chain: Allow reading more than a single sector

Signed-off-by: Shao Miller <shao.miller@yrdsb.edu.on.ca>

diff --git a/com32/modules/chain.c b/com32/modules/chain.c
index 7f83b7e..9fbb39e 100644 (file)
--- a/com32/modules/chain.c
+++ b/com32/modules/chain.c
@@ -204,18 +204,23 @@ struct ebios_dapa {
     uint64_t lba;
 };
 
-static void *read_sector(unsigned int lba)
+/* Read count sectors from drive, starting at lba.  Return a new buffer */
+static void *read_sectors(uint64_t lba, uint8_t count)
 {
     com32sys_t inreg;
     struct ebios_dapa *dapa = __com32.cs_bounce;
     void *buf = (char *)__com32.cs_bounce + SECTOR;
     void *data;
 
+    if (!count)
+       /* Silly */
+       return NULL;
+
     memset(&inreg, 0, sizeof inreg);
 
     if (disk_info.ebios) {
        dapa->len = sizeof(*dapa);
-       dapa->count = 1;        /* 1 sector */
+       dapa->count = count;
        dapa->off = OFFS(buf);
        dapa->seg = SEG(buf);
        dapa->lba = lba;
@@ -246,7 +251,8 @@ static void *read_sector(unsigned int lba)
        if (s > 63 || h > 256 || c > 1023)
            return NULL;
 
-       inreg.eax.w[0] = 0x0201;        /* Read one sector */
+       inreg.eax.b[0] = count;
+       inreg.eax.b[1] = 0x02;  /* Read */
        inreg.ecx.b[1] = c & 0xff;
        inreg.ecx.b[0] = s + (c >> 6);
        inreg.edx.b[1] = h;
@@ -260,7 +266,7 @@ static void *read_sector(unsigned int lba)
 
     data = malloc(SECTOR);
     if (data)
-       memcpy(data, buf, SECTOR);
+       memcpy(data, buf, count * SECTOR);
     return data;
 }
 
@@ -329,7 +335,7 @@ static int write_verify_sector(unsigned int lba, const void *buf)
     rv = write_sector(lba, buf);
     if (rv)
        return rv;              /* Write failure */
-    rb = read_sector(lba);
+    rb = read_sectors(lba, 1);
     if (!rb)
        return -1;              /* Readback failure */
     rv = memcmp(buf, rb, SECTOR);
@@ -348,7 +354,7 @@ static int find_disk(uint32_t mbr_sig)
     for (drive = 0x80; drive <= 0xff; drive++) {
        if (get_disk_params(drive))
            continue;           /* Drive doesn't exist */
-       if (!(buf = read_sector(0)))
+       if (!(buf = read_sectors(0, 1)))
            continue;           /* Cannot read sector */
        is_me = (*(uint32_t *) ((char *)buf + 440) == mbr_sig);
        free(buf);
@@ -452,7 +458,7 @@ static struct part_entry *find_logical_partition(int whichpart, char *table,
                continue;
 
        /* Process this partition */
-       if (!(sector = read_sector(ptab[i].start_lba)))
+       if (!(sector = read_sectors(ptab[i].start_lba, 1)))
            continue;           /* Read error, must be invalid */
 
        found = find_logical_partition(whichpart, sector, &ptab[i],
@@ -841,7 +847,7 @@ int main(int argc, char *argv[])
     }
 
     /* Get MBR */
-    if (!(mbr = read_sector(0))) {
+    if (!(mbr = read_sectors(0, 1))) {
        error("Cannot read Master Boot Record\n");
        goto bail;
     }
@@ -969,7 +975,7 @@ int main(int argc, char *argv[])
        /* Actually read the boot sector */
        if (!partinfo) {
            data[ndata].data = mbr;
-       } else if (!(data[ndata].data = read_sector(partinfo->start_lba))) {
+       } else if (!(data[ndata].data = read_sectors(partinfo->start_lba, 1))) {
            error("Cannot read boot sector\n");
            goto bail;
        }