https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=281020
Bug ID: 281020
Summary: Cannot play sound tracks on mixed-mode CDs (read()
fails with EINVAL)
Product: Base System
Version: 14.1-RELEASE
Hardware: Any
OS: Any
Status: New
Severity: Affects Some People
Priority: ---
Component: kern
Assignee: [email protected]
Reporter: [email protected]
On a mixed-mode CD (a CD with both data and sound tracks), it is not possible
to play the sound tracks.
The way that eg. multimedia/vlc reads sound from a CD involves:
int fd = open("/dev/cd0", ...)
int block_size = 2352;
ioctl(fd, CDRIOCSETBLOCKSIZE, &block_size);
lseek(fd, some multiple of 2352, SEEK_SET);
read(fd, buffer, some multiple of 2352);
and on a pure sound CD, this works perfectly, both in VLC and a test
application I made.
However when using that code on a mixed-mode CD (with both data and sound
tracks), read() always fails with EINVAL, whether the offset is within a data
track or a sound track. The only way to make read() succeed on such CDs, is to
use a block size of 2048, and an offset that places the read within a data
track. Attempting to read music tracks always fails with EINVAL, regardless of
the block size.
It will take me some time to confirm, but this may be a regression from commit
dd78f43259efd551f76a6cb7744bce49c215863e, which was meant to "make the media
check asynchronous", but also made many other changes, including setting a
block size of 2352 for pure sound CDs (which could be why they still work, but
mixed-mode CDs don't).
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