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/*
* Copyright (c) 2000-2007 Niels Provos <provos@citi.umich.edu>
* Copyright (c) 2007-2012 Niels Provos and Nick Mathewson
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef EVBUFFER_INTERNAL_H_INCLUDED_
#define EVBUFFER_INTERNAL_H_INCLUDED_
#ifdef __cplusplus
extern "C" {
#endif
#include "event2/event-config.h"
#include "evconfig-private.h"
#include "event2/util.h"
#include "event2/event_struct.h"
#include "util-internal.h"
#include "defer-internal.h"
/* Experimental cb flag: "never deferred." Implementation note:
* these callbacks may get an inaccurate view of n_del/n_added in their
* arguments. */
#define EVBUFFER_CB_NODEFER 2
#ifdef _WIN32
#include <winsock2.h>
#endif
#include <sys/queue.h>
/* Minimum allocation for a chain. We define this so that we're burning no
* more than 5% of each allocation on overhead. It would be nice to lose even
* less space, though. */
#if EVENT__SIZEOF_VOID_P < 8
#define MIN_BUFFER_SIZE 512
#else
#define MIN_BUFFER_SIZE 1024
#endif
/** A single evbuffer callback for an evbuffer. This function will be invoked
* when bytes are added to or removed from the evbuffer. */
struct evbuffer_cb_entry {
/** Structures to implement a doubly-linked queue of callbacks */
LIST_ENTRY(evbuffer_cb_entry) next;
/** The callback function to invoke when this callback is called.
If EVBUFFER_CB_OBSOLETE is set in flags, the cb_obsolete field is
valid; otherwise, cb_func is valid. */
union {
evbuffer_cb_func cb_func;
evbuffer_cb cb_obsolete;
} cb;
/** Argument to pass to cb. */
void *cbarg;
/** Currently set flags on this callback. */
ev_uint32_t flags;
};
struct bufferevent;
struct evbuffer_chain;
struct evbuffer {
/** The first chain in this buffer's linked list of chains. */
struct evbuffer_chain *first;
/** The last chain in this buffer's linked list of chains. */
struct evbuffer_chain *last;
/** Pointer to the next pointer pointing at the 'last_with_data' chain.
*
* To unpack:
*
* The last_with_data chain is the last chain that has any data in it.
* If all chains in the buffer are empty, it is the first chain.
* If the buffer has no chains, it is NULL.
*
* The last_with_datap pointer points at _whatever 'next' pointer_
* points at the last_with_datap chain. If the last_with_data chain
* is the first chain, or it is NULL, then the last_with_datap pointer
* is &buf->first.
*/
struct evbuffer_chain **last_with_datap;
/** Total amount of bytes stored in all chains.*/
size_t total_len;
/** Number of bytes we have added to the buffer since we last tried to
* invoke callbacks. */
size_t n_add_for_cb;
/** Number of bytes we have removed from the buffer since we last
* tried to invoke callbacks. */
size_t n_del_for_cb;
#ifndef EVENT__DISABLE_THREAD_SUPPORT
/** A lock used to mediate access to this buffer. */
void *lock;
#endif
/** True iff we should free the lock field when we free this
* evbuffer. */
unsigned own_lock : 1;
/** True iff we should not allow changes to the front of the buffer
* (drains or prepends). */
unsigned freeze_start : 1;
/** True iff we should not allow changes to the end of the buffer
* (appends) */
unsigned freeze_end : 1;
/** True iff this evbuffer's callbacks are not invoked immediately
* upon a change in the buffer, but instead are deferred to be invoked
* from the event_base's loop. Useful for preventing enormous stack
* overflows when we have mutually recursive callbacks, and for
* serializing callbacks in a single thread. */
unsigned deferred_cbs : 1;
#ifdef _WIN32
/** True iff this buffer is set up for overlapped IO. */
unsigned is_overlapped : 1;
#endif
/** Zero or more EVBUFFER_FLAG_* bits */
ev_uint32_t flags;
/** Used to implement deferred callbacks. */
struct event_base *cb_queue;
/** A reference count on this evbuffer. When the reference count
* reaches 0, the buffer is destroyed. Manipulated with
* evbuffer_incref and evbuffer_decref_and_unlock and
* evbuffer_free. */
int refcnt;
/** A struct event_callback handle to make all of this buffer's callbacks
* invoked from the event loop. */
struct event_callback deferred;
/** A doubly-linked-list of callback functions */
LIST_HEAD(evbuffer_cb_queue, evbuffer_cb_entry) callbacks;
/** The parent bufferevent object this evbuffer belongs to.
