Cartridge Services — File I/O Interface

This section describes the file I/O interface functions.

Table 20-6 File I/O Interface Functions

Function/Page Purpose

OCIFileClose()

Closes a previously opened file.

OCIFileExists()

Tests to see if the file exists.

OCIFileFlush()

Writes buffered data to a file.

OCIFileGetLength()

Gets the length of a file.

OCIFileInit()

Initializes the OCIFile package.

OCIFileOpen()

Opens a file.

OCIFileRead()

Reads from a file into a buffer.

OCIFileSeek()

Changes the current position in a file.

OCIFileTerm()

Terminates the OCIFile package.

OCIFileWrite()

Writes buflen bytes into the file.


See Also:

For more information about using these functions, see Oracle Database Data Cartridge Developer's Guide

OCIFileObject

The OCIFileObject data structure holds information about the way in which a file should be opened and the way in which it will be accessed once it has been opened. When this structure is initialized by OCIFileOpen(), it becomes an identifier through which operations can be performed on that file. It is a necessary parameter to every function that operates on open files. This data structure is opaque to OCIFile clients. It is initialized by OCIFileOpen() and terminated by OCIFileClose().

OCIFileInit()

Purpose

Initializes the OCIFile package. It must be called before any other OCIFile routine is called.

Syntax

sword OCIFileInit( void     *hndl, 
                   OCIError *err );

Parameters

hndl (IN)

The OCI environment or user session handle.

err (IN/OUT)

The OCI error handle; if there is an error, it is recorded in err and this function returns OCI_ERROR; diagnostic information can be obtained by calling OCIErrorGet().

Returns

OCI_SUCCESS,

OCI_INVALID_HANDLE,

OCI_ERROR.

OCIFileTerm()

Purpose

Terminates the OCIFile package. It must be called after the OCIFile package is no longer being used.

Syntax

sword OCIFileTerm( void     *hndl, 
                   OCIError *err );

Parameters

hndl (IN)

The OCI environment or user session handle.

err (IN/OUT)

The OCI error handle; if there is an error, it is recorded in err and this function returns OCI_ERROR; diagnostic information can be obtained by calling OCIErrorGet().

Returns

OCI_SUCCESS,

OCI_INVALID_HANDLE,

OCI_ERROR.

OCIFileOpen()

Purpose

Opens a file.

Syntax

sword OCIFileOpen( void  *hndl, 
                   OCIError       *err, 
                   OCIFileObject  **filep, 
                   OraText        *filename, 
                   OraText        *path, 
                   ub4            mode, 
                   ub4            create, 
                   ub4            type );

Parameters

hndl (IN)

The OCI environment or user session handle.

err (IN/OUT)

The OCI error handle; if there is an error, it is recorded in err and this function returns OCI_ERROR; diagnostic information can be obtained by calling OCIErrorGet().

filep (IN/OUT)

The file identifier.

filename (IN)

The file name as a NULL-terminated string.

path (IN)

The path of the file as a NULL-terminated string.

mode (IN)

The mode in which to open the file. Valid modes are

OCI_FILE_READ_ONLY,

OCI_FILE_WRITE_ONLY,

OCI_FILE_READ_WRITE.

create (IN)

Indicates if the file be created if it does not exist — valid values are:

OCI_FILE_TRUNCATE — create a file regardless of whether or not it exists. If the file already exists overwrite the existing file.

OCI_FILE_EXCL — fail if the file exists, else create.

OCI_FILE_CREATE — open the file if it exists, and create it if it does not.

OCI_FILE_APPEND — set the file pointer to the end of the file prior to writing. This flag can be ORed with OCI_FILE_CREATE

type (IN)

File type. Valid values are

OCI_FILE_TEXT,

OCI_FILE_BIN,

OCI_FILE_STDIN,

OCI_FILE_STDOUT,

OCI_FILE_STDERR.

Returns

OCI_SUCCESS,

OCI_INVALID_HANDLE,

OCI_ERROR.

OCIFileClose()

Purpose

Closes a previously opened file.

Syntax

sword OCIFileClose( void          *hndl, 
                    OCIError      *err, 
                    OCIFileObject *filep );

Parameters

hndl (IN)

The OCI environment or user session handle.

err (IN/OUT)

The OCI error handle. If there is an error, it is recorded in err and this function returns OCI_ERROR. Diagnostic information can be obtained by calling OCIErrorGet().

filep (IN/OUT)

A pointer to a file identifier to be closed.

Comments

Once this returns, the OCIFileObject structure pointed to by filep will have been destroyed. Therefore, you should not attempt to access this structure after this returns.

Returns

OCI_SUCCESS,

OCI_INVALID_HANDLE,

OCI_ERROR.

OCIFileRead()

Purpose

Reads from a file into a buffer.

