| Long-running process protocol |
| ============================= |
| |
| This protocol is used when Git needs to communicate with an external |
| process throughout the entire life of a single Git command. All |
| communication is in pkt-line format (see technical/protocol-common.txt) |
| over standard input and standard output. |
| |
| Handshake |
| --------- |
| |
| Git starts by sending a welcome message (for example, |
| "git-filter-client"), a list of supported protocol version numbers, and |
| a flush packet. Git expects to read the welcome message with "server" |
| instead of "client" (for example, "git-filter-server"), exactly one |
| protocol version number from the previously sent list, and a flush |
| packet. All further communication will be based on the selected version. |
| The remaining protocol description below documents "version=2". Please |
| note that "version=42" in the example below does not exist and is only |
| there to illustrate how the protocol would look like with more than one |
| version. |
| |
| After the version negotiation Git sends a list of all capabilities that |
| it supports and a flush packet. Git expects to read a list of desired |
| capabilities, which must be a subset of the supported capabilities list, |
| and a flush packet as response: |
| ------------------------ |
| packet: git> git-filter-client |
| packet: git> version=2 |
| packet: git> version=42 |
| packet: git> 0000 |
| packet: git< git-filter-server |
| packet: git< version=2 |
| packet: git< 0000 |
| packet: git> capability=clean |
| packet: git> capability=smudge |
| packet: git> capability=not-yet-invented |
| packet: git> 0000 |
| packet: git< capability=clean |
| packet: git< capability=smudge |
| packet: git< 0000 |
| ------------------------ |
| |
| Shutdown |
| -------- |
| |
| Git will close |
| the command pipe on exit. The filter is expected to detect EOF |
| and exit gracefully on its own. Git will wait until the filter |
| process has stopped. |
