EXTRACTOR_MetaType meta_type;
/**
* Format of the meta data.
*/
enum EXTRACTOR_MetaFormat meta_format;
/**
* Number of bytes of meta data (value)
*/
size_t data_len;
/**
* Length of the mime type string describing the meta data value's mime type,
* including 0-terminator, 0 for mime type of "NULL".
*/
size_t mime_len;
};
/**
* Create a shared memory area.
*
* @param size size of the shared area
* @return NULL on error
*/
struct EXTRACTOR_SharedMemory *
EXTRACTOR_IPC_shared_memory_create_ (size_t size);
/**
* Destroy shared memory area.
*
* @param shm memory area to destroy
* @return NULL on error
*/
void
EXTRACTOR_IPC_shared_memory_destroy_ (struct EXTRACTOR_SharedMemory *shm);
/**
* Initialize shared memory area from data source.
*
* @param shm memory area to initialize
* @param ds data source to use for initialization
* @param off offset to use in data source
* @param size number of bytes to copy
* @return -1 on error, otherwise number of bytes copied
*/
ssize_t
EXTRACTOR_IPC_shared_memory_set_ (struct EXTRACTOR_SharedMemory *shm,
struct EXTRACTOR_Datasource *ds,
uint64_t off,
size_t size);
/**
* Create a channel to communicate with a process wrapping
* the plugin of the given name. Starts the process as well.
*
* @param plugin the plugin
* @param shm memory to share with the process
* @return NULL on error, otherwise IPC channel
*/
struct EXTRACTOR_Channel *
EXTRACTOR_IPC_channel_create_ (struct EXTRACTOR_PluginList *plugin,
struct EXTRACTOR_SharedMemory *shm);
/**
* Destroy communication channel with a plugin/process. Also
* destroys the process.
*
* @param channel channel to communicate with the plugin
*/
void
EXTRACTOR_IPC_channel_destroy_ (struct EXTRACTOR_Channel *channel);
/**
* Send data via the given IPC channel (blocking).
*
* @param channel channel to communicate with the plugin
* @param buf data to send
* @param size number of bytes in buf to send
* @return -1 on error, number of bytes sent on success
* (never does partial writes)
*/
ssize_t
EXTRACTOR_IPC_channel_send_ (struct EXTRACTOR_Channel *channel,
const void *data,
size_t size);
/**
* Handler for a message from one of the plugins.
*
* @param cls closure
* @param short_libname library name of the channel sending the message
* @param msg header of the message from the plugin
* @param value 'data' send from the plugin
* @param mime mime string send from the plugin
*/
typedef void (*EXTRACTOR_ChannelMessageProcessor) (void *cls,
struct EXTRACTOR_PluginList *plugin,
const struct IpcHeader *msg,
const void *value,
const char *mime);
/**
* Process a reply from channel (seek request, metadata and done message)
*
* @param plugin plugin this communication is about
* @param buf buffer with data from IPC channel
* @param size number of bytes in buffer
* @param proc metadata callback
* @param proc_cls callback cls
* @return number of bytes processed, -1 on error
*/
ssize_t
EXTRACTOR_IPC_process_reply_ (struct EXTRACTOR_PluginList *plugin,
const void *data,
size_t size,
EXTRACTOR_ChannelMessageProcessor proc,
void *proc_cls);
/**
* Receive data from any of the given IPC channels (blocking).
* Wait for one of the plugins to reply.
*
* @param channels array of channels, channels that break may be set to NULL
* @param num_channels length of the 'channels' array
* @param proc function to call to process messages (may be called
* more than once)
* @param proc_cls closure for 'proc'
* @return -1 on error (i.e. no response in 10s), 1 on success
*/
int
EXTRACTOR_IPC_channel_recv_ (struct EXTRACTOR_Channel **channels,
unsigned int num_channels,
EXTRACTOR_ChannelMessageProcessor proc,
void *proc_cls);
#endif
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