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virsh vol-upload/download disallow negative offset

Browse Source 
https://bugzilla.redhat.com/show_bug.cgi?id=1087104

Commit id 'c6212539' explicitly allowed a negative value to be used for
offset and length as a shorthand for the largest value after commit id
'f18c02ec' modified virStrToLong_ui() to essentially disallow a negative
value.

However, allowing a negative value for offset ONLY worked if the negative
value was -1 since the eventual lseek() does allow a -1 to mean the end
of the file.  Providing other negative values resulted in errors such as:

$ virsh vol-download --pool default qcow3-vol2 /home/vm-images/raw \
  --offset -2 --length -1000
error: cannot download from volume qcow3-vol2
error: Unable to seek /home/vm-images/qcow3-vol2 to 18446744073709551614: Invalid argument

$

Thus, it seems unreasonable to expect or allow a negative value for offset
since the only benefit is to lseek() to the end of the file and then only
take advantage of how the OS would handle such a seek. For the purposes of
upload or download of volume data, that seems to be a no-op.  Therefore,
disallow a negative value for offset.

Additionally, modify the man page for vol-upload and vol-download to provide
more details regarding the valid values for both offset and length.
This commit is contained in:
John Ferlan 2014-07-15 08:26:28 -04:00
parent e00eb2ccfe
commit 570d0f6387
2 changed files with 11 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
tools/virsh-volume.c
View File

@ -787,13 +787,13 @@ cmdVolDownload(vshControl *ctl, const vshCmd *cmd)
unsigned long long offset = 0, length = 0;
bool created = false;
if (vshCommandOptULongLongWrap(cmd, "offset", &offset) < 0) {
vshError(ctl, _("Unable to parse integer"));
if (vshCommandOptULongLong(cmd, "offset", &offset) < 0) {
vshError(ctl, _("Unable to parse offset value"));
return false;
}
if (vshCommandOptULongLongWrap(cmd, "length", &length) < 0) {
vshError(ctl, _("Unable to parse integer"));
vshError(ctl, _("Unable to parse length value"));
return false;
}

10
tools/virsh.pod
View File

@ -2961,7 +2961,10 @@ is in.
I<vol-name-or-key-or-path> is the name or key or path of the volume where the
file will be uploaded.
I<--offset> is the position in the storage volume at which to start writing
the data. I<--length> is an upper bound of the amount of data to be uploaded.
the data. The value must be 0 or larger. I<--length> is an upper bound
of the amount of data to be uploaded. A negative value is interpreted
as an unsigned long long value to essentially include everything from
the offset to the end of the volume.
An error will occur if the I<local-file> is greater than the specified length.
=item B<vol-download> [I<--pool> I<pool-or-uuid>] [I<--offset> I<bytes>]
@ -2972,7 +2975,10 @@ I<--pool> I<pool-or-uuid> is the name or UUID of the storage pool the volume
is in.
I<vol-name-or-key-or-path> is the name or key or path of the volume to download.
I<--offset> is the position in the storage volume at which to start reading
the data. I<--length> is an upper bound of the amount of data to be downloaded.
the data. The value must be 0 or larger. I<--length> is an upper bound of
the amount of data to be downloaded. A negative value is interpreted as
an unsigned long long value to essentially include everything from the
offset to the end of the volume.
=item B<vol-wipe> [I<--pool> I<pool-or-uuid>] [I<--algorithm> I<algorithm>]
I<vol-name-or-key-or-path>