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Annotation of researchv9/sys.vax/sys/rdwri.c, revision 1.1

1.1     ! root        1: /*     rdwri.c 4.6     81/03/08        */
        !             2: 
        !             3: #include "../h/param.h"
        !             4: #include "../h/systm.h"
        !             5: #include "../h/inode.h"
        !             6: #include "../h/dir.h"
        !             7: #include "../h/user.h"
        !             8: #include "../h/buf.h"
        !             9: #include "../h/conf.h"
        !            10: #include "../h/cmap.h"
        !            11: #include "../h/proc.h"
        !            12: #include "../h/acct.h"
        !            13: 
        !            14: /*
        !            15:  * Read the file corresponding to
        !            16:  * the inode pointed at by the argument.
        !            17:  * The actual read arguments are found
        !            18:  * in the variables:
        !            19:  *     u_base          core address for destination
        !            20:  *     u_offset        byte offset in file
        !            21:  *     u_count         number of bytes to read
        !            22:  *     u_segflg        read to kernel/user
        !            23:  */
        !            24: readi(ip)
        !            25: register struct inode *ip;
        !            26: {
        !            27: 
        !            28:        if(u.u_count == 0)
        !            29:                return;
        !            30:        ip->i_flag |= IACC;
        !            31:        if (ip->i_sptr) {
        !            32:                u.u_nbadio = 0; /* approximates a bad-count per stream */
        !            33:                stread(ip);
        !            34:                return;
        !            35:        }
        !            36:        (*fstypsw[ip->i_fstyp].t_read)(ip);
        !            37: }
        !            38: 
        !            39: /*
        !            40:  * Write the file corresponding to
        !            41:  * the inode pointed at by the argument.
        !            42:  * The actual write arguments are found
        !            43:  * in the variables:
        !            44:  *     u_base          core address for source
        !            45:  *     u_offset        byte offset in file
        !            46:  *     u_count         number of bytes to write
        !            47:  *     u_segflg        write to kernel/user/user I
        !            48:  */
        !            49: 
        !            50: writei(ip)
        !            51: register struct inode *ip;
        !            52: {
        !            53: 
        !            54:        if (ip->i_sptr) {
        !            55:                ip->i_flag |= IUPD|ICHG;
        !            56:                stwrite(ip);
        !            57:                return;
        !            58:        }
        !            59:        (*fstypsw[ip->i_fstyp].t_write)(ip);
        !            60: }
        !            61: 
        !            62: /*
        !            63:  * Return the logical maximum
        !            64:  * of the 2 arguments.
        !            65:  */
        !            66: unsigned
        !            67: max(a, b)
        !            68: unsigned a, b;
        !            69: {
        !            70: 
        !            71:        if(a > b)
        !            72:                return(a);
        !            73:        return(b);
        !            74: }
        !            75: 
        !            76: /*
        !            77:  * Return the logical minimum
        !            78:  * of the 2 arguments.
        !            79:  */
        !            80: unsigned
        !            81: min(a, b)
        !            82: unsigned a, b;
        !            83: {
        !            84: 
        !            85:        if(a < b)
        !            86:                return(a);
        !            87:        return(b);
        !            88: }
        !            89: 
        !            90: /*
        !            91:  * Move n bytes at byte location
        !            92:  * &bp->b_un.b_addr[o] to/from (flag) the
        !            93:  * user/kernel (u.segflg) area starting at u.base.
        !            94:  * Update all the arguments by the number
        !            95:  * of bytes moved.
        !            96:  */
        !            97: iomove(cp, n, flag)
        !            98:        register caddr_t cp;
        !            99:        register unsigned n;
        !           100: {
        !           101:        register int t;
        !           102: 
        !           103:        if (n==0)
        !           104:                return;
        !           105:        if (u.u_segflg != 1) {
        !           106:                if (flag==B_WRITE)
        !           107:                        t = copyin(u.u_base, (caddr_t)cp, n);
        !           108:                else
        !           109:                        t = copyout((caddr_t)cp, u.u_base, n);
        !           110:                if (t) {
        !           111:                        u.u_error = EFAULT;
        !           112:                        return;
        !           113:                }
        !           114:        } else
        !           115:                if (flag == B_WRITE)
        !           116:                        bcopy(u.u_base, (caddr_t)cp, n);
        !           117:                else
        !           118:                        bcopy((caddr_t)cp, u.u_base, n);
        !           119:        u.u_base += n;
        !           120:        u.u_offset += n;
        !           121:        u.u_count -= n;
        !           122: }

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