sub-process: refactor handshake to common function
Refactor, into a common function, the version and capability negotiation
done when invoking a long-running process as a clean or smudge filter.
This will be useful for other Git code that needs to interact similarly
with a long-running process.
As you can see in the change to t0021, this commit changes the error
message reported when the long-running process does not introduce itself
with the expected "server"-terminated line. Originally, the error
message reports that the filter "does not support filter protocol
version 2", differentiating between the old single-file filter protocol
and the new multi-file filter protocol - I have updated it to something
more generic and useful.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/sub-process.h b/sub-process.h
index e546216..caa91a9 100644
--- a/sub-process.h
+++ b/sub-process.h
@@ -29,6 +29,16 @@ struct subprocess_entry {
struct child_process process;
};
+struct subprocess_capability {
+ const char *name;
+
+ /*
+ * subprocess_handshake will "|=" this value to supported_capabilities
+ * if the server reports that it supports this capability.
+ */
+ unsigned int flag;
+};
+
/* subprocess functions */
/* Function to test two subprocess hashmap entries for equality. */
@@ -63,6 +73,22 @@ static inline struct child_process *subprocess_get_child_process(
}
/*
+ * Perform the version and capability negotiation as described in the "Long
+ * Running Filter Process" section of the gitattributes documentation using the
+ * given requested versions and capabilities. The "versions" and "capabilities"
+ * parameters are arrays terminated by a 0 or blank struct.
+ *
+ * This function is typically called when a subprocess is started (as part of
+ * the "startfn" passed to subprocess_start).
+ */
+int subprocess_handshake(struct subprocess_entry *entry,
+ const char *welcome_prefix,
+ int *versions,
+ int *chosen_version,
+ struct subprocess_capability *capabilities,
+ unsigned int *supported_capabilities);
+
+/*
* Helper function that will read packets looking for "status=<foo>"
* key/value pairs and return the value from the last "status" packet
*/
