An idea beyond this patch is to disallow r/w mounts for storage devices
emulated with
g_file_storage with 'ro=1'. This is done by setting device type to TYPE_ROM
instead
of TYPE_DISK.
Dmitry
--- linux.orig/drivers/usb/gadget/file_storage.c 2005-10-31
14:26:41.000000000 +0300
+++ linux/drivers/usb/gadget/file_storage.c 2005-12-08 18:36:26.000000000
+0300
@@ -517,6 +517,11 @@
#define SS_WRITE_ERROR 0x030c02
#define SS_WRITE_PROTECTED 0x072700
+/* Subset of SCSI device types we emulate */
+#define SD_TYPE_DISK 0x00
+#define SD_TYPE_ROM 0x05
+#define SD_TYPE_NO_LUN 0x7f
+
#define SK(x) ((u8) ((x) >> 16)) // Sense Key byte, etc.
#define ASC(x) ((u8) ((x) >> 8))
#define ASCQ(x) ((u8) (x))
@@ -2028,17 +2033,25 @@
if (!fsg->curlun) { // Unsupported LUNs are okay
fsg->bad_lun_okay = 1;
memset(buf, 0, 36);
- buf[0] = 0x7f; // Unsupported, no device-type
+ buf[0] = SD_TYPE_NO_LUN; // Unsupported, no device-type
return 36;
}
- memset(buf, 0, 8); // Non-removable, direct-access device
- if (mod_data.removable)
- buf[1] = 0x80;
+ if (fsg->curlun->ro == 1) {
+ DBG(fsg, "LUN%d: will emulate SCSI CDROM\n", fsg->lun);
+ buf[0] = SD_TYPE_ROM;
+ }
+ else {
+ DBG(fsg, "LUN%d: will emulate SCSI disk\n", fsg->lun);
+ buf[0] = SD_TYPE_DISK;
+ }
+ buf[1] = mod_data.removable ? 0x80 : 0x0;
buf[2] = 2; // ANSI SCSI level 2
buf[3] = 2; // SCSI-2 INQUIRY data format
buf[4] = 31; // Additional length
// No special options
+ memset(buf + 5, 0, 3);
+
sprintf(buf + 8, "%-8s%-16s%04x", vendor_id, product_id,
mod_data.release);
return 36;
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