odbx_lo_read man page

odbx_lo_read — Reads content from a large object


#include <opendbx/api.h>

ssize_todbx_lo_read (odbx_lo_t*lo, void* buffer, size_t buflen);


To get the content of a large object, odbx_lo_read() fetches the data in one or more pieces from the server and stores it into the user supplied buffer. After opening the large object using odbx_lo_open(), the first call to odbx_lo_read() will return the bytes from the beginning. The second and all other calls will store subsequent parts of the large object content into the buffer until the end of the data is reached. To reread the content a second time, you have to close the large object handle and reopen it again as some databases provide no way to reposition the internal file position indicator for the stream.

The lo parameter has to be the large object handle created and returned by odbx_lo_open() via its second parameter. It becomes invalid after it was supplied to odbx_lo_close() and this function will return an error in this case. The large object content fetched from the server is stored into the user supplied buffer up to buflen bytes.

Return Value

odbx_lo_read() returns the number of bytes placed into buffer, which may be up to buflen bytes. If the end of the content is reached and no more data is available, the return value will be 0. On error, a code whose value is less than zero is returned if one of the operations couldn't be completed successfully. Possible error codes are listed in the error section and they can be feed to odbx_error() and odbx_error_type() to get further details.


The native database library couldn't read from the large object
lo is NULL or the supplied large object handle is invalid

See Also

odbx_lo_open(), odbx_lo_close()


OpenDBX 4 February 2016