lflputc.c File Reference

#include <xinu.h>

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Functions
devcall	lflputc (struct dentry *devptr, char ch)

Function Documentation

lflputc()

devcall lflputc	(	struct dentry *	devptr,
		char	ch
	)

Definition at line 9 of file lflputc.c.

References dentry::dvminor, ldentry::ld_size, LF_BLKSIZ, Lf_data, lfdata::lf_dirdirty, LF_USED, lflcblk::lfbyte, lflcblk::lfdbdirty, lflcblk::lfdblock, lflcblk::lfdirptr, lfltab, lflcblk::lfmutex, lflcblk::lfpos, lfsetup(), lflcblk::lfstate, OK, signal(), SYSERR, TRUE, and wait().

Referenced by lflwrite().

{
    struct  lflcblk *lfptr;     /* Ptr to open file table entry */
    struct  ldentry *ldptr;     /* Ptr to file's entry in the   */
                    /*  in-memory directory     */

    /* Obtain exclusive use of the file */

    lfptr = &lfltab[devptr->dvminor];
    wait(lfptr->lfmutex);

    /* If file is not open, return an error */

    if (lfptr->lfstate != LF_USED) {
        signal(lfptr->lfmutex);
        return SYSERR;
    }

    /* Return SYSERR for an attempt to skip bytes beyond the byte   */
    /*  that is currently the end of the file           */

    ldptr = lfptr->lfdirptr;
    if (lfptr->lfpos > ldptr->ld_size) {
        signal(lfptr->lfmutex);
        return SYSERR;
    }

    /* If pointer is outside current block, set up new block */

    if (lfptr->lfbyte >= &lfptr->lfdblock[LF_BLKSIZ]) {

        /* Set up block for current file position */

        lfsetup(lfptr);
    }

    /* If appending a byte to the file, increment the file size.    */
    /*   Note: comparison might be equal, but should not be greater.*/

    if (lfptr->lfpos >= ldptr->ld_size) {
        ldptr->ld_size++;
        Lf_data.lf_dirdirty = TRUE;
    }

    /* Place byte in buffer and mark buffer "dirty" */

    *lfptr->lfbyte++ = ch;
    lfptr->lfpos++;
    lfptr->lfdbdirty = TRUE;

    signal(lfptr->lfmutex);
    return OK;
}

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