If the filter command (a string value) is defined via
`filter.<driver>.process` then Git can process all blobs with a
single filter invocation for the entire life of a single Git
-command. This is achieved by using a packet format (pkt-line,
-see technical/protocol-common.txt) based protocol over standard
-input and standard output as follows. All packets, except for the
-"*CONTENT" packets and the "0000" flush packet, are considered
-text and therefore are terminated by a LF.
-
-Git starts the filter when it encounters the first file
-that needs to be cleaned or smudged. After the filter started
-Git sends a welcome message ("git-filter-client"), a list of supported
-protocol version numbers, and a flush packet. Git expects to read a welcome
-response message ("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
-------------------------
-Supported filter capabilities in version 2 are "clean", "smudge",
-and "delay".
+command. This is achieved by using the long-running process protocol
+(described in technical/long-running-process-protocol.txt).
+
+When Git encounters the first file that needs to be cleaned or smudged,
+it starts the filter and performs the handshake. In the handshake, the
+welcome message sent by Git is "git-filter-client", only version 2 is
+suppported, and the supported capabilities are "clean", "smudge", and
+"delay".
Afterwards Git sends a list of "key=value" pairs terminated with
a flush packet. The list will contain at least the filter command
with the next file that needs to be processed. Depending on the
`filter.<driver>.required` flag Git will interpret that as error.
-After the filter has processed a command it is expected to wait for
-a "key=value" list containing the next command. 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.
-
Delay
^^^^^