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Annotation of 43BSD/ingres/source/iutil/opencat.c, revision 1.1

1.1     ! root        1: # include      <ingres.h>
        !             2: # include      <aux.h>
        !             3: # include      <opsys.h>
        !             4: # include      <access.h>
        !             5: # include      <sccs.h>
        !             6: 
        !             7: SCCSID(@(#)opencat.c   8.2     1/15/85)
        !             8: 
        !             9: /*
        !            10: **  OPENCATALOG -- open system catalog
        !            11: **
        !            12: **     This routine opens a system catalog into a predetermined
        !            13: **     cache.  If the catalog is already open, it is not reopened.
        !            14: **
        !            15: **     The 'Desxx' struct defines which relations may be opened
        !            16: **     in this manner and is defined in .../source/aux.h.
        !            17: **
        !            18: **     The relation should not be closed after use (except in
        !            19: **     special cases); however, it should be noclose'd after use
        !            20: **     if the number of tuples in the catalog may have changed.
        !            21: **
        !            22: **     The Desxx structure has an alias field which
        !            23: **     is the address of the 'Admin' structure cache which holds
        !            24: **     the relation descriptor.  Thus, an openr need never actually
        !            25: **     occur.
        !            26: **
        !            27: **     The actual desxx structure definition is in the file
        !            28: **     
        !            29: **             catalog_desc.c
        !            30: **
        !            31: **     which defines which relations can be cached and if any
        !            32: **     alias descriptors exist for the relations. That file
        !            33: **     can be redefined to include various caching.
        !            34: **
        !            35: **
        !            36: **     Parameters:
        !            37: **             name -- the name of the relation to open.  It must
        !            38: **                     match one of the names in the Desxx
        !            39: **                     structure.
        !            40: **             mode -- just like 'mode' to openr.  If zero, it
        !            41: **                     is opened read-only; if two, it is opened
        !            42: **                     read/write.  In fact, the catalog is always
        !            43: **                     opened read/write, but the flags are set
        !            44: **                     right for concurrency to think that you are
        !            45: **                     using it as you have declared.
        !            46: **
        !            47: **     Returns:
        !            48: **             none
        !            49: **
        !            50: **     Side Effects:
        !            51: **             A relation is (may be) opened.
        !            52: **
        !            53: **     Trace Flags:
        !            54: **             none
        !            55: */
        !            56: 
        !            57: opencatalog(name, mode)
        !            58: char   *name;
        !            59: int    mode;
        !            60: {
        !            61:        int                     i;
        !            62:        register DESC           *d;
        !            63:        register char           *n;
        !            64:        register struct desxx   *p;
        !            65:        extern struct desxx     Desxx[];
        !            66:        extern long             CmOfiles;
        !            67: 
        !            68:        n = name;
        !            69: 
        !            70:        /* find out which descriptor it is */
        !            71:        for (p = Desxx; p->cach_relname; p++)
        !            72:                if (sequal(n, p->cach_relname))
        !            73:                        break;
        !            74:        if (!p->cach_relname)
        !            75:                syserr("opencatalog: (%s)", n);
        !            76: 
        !            77:        d = p->cach_desc;
        !            78: 
        !            79:        /* if it's already open, just return */
        !            80:        if (d->relopn)
        !            81:        {
        !            82:                clearkeys(d);
        !            83:        }
        !            84:        else
        !            85:        {
        !            86:                /* not open, open it */
        !            87:                if (p->cach_alias)
        !            88:                {
        !            89:                        acc_init();
        !            90:                        bmove((char *) p->cach_alias, (char *) d, sizeof (*d));
        !            91:                }
        !            92:                else
        !            93:                {
        !            94:                        if ((i = openr(d, OR_WRITE, n)) != 0)
        !            95:                                syserr("opencatalog: openr(%s) %d", n, i);
        !            96:                }
        !            97: 
        !            98:                /* mark it as an open file */
        !            99:                CmOfiles |= 1 << d->relfp;
        !           100:        }
        !           101: 
        !           102:        /* determine the mode to mark it as for concurrency */
        !           103:        switch (mode)
        !           104:        {
        !           105:          case OR_READ: /* read only */
        !           106:                d->relopn = abs(d->relopn);
        !           107:                break;
        !           108: 
        !           109:          case OR_WRITE:        /* read-write */
        !           110:                d->relopn = -abs(d->relopn);
        !           111:                break;
        !           112: 
        !           113:          default:
        !           114:                syserr("opencatalog(%s): mode %d", n, mode);
        !           115:        }
        !           116: 
        !           117:        return;
        !           118: }

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