The File Open function opens a file for subsequent read and write operations.
The term file refers to a data source or destination on any sort of data storage device (such as magnetic tape, disk, CD‑ROM, or another database) that an Access Module supports. The terms read and write refer to data moving from (read) and to (write) the data source/destination. The structure follows:
typedef struct _pmiOpen
{
char EyeCatcher[pmiMAX_EC_LEN]; /* Struct eyecatcher string */
pmUInt32 StructLength; /* Length of this structure */
void *PIData; /* Access module Internal Data Pointer */
pmOpenMode_t OpenMode; /* provided to Access Module */
pmUInt16 BlkHeaderLen; /* defined by Access Module */
pmUInt32 BlkSize; /* defined by Access Module */
/* File Internal Data */
void *FIData; /*(returned/used by Access Module) */
/* File (data stream) supplied to Access Module */
pmUInt16 FileNameL; /* Name length */
har FileName[pmiMAX_DDNAME_LEN+1]; /* Name */
} pmiOpen_t;
where:
|
Parameter |
Field |
Description |
|
EyeCatcher |
input |
Structure description string, such as pmOpenParms. |
|
StructLength |
input |
Total structure length, including the EyeCatcher string. |
|
PIData |
input |
Value provided by the Access Module in response to a previous initialization request call. This value identifies the instance of the Access Module opening the file. |
|
OpenMode |
input |
Indicates the intended use of the file to be opened. The following values are supported. |
|
BlkHeaderLen |
output |
Number of device‑dependent bytes that prefix the user data in each block. |
|
BlkSize |
output |
Size, in bytes, of the data blocks to be either read from or written to the file. |
|
FIData |
output |
Handle/pointer to internal Access Module data. There are no restrictions on the FIData value, and the assigned value will be returned in a subsequent call to the Access Module. |
|
FileNameL |
input |
Length of FileName parameter. |
|
FileName |
input |
Name of the file to be opened. |