1odbx_lo_read(3) OpenDBX odbx_lo_read(3)
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6 odbx_lo_read - Reads content from a large object
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9 #include <opendbx/api.h>
10 ssize_t odbx_lo_read (odbx_lo_t* lo, void* buffer, size_t buflen);
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15 To get the content of a large object, odbx_lo_read() fetches the data
16 in one or more pieces from the server and stores it into the user sup‐
17 plied buffer. After opening the large object using odbx_lo_open(), the
18 first call to odbx_lo_read() will return the bytes from the beginning.
19 The second and all other calls will store subsequent parts of the large
20 object content into the buffer until the end of the data is reached. To
21 reread the content a second time, you have to close the large object
22 handle and reopen it again as some databases provide no way to reposi‐
23 tion the internal file position indicator for the stream.
24 The lo parameter has to be the large object handle created and returned
26 by odbx_lo_open() via its second parameter. It becomes invalid after it
27 was supplied to odbx_lo_close() and this function will return an error
28 in this case. The large object content fetched from the server is
29 stored into the user supplied buffer up to buflen bytes.
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32 odbx_lo_read() returns the number of bytes placed into buffer, which
33 may be up to buflen bytes. If the end of the content is reached and no
34 more data is available, the return value will be 0. On error, a code
35 whose value is less than zero is returned if one of the operations
36 couldn't be completed successfully. Possible error codes are listed in
37 the error section and they can be feed to odbx_error() and odbx_er‐
38 ror_type() to get further details.
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41 -ODBX_ERR_BACKEND
42 The native database library couldn't read from the large object
43 -ODBX_ERR_HANDLE
45 lo is NULL or the supplied large object handle is invalid
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48 odbx_lo_open(), odbx_lo_close()
49 29 January 2020 odbx_lo_read(3)