* NULL if the evbuffer stands alone. */
struct bufferevent *parent;
};
/** A single item in an evbuffer. */
struct evbuffer_chain {
/** points to next buffer in the chain */
struct evbuffer_chain *next;
/** total allocation available in the buffer field. */
size_t buffer_len;
/** unused space at the beginning of buffer or an offset into a
* file for sendfile buffers. */
ev_off_t misalign;
/** Offset into buffer + misalign at which to start writing.
* In other words, the total number of bytes actually stored
* in buffer. */
size_t off;
/** Set if special handling is required for this chain */
unsigned flags;
#define EVBUFFER_FILESEGMENT 0x0001 /**< A chain used for a file segment */
#define EVBUFFER_SENDFILE 0x0002 /**< a chain used with sendfile */
#define EVBUFFER_REFERENCE 0x0004 /**< a chain with a mem reference */
#define EVBUFFER_IMMUTABLE 0x0008 /**< read-only chain */
/** a chain that mustn't be reallocated or freed, or have its contents
* memmoved, until the chain is un-pinned. */
#define EVBUFFER_MEM_PINNED_R 0x0010
#define EVBUFFER_MEM_PINNED_W 0x0020
#define EVBUFFER_MEM_PINNED_ANY (EVBUFFER_MEM_PINNED_R|EVBUFFER_MEM_PINNED_W)
/** a chain that should be freed, but can't be freed until it is
* un-pinned. */
#define EVBUFFER_DANGLING 0x0040
/** a chain that is a referenced copy of another chain */
#define EVBUFFER_MULTICAST 0x0080
/** number of references to this chain */
int refcnt;
/** Usually points to the read-write memory belonging to this
* buffer allocated as part of the evbuffer_chain allocation.
* For mmap, this can be a read-only buffer and
* EVBUFFER_IMMUTABLE will be set in flags. For sendfile, it
* may point to NULL.
*/
unsigned char *buffer;
};
/** callback for a reference chain; lets us know what to do with it when
* we're done with it. Lives at the end of an evbuffer_chain with the
* EVBUFFER_REFERENCE flag set */
struct evbuffer_chain_reference {
evbuffer_ref_cleanup_cb cleanupfn;
void *extra;
};
/** File segment for a file-segment chain. Lives at the end of an
* evbuffer_chain with the EVBUFFER_FILESEGMENT flag set. */
struct evbuffer_chain_file_segment {
struct evbuffer_file_segment *segment;
#ifdef _WIN32
/** If we're using CreateFileMapping, this is the handle to the view. */
HANDLE view_handle;
#endif
};
/* Declared in event2/buffer.h; defined here. */
struct evbuffer_file_segment {
void *lock; /**< lock prevent concurrent access to refcnt */
int refcnt; /**< Reference count for this file segment */
unsigned flags; /**< combination of EVBUF_FS_* flags */
/** What kind of file segment is this? */
unsigned can_sendfile : 1;
unsigned is_mapping : 1;
/** The fd that we read the data from. */
int fd;
/** If we're using mmap, this is the raw mapped memory. */
void *mapping;
#ifdef _WIN32
/** If we're using CreateFileMapping, this is the mapping */
HANDLE mapping_handle;
#endif
/** If we're using mmap or IO, this is the content of the file
* segment. */
char *contents;
/** Position of this segment within the file. */
ev_off_t file_offset;
/** If we're using mmap, this is the offset within 'mapping' where
* this data segment begins. */
ev_off_t mmap_offset;
/** The length of this segment. */
