chain.c32: Fix chaining to MBRs

The change to load the bootsector even when loading a bootstrap from a
file broke the handing of chainloading the MBR of a disk.  Fix this.

Debugging-info-by: Thomas Mieslinger <thomas.mieslinger@lundl.de>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

diff --git a/com32/modules/chain.c b/com32/modules/chain.c
index 9b6988d..160aa70 100644 (file)
--- a/com32/modules/chain.c
+++ b/com32/modules/chain.c
@@ -690,7 +690,6 @@ static void usage(void)
 int main(int argc, char *argv[])
 {
     char *mbr, *p;
-    void *boot_sector = NULL;
     struct part_entry *partinfo;
     struct syslinux_rm_regs regs;
     char *drivename, *partition;
@@ -850,7 +849,6 @@ int main(int argc, char *argv[])
        /* Boot the MBR */
 
        partinfo = NULL;
-       boot_sector = mbr;
     } else if (whichpart <= 4) {
        /* Boot a primary partition */
 
@@ -950,10 +948,11 @@ int main(int argc, char *argv[])
        ndata++;
     }
 
-    if (partinfo && (!opt.loadfile || data[0].base >= 0x7c00 + SECTOR)) {
+    if (!opt.loadfile || data[0].base >= 0x7c00 + SECTOR) {
        /* Actually read the boot sector */
-       /* Pick the first buffer that isn't already in use */
-       if (!(data[ndata].data = read_sector(partinfo->start_lba))) {
+       if (!partinfo) {
+           data[ndata].data = mbr;
+       } else if (!(data[ndata].data = read_sector(partinfo->start_lba))) {
            error("Cannot read boot sector\n");
            goto bail;
        }
@@ -972,7 +971,7 @@ int main(int argc, char *argv[])
         * the string "cmdcons\0" to memory location 0000:7C03.
         * Memory location 0000:7C00 contains the bootsector of the partition.
         */
-       if (opt.cmldr) {
+       if (partinfo && opt.cmldr) {
            memcpy((char *)data[ndata].data+3, cmldr_signature,
                   sizeof cmldr_signature);
        }