t_alloc(S)                (TLI/XTI) 6 January 1993                t_alloc(S)


 Name

    t_alloc - allocate a library structure

 Syntax


    TLI syntax


    cc  . . .  -lnsls


    #include <sys/tiuser.h>

    char * t_alloc (fd, struct_type, fields)
    int fd, struct_type, fields;


    XTI syntax


    cc  . . . -lxti


    #include <xti.h>

    char * t_alloc (fd, struct_type, fields)
    int fd, struct_type, fields;


 Description

    The talloc function dynamically allocates memory for the various trans-
    port function argument structures as specified below.  This function
    allocates memory for the specified structure, and also allocates memory
    for buffers referenced by the structure.

    The structure to allocate is specified by structtype, and can be one of
    the following:

    TLI structtype   XTI structtype   Allocated
    Value             Value             Structure
    ___________________________________________________________________
    TBIND            TBINDSTR        struct t_bind
    TCALL            TCALLSTR        struct t_call
    TDIS             TDISSTR         struct t_discon
    TINFO            TINFOSTR        struct t_info
    TOPTMGMT         TOPTMGMTSTR     struct t_optmgmt
    TUDERROR         TUDERRORSTR     struct t_uderr
    TUNITDATA        TUNITDATASTR    struct t_unitdata


    Each of these structures may subsequently be used as an argument to one
    or more transport functions.

    Each of the previously listed structures, except TINFO (TLI) or
    TINFOSTR (XTI), contains at least one field of type struct netbuf.
    netbuf is described in netbuf(FP).  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:

    TALL     All relevant fields of the given structure.

    TADDR    The addr field of the tbind, tcall, tunitdata, or tuderr
              structures.

    TOPT     The opt field of the toptmgmt, tcall, tunitdata, or tuderr
              structures.

    TUDATA   The udata field of the tcall, tdiscon, or tunitdata struc-
              tures.

    For each field specified in fields, talloc allocates memory for the
    buffer associated with the field, and initialize the buf pointer and max-
    len (see netbuf in netbuf(FP) for a description of the buf and maxlen)
    fields accordingly.  The length of the buffer allocated is based on the
    same size information that is returned to the user on topen and
    tgetinfo. Thus, fd must refer to the transport endpoint through which
    the newly allocated structure is passed, so that the appropriate size in-
    formation can be accessed.  If the size value associated with any speci-
    fied field is -1 or -2 (see topen or tgetinfo), talloc is unable to
    determine the size of the buffer to allocate and fails, setting terrno
    to TSYSERR and errno to EINVAL.  For any field not specified in fields,
    buf is set to NULL and maxlen is set to zero.

    Use of talloc to allocate structures helps ensure the compatibility of
    user programs with future releases of the transport interface.

    On failure, terrno may be set to one of the following:

    [TBADF]             The specified file descriptor does not refer to a
                        transport endpoint.

    [TNOSTRUCTYPE]      For XTI, an incorrect value was specified in the
                        structtype argument.

    [TSYSERR]           A system error has occurred during execution of this
                        function.  The following conditions accompany this
                        error:

                        terrno Value   errno Value   Cause
                        _____________________________________________________
                        TSYSERR         not set       Device or system
                                                      failure
                        TSYSERR         EINVAL        structtype out of
                                                      range, or internal
                                                      error
                        TSYSERR         ENOMEM        Memory could not be
                                                      allocated for specified
                                                      structtype request


 See also

    netbuf(FP), tfree(S), tgetinfo(S), topen(S), tinfo(FP)

 Diagnostics

    On successful completion, talloc returns a pointer to the newly allo-
    cated structure.  On failure, NULL is returned.

 Standards conformance

    talloc is conformant with:
    AT&T SVID Issue 2;
    X/Open Portability Guide, Issue 3, 1989;
    and Intel386 Binary Compatibility Specification, Edition 2 (iBCSe2).