Wrap all the ref updates inside a transaction.

Signed-off-by: Ronnie Sahlberg <sahlb...@google.com>
---
 builtin/receive-pack.c | 96 +++++++++++++++++++++++++++++++++-----------------
 1 file changed, 63 insertions(+), 33 deletions(-)

diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c
index c323081..b51f8ae 100644
--- a/builtin/receive-pack.c
+++ b/builtin/receive-pack.c
@@ -194,7 +194,7 @@ static void write_head_info(void)
 
 struct command {
        struct command *next;
-       const char *error_string;
+       char *error_string;
        unsigned int skip_update:1,
                     did_not_exist:1;
        int index;
@@ -468,19 +468,18 @@ static int update_shallow_ref(struct command *cmd, struct 
shallow_info *si)
        return 0;
 }
 
-static const char *update(struct command *cmd, struct shallow_info *si)
+static char *update(struct command *cmd, struct shallow_info *si)
 {
        const char *name = cmd->ref_name;
        struct strbuf namespaced_name_buf = STRBUF_INIT;
        const char *namespaced_name;
        unsigned char *old_sha1 = cmd->old_sha1;
        unsigned char *new_sha1 = cmd->new_sha1;
-       struct ref_lock *lock;
 
        /* only refs/... are allowed */
        if (!starts_with(name, "refs/") || check_refname_format(name + 5, 0)) {
                rp_error("refusing to create funny ref '%s' remotely", name);
-               return "funny refname";
+               return xstrdup("funny refname");
        }
 
        strbuf_addf(&namespaced_name_buf, "%s%s", get_git_namespace(), name);
@@ -498,20 +497,20 @@ static const char *update(struct command *cmd, struct 
shallow_info *si)
                        rp_error("refusing to update checked out branch: %s", 
name);
                        if (deny_current_branch == DENY_UNCONFIGURED)
                                refuse_unconfigured_deny();
-                       return "branch is currently checked out";
+                       return xstrdup("branch is currently checked out");
                }
        }
 
        if (!is_null_sha1(new_sha1) && !has_sha1_file(new_sha1)) {
                error("unpack should have generated %s, "
                      "but I can't find it!", sha1_to_hex(new_sha1));
-               return "bad pack";
+               return xstrdup("bad pack");
        }
 
        if (!is_null_sha1(old_sha1) && is_null_sha1(new_sha1)) {
                if (deny_deletes && starts_with(name, "refs/heads/")) {
                        rp_error("denying ref deletion for %s", name);
-                       return "deletion prohibited";
+                       return xstrdup("deletion prohibited");
                }
 
                if (!strcmp(namespaced_name, head_name)) {
@@ -526,7 +525,7 @@ static const char *update(struct command *cmd, struct 
shallow_info *si)
                                if (deny_delete_current == DENY_UNCONFIGURED)
                                        
refuse_unconfigured_deny_delete_current();
                                rp_error("refusing to delete the current 
branch: %s", name);
-                               return "deletion of the current branch 
prohibited";
+                               return xstrdup("deletion of the current branch 
prohibited");
                        }
                }
        }
@@ -544,19 +543,19 @@ static const char *update(struct command *cmd, struct 
shallow_info *si)
                    old_object->type != OBJ_COMMIT ||
                    new_object->type != OBJ_COMMIT) {
                        error("bad sha1 objects for %s", name);
-                       return "bad ref";
+                       return xstrdup("bad ref");
                }
                old_commit = (struct commit *)old_object;
                new_commit = (struct commit *)new_object;
                if (!in_merge_bases(old_commit, new_commit)) {
                        rp_error("denying non-fast-forward %s"
                                 " (you should pull first)", name);
-                       return "non-fast-forward";
+                       return xstrdup("non-fast-forward");
                }
        }
        if (run_update_hook(cmd)) {
                rp_error("hook declined to update %s", name);
-               return "hook declined";
+               return xstrdup("hook declined");
        }
 
        if (is_null_sha1(new_sha1)) {
@@ -571,24 +570,32 @@ static const char *update(struct command *cmd, struct 
shallow_info *si)
                }
                if (delete_ref(namespaced_name, old_sha1, 0)) {
                        rp_error("failed to delete %s", name);
-                       return "failed to delete";
+                       return xstrdup("failed to delete");
                }
                return NULL; /* good */
        }
        else {
+               struct strbuf err = STRBUF_INIT;
+               struct ref_transaction *transaction;
+
                if (shallow_update && si->shallow_ref[cmd->index] &&
                    update_shallow_ref(cmd, si))
-                       return "shallow error";
-
-               lock = lock_any_ref_for_update(namespaced_name, old_sha1,
-                                              0, NULL);
-               if (!lock) {
-                       rp_error("failed to lock %s", name);
-                       return "failed to lock";
-               }
-               if (write_ref_sha1(lock, new_sha1, "push")) {
-                       return "failed to write"; /* error() already called */
+                       return xstrdup("shallow error");
+
+               transaction = ref_transaction_begin(&err);
+               if (!transaction ||
+                   ref_transaction_update(transaction, namespaced_name,
+                                          new_sha1, old_sha1, 0, 1, &err) ||
+                   ref_transaction_commit(transaction, "push", &err)) {
+                       char *str = strbuf_detach(&err, NULL);
+                       ref_transaction_free(transaction);
+
+                       rp_error("%s", str);
+                       return str;
                }
+
+               ref_transaction_free(transaction);
+               strbuf_release(&err);
                return NULL; /* good */
        }
 }
@@ -647,6 +654,9 @@ static void check_aliased_update(struct command *cmd, 
struct string_list *list)
        char cmd_oldh[41], cmd_newh[41], dst_oldh[41], dst_newh[41];
        int flag;
 
