T_ALLOC(3N) (Networking Support Utilities) T_ALLOC(3N)
NAME
t_alloc - allocate a library structure
SYNOPSIS
#include <tiuser.h>
char *talloc(fd, structtype, fields)
int fd;
int structtype;
int fields;
DESCRIPTION
The t_alloc function dynamically allocates memory for the
various transport function argument structures as specified
below. This function will allocate memory for the specified
structure, and will also allocate memory for buffers
referenced by the structure.
The structure to allocate is specified by struct_type, and
can be one of the following:
T_BIND struct t_bind
T_CALL struct t_call
T_OPTMGMT struct t_optmgmt
T_DIS struct t_discon
T_UNITDATA struct t_unitdata
T_UDERROR struct t_uderr
T_INFO struct t_info
where each of these structures may subsequently be used as
an argument to one or more transport functions.
Each of the above structures, except T_INFO, contains at
least one field of type struct netbuf. Netbuf is described
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T_ALLOC(3N) (Networking Support Utilities) T_ALLOC(3N)
in intro(3). For each field of this type, the user may
specify that the buffer for that field should be allocated
as well. The fields argument specifies this option, where
the argument is the bitwise-OR of any of the following:
T_ADDR The addr field of the t_bind, t_call, t_unitdata,
or t_uderr structures.
T_OPT The opt field of the t_optmgmt, t_call,
t_unitdata, or t_uderr structures.
T_UDATA The udata field of the t_call, t_discon, or
t_unitdata structures.
T_ALL All relevant fields of the given structure.
For each field specified in fields, t_alloc will allocate
memory for the buffer associated with the field, and
initialize the buf pointer and maxlen [see netbuf in
intro(3) for description of buf and maxlen] field
accordingly. The length of the buffer allocated will be
based on the same size information that is returned to the
user on t_open and t_getinfo. Thus, fd must refer to the
transport endpoint through which the newly allocated
structure will be passed, so that the appropriate size
information can be accessed. If the size value associated
with any specified field is -1 or -2 (see t_open or
t_getinfo), t_alloc will be unable to determine the size of
the buffer to allocate and will fail, setting t_errno to
TSYSERR and errno to EINVAL. For any field not specified in
fields, buf will be set to NULL and maxlen will be set to
zero.
Use of t_alloc to allocate structures will help ensure the
compatibility of user programs with future releases of the
transport interface.
On failure, t_errno may be set to one of the following:
[TBADF] The specified file descriptor does not refer
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T_ALLOC(3N) (Networking Support Utilities) T_ALLOC(3N)
to a transport endpoint.
[TSYSERR] A system error has occurred during execution
of this function.
SEE ALSO
intro(3), t_free(3N), t_getinfo(3N), t_open(3N).
Network Programmer's Guide, Vol. 1.
DIAGNOSTICS
On successful completion, t_alloc returns a pointer to the
newly allocated structure. On failure, NULL is returned.
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