Function-Independent Structure

Function‑Independent Structure

The general, function‑independent structure identifies a requested function and provides the specifications required by all Access Module function calls. For detailed examples, refer to the pmdcomt.h and pmddamt.h header files in Chapter 4: “Header File Examples.”

typedef struct _pmiCmdBlock

  char         EyeCatcher[pmiMAX_EC_LEN];/* Struct eyecatcher string */

  pmUInt32     StructLength;             /* Length of this structure */

  pmUInt32     Reqtype;                /* function request indicator */

  pmReturnType Retcode;        /* identical to function return value */

  pmTrceLvl_t  TraceLvl;         /* Requested diagnostic trace level */

                                           /* Descriptive error text */

  pmNameBuf_t  ErrMsg;                /* when Retcode is pmrcFailure */

} pmiCmdBlock_t;

where:

Parameter	Field	Description
EyeCatcher	input	Structure description string, such as pmCmdBlock.
StructLength	input	Total structure length, including the EyeCatcher string.
Reqtype	input	Specific function request, as listed in Table 4.
Retcode	output	Value assigned by the Access Module function as one of those defined in the pmdcomt.h. header file. Although additional function‑specific return codes are defined with each function, typical interface return codes are listed in Table 5.
TraceLvl	input	Default trace level to be associated with all functions related to this operation.
ErrMsg	output	Two‑field value assigned by the Access Module function when Retcode is set to pmrcFailure. These fields provide the following: Descriptive error text of up to 32,000 bytes, maximum Length of the text Whenever an error condition is detected, the Access Module must map the error to one of the error codes defined in the pmdcomt.h header file. If a well‑defined match is not found, the Access Module must return a value of pmrcFailure and provide an error description string in this ErrMsg field. The client utility then presents the error message to the user.

The following table lists the function requests for Reqtype.

Table 4: Reqtype Function Requests
Reqtype	Description
pmiPIDMOptInit	Access Module initialization
pmiPIDMOptOpen	File open
pmiPIDMOptClose	File close
pmiPIDMOptCloseR	File close and release media
pmiPIDMOptRead	File read
pmiPIDMOptWrite	File write
pmiPIDMOptGetPos	Get position of currently open file
pmiPIDMOptSetPos	Set position of currently open file
pmiPIDMOptShut	Access Module shutdown (cleanup)
pmiPIDMOptID	Access Module identification
pmiPIDMOptGetA_A	Get (obtain) an Access Module attribute
pmiPIDMOptGetF_A	Get (obtain) a file attribute
pmiPIDMOptPutA_A	Put (provide) an Access Module attribute
pmiPIDMOptPutF_A	Put (provide) a file attribute

The following table lists typical interface return codes.

Table 5: Typical Interface Return Codes
Return Code	Description
pmrcOK	No error conditions encountered.
pmrcUnsupported	The function requested by Reqtype is not supported.
pmrcBadTraceLvl	The value of TraceLvl is out of range.
pmrcBadParm	One or more of the supplied parameters is invalid.
pmrcAPInotReady	The Access Module has not been initialized.
pmrcAllocErr	A memory allocation error occurred.
pmrcFailure	General failure return code. See the description of the ErrMsg parameter.

See Chapter 3: “Access Module Functions” for more information about Access Module functions.

Function-Independent Structure - Access Module

Teradata Tools and Utilities Access Modules Programmer Guide

Function‑Independent Structure