+       if (cmd->error_string)
+               die("BUG: check_alised_update called with failed cmd");
+
        strbuf_addf(&buf, "%s%s", get_git_namespace(), cmd->ref_name);
        dst_name = resolve_ref_unsafe(buf.buf, sha1, 0, &flag);
        strbuf_release(&buf);
@@ -658,7 +668,7 @@ static void check_aliased_update(struct command *cmd, 
struct string_list *list)
        if (!dst_name) {
                rp_error("refusing update to broken symref '%s'", 
cmd->ref_name);
                cmd->skip_update = 1;
-               cmd->error_string = "broken symref";
+               cmd->error_string = xstrdup("broken symref");
                return;
        }
 
@@ -684,8 +694,9 @@ static void check_aliased_update(struct command *cmd, 
struct string_list *list)
                 cmd->ref_name, cmd_oldh, cmd_newh,
                 dst_cmd->ref_name, dst_oldh, dst_newh);
 
-       cmd->error_string = dst_cmd->error_string =
-               "inconsistent aliased update";
+       cmd->error_string = xstrdup("inconsistent aliased update");
+       free(dst_cmd->error_string);
+       dst_cmd->error_string = xstrdup("inconsistent aliased update");
 }
 
 static void check_aliased_updates(struct command *commands)
@@ -733,7 +744,9 @@ static void set_connectivity_errors(struct command 
*commands,
                if (!check_everything_connected(command_singleton_iterator,
                                                0, &singleton))
                        continue;
-               cmd->error_string = "missing necessary objects";
+               if (cmd->error_string)  /* can't happen */
+                       continue;
+               cmd->error_string = xstrdup("missing necessary objects");
        }
 }
 
@@ -770,9 +783,9 @@ static void reject_updates_to_hidden(struct command 
*commands)
                if (cmd->error_string || !ref_is_hidden(cmd->ref_name))
                        continue;
                if (is_null_sha1(cmd->new_sha1))
-                       cmd->error_string = "deny deleting a hidden ref";
+                       cmd->error_string = xstrdup("deny deleting a hidden 
ref");
                else
-                       cmd->error_string = "deny updating a hidden ref";
+                       cmd->error_string = xstrdup("deny updating a hidden 
ref");
        }
 }
 
@@ -786,8 +799,11 @@ static void execute_commands(struct command *commands,
        struct iterate_data data;
 
        if (unpacker_error) {
-               for (cmd = commands; cmd; cmd = cmd->next)
-                       cmd->error_string = "unpacker error";
+               for (cmd = commands; cmd; cmd = cmd->next) {
+                       if (cmd->error_string)  /* can't happen */
+                               continue;
+                       cmd->error_string = xstrdup("unpacker error");
+               }
                return;
        }
 
@@ -800,8 +816,9 @@ static void execute_commands(struct command *commands,
 
        if (run_receive_hook(commands, "pre-receive", 0)) {
                for (cmd = commands; cmd; cmd = cmd->next) {
-                       if (!cmd->error_string)
-                               cmd->error_string = "pre-receive hook declined";
+                       if (cmd->error_string)
+                               continue;
+                       cmd->error_string = xstrdup("pre-receive hook 
declined");
                }
                return;
        }
@@ -1079,7 +1096,8 @@ static void update_shallow_info(struct command *commands,
                if (is_null_sha1(cmd->new_sha1))
                        continue;
                if (ref_status[cmd->index]) {
-                       cmd->error_string = "shallow update not allowed";
+                       free(cmd->error_string);
+                       cmd->error_string = xstrdup("shallow update not 
allowed");
                        cmd->skip_update = 1;
                }
        }
@@ -1120,6 +1138,17 @@ static int delete_only(struct command *commands)
        return 1;
 }
 
+static void free_commands(struct command *commands)
+{
+       while (commands) {
+               struct command *next = commands->next;
+
+               free(commands->error_string);
+               free(commands);
+               commands = next;
+       }
+}
+
 int cmd_receive_pack(int argc, const char **argv, const char *prefix)
 {
        int advertise_refs = 0;
@@ -1215,5 +1244,6 @@ int cmd_receive_pack(int argc, const char **argv, const 
char *prefix)
                packet_flush(1);
        sha1_array_clear(&shallow);
        sha1_array_clear(&ref);
+       free_commands(commands);
        return 0;
 }
-- 
2.0.0.438.gec92e5c

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