Merge branch 'nd/shallow-clone'

Fetching from a shallow-cloned repository used to be forbidden,
primarily because the codepaths involved were not carefully vetted
and we did not bother supporting such usage. This attempts to allow
object transfer out of a shallow-cloned repository in a controlled
way (i.e. the receiver become a shallow repository with truncated
history).

* nd/shallow-clone: (31 commits)
  t5537: fix incorrect expectation in test case 10
  shallow: remove unused code
  send-pack.c: mark a file-local function static
  git-clone.txt: remove shallow clone limitations
  prune: clean .git/shallow after pruning objects
  clone: use git protocol for cloning shallow repo locally
  send-pack: support pushing from a shallow clone via http
  receive-pack: support pushing to a shallow clone via http
  smart-http: support shallow fetch/clone
  remote-curl: pass ref SHA-1 to fetch-pack as well
  send-pack: support pushing to a shallow clone
  receive-pack: allow pushes that update .git/shallow
  connected.c: add new variant that runs with --shallow-file
  add GIT_SHALLOW_FILE to propagate --shallow-file to subprocesses
  receive/send-pack: support pushing from a shallow clone
  receive-pack: reorder some code in unpack()
  fetch: add --update-shallow to accept refs that update .git/shallow
  upload-pack: make sure deepening preserves shallow roots
  fetch: support fetching from a shallow repository
  clone: support remote shallow repository
  ...

1 files changed, 30 insertions, 5 deletions

diff --git a/remote-curl.c b/remote-curl.c
index e38c4b026f..10cb0114ea 100644
--- a/remote-curl.c
+++ b/remote-curl.c
@@ -10,6 +10,7 @@
 #include "sideband.h"
 #include "argv-array.h"
 #include "credential.h"
+#include "sha1-array.h"
 
 static struct remote *remote;
 /* always ends with a trailing slash */
@@ -20,6 +21,8 @@ struct options {
 	unsigned long depth;
 	unsigned progress : 1,
 		check_self_contained_and_connected : 1,
+		cloning : 1,
+		update_shallow : 1,
 		followtags : 1,
 		dry_run : 1,
 		thin : 1;
@@ -87,8 +90,23 @@ static int set_option(const char *name, const char *value)
 		string_list_append(&cas_options, val.buf);
 		strbuf_release(&val);
 		return 0;
-	}
-	else {
+	} else if (!strcmp(name, "cloning")) {
+		if (!strcmp(value, "true"))
+			options.cloning = 1;
+		else if (!strcmp(value, "false"))
+			options.cloning = 0;
+		else
+			return -1;
+		return 0;
+	} else if (!strcmp(name, "update-shallow")) {
+		if (!strcmp(value, "true"))
+			options.update_shallow = 1;
+		else if (!strcmp(value, "false"))
+			options.update_shallow = 0;
+		else
+			return -1;
+		return 0;
+	} else {
 		return 1 /* unsupported */;
 	}
 }
@@ -99,6 +117,7 @@ struct discovery {
 	char *buf;
 	size_t len;
 	struct ref *refs;
+	struct sha1_array shallow;
 	unsigned proto_git : 1;
 };
 static struct discovery *last_discovery;
@@ -107,7 +126,7 @@ static struct ref *parse_git_refs(struct discovery *heads, int for_push)
 {
 	struct ref *list = NULL;
 	get_remote_heads(-1, heads->buf, heads->len, &list,
-			 for_push ? REF_NORMAL : 0, NULL);
+			 for_push ? REF_NORMAL : 0, NULL, &heads->shallow);
 	return list;
 }
 
@@ -168,6 +187,7 @@ static void free_discovery(struct discovery *d)
 	if (d) {
 		if (d == last_discovery)
 			last_discovery = NULL;
+		free(d->shallow.sha1);
 		free(d->buf_alloc);
 		free_refs(d->refs);
 		free(d);
@@ -699,7 +719,7 @@ static int fetch_git(struct discovery *heads,
 	struct strbuf preamble = STRBUF_INIT;
 	char *depth_arg = NULL;
 	int argc = 0, i, err;
-	const char *argv[16];
+	const char *argv[17];
 
 	argv[argc++] = "fetch-pack";
 	argv[argc++] = "--stateless-rpc";
@@ -715,6 +735,10 @@ static int fetch_git(struct discovery *heads,
 	}
 	if (options.check_self_contained_and_connected)
 		argv[argc++] = "--check-self-contained-and-connected";
+	if (options.cloning)
+		argv[argc++] = "--cloning";
+	if (options.update_shallow)
+		argv[argc++] = "--update-shallow";
 	if (!options.progress)
 		argv[argc++] = "--no-progress";
 	if (options.depth) {
@@ -730,7 +754,8 @@ static int fetch_git(struct discovery *heads,
 		struct ref *ref = to_fetch[i];
 		if (!ref->name || !*ref->name)
 			die("cannot fetch by sha1 over smart http");
-		packet_buf_write(&preamble, "%s\n", ref->name);
+		packet_buf_write(&preamble, "%s %s\n",
+				 sha1_to_hex(ref->old_sha1), ref->name);
 	}
 	packet_buf_flush(&preamble);