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VMS Help DCE, DCE_RPC, Application Routines, cs_byte_net_size *Conan The Librarian |
NAME
cs_byte_net_size - Calculates the necessary buffer size for code
set conversion from a local code set to a
network code set
Used by client and server applications.
SYNOPSIS
#include <dce/codesets_stub.h>
void cs_byte_net_size( rpc_binding_handle_t binding,
unsigned32 network_code_set_value,
unsigned32 local_buffer_size,
idl_cs_convert_t *conversion_type,
unsigned32 *network_buffer_size,
error_status_t *status );
PARAMETERS
Input
binding
Specifies the target binding handle from which to obtain buffer
size evaluation information. When called from the client stub,
this value is the binding handle of a compatible server returned
by the rpc_ns_binding_import_next() or rpc_ns_binding_select()
routine. When called from the server stub, this value is a
pointer to binding information that the client stub passed in
the RPC call.
network_code_set_value
The registered hexadecimal integer value that represents
the code set to be used to transmit character data over the
network. In general, the "network" code set is the code set
that the client application's code sets evaluation routine has
determined to be compatible for this client and server. When
the caller is the client stub, this value is the sending tag.
When the caller is the server stub, this value is the receiving
tag.
local_buffer_size
The size, in units of idl_byte, of the buffer that is allocated
for the international character data. This value is the local
value of the size_is variable for the array; that is, the value
is the size of the marshalled string if no conversion is done.
Output
conversion_type
A pointer to the enumerated type defined in dce/idlbase.h that
indicates whether data conversion is necessary and whether or
not existing storage is sufficient for storing the results of
the conversion. The conversion type can be one of the following
values:
idl_cs_no_convert
No code set conversion is required.
idl_cs_in_place_convert
Code set conversion can be performed in the
current buffer.
idl_cs_new_buffer_convert
The converted data must be written to a new buffer.
network_buffer_size
A pointer to the buffer size that needs to be allocated to contain
the converted data, in units of idl_byte. This value is to be used
as the network value of the size_is variable for the array, and is
non-NULL only if a conformant or conformant varying array is to be
marshalled. A value of NULL in this parameter indicates that a
fixed or varying array is to be marshalled.
status
Returns the status code from this routine. This status code
indicates whether the routine completed successfully or, if
not, why not. The possible status codes and their meanings
are as follows:
rpc_s_ok Success.
rpc_s_ss_incompatible_codesets
The specified code set does not match the code
set specified in the sending tag in the binding
handle. If this error occurs in the server
stub, an exception is raised to the client
application.
When invoked from the server stub, this routine calls the routines
dcs_cs_loc_to_rgy() and rpc_rgy_get_max_bytes(). If either of
these routines returns an error, the cs_byte_net_size() routine
raises an exception to the client application.
DESCRIPTION
The cs_byte_net_size() routine belongs to a set of DCE RPC routines
for use by client and server applications that are transferring
international character data in a heterogeneous character set and
code sets environment.
The cs_byte_net_size() routine is one of the DCE RPC buffer sizing
routines that RPC stubs use before they marshall or unmarshall data
to determine whether or not the buffers allocated for code set
conversion need to be enlarged to hold the converted data. The
buffer sizing routines determine the type of conversion required
and calculate the size of the necessary buffer (if a new one is
required). The RPC stub then allocates a buffer of that size before
it calls one of the code set conversion routines.
Client and server stubs call the cs_byte_*_size routines when the
cs_byte type (which is equivalent to byte) has been specified as
the local data type using the cs_char attribute in the attribute
configuration file for the application. Applications do not call
the cs_byte_net_size() routine directly. Client and server stubs
call the routine before they marshall any data. The stubs pass the
routine a binding handle and a code set value that identifies the
code set to be used to transfer international character data over
the network. The stubs also specify the local storage size of the
data, in units of byte.
When called from a client stub, the cs_byte_net_size() routine
determines the value of conversion_type from the client and server's
code set tag information set up the binding handle by a code sets
evaluation routine or a tag-setting routine. If the conversion type
specified in the handle is idl_cs_new_buffer_convert, the routine
sets the conversion_type parameter to this value and, if a
conformant or conformant varying array is to be marshalled,
calculates a new buffer size by multiplying the value of
local_buffer_size by the c_max_bytes value for the code set
specified in network_code_set_value (the sending tag parameter).
The routine returns the new buffer size in the network_buffer_size
parameter. The size is specified in units of cs_byte, which is the
network representation used for international character data (and
is equivalent to the byte type). For fixed and varying arrays, the
routine assumes that local_buffer_size is sufficient to store the
converted data.
If the handle information specifies idl_cs_convert_in_place or
idl_cs_no_convert, the routine assumes that local_buffer_size can
store the converted data (or that no conversion is necessary) and
returns idl_cs_convert_in_place (or idl_cs_no_convert) in the
conversion_type parameter. The routine also returns the value of
local_buffer_size in network_buffer_size if a conformant or
conformant varying array is to be marshalled.
In cases where the binding handle does not contain the results of
character and code sets evaluation, or where it is being called from
the server stub, the cs_byte_net_size() routine determines the value
of conversion_type itself using the local code set value and the
code set value passed in the network_code_set_value parameter and
returns the appropriate conversion_type value. If a conformant or
conformant varying array is to be marshalled, and the routine finds
that a new buffer is required to hold the converted data, the routine
calculates the size of this new buffer (by multiplying the value of
local_buffer_size by the network code set c_max_bytes value) and
returns the results, in units of cs_byte, in network_buffer_size.
Permissions Required
No permissions are required.
RETURN VALUES
No value is returned.
RELATED INFORMATION
Functions: cs_byte_local_size
wchar_t_local_size
wchar_t_net_size
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