Hp XP P9500 Storage Manuel d'utilisateur télécharger pdf (Page 125)

When the datasetOpen function terminates successfully, it returns a handle that identifies the dataset

opened. The datasetHandle information is used as the argument of subsequent functions such as

datasetGet, datasetPut, or datasetClose. Do not change the datasetHandle value returned

by this function. If the datasetOpen function terminates unsuccessfully, it returns a value of -1. To

get the error code information, execute the datasetGetLastError function (see “Acquiring Error

Information” on page 127).

The datasetOpen function has the following restrictions:

• Only one dataset at a time can be open within one process. When multiple datasets need to be

opened, the open dataset must be closed before another dataset can be opened. This restriction

does not apply to open-system files.

• A dataset that is being accessed by the datasetFindFirstFile or datasetFindNextFile

function cannot be opened. The datasetFindClose function must be executed before the

dataset can be opened. This restriction does not apply to open-system files.

Reading Data

reclen = datasetGet (datasetHandle, buf, buflen)

The datasetGet function reads one record from the specified dataset (datasetHandle) and puts

the record into a buffer (buf) of length buflen. The datasetGet function extracts only the data

entity from each record and does not transfer the BL and RL bytes for variable-length records to the

buffer. Table 42 on page 125 shows the datasetGet arguments and return values.

Table 42 DatasetGet Function

DescriptionTypeValueItem

The datasetHandle value returned by the

datasetOpen function.

DATASET_HANDLEdatasetHandle

Argument

Buffer area for storing the read data.char *buf

Size of the buffer area. If the record is larger

than buflen or equal to zero, datasetGet

returns an error and does not transfer any

data to the buf.

longbuflen

Data entity size transferred to the buffer

long

reclen

Return value

Abnormal end-1

Figure 77 on page 126 shows the format requirements for variable-length records accessed by the

datasetGet function. Each variable-length block must start with the 2-byte BL field, and each

variable-length record must start with the 2-byte RL field. The datasetGet function automatically

extracts the data entities without the BL and RL fields.

HP StorageWorks P9000 Data Exchange User Guide 125

1 2 ... 120 121 122 123 124 125 126 127 128 129 130 ... 181 182

Pas de commentaire

Hp XP P9500 Storage Manuel d'utilisateur Page 125