Patchwork raw-posix: Detect CDROM via ioctl

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Submitter Cole Robinson
Date Jan. 11, 2010, 6:30 p.m.
Message ID <1263234619-14522-1-git-send-email-crobinso@redhat.com>
Download mbox | patch
Permalink /patch/42651/
State New
Headers show

Comments

Cole Robinson - Jan. 11, 2010, 6:30 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.

Signed-off-by: Cole Robinson <crobinso@redhat.com>
---
 block/raw-posix.c |   18 +++++++++++++++++-
 1 files changed, 17 insertions(+), 1 deletions(-)
Simon Horman - Jan. 11, 2010, 11:13 p.m.
On Mon, Jan 11, 2010 at 01:30:18PM -0500, 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.
> 
> Signed-off-by: Cole Robinson <crobinso@redhat.com>
> ---
>  block/raw-posix.c |   18 +++++++++++++++++-
>  1 files changed, 17 insertions(+), 1 deletions(-)
> 
> diff --git a/block/raw-posix.c b/block/raw-posix.c
> index 5a6a22b..3ec58d0 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;
> +
>      if (strstart(filename, "/dev/cd", NULL))
>          return 100;
> -    return 0;
> +
> +    fd = open(filename, O_RDONLY | O_NONBLOCK);
> +    if (fd < 0) {
> +        return 0;
> +    }
> +
> +    /* Attempt to detect via a CDROM specific ioctl */
> +    if (ioctl(fd, CDROM_DRIVE_STATUS, CDSL_CURRENT) < 0 && errno == EINVAL) {
> +        ret = 0;
> +    } else {
> +        ret = 100;
> +    }
> +
> +    close(fd);
> +    return ret;
>  }
>  
>  static int cdrom_is_inserted(BlockDriverState *bs)

Does this render the remaining "/dev/cd" check unnecessary?
Likewise for the similar change that you posted for floppies.
Cole Robinson - Jan. 12, 2010, 12:01 a.m.
On 01/11/2010 06:13 PM, Simon Horman wrote:
> On Mon, Jan 11, 2010 at 01:30:18PM -0500, 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.
>>
>> Signed-off-by: Cole Robinson <crobinso@redhat.com>
>> ---
>>  block/raw-posix.c |   18 +++++++++++++++++-
>>  1 files changed, 17 insertions(+), 1 deletions(-)
>>
>> diff --git a/block/raw-posix.c b/block/raw-posix.c
>> index 5a6a22b..3ec58d0 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;
>> +
>>      if (strstart(filename, "/dev/cd", NULL))
>>          return 100;
>> -    return 0;
>> +
>> +    fd = open(filename, O_RDONLY | O_NONBLOCK);
>> +    if (fd < 0) {
>> +        return 0;
>> +    }
>> +
>> +    /* Attempt to detect via a CDROM specific ioctl */
>> +    if (ioctl(fd, CDROM_DRIVE_STATUS, CDSL_CURRENT) < 0 && errno == EINVAL) {
>> +        ret = 0;
>> +    } else {
>> +        ret = 100;
>> +    }
>> +
>> +    close(fd);
>> +    return ret;
>>  }
>>  
>>  static int cdrom_is_inserted(BlockDriverState *bs)
> 
> Does this render the remaining "/dev/cd" check unnecessary?
> Likewise for the similar change that you posted for floppies.
> 

Probably, but I figured I'd be conservative and keep the check in place to
avoid possible regressions. If one of the regular devs/maintainers wants it
removed I'll respin the patches.

Thanks,
Cole

Patch

diff --git a/block/raw-posix.c b/block/raw-posix.c
index 5a6a22b..3ec58d0 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;
+
     if (strstart(filename, "/dev/cd", NULL))
         return 100;
-    return 0;
+
+    fd = open(filename, O_RDONLY | O_NONBLOCK);
+    if (fd < 0) {
+        return 0;
+    }
+
+    /* Attempt to detect via a CDROM specific ioctl */
+    if (ioctl(fd, CDROM_DRIVE_STATUS, CDSL_CURRENT) < 0 && errno == EINVAL) {
+        ret = 0;
+    } else {
+        ret = 100;
+    }
+
+    close(fd);
+    return ret;
 }
 
 static int cdrom_is_inserted(BlockDriverState *bs)