Patchwork [v3] raw-posix: Detect CDROM via ioctl

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Submitter Cole Robinson
Date Jan. 13, 2010, 11:45 p.m.
Message ID <1263426345-13558-1-git-send-email-crobinso@redhat.com>
Download mbox | patch
Permalink /patch/42840/
State New
Headers show

Comments

Cole Robinson - Jan. 13, 2010, 11:45 p.m.
Current CDROM detection is hardcoded based on source file name.
Make this smarter by attempting a CDROM specific ioctl.

This makes '-cdrom /dev/sr0' succeed with no media present.

v2:
    Give ioctl check higher priority than filename check,

v3:
    Actually initialize 'prio' variable
    Check for ioctl success rather than absence of specific failure

Signed-off-by: Cole Robinson <crobinso@redhat.com>
---
 block/raw-posix.c |   20 ++++++++++++++++++--
 1 files changed, 18 insertions(+), 2 deletions(-)
malc - Jan. 14, 2010, 12:11 a.m.
On Wed, 13 Jan 2010, Cole Robinson wrote:

> Current CDROM detection is hardcoded based on source file name.
> Make this smarter by attempting a CDROM specific ioctl.
> 
> This makes '-cdrom /dev/sr0' succeed with no media present.
> 
> v2:
>     Give ioctl check higher priority than filename check,
> 
> v3:
>     Actually initialize 'prio' variable
>     Check for ioctl success rather than absence of specific failure

Does it even compile on BSDs, Darwin etc?

[..snip..]
Cole Robinson - Jan. 14, 2010, 1:48 a.m.
On 01/13/2010 07:11 PM, malc wrote:
> On Wed, 13 Jan 2010, Cole Robinson wrote:
> 
>> Current CDROM detection is hardcoded based on source file name.
>> Make this smarter by attempting a CDROM specific ioctl.
>>
>> This makes '-cdrom /dev/sr0' succeed with no media present.
>>
>> v2:
>>     Give ioctl check higher priority than filename check,
>>
>> v3:
>>     Actually initialize 'prio' variable
>>     Check for ioctl success rather than absence of specific failure
> 
> Does it even compile on BSDs, Darwin etc?
> 

The changed functions are all under #ifdef __linux__, so I assume its fine.
Haven't tested though.

- Cole
malc - Jan. 14, 2010, 10:45 a.m.
On Wed, 13 Jan 2010, Cole Robinson wrote:

> On 01/13/2010 07:11 PM, malc wrote:
> > On Wed, 13 Jan 2010, Cole Robinson wrote:
> > 
> >> Current CDROM detection is hardcoded based on source file name.
> >> Make this smarter by attempting a CDROM specific ioctl.
> >>
> >> This makes '-cdrom /dev/sr0' succeed with no media present.
> >>
> >> v2:
> >>     Give ioctl check higher priority than filename check,
> >>
> >> v3:
> >>     Actually initialize 'prio' variable
> >>     Check for ioctl success rather than absence of specific failure
> > 
> > Does it even compile on BSDs, Darwin etc?
> > 
> 
> The changed functions are all under #ifdef __linux__, so I assume its fine.
> Haven't tested though.

Fine if so, it's not immediatelly aparent from the patches nor from
the commit messages though.
Cole Robinson - Jan. 14, 2010, 4:09 p.m.
On 01/14/2010 05:45 AM, malc wrote:
> On Wed, 13 Jan 2010, Cole Robinson wrote:
> 
>> On 01/13/2010 07:11 PM, malc wrote:
>>> On Wed, 13 Jan 2010, Cole Robinson wrote:
>>>
>>>> Current CDROM detection is hardcoded based on source file name.
>>>> Make this smarter by attempting a CDROM specific ioctl.
>>>>
>>>> This makes '-cdrom /dev/sr0' succeed with no media present.
>>>>
>>>> v2:
>>>>     Give ioctl check higher priority than filename check,
>>>>
>>>> v3:
>>>>     Actually initialize 'prio' variable
>>>>     Check for ioctl success rather than absence of specific failure
>>>
>>> Does it even compile on BSDs, Darwin etc?
>>>
>>
>> The changed functions are all under #ifdef __linux__, so I assume its fine.
>> Haven't tested though.
> 
> Fine if so, it's not immediatelly aparent from the patches nor from
> the commit messages though.
> 

True. I'll resend with a better commit message.

Thanks,
Cole

Patch

diff --git a/block/raw-posix.c b/block/raw-posix.c
index 5a6a22b..a2c7508 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -1140,9 +1140,25 @@  static int cdrom_open(BlockDriverState *bs, const char *filename, int flags)
 
 static int cdrom_probe_device(const char *filename)
 {
+    int fd, ret;
+    int prio = 0;
+
     if (strstart(filename, "/dev/cd", NULL))
-        return 100;
-    return 0;
+        prio = 50;
+
+    fd = open(filename, O_RDONLY | O_NONBLOCK);
+    if (fd < 0) {
+        goto out;
+    }
+
+    /* Attempt to detect via a CDROM specific ioctl */
+    ret = ioctl(fd, CDROM_DRIVE_STATUS, CDSL_CURRENT);
+    if (ret >= 0)
+        prio = 100;
+
+    close(fd);
+out:
+    return prio;
 }
 
 static int cdrom_is_inserted(BlockDriverState *bs)