mdiskchk: Add --no-sequential mode

It might be useful to suppress MDISKCHK.COM's classic behaviour
of probing all BIOS drive numbers in search of MEMDISKs.  Some BIOSes
might not enjoy being probed.

Reported-by: bylokk
Reported-by: Gert Hulselmans <gerth@zytor.com>
Signed-off-by: Shao Miller <shao.miller@yrdsb.edu.on.ca>

diff --git a/dosutil/mdiskchk.c b/dosutil/mdiskchk.c
index ddc5763..f7bde61 100644 (file)
--- a/dosutil/mdiskchk.c
+++ b/dosutil/mdiskchk.c
@@ -200,7 +200,8 @@ static MDISKCHK_FUNC_DECL(show_usage)
           "Action: --safe-hooks . . Will scan INT 13h \"safe hook\" chain\n"
           "        --mbfts . . . .  Will scan memory for MEMDISK mBFTs\n"
           "        --batch-output . Will output SET command output based\n"
-          "                         on MEMDISK kernel arguments\n");
+          "                         on MEMDISK kernel arguments\n"
+          "        --no-sequential  Suppresses probing all drive numbers\n");
 }
 
 /* Search memory for mBFTs and report them via the output method */
@@ -297,6 +298,7 @@ int main(int argc, char *argv[])
 {
     int d;
     int found = 0;
+    int sequential_scan = 1;   /* Classic behaviour */
     const struct memdiskinfo *m;
 
     /* Default behaviour */
@@ -331,6 +333,10 @@ int main(int argc, char *argv[])
            case 'b':
                show_memdisk = batch_output;
                break;
+           case 'N':
+           case 'n':
+               sequential_scan = 0;
+               break;
            default:
                usage = show_usage;
        } /* switch */
@@ -338,6 +344,8 @@ int main(int argc, char *argv[])
 
     safe_hooks();
     mbfts();
+    if (!sequential_scan)
+       goto skip_sequential;
     for (d = 0; d <= 0xff; d++) {
        m = query_memdisk(d);
        if (m != NULL) {
@@ -345,6 +353,7 @@ int main(int argc, char *argv[])
            show_memdisk(d, m);
        }
     }
+skip_sequential:
     usage();
 
     return found;