add a signature mechanism for ioctl control strings

1 files changed, 18 insertions, 4 deletions

diff --git a/dos/chudisk.c b/dos/chudisk.c
index c7c0968..d822110 100644
--- a/dos/chudisk.c
+++ b/dos/chudisk.c
@@ -598,10 +598,13 @@ void interrupt_routine()
 			return;
 		}
 		// If there's enough space, return our internal config string.
-		if (saved_drs->cmd.ioctlrw.len >= 3 + 2 + 1 + 5 + 1) {
+		if (saved_drs->cmd.ioctlrw.len >= 2 + /*B*/3 + /*3*/2 + /*R*/2 + /*S*/5 + /*L*/5 + 1) {
 			uint8_t far * buf = saved_drs->cmd.ioctlrw.buffer;
 			int len = 0;
-			// B = base port (2 byte)
+			// signature (2 bytes)
+			buf[len++] = 'C';
+			buf[len++] = 'H';
+			// B = base port (2 bytes)
 			buf[len++] = 'B';
 			_fmemcpy(&buf[len], &ch375_dev.io_base, sizeof(ch375_dev.io_base));
 			len += sizeof(ch375_dev.io_base);
@@ -615,6 +618,10 @@ void interrupt_routine()
 			buf[len++] = 'S';
 			_fmemcpy(&buf[len], &data.unit[saved_drs->unit].start_sector, sizeof(uint32_t));
 			len += sizeof(uint32_t);
+			// L = partition len (4 bytes)
+			buf[len++] = 'L';
+			_fmemcpy(&buf[len], &data.unit[saved_drs->unit].sectors, sizeof(uint32_t));
+			len += sizeof(uint32_t);
 			buf[len++] = '\0';
 			saved_drs->cmd.ioctlrw.len = len;
 		} else {
@@ -632,7 +639,14 @@ void interrupt_routine()
 		if (saved_drs->cmd.ioctlrw.len >= 2) {
 			uint8_t far * buf = saved_drs->cmd.ioctlrw.buffer;
 			int i = 0;
-			do {
+			if (buf[i] != 'C' || buf[i+1] != 'H') {
+				dprintf(" invalid signature\n");
+				saved_drs->cmd.ioctlrw.len = 0;
+				saved_drs->status = DOS_DD_ERR_UNKNOWN_COMMAND | DOS_DD_STATUS_ERROR_DONE;
+				return;
+			}
+			i += 2;
+			while (i < saved_drs->cmd.ioctlrw.len) {
 				char c = buf[i++];
 				switch (c) {
 				case 'S': // Partition start (5 bytes)
@@ -659,7 +673,7 @@ void interrupt_routine()
 					saved_drs->status = DOS_DD_ERR_WRITE_FAULT | DOS_DD_STATUS_ERROR_DONE;
 					return;
 				}
-			} while (i < saved_drs->cmd.ioctlrw.len);
+			}
 		} else {
 			saved_drs->cmd.ioctlrw.len = 0;
 			saved_drs->status = DOS_DD_ERR_WRITE_FAULT | DOS_DD_STATUS_ERROR_DONE;