[libvirt] [PATCH 17/25] utils: Add a helper to get the device name that sg device mapped to

[Osier Yang]

On 07/05/13 22:51, Osier Yang wrote:
> On 07/05/13 22:00, John Ferlan wrote:
>> On 05/03/2013 02:07 PM, Osier Yang wrote:
>>> E.g.
>>>
>>> % sg_map
>>> /dev/sg0  /dev/sda
>>> /dev/sg1  /dev/sr0
>>>
>>> What the helper gets for /dev/sg0 is /dev/sda, it will be used by
>>> later patch.
>>> ---
>>>   src/libvirt_private.syms |  1 +
>>>   src/util/virscsi.c       | 47 
>>> +++++++++++++++++++++++++++++++++++++++++++++++
>>>   src/util/virscsi.h       |  4 ++++
>>>   3 files changed, 52 insertions(+)
>>>
>>> diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
>>> index fa59c14..8a7105c 100644
>>> --- a/src/libvirt_private.syms
>>> +++ b/src/libvirt_private.syms
>>> @@ -1692,6 +1692,7 @@ virSCSIDeviceFileIterate;
>>>   virSCSIDeviceFree;
>>>   virSCSIDeviceGetAdapter;
>>>   virSCSIDeviceGetBus;
>>> +virSCSIDeviceGetDevName;
>>>   virSCSIDeviceGetName;
>>>   virSCSIDeviceGetReadonly;
>>>   virSCSIDeviceGetSgName;
>>> diff --git a/src/util/virscsi.c b/src/util/virscsi.c
>>> index 7d3d40e..f337c75 100644
>>> --- a/src/util/virscsi.c
>>> +++ b/src/util/virscsi.c
>>> @@ -143,6 +143,53 @@ cleanup:
>>>       return sg;
>>>   }
>>>   +/* Returns device name (e.g. "sdc") on success, or NULL
>>> + * on failure.
>>> + */
>>> +char *
>>> +virSCSIDeviceGetDevName(const char *adapter,
>>> +                        unsigned int bus,
>>> +                        unsigned int target,
>>> +                        unsigned int unit)
>>> +{
>>> +    DIR *dir = NULL;
>>> +    struct dirent *entry;
>>> +    char *path = NULL;
>>> +    char *name = NULL;
>>> +    unsigned int adapter_id;
>>> +
>>> +    if (virSCSIDeviceGetAdapterId(adapter, &adapter_id) < 0)
>>> +        return NULL;
>>> +
>>> +    if (virAsprintf(&path,
>>> +                    SYSFS_SCSI_DEVICES "/%d:%d:%d:%d/block",
>>> +                    adapter_id, bus, target, unit) < 0) {
>>> +        virReportOOMError();
>>> +        return NULL;
>>> +    }
>>> +
>>> +    if (!(dir = opendir(path))) {
>>> +        virReportError(VIR_ERR_INTERNAL_ERROR,
>>> +                       _("Failed to open %s"), path);
>>> +        goto cleanup;
>>> +    }
>>> +
>>> +    while ((entry = readdir(dir))) {
>>> +        if (entry->d_name[0] == '.')
>>> +            continue;
>>> +
>>> +        if (!(name = strdup(entry->d_name))) {
>>> +            virReportOOMError();
>>> +            goto cleanup;
>>> +        }
>> If 'name' then what - we go back to the top of the loop and if there's
>> more entries then we'll strdup() another name....  Although I have to
>> wonder if there can be more than non hidden entry in the list...  Makes
>> me wonder about my earlier reviews which didn't think about the loop
>> exit (that is virSCSIDeviceGetSgName())
>
> It's the only one entry (except the hidden entries), same for
> virSCSIDeviceGetSgName. But adding the "break" is better,
> to avoid it loops 1 more. Will change when pushing.
>
Actually adding the break looks a bit strange, and I think we won't care
it tries one more condition checking..

So I pushed this as-is.