141 lines
3.0 KiB
C
141 lines
3.0 KiB
C
/**************************************************************************
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***************************************************************************
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W E G A - Quelle (C) TU KMSt / ZFT/KEAW Abt. WAE - 1988
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Programm: dosdel.c
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Bearbeiter : P. Hoge
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Datum : 24.11.89
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Version : 1.3
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***************************************************************************
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**************************************************************************/
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#include "dos.h"
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/* dosdel
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* Loescht die DCP-Datei fn auf dem Datentraeger dp.
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* Liefert 0, wenn nicht gefunden,
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* -1, bei Lesefehler,
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* -2, bei Schreibfehler und
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* -3, falls fn ein Verzeichnis bzw
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* schreibgeschuetzt ist.
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*/
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dosdel(fn,dp)
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register char *fn;
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register struct dosdisc *dp;
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{
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register struct dostat fnrec, dirrec;
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long adr;
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unsigned char delsign=0xe5;
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char s[LMAX],*file,*strrchr();
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unsigned dnum,nxt,dosnxt();
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int res;
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strcpy(s,fn);
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fn = s;
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if ((res=dosopn(fn,dp,&fnrec)) < 1)
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return(res);
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if (fnrec.mode == _SDIR || fnrec.flag == RO)
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return(-3);
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if (fn[0] == '/')
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fn++;
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if ((file=strrchr(fn,'/')) == 0) { /* main directory */
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file = fn;
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dnum = dp->dirnum;
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adr = dp->maindir;
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nxt = 0;
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}
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else { /* sub directory */
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fn[strlen(fn)-strlen(file)] = '\0';
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file++;
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if ((res=dosopn(fn,dp,&dirrec)) < 1)
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return(res);
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nxt = dirrec.first;
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adr = DOSADR(nxt,dp->clustsiz)+dp->data;
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dnum = dp->clustsiz/32;
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}
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/* Suchen des zu loeschenden Eintrages */
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while (-1) {
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if ((res=dosrde(dp->fd,file,dnum,adr,&fnrec)) < 0)
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return(res);
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if (res == 1) {
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lseek(dp->fd,(long)-32,1);
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if (write(dp->fd,&delsign,1) != 1)
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return(-2);
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return(fatdel(&fnrec,dp));
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}
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if (nxt == 0)
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return(0);
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if ((nxt=dosnxt(dp->fd,nxt,dp->fat1,dp->fatlen)) < 1)
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return(0);
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/* naechsten Cluster lesen */
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adr = DOSADR(nxt,dp->clustsiz)+dp->data;
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}
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}
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/* fatdel
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* Gibt die Belegungskette der DCP-Datei stp
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* frei. Liefert -1 bei Lese- und -2 bei Schreibfehler.
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*/
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fatdel(stp,dp)
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register struct dostat *stp;
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register struct dosdisc *dp;
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{
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register int res;
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register unsigned first, next;
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next = stp->first;
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while (next) {
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first = next;
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next = dosnxt(dp->fd,first,dp->fat1,dp->fatlen);
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if ((res=fatput(first,0x0000,dp)) < 0)
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return(res);
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}
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return(1);
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}
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/* fatput
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* Schreibt in alle FAT-Versionen fuer den Wert
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* des Eintrages ent den Wert val.
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* Liefert -1 bei Lesefehler
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* und -2 bei Schreibfehler.
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*/
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fatput(ent,val,dp)
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register unsigned ent,val;
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register struct dosdisc *dp;
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{
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register long fat=dp->fat1;
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unsigned char b[2];
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int n;
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for (n = dp->fatnum; n >= 1; n--) {
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if (dp->fatlen == 12) {
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val &= 0x0fff;
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lseek(dp->fd,fat+(long)(1.5*ent),0);
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if (read(dp->fd,b,2) != 2)
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return(-1);
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lseek(dp->fd,(long)-2,1);
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if (ent % 2 == 0) {
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b[0] = val%256;
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b[1] = (b[1]/16)*16+(val/256);
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}
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else {
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b[1] = val/16;
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b[0] = (val%16)*16+(b[0]&0x0f);
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}
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}
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else {
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lseek(dp->fd,fat+(long)(2*ent),0);
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b[0] = val% 256;
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b[1] = val/256;
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}
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if (write(dp->fd,b,2) != 2)
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return(-2);
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fat = (dp->maindir-fat)/n+fat;
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}
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return(1);
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}
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