cdrom_id: Try reading the medium if all MMC commands fail

Reportedly, some "when I'm grown up I want to be a CD drive" fake USB CD sticks
like the IronKey neither support the SCSI "GET CONFIGURATION" nor the older
(pre-MMC2) "READ DISC INFORMATION" command. In that case, check if we can read
data from the drive, and assume that we have a CD-ROM medium if it succeeds.

diff --git a/extras/cdrom_id/cdrom_id.c b/extras/cdrom_id/cdrom_id.c
index 0153af66330aeccc7be0248ca6a3656585b4274c..f65f04f9dc1870e86f52111adfe916b548e9b33f 100644 (file)
--- a/extras/cdrom_id/cdrom_id.c
+++ b/extras/cdrom_id/cdrom_id.c
@@ -350,6 +350,34 @@ static int feature_profiles(struct udev *udev, const unsigned char *profiles, si
        return 0;
 }
 
+static int cd_profiles_broken_mmc(struct udev *udev, int fd)
+{
+       struct scsi_cmd sc;
+       unsigned char buffer[16 * 2048];
+       int err;
+
+       /* we land here if both the standard and the old MMC commands failed;
+        * this might happen on broken wanna-be-CD USB drives like the IronKey.
+        * As a last resort, try to read data to see whether it has a medium.
+        */
+       scsi_cmd_init(udev, &sc, buffer, sizeof(buffer));
+       scsi_cmd_set(udev, &sc, 0, 0x28);
+       scsi_cmd_set(udev, &sc, 5, 0);
+       scsi_cmd_set(udev, &sc, 8, 16);
+       scsi_cmd_set(udev, &sc, 9, 0);
+       err = scsi_cmd_run(udev, &sc, fd, buffer, sizeof(buffer));
+       if ((err != 0)) {
+           info(udev, "READ DATA failed, assuming no medium\n");
+           return -1;
+       }
+
+       /* that's all we can claim if we can read data */
+       info(udev, "READ DATA succeeded, assuming CD-ROM medium\n");
+       cd_media = 1;
+       cd_media_cd_rom = 1;
+       return 0;
+}
+
 static int cd_profiles_old_mmc(struct udev *udev, int fd)
 {
        struct scsi_cmd sc;
@@ -364,8 +392,8 @@ static int cd_profiles_old_mmc(struct udev *udev, int fd)
        err = scsi_cmd_run(udev, &sc, fd, header, sizeof(header));
        if ((err != 0)) {
                info_scsi_cmd_err(udev, "READ DISC INFORMATION", err);
-               info(udev, "no current profile, assuming no media\n");
-               return -1;
+               info(udev, "no current profile, probing readability of medium\n");
+               return cd_profiles_broken_mmc(udev, fd);
        };
 
        cd_media = 1;