Table of Contents

Name

linx_alloc() - Allocate a signal buffer on a LINX endpoint

Synopsis

#include <linx_types.h>
#include <linx.h>

union LINX_SIGNAL *linx_alloc(LINX *linx, LINX_OSBUFSIZE size, LINX_SIGSELECT sig_no);

Description

linx_alloc() is used to allocate a signal buffer of the indicated size, to be transmitted from this LINX endpoint or to be used as buffer for a message received at this LINX endpoint via linx_receive_w_buf(3) . The first four bytes of the signal buffer are initialized with the provided sig_no. The signal number can later be replaced by simply writing a new signal number in the first location. The allocated signal buffer implicitely holds information about the sender.

The new buffer is owned by the LINX endpoint, on which it was created. Also a received signal buffer is owned by the receiving LINX endpoint. Unless the buffer is sent (a received buffer can be reused for sending), the owner must free the buffer by calling linx_free_buf(3) with the same linx handle. The buffer will also be freed if the owning LINX endpoint is closed or the calling process exits. The buffer ownership is transferred when successfully using any of the transmission functions, e.g. linx_send(3) .

linx is the handle to the LINX endpoint.

size is the size in bytes of the new signal buffer. The minimum size is 4 bytes, needed to store the sig_no. The maximum size of the signal buffer is 65536 bytes. Thus the space for a payload, excluding the signal number, can be in the range 0 - 65532 bytes.

sig_no is the signal number, stored at the beginning of the signal buffer.

If linx is not a valid LINX endpoint, i.e. created with linx_open(3) then abort(3) is called.

Return Value

Returns a pointer to the allocated signal buffer if successful. On failure, LINX_NIL is returned and errno will be set.

Errors

EMSGSIZE if size is invalid.

ENOMEM if there is not enough memory.

Bugs/Limitations

The maximum signal buffer size is currently set to 65536 bytes. This limitation may be changed or removed in future versions.

Notes

A signal buffer can be only be transferred through the owning LINX endpoint, i.e. where it was created or where it was received. It can not be reused and transferred through another LINX endpoint.

If a process, which has allocated signal buffers, fork(2) , both instances will have copies of the signal buffers. As only one process may use a LINX endpoint and the endpoint's resources, either the parent or the child __must__ close the LINX endpoint with linx_close(3) .

See Also

linx(7) , linx_close(3) , linx_free_buf(3) , linx_hunt(3) , linx_send(3) , fork(2)

Author

Enea LINX team

Copyright

Copyright (c) 2006-2007, Enea Software AB All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 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. Neither the name of Enea Software AB nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT OWNER OR CONTRIBUTORS 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.

Table of Contents