add a signature mechanism for ioctl control strings

4 files changed, 73 insertions, 19 deletions

diff --git a/dos/chud.c b/dos/chud.c
index c6d728c..498d97b 100644
--- a/dos/chud.c
+++ b/dos/chud.c
@@ -20,11 +20,13 @@
 #include <stdlib.h>
 #include <stdint.h>
 #include <string.h>
+#include <errno.h>
 #include <dos.h>
 #include <dosfunc.h>
 #include <io.h>
 
 #include "inc/mbr.h"
+#include "inc/dosapi.h"
 #include "inc/dosdrv.h"
 
 #include "chudisk.h"
@@ -56,11 +58,10 @@ static int ioctl_read_control(uint8_t drive, void *buffer, int len)
 	regs.x.dx = FP_OFF(buffer);
 
 	intdos(&regs, &regs);
-
 	if (regs.x.cflag) {
-		return -1;
+		return -1; // Generic error, but errno should be properly set
 	} else {
-		return regs.x.ax;
+		return regs.x.ax; // Number of bytes read
 	}
 }
 
@@ -74,7 +75,6 @@ static int ioctl_write_control(uint8_t drive, void *buffer, int len)
 	regs.x.dx = FP_OFF(buffer);
 
 	intdos(&regs, &regs);
-
 	if (regs.x.cflag) {
 		return -1;
 	} else {
@@ -98,9 +98,34 @@ static int ioctl_read_abs_sector(uint8_t drive, void *buffer, uint32_t sector, i
 	regs.h.cl = CHUDISK_IOCTL_DISK_READ_ABS_SECTOR;
 	regs.x.dx = FP_OFF(&ciod);
 
-	intdos(&regs, &regs);
-
-	return regs.x.cflag ? -1 : 0;
+	if (intdos(&regs, &regs) == 0) {
+		return 0;
+	} else {
+		struct DOSERROR err;
+		// Get the extended error from DOS, more useful than a simple EACCES
+		// and translate to watcom's errno
+		switch (dosexterr(&err)) {
+		case DOS_ERROR_INVALID_FUNCTION:
+			errno = EINVAL;
+			break;
+		case DOS_ERROR_FILE_NOT_FOUND:
+		case DOS_ERROR_PATH_NOT_FOUND:
+			errno = ENOENT;
+			break;
+		case DOS_ERROR_INVALID_DRIVE:
+			errno = ENODEV;
+			break;
+		case DOS_ERROR_READ_FAULT:
+		case DOS_ERROR_WRITE_FAULT:
+		case DOS_ERROR_GEN_FAILURE:
+			errno = EIO;
+			break;
+		default:
+			errno = EFAULT;
+			break;
+		}
+		return -errno;
+	}
 }
 
 static void dos_disk_reset()
@@ -123,6 +148,11 @@ static int parse_chudisk_control_string(const char *b, int len)
 	}
 	i = 0;
 #endif
+	// signature
+	if (b[i] != 'C' || b[i+1] != 'H') {
+		return -1;
+	}
+	i+=2;
 	while (i < len) {
 		char c = b[i++];
 		switch (c) {
@@ -345,7 +375,7 @@ static void usage()
 
 int main(int argc, const char *argv[])
 {
-	static char buffer[16];
+	static char buffer[32];
 	int i;
 	unsigned part;
 
@@ -399,10 +429,12 @@ int main(int argc, const char *argv[])
 	dos_disk_reset(); // Flush caches before we swap the drive...
 
 	i = 0;
-	buffer[i++] = 'S';
+	buffer[i++] = 'C'; // Signature
+	buffer[i++] = 'H';
+	buffer[i++] = 'S'; // Partition start sector
 	memcpy(&buffer[i], &partinfo[part-1].start_sector, sizeof(uint32_t));
 	i+=sizeof(uint32_t);
-	buffer[i++] = 'L';
+	buffer[i++] = 'L'; // Partition len
 	memcpy(&buffer[i], &partinfo[part-1].num_sectors, sizeof(uint32_t));
 	i+=sizeof(uint32_t);
 	buffer[i] = '\0';
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;
diff --git a/dos/chudisk.h b/dos/chudisk.h
index 1d2fbe4..bc7f12d 100644
--- a/dos/chudisk.h
+++ b/dos/chudisk.h
@@ -54,7 +54,7 @@ extern struct chudisk_data
 	struct chudisk_unit {
 		/** Whether the partition exists (start_sector points to it) */
 		bool exists;
-		/** Note in theory may be zero (superfloppy) */
+		/** Start sector of partition. Note in theory may be zero (superfloppy) */
 		uint32_t start_sector;
 		/** Number of sectors for this partition. */
 		uint32_t sectors;
@@ -78,15 +78,21 @@ extern uint8_t wait_for_ch375_result(unsigned int max_ticks);
 // TODO Not sure we can really happily add custom minors here,
 // but then again DOS outright refuses to accept any other major
 enum CHUDISK_IOCTL_DISK_MINOR {
+	/** Read an absolute disk sector.
+	 *  This ignores any configured partition on this unit. */
 	CHUDISK_IOCTL_DISK_READ_ABS_SECTOR = 0xC1
 };
 
 typedef _Packed union CHUDISK_IOCTL_DISK_DATA
 {
+	/* @see CHUDISK_IOCTL_DISK_READ_ABS_SECTOR */
 	struct CHUDISK_RWABSSECTOR {
-	    uint32_t sector;
-	    uint8_t sectors;
-	    void far * buffer;
+		/** Absolute starting sector. */
+		uint32_t sector;
+		/** Number of sectors to read. */
+		uint8_t sectors;
+		/** Buffer to read data into. */
+		void far * buffer;
 	} rwabs;
 } CHUDISK_IOCTL_DISK_DATA;
 
diff --git a/dos/inc/dosapi.h b/dos/inc/dosapi.h
index 18dbde0..8295660 100644
--- a/dos/inc/dosapi.h
+++ b/dos/inc/dosapi.h
@@ -57,7 +57,9 @@ enum dos_error {
 	DOS_ERROR_SEEK = 25,
 	DOS_ERROR_NOT_DOS_DISK = 26,
 	DOS_ERROR_SECTOR_NOT_FOUND = 27,
-
+	DOS_ERROR_OUT_OF_PAPER = 28,
+	DOS_ERROR_WRITE_FAULT = 29,
+	DOS_ERROR_READ_FAULT = 30,
 	DOS_ERROR_GEN_FAILURE = 31,
 
 	DOS_ERROR_HANDLE_EOF = 38,