[libvirt] [PATCHv2 07/33] storage: Add support for access to files using provided uid/gid

[Peter Krempa]

On 05/23/14 00:59, Eric Blake wrote:
> On 05/22/2014 07:47 AM, Peter Krempa wrote:
>> To allow using the storage driver APIs to access files on various
>> storage sources in an universal fashion possibly on storage such as nfs
> 
> s/an universal/a universal/
> 
>> with root squash we'll need to store the desired uid/gid in the
>> metadata.
>>
>> Add new initialisation API that will store the desired uid/gid and a
>> wrapper for the current use. Additionally add docs for the two APIs.
>> ---
>>  src/storage/storage_backend.h |  3 +++
>>  src/storage/storage_driver.c  | 39 ++++++++++++++++++++++++++++++++++++++-
>>  src/storage/storage_driver.h  |  5 +++--
>>  3 files changed, 44 insertions(+), 3 deletions(-)
> 
>>
>> +/**
>> + * virStorageFileInitAs:
>> + *
>> + * @src: storage source definition
>> + * @uid: uid to access the file as, -1 for current uid
>> + * @gid: gid to access the file as, -1 for current gid
> 
> Correct grammar as written, but didn't flow well and took me two reads
> to avoid confusion.  Would be easier with the addition of "or", as in:
> 
> @xid: xid to access the file as, or -1 for current xid
> 
> or even:
> 
> @xid: xid used to access the file, or -1 for current xid
> 
>>
>> +    if (uid == (uid_t) -1)
>> +        src->drv->uid = geteuid();
>> +    else
>> +        src->drv->uid = uid;
> 
> Do we need to do the conversion here, or can we store -1 and let other
> routines later do the conversion?  I'm not sure if it matters either
> way, so I'm fine leaving it this way.

We've got a syntax check for that :)

src/storage/storage_driver.c:2825:    if (uid == -1)
maint.mk: cast -1 to ([ug]id_t) before comparing against id
make: *** [sc_prohibit_risky_id_promotion] Error 1


> 
> 
>> +int
>> +virStorageFileInit(virStorageSourcePtr src)
>> +{
>> +    return virStorageFileInitAs(src, (uid_t) -1, (gid_t) -1);
> 
> Casts aren't strictly necessary on this line (the C compiler does the
> correct conversion from int to uid_t thanks to the function prototype).

The compiler and syntax check are quiet here, so I've removed them.

> 
> ACK with the comment and cast cleanup.
> 

Peter


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