On 05/17/2017 08:41 AM, Michal Privoznik wrote:
On 05/16/2017 10:55 PM, John Ferlan wrote:
On 05/16/2017 10:03 AM, Michal Privoznik wrote:
This function takes a FD and determines whether the current position is in data section or in a hole. In addition to that, it also determines how much bytes are there remaining till the current section ends.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com> --- src/libvirt_private.syms | 1 + src/util/virfile.c | 82 +++++++++++++++++++ src/util/virfile.h | 4 + tests/virfiletest.c | 203 +++++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 290 insertions(+)
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms index bbe283529..4102a002b 100644 --- a/src/libvirt_private.syms +++ b/src/libvirt_private.syms @@ -1628,6 +1628,7 @@ virFileGetHugepageSize; virFileGetMountReverseSubtree; virFileGetMountSubtree; virFileHasSuffix; +virFileInData; virFileIsAbsPath; virFileIsDir; virFileIsExecutable; diff --git a/src/util/virfile.c b/src/util/virfile.c index ea44a647c..5b10f9489 100644 --- a/src/util/virfile.c +++ b/src/util/virfile.c @@ -3793,6 +3793,88 @@ virFileComparePaths(const char *p1, const char *p2) cleanup: VIR_FREE(res1); VIR_FREE(res2); + + return ret; +} + +
Still undocumented.
I know it got discussed a few times... I guess the odd thing I find about "long long" is that all the stream mgmt lengths/sizes, etc. are size_t. You also only test for smaller values only. Just saying...
That's true for areas where we need to address individual bytes in buffers, e.g. virStreamRecv & virStreamSend. When it comes to file offsets like in virStorageVolDownload and virStorageVolUpload we use ULL.
Please just add the function description *and* why a long long is being used here. Also a brief summary of what's being done and of course that lseek @cleanup:
How about this:
Works for me with the one adjustment below: Thanks - Reviewed-by: John Ferlan <jferlan@redhat.com> John
+/** + * virFileInData: + * @fd: file to check + * @inData: true if current position in the @fd is in data section + * @length: amount of bytes until the end of the current section + * + * With sparse files not every extent has to be physically stored on + * the disk. This results in so called data or hole sections. This + * functions checks whether the current position in the file @fd is
function
+ * in a data section (@inData = 1) or in a hole (@inData = 0). Also, + * it sets @length to match the number of bytes remaining until the + * end of the current section. + * + * As a special case, there is an implicit hole at the end of any + * file. In this case, the function sets @inData = 0, @length = 0. + * + * Upon its return, the position in the @fd is left unchanged, i.e. + * despite this function lseek()-ing back and forth it always + * restores the original position in the file. + * + * NB, @length is type of long long because it corresponds to off_t + * the best. + * + * Returns 0 on success, + * -1 otherwise. + */
Michal