[aperi-dev] Help, please, review Agent->ProbeLinux() error handling...

["Robert Wipfel" <rawipfel@xxxxxxxxxx>]

Hi,

I've been working on a fix for bug #208708

Question at the top: should FindPartitions() really return 8 to abort
the probe when it fails to get partition info from a device?

Details:

The first part of the fix changes ProbeLinux.java to search for SCSI
controllers in /sys/class/scsi_host (rather than /proc/scsi/*/host#)

These SCSI devices are present:

linux:/sys/class/scsi_host # lsscsi
[0:0:8:0]    enclosu DP       BACKPLANE        1.05  -
[0:2:0:0]    disk    DELL     PERC 5/i         1.03  /dev/sda
[1:0:0:0]    storage COMPAQ   MSA1000          5.10  -
[1:0:0:1]    disk    COMPAQ   MSA1000 VOLUME   5.10  /dev/sdb
[1:0:0:2]    disk    COMPAQ   MSA1000 VOLUME   5.10  /dev/sdc
[1:0:0:3]    disk    COMPAQ   MSA1000 VOLUME   5.10  /dev/sdd
[1:0:0:4]    disk    COMPAQ   MSA1000 VOLUME   5.10  /dev/sde
[2:0:0:0]    cd/dvd  Dell     Virtual  CDROM   123   /dev/sr0
[3:0:0:0]    disk    Dell     Virtual  Floppy  123   /dev/sdf

But because

[3:0:0:0]    disk    Dell     Virtual  Floppy  123   /dev/sdf

looks like a SCSI disk, the agent tries to FindPartitions(), which runs
sfdisk -l -uS /dev/sdf

But it's not really a disk, it's a virtual floppy with no media present,
and sfdisk fails to open the device.

which means that ProbeLinux.java line 350 returns an error x == 8

            x = probeSCSIDevice(buf.toString(), sgFlag, sgBuf.toString());

            buf.setLength(7);
            sgBuf.setLength(7);

            if (x > rc)
               rc = x;
         }
      }

      if (rc > 4)
         throw new GeneralException();

The native probeSCSIDevice() calls FindPartitions(). Should this 
return 8, to abort the probe, just because sfdisk failed on a non-disk?

 * Returns one of the following:
 *
 *   0 : Success. This does not necessarily mean that *ptr is non-NULL.
 *   4 : Device should not be saved.
 *   8 : Probe should be aborted.
 */
static int
FindPartitions(JNIEnv *env, struct device *devStruct, struct chunk **ptr)

Thanks,
Robert