source: buchla-68k/libcio/writern.c@ e225e77

/*
   =============================================================================
        writern.c -- write a random sector onto a file
        Version 6 -- 1987-12-15 -- D.N. Lynx Crowe

        int
        WriteRN(fcp, buf)
        struct fcb *fcp;
        char *buf;

                Writes a sector onto file 'fcp' from 'buf'.  Seeks as needed.
                Returns SUCCESS (0) if OK,  FAILURE (-1) for errors.
   =============================================================================
*/

#define DEBUGIT         0

#include "stddefs.h"
#include "biosdefs.h"
#include "errno.h"
#include "errdefs.h"
#include "fspars.h"

extern  int32_t _berrno;
extern  int16_t _seek(struct fcb *fcp);

#if DEBUGIT
extern  short   fsdebug;
#endif

#if     TBUFFER
extern  int32_t _secwr(int8_t *buf, int16_t rec);

extern  int16_t _alcnew(struct fcb *fcp);
#endif

/* 

*/

/*
   =============================================================================
        WriteRN(fcp, buf) -- Writes a sector onto file 'fcp' from 'buf'.
        Seeks as needed.  Returns SUCCESS (0) if OK,  FAILURE (-1) for errors.
   =============================================================================
*/

int16_t WriteRN(struct fcb *fcp, int8_t *buf)
{
        int16_t sv;             /* seek return code */
        int32_t brc;            /* bios return code */

        if (sv = _seek(fcp)) {          /* try to find the sector we want */

                if (sv < 0) {                   /* seek error ? */

#if DEBUGIT
        if (fsdebug)
                printf("WriteRN():  _seek FAILED (%d) - curlsn=%ld, curdsn=%ld\n",
                        sv, fcp->curlsn, fcp->curdsn);
#endif

                        errno = EIO;            /* I/O error or seek past EOF */
                        return(FAILURE);

                } else if (sv EQ 2) {           /* at hard EOF ? */

                        if (_alcnew(fcp)) {     /* allocate a new cluster */

                                errno = EIO;
                                return(FAILURE);
                        }
#if DEBUGIT
        if (fsdebug)
                printf("WriteRN():  cluster allocated - curcls=%d, clsec=%d\n",
                        fcp->curcls, fcp->clsec);
#endif

                }
        }

#if DEBUGIT
        if (fsdebug)
                printf("WriteRN():  curlsn=%ld, curdsn=%ld\n",
                        fcp->curlsn, fcp->curdsn);
#endif

        /* write the sector */

        if (brc = BIOS(B_RDWR, 1, buf, 1, (int16_t)fcp->curdsn, 0)) {

#if DEBUGIT
        if (fsdebug)
                printf("WriteRN():  B_RDWR FAILED - brc=%ld\n", brc);
#endif

                _berrno = brc;                  /* log the error */
                errno = EIO;                    /* ... as an I/O error */
                return(FAILURE);                /* return:  ERROR */
        }

#if     TBUFFER
        _secwr(buf, (int16_t)fcp->curdsn);
#endif

        return(SUCCESS);                /* return:  SUCCESS */
}