August 11, 2019 11:04 AM, "Pratyush Yadav" <me@xxxxxxxxxxxxxxxxx> wrote: > On 10/08/19 11:47PM, Farhan Khan wrote: > >> Hi, >> >> I am trying to write an implementation of git clone over ssh and am a little confused how to >> determine a server response has ended. Specifically, after a client sends its requested 'want', the >> server sends the pack content over. However, how does the client know to stop reading data? If I >> run a simple read() of the file descriptor: >> >> A. If I use reading blocking, the client will wait until new data is available, potentially >> forever. >> B. If I use non-blocking, the client might terminate reading for new data, when in reality new data >> is in transit. >> >> I do not see a mechanism to specify the size or to indicate the end of the pack content. Am I >> missing something? > > Well, I am not very familiar with git-clone internals, but I did some > digging around, and I think I know what answer to your problem is. > > Looking at Documentation/technical/protocol-v2.txt:34, the flush packet > indicates the end of a message. Looking in the output section of the > fetch command (protocol-v2.txt:342), it sends you some optional > sections, and then the packfile and then sends a flush packet. > > So your read should stop reading data when it sees the flush packet. > > Another way would be to look at the packfile contents. Looking at > Documentation/technical/pack-format.txt, the packfile contains the > number of objects in the packfile, and each object entry has the object > size. So you can stop reading after you have received the last object in > the packfile (plus the 20-byte trailer). > > I don't know which is the better way, but the former seems like a better > choice to me. > > -- > Regards, > Pratyush Yadav Hi Pratyush, Thanks for your reply! Unless I am mistaken, a pack file does not end in a flush_pkt. I ran some tests and did not see the stream end in "0000". Is there is a mistake somewhere on my end? --- Farhan Khan PGP Fingerprint: 1312 89CE 663E 1EB2 179C 1C83 C41D 2281 F8DA C0DE
