Merge branch 'jk/quarantine-received-objects'

In order for the receiving end of "git push" to inspect the
received history and decide to reject the push, the objects sent
from the sending end need to be made available to the hook and
the mechanism for the connectivity check, and this was done
traditionally by storing the objects in the receiving repository
and letting "git gc" to expire it.  Instead, store the newly
received objects in a temporary area, and make them available by
reusing the alternate object store mechanism to them only while we
decide if we accept the check, and once we decide, either migrate
them to the repository or purge them immediately.

* jk/quarantine-received-objects:
  tmp-objdir: do not migrate files starting with '.'
  tmp-objdir: put quarantine information in the environment
  receive-pack: quarantine objects until pre-receive accepts
  tmp-objdir: introduce API for temporary object directories
  check_connected: accept an env argument

1 files changed, 40 insertions, 1 deletions

diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c
index f7cd18025..04ed38e17 100644
--- a/builtin/receive-pack.c
+++ b/builtin/receive-pack.c
@@ -20,6 +20,7 @@
 #include "gpg-interface.h"
 #include "sigchain.h"
 #include "fsck.h"
+#include "tmp-objdir.h"
 
 static const char * const receive_pack_usage[] = {
 	N_("git receive-pack <git-dir>"),
@@ -86,6 +87,8 @@ static enum {
 } use_keepalive;
 static int keepalive_in_sec = 5;
 
+static struct tmp_objdir *tmp_objdir;
+
 static enum deny_action parse_deny_action(const char *var, const char *value)
 {
 	if (value) {
@@ -664,6 +667,9 @@ static int run_and_feed_hook(const char *hook_name, feed_fn feed,
 	} else
 		argv_array_pushf(&proc.env_array, "GIT_PUSH_OPTION_COUNT");
 
+	if (tmp_objdir)
+		argv_array_pushv(&proc.env_array, tmp_objdir_env(tmp_objdir));
+
 	if (use_sideband) {
 		memset(&muxer, 0, sizeof(muxer));
 		muxer.proc = copy_to_sideband;
@@ -763,6 +769,7 @@ static int run_update_hook(struct command *cmd)
 	proc.stdout_to_stderr = 1;
 	proc.err = use_sideband ? -1 : 0;
 	proc.argv = argv;
+	proc.env = tmp_objdir_env(tmp_objdir);
 
 	code = start_command(&proc);
 	if (code)
@@ -834,6 +841,7 @@ static int update_shallow_ref(struct command *cmd, struct shallow_info *si)
 		    !delayed_reachability_test(si, i))
 			sha1_array_append(&extra, si->shallow->sha1[i]);
 
+	opt.env = tmp_objdir_env(tmp_objdir);
 	setup_alternate_shallow(&shallow_lock, &opt.shallow_file, &extra);
 	if (check_connected(command_singleton_iterator, cmd, &opt)) {
 		rollback_lock_file(&shallow_lock);
@@ -1241,12 +1249,17 @@ static void set_connectivity_errors(struct command *commands,
 
 	for (cmd = commands; cmd; cmd = cmd->next) {
 		struct command *singleton = cmd;
+		struct check_connected_options opt = CHECK_CONNECTED_INIT;
+
 		if (shallow_update && si->shallow_ref[cmd->index])
 			/* to be checked in update_shallow_ref() */
 			continue;
+
+		opt.env = tmp_objdir_env(tmp_objdir);
 		if (!check_connected(command_singleton_iterator, &singleton,
-				     NULL))
+				     &opt))
 			continue;
+
 		cmd->error_string = "missing necessary objects";
 	}
 }
@@ -1429,6 +1442,7 @@ static void execute_commands(struct command *commands,
 	data.si = si;
 	opt.err_fd = err_fd;
 	opt.progress = err_fd && !quiet;
+	opt.env = tmp_objdir_env(tmp_objdir);
 	if (check_connected(iterate_receive_command_list, &data, &opt))
 		set_connectivity_errors(commands, si);
 
@@ -1445,6 +1459,19 @@ static void execute_commands(struct command *commands,
 		return;
 	}
 
+	/*
+	 * Now we'll start writing out refs, which means the objects need
+	 * to be in their final positions so that other processes can see them.
+	 */
+	if (tmp_objdir_migrate(tmp_objdir) < 0) {
+		for (cmd = commands; cmd; cmd = cmd->next) {
+			if (!cmd->error_string)
+				cmd->error_string = "unable to migrate objects to permanent storage";
+		}
+		return;
+	}
+	tmp_objdir = NULL;
+
 	check_aliased_updates(commands);
 
 	free(head_name_to_free);
@@ -1640,6 +1667,18 @@ static const char *unpack(int err_fd, struct shallow_info *si)
 		argv_array_push(&child.args, alt_shallow_file);
 	}
 
+	tmp_objdir = tmp_objdir_create();
+	if (!tmp_objdir)
+		return "unable to create temporary object directory";
+	child.env = tmp_objdir_env(tmp_objdir);
+
+	/*
+	 * Normally we just pass the tmp_objdir environment to the child
+	 * processes that do the heavy lifting, but we may need to see these
+	 * objects ourselves to set up shallow information.
+	 */
+	tmp_objdir_add_as_alternate(tmp_objdir);
+
 	if (ntohl(hdr.hdr_entries) < unpack_limit) {
 		argv_array_pushl(&child.args, "unpack-objects", hdr_arg, NULL);
 		if (quiet)