Fix bug 1819 by setting FAT32 fields of FAT12/16 DPBs on Int21/7302

git-svn-id: https://svn.code.sf.net/p/freedos/svn/kernel/branches/UNSTABLE@1068 6ac86273-5f31-0410-b378-82cca8765d1b

docs/history.txt

@@ -5,6 +5,8 @@
         - bugfix: call_nls: DI register was not preserved
       * exeflat.c
         - new version exploiting better UPX compression for SYS files; calls UPX itself
+      * inthndlr.c
+        - int21/ah=6/dl=ff now calls int28
 + Changes Tom
 	* inthndlr.c
 	  - improve handling of case where eg. FindFirst(I:\*.*) fails, causes Int24,
@@ -309,6 +311,7 @@
         - set AX = ES after Int 21h/4Ah (undocumented but expected by BRUN45)
           (the last 2 changes needed to fix bugs discovered by Michael Devore)
         - added Int 2Fh/2Fh processing to set DOS version as per MS-DOS 4.0
+        - set FAT32 fields of FAT12/16 DPBs on Int21h/7302h. Fixes bug 1819
         * autoexec.bat now single-line for FreeCOM compatibility when EOL=LF
         * break.c: check_handle_break() return was undefined if no Ctrl-break
         * config.sys: all commands removed as they were close to defaults

kernel/inthndlr.c

@@ -196,6 +196,18 @@ int int21_fat32(lregs *r)
       xddp = MK_FP(r->ES, r->DI);
       
       fmemcpy(&xddp->xdd_dpb, dpb, sizeof(struct dpb));
+      if (!ISFAT32(dpb))
+      { /* FAT12/16 - set FAT32 fields. This helps DOSLFN 0.33+ */
+        xddp->xdd_dpb.dpb_nfreeclst_un.dpb_nfreeclst_st.dpb_nfreeclst_hi = 0;
+        xddp->xdd_dpb.dpb_xflags = 0;
+        xddp->xdd_dpb.dpb_xfsinfosec = 0xFFFF; /* unknown */
+        xddp->xdd_dpb.dpb_xbackupsec = 0xFFFF;
+        xddp->xdd_dpb.dpb_xdata = dpb->dpb_data;
+        xddp->xdd_dpb.dpb_xsize = dpb->dpb_size;
+        xddp->xdd_dpb.dpb_xfatsize = dpb->dpb_fatsize;
+        xddp->xdd_dpb.dpb_xrootclst = 0; /* impossible cluster number */
+        xddp->xdd_dpb.dpb_xcluster = dpb->dpb_cluster;
+      }
       xddp->xdd_dpbsize = sizeof(struct dpb);
       break;
     }