79 lines
1.9 KiB
C
79 lines
1.9 KiB
C
/*-------------------------------------------------------------------------
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*
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* beard.c
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* sample routines to use large objects
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*
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* Portions Copyright (c) 1996-2000, PostgreSQL, Inc
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/tutorial/Attic/beard.c,v 1.4 2000/06/09 01:11:16 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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typedef struct ImageHdr
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{
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int size;
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} ImageHdr;
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#define BUFSIZE 10
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/*
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* beard -
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* clips lower 1/3 of picture and return as large object
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*/
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Oid
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beard(Oid picture)
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{
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Oid beard;
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int pic_fd,
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beard_fd;
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ImageHdr ihdr;
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char buf[BUFSIZE];
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int cc;
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pic_fd = DatumGetInt32(DirectFunctionCall2(lo_open,
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ObjectIdGetDatum(picture),
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Int32GetDatum(INV_READ)));
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if (pic_fd < 0)
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elog(ERROR, "Cannot access picture large object");
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if (lo_read(pic_fd, (char *) &ihdr, sizeof(ihdr)) != sizeof(ihdr))
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elog(ERROR, "Picture large object corrupted");
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beardOffset = (ihdr.size / 3) * 2;
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/*
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* new large object
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*/
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beard = DatumGetObjectId(DirectFunctionCall1(lo_creat,
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Int32GetDatum(INV_MD)));
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if (beard == InvalidOid)
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elog(ERROR, "Cannot create new large object");
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beard_fd = DatumGetInt32(DirectFunctionCall2(lo_open,
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ObjectIdGetDatum(beard),
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Int32GetDatum(INV_WRITE)));
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if (beard_fd < 0)
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elog(ERROR, "Cannot access beard large object");
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if (DatumGetInt32(DirectFunctionCall3(lo_lseek,
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Int32GetDatum(pic_fd),
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Int32GetDatum(beardOffset),
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Int32GetDatum(SEEK_SET))) < 0)
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elog(ERROR, "Cannot seek in picture large object");
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while ((cc = lo_read(pic_fd, buf, BUFSIZE)) > 0)
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{
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if (lo_write(beard_fd, buf, cc) != cc)
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elog(ERROR, "error while writing large object");
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}
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DirectFunctionCall1(lo_close, Int32GetDatum(pic_fd));
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DirectFunctionCall1(lo_close, Int32GetDatum(beard_fd));
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return beard;
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}
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