ev_off_t length;
};
/** Information about the multicast parent of a chain. Lives at the
* end of an evbuffer_chain with the EVBUFFER_MULTICAST flag set. */
struct evbuffer_multicast_parent {
/** source buffer the multicast parent belongs to */
struct evbuffer *source;
/** multicast parent for this chain */
struct evbuffer_chain *parent;
};
#define EVBUFFER_CHAIN_SIZE sizeof(struct evbuffer_chain)
/** Return a pointer to extra data allocated along with an evbuffer. */
#define EVBUFFER_CHAIN_EXTRA(t, c) (t *)((struct evbuffer_chain *)(c) + 1)
/** Assert that we are holding the lock on an evbuffer */
#define ASSERT_EVBUFFER_LOCKED(buffer) \
EVLOCK_ASSERT_LOCKED((buffer)->lock)
#define EVBUFFER_LOCK(buffer) \
do { \
EVLOCK_LOCK((buffer)->lock, 0); \
} while (0)
#define EVBUFFER_UNLOCK(buffer) \
do { \
EVLOCK_UNLOCK((buffer)->lock, 0); \
} while (0)
#define EVBUFFER_LOCK2(buffer1, buffer2) \
do { \
EVLOCK_LOCK2((buffer1)->lock, (buffer2)->lock, 0, 0); \
} while (0)
#define EVBUFFER_UNLOCK2(buffer1, buffer2) \
do { \
EVLOCK_UNLOCK2((buffer1)->lock, (buffer2)->lock, 0, 0); \
} while (0)
/** Increase the reference count of buf by one. */
void evbuffer_incref_(struct evbuffer *buf);
/** Increase the reference count of buf by one and acquire the lock. */
void evbuffer_incref_and_lock_(struct evbuffer *buf);
/** Pin a single buffer chain using a given flag. A pinned chunk may not be
* moved or freed until it is unpinned. */
void evbuffer_chain_pin_(struct evbuffer_chain *chain, unsigned flag);
/** Unpin a single buffer chain using a given flag. */
void evbuffer_chain_unpin_(struct evbuffer_chain *chain, unsigned flag);
/** As evbuffer_free, but requires that we hold a lock on the buffer, and
* releases the lock before freeing it and the buffer. */
void evbuffer_decref_and_unlock_(struct evbuffer *buffer);
/** As evbuffer_expand, but does not guarantee that the newly allocated memory
* is contiguous. Instead, it may be split across two or more chunks. */
int evbuffer_expand_fast_(struct evbuffer *, size_t, int);
/** Helper: prepares for a readv/WSARecv call by expanding the buffer to
* hold enough memory to read 'howmuch' bytes in possibly noncontiguous memory.
* Sets up the one or two iovecs in 'vecs' to point to the free memory and its
* extent, and *chainp to point to the first chain that we'll try to read into.
* Returns the number of vecs used.
*/
int evbuffer_read_setup_vecs_(struct evbuffer *buf, ev_ssize_t howmuch,
struct evbuffer_iovec *vecs, int n_vecs, struct evbuffer_chain ***chainp,
int exact);
/* Helper macro: copies an evbuffer_iovec in ei to a win32 WSABUF in i. */
#define WSABUF_FROM_EVBUFFER_IOV(i,ei) do { \
(i)->buf = (ei)->iov_base; \
(i)->len = (unsigned long)(ei)->iov_len; \
} while (0)
/* XXXX the cast above is safe for now, but not if we allow mmaps on win64.
* See note in buffer_iocp's launch_write function */
/** Set the parent bufferevent object for buf to bev */
void evbuffer_set_parent_(struct evbuffer *buf, struct bufferevent *bev);
void evbuffer_invoke_callbacks_(struct evbuffer *buf);
#ifdef __cplusplus
}
#endif
#endif /* EVBUFFER_INTERNAL_H_INCLUDED_ */
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