[DVDnav-discuss] dvdnav patches from handbrake project

[John Stebbins]

On 06/03/2010 01:49 AM, Nico Sabbi wrote:
> Sorry for the hand-quote, I don't have the original message right here.
>
>
> John Stebbins wrote:
>
>> To keep things organized, here's current status of these patches.
>> These are pending:
>>     * read-block2char.patch
>
> This one is really disturbing me:
>> Index: libdvdread/src/dvd_reader.c
>> ===================================================================
>> --- libdvdread/src/dvd_reader.c    (revision 1194)
>> +++ libdvdread/src/dvd_reader.c    (working copy)
>> @@ -318,7 +318,7 @@
>>    char *new_path;
>>
>>    /* If it doesn't start with "/dev/" or does start with "/dev/r"
>> exit */
>> -  if( !strncmp( path, "/dev/",  5 ) || strncmp( path, "/dev/r", 6 ) )
>> +  if( strncmp( path, "/dev/",  5 ) || !strncmp( path, "/dev/r", 6 ) )
>>      return (char *) strdup( path );
>>
>>    /* Replace "/dev/" with "/dev/r" */
>
> The function is supposed to replace -on most BSDs- access to a block
> device to the equivalent raw device,
> returning in a string the correct device name to use.
> Now, it's true that in the current code the comment reads one thing
> and the code does the exact opposite, but
> both the original code and the patched one don't make sense to me:
> -if the string starts with /dev/ it's not necesserily correct or wrong
> -it the string starts with /dev/r it IS correct and doesn't need to be
> replaced, so
> return (char *) strdup( path );
> is fine
>
> In practice to me the right code to use seems:
>   /* If the string starts with "/dev/r"  then return it */
>   if(!strncmp( path, "/dev/r", 6 ) )
>     return (char *) strdup( path );
>
>
> of course if the string doesn't start with /dev/ it's wrong, but this
> is the idiot's business (that didn't specify a correct
> device to use).
> Am I missing something?
>
I think the idea here is that the name should only be changed if it is a
standard system device.  The user could create his own device node
elsewhere in the filesystem and use it.  In this case, modifying the
name would make it fail where it would have succeeded if you had not
modified the name (assuming the user knew what he was doing and created
a raw block device).