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cdrom_id: Fix DVD blank detection for sloppy firmware

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Reportedly, many CD drive firmwares will only consider the MSB in a READ
command, thus if we request 17 blocks to be read, we'll actually only get 16 in
many cases, and thus miss out the interesting sector #17. This would lead to
falsely considering nonempty DVDs as blank.

Fetch 32 blocks now, which should work everywhere.

Signed-off-by: Martin Pitt <martin.pitt@ubuntu.com>
This commit is contained in:
Jan Drzewiecki
2010-08-31 00:41:35 +02:00
committed by Martin Pitt
parent 2458db3edd
commit 5e267ea5a3
1 changed files with 2 additions and 2 deletions
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extras/cdrom_id/cdrom_id.c
+2 -2
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@@ -590,7 +590,7 @@ static int cd_media_info(struct udev *udev, int fd)
* always "complete", DVD-RAM are "other" or "complete" if the disc is
* write protected; we need to check the contents if it is blank */
if ((cd_media_dvd_rw_ro || cd_media_dvd_plus_rw || cd_media_dvd_plus_rw_dl || cd_media_dvd_ram) && (header[2] & 3) > 1) {
unsigned char buffer[17 * 2048];
unsigned char buffer[32 * 2048];
unsigned char result, len;
int block, offset;
@@ -661,7 +661,7 @@ static int cd_media_info(struct udev *udev, int fd)
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, 17);
scsi_cmd_set(udev, &sc, 8, 32);
scsi_cmd_set(udev, &sc, 9, 0);
err = scsi_cmd_run(udev, &sc, fd, buffer, sizeof(buffer));
if ((err != 0)) {