Annotation of researchv10dc/cmd/ps/memrd.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * various memory-reading primitives
        !             3:  */
        !             4: 
        !             5: #include "ps.h"
        !             6: 
        !             7: /*
        !             8:  * read the memory page corresponding to a VAX pte
        !             9:  *
        !            10:  * trickiness:
        !            11:  * the call to memrd assumes memory == /dev/mem, not /dev/kmem
        !            12:  * if mode == 0, this is wrong.
        !            13:  * but if mode == 0, rdpage is called only when the process is
        !            14:  * entirely swapped out, and hence its pages are all in the swap area
        !            15:  * this could use some cleaning up
        !            16:  */
        !            17: rdpage(up, pgno, pte, buf)
        !            18: register struct user *up;
        !            19: int pgno;
        !            20: register struct pte *pte;
        !            21: char *buf;
        !            22: {
        !            23: 
        !            24:        if (pte->pg_v   /* in memory */
        !            25:        ||  (pte->pg_fod == 0 && pte->pg_pfnum))        /* or unreferenced but in memory */
        !            26:                return (memrd(memory, buf, NBPG, ctob(pte->pg_pfnum)));
        !            27:        if (pte->pg_fod) {      /* assume fill-zero */
        !            28:                memset(buf, 0, NBPG);
        !            29:                return (NBPG);
        !            30:        }
        !            31:        /*
        !            32:         * page is in the swap area
        !            33:         * assume stack segment
        !            34:         */
        !            35:        return (memrd(drum, buf, NBPG,
        !            36:                ctob(up->u_smap.dm_map[0] + DMMIN - pgno - 1)));
        !            37: }
        !            38: 
        !            39: /*
        !            40:  * read a chunk of something at some offset in some file
        !            41:  */
        !            42: 
        !            43: memrd(fd, buf, size, off)
        !            44: int fd;
        !            45: char *buf;
        !            46: int size;
        !            47: long off;
        !            48: {
        !            49: 
        !            50:        lseek(fd, off, 0);
        !            51:        return (read(fd, buf, size));
        !            52: }

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