Syntax

sword OCIFileRead( void          *hndl, 
                   OCIError      *err, 
                   OCIFileObject *filep, 
                   void          *bufp, 
                   ub4           bufl, 
                   ub4           *bytesread );

Parameters

hndl (IN)

The OCI environment or user session handle.

err (IN/OUT)

The OCI error handle; if there is an error, it is recorded in err and this function returns OCI_ERROR; diagnostic information can be obtained by calling OCIErrorGet().

filep (IN/OUT)

A file identifier that uniquely references the file.

bufp(IN)

The pointer to a buffer into which the data will be read. The length of the allocated memory is assumed to be bufl.

bufl (IN)

The length of the buffer in bytes.

bytesread (OUT)

The number of bytes read.

Comments

As many bytes as possible will be read into the user buffer. The read will end either when the user buffer is full, or when it reaches end-of-file.

Returns

OCI_SUCCESS,

OCI_INVALID_HANDLE,

OCI_ERROR.

OCIFileWrite()

Purpose

Writes buflen bytes into the file.

Syntax

sword OCIFileWrite( void          *hndl, 
                    OCIError      *err, 
                    OCIFileObject *filep, 
                    void          *bufp, 
                    ub4           buflen, 
                    ub4           *byteswritten );

Parameters

hndl (IN)

The OCI environment or user session handle.

err (IN/OUT)

The OCI error handle; if there is an error, it is recorded in err and this function returns OCI_ERROR; diagnostic information can be obtained by calling OCIErrorGet().

filep (IN/OUT)

A file identifier that uniquely references the file.

bufp(IN)

The pointer to a buffer from into which the data will be written. The length of the allocated memory is assumed to be buflen.

buflen (IN)

The length of the buffer in bytes.

bytesread (OUT)

The number of bytes written.

Returns

OCI_SUCCESS, OCI_INVALID_HANDLE, OCI_ERROR.

OCIFileSeek()

Purpose

Changes the current position in a file.

Syntax

sword OCIFileSeek( void          *hndl, 
                   OCIError      *err, 
                   OCIFileObject *filep, 
                   uword         origin, 
                   ubig_ora      offset, 
                   sb1           dir );

Parameters

hndl (IN)

The OCI environment or user session handle.

err (IN/OUT)

The OCI error handle; if there is an error, it is recorded in err and this function returns OCI_ERROR; diagnostic information can be obtained by calling OCIErrorGet().

filep (IN/OUT)

A file identifier that uniquely references the file.

origin(IN)

The starting point we want to seek from. The starting point may be

OCI_FILE_SEEK_BEGINNING (beginning),

OCI_FILE_SEEK_CURRENT (current position),

OCI_FILE_SEEK_END (end of file).

offset (IN)

The number of bytes from the origin you want to start reading from.

dir (IN)

The direction to go from the origin.

Note:

The direction can be either OCIFILE_FORWARD or OCIFILE_BACKWARD.

Comments

This will allow a seek past the end of the file. Reading from such a position will cause an end-of-file condition to be reported. Writing to such a position will not work on all file systems. This is because some systems do not allow files to grow dynamically. They require that files be preallocated with a fixed size. Note that this function performs a seek to a byte location.

Returns

OCI_SUCCESS, OCI_INVALID_HANDLE, OCI_ERROR.

OCIFileExists()

Purpose

Tests to see if the file exists.

Syntax

sword OCIFileExists( void     *hndl, 
                     OCIError *err, 
                     OraText  *filename, 
                     OraText  *path, 
                     ub1      *flag );

Parameters

hndl (IN)

The OCI environment or user session handle.

err (IN/OUT)

The OCI error handle; if there is an error, it is recorded in err and this function returns OCI_ERROR; diagnostic information can be obtained by calling OCIErrorGet().

filename (IN)

The file name as a NULL-terminated string.

path (IN)

The path of the file as a NULL-terminated string.

flag (OUT)

Set to TRUE if the file exists or FALSE if it does not.

Returns

OCI_SUCCESS,

OCI_INVALID_HANDLE,

OCI_ERROR.

OCIFileGetLength()

Purpose

Gets the length of a file.

Syntax

sword OCIFileGetLength( void     *hndl, 
                        OCIError *err, 
                        OraText  *filename, 
                        OraText  *path, 
                        ubig_ora *lenp );

Parameters

hndl (IN)

The OCI environment or user session handle.

err (IN/OUT)

The OCI error handle; if there is an error, it is recorded in err and this function returns OCI_ERROR; diagnostic information can be obtained by calling OCIErrorGet().

filename (IN)

The file name as a NULL-terminated string.

path (IN)

The path of the file as a NULL-terminated string.

lenp (OUT)

Set to the length of the file in bytes.

Returns

OCI_SUCCESS,

OCI_INVALID_HANDLE,

OCI_ERROR.

OCIFileFlush()

Purpose

Writes buffered data to a file.

Syntax

sword OCIFileFlush( void          *h
                    OCIError      *err, 
                    OCIFileObject *filep );

Parameters

hndl (IN)

The OCI environment or user session handle.

err (IN/OUT)

The OCI error handle; if there is an error, it is recorded in err and this function returns OCI_ERROR; diagnostic information can be obtained by calling OCIErrorGet().

filep (IN/OUT)

A file identifier that uniquely references the file.

Returns

OCI_SUCCESS,

OCI_INVALID_HANDLE,

OCI_ERROR.