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Re: [PATCH v14 24/40] receive-pack.c: use a reference transaction for updating the refs

From
Jonathan Nieder <jrnieder@gmail.com>
Date
Jun 10, 2014, 23:18 UTC
Message-ID
<20140610231841.GC8557@google.com>
In-Reply-To
<1402093758-3162-25-git-send-email-sahlberg@google.com>
Ronnie Sahlberg wrote:
Show 7 quoted lines
> --- a/builtin/receive-pack.c
> +++ b/builtin/receive-pack.c
> @@ -46,6 +46,7 @@ static void *head_name_to_free;
>  static int sent_capabilities;
>  static int shallow_update;
>  static const char *alt_shallow_file;
> +static struct string_list error_strings = STRING_LIST_INIT_DUP;
[...]
> @@ -576,19 +576,31 @@ static const char *update(struct command *cmd, struct shallow_info *si)
[...]
Show 9 quoted lines
> +		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)) {
> +
> +			const char *str;
> +			string_list_append(&error_strings, err.buf);
> +			str = error_strings.items[error_strings.nr - 1].string;
[...]
> +			return str;
[...]
Show 6 quoted lines
> @@ -1215,5 +1227,6 @@ int cmd_receive_pack(int argc, const char **argv, const char *prefix)
>  		packet_flush(1);
>  	sha1_array_clear(&shallow);
>  	sha1_array_clear(&ref);
> +	string_list_clear(&error_strings, 0);
>  	return 0;

I think it's okay to let error strings accumulate like this because there will not be too many of them. Still I wonder, would it work to change the convention to transfer ownership of the string to the caller?

Ultimately 'commands' is leaked so we could even avoid the strdups but I'd rather leave it possible to clean up.

Something like this:
diff --git i/builtin/receive-pack.c w/builtin/receive-pack.c
index 13f4a63..d8ab7b2 100644
--- i/builtin/receive-pack.c
+++ w/builtin/receive-pack.c
@@ -46,7 +46,6 @@ static void *head_name_to_free;
 static int sent_capabilities;
 static int shallow_update;
 static const char *alt_shallow_file;
-static struct string_list error_strings = STRING_LIST_INIT_DUP;
 
 static enum deny_action parse_deny_action(const char *var, const char *value)
 {
@@ -195,7 +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;
@@ -469,7 +468,7 @@ 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;
@@ -589,12 +588,9 @@ static const char *update(struct command *cmd, struct shallow_info *si)
 					   new_sha1, old_sha1, 0, 1, &err) ||
 		    ref_transaction_commit(transaction, "push", &err)) {
 
-			const char *str;
-			string_list_append(&error_strings, err.buf);
-			str = error_strings.items[error_strings.nr - 1].string;
-			strbuf_release(&err);
-
+			char *str = strbuf_detach(&err, NULL);
 			ref_transaction_free(transaction);
+
 			rp_error("%s", str);
 			return str;
 		}
@@ -659,6 +655,9 @@ 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);
@@ -670,7 +669,7 @@ 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;
 	}
 
@@ -696,8 +695,9 @@ 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)
@@ -745,7 +745,9 @@ 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");
 	}
 }
 
@@ -782,9 +784,9 @@ 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");
 	}
 }
 
@@ -798,8 +800,11 @@ 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;
 	}
 
@@ -812,8 +817,9 @@ 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;
 	}
@@ -1091,7 +1097,8 @@ 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;
 		}
 	}
@@ -1227,6 +1234,5 @@ int cmd_receive_pack(int argc, const char **argv, const char *prefix)
 		packet_flush(1);
 	sha1_array_clear(&shallow);
 	sha1_array_clear(&ref);
-	string_list_clear(&error_strings, 0);
 	return 0;
 }
Previous: Ronnie SahlbergNext: Ronnie Sahlberg
Message 31 of 51 in “Use ref transactions”
  1. 00/40 Use ref transactionsRonnie Sahlberg, Jun 6, 2014
  2. 01/40 refs.c: remove ref_transaction_rollbackRonnie Sahlberg, Jun 6, 2014
  3. 02/40 refs.c: ref_transaction_commit should not free the transactionRonnie Sahlberg, Jun 6, 2014
  4. 03/40 refs.c: constify the sha arguments for ref_transaction_create|delete|updateRonnie Sahlberg, Jun 6, 2014
  5. 04/40 refs.c: allow passing NULL to ref_transaction_freeRonnie Sahlberg, Jun 6, 2014
  6. 05/40 refs.c: add a strbuf argument to ref_transaction_commit for error loggingRonnie Sahlberg, Jun 6, 2014
  7. 06/40 refs.c: add an err argument to repack_without_refsRonnie Sahlberg, Jun 6, 2014
  8. Jonathan NiederJun 10, 2014
  9. Ronnie SahlbergJun 10, 2014
  10. 07/40 refs.c: make ref_update_reject_duplicates take a strbuf argument for errorsRonnie Sahlberg, Jun 6, 2014
  11. 08/40 refs.c: add an err argument to delete_ref_looseRonnie Sahlberg, Jun 6, 2014
  12. Jonathan NiederJun 10, 2014
  13. Ronnie SahlbergJun 11, 2014
  14. 09/40 refs.c: make update_ref_write update a strbuf on failureRonnie Sahlberg, Jun 6, 2014
  15. 10/40 update-ref: use err argument to get error from ref_transaction_commitRonnie Sahlberg, Jun 6, 2014
  16. 11/40 refs.c: remove the onerr argument to ref_transaction_commitRonnie Sahlberg, Jun 6, 2014
  17. 12/40 refs.c: change ref_transaction_update() to do error checking and return statusRonnie Sahlberg, Jun 6, 2014
  18. 13/40 refs.c: change ref_transaction_create to do error checking and return statusRonnie Sahlberg, Jun 6, 2014
  19. 14/40 refs.c: update ref_transaction_delete to check for error and return statusRonnie Sahlberg, Jun 6, 2014
  20. 15/40 refs.c: make ref_transaction_begin take an err argumentRonnie Sahlberg, Jun 6, 2014
  21. 16/40 refs.c: add transaction.status and track OPEN/CLOSED/ERRORRonnie Sahlberg, Jun 6, 2014
  22. Jonathan NiederJun 10, 2014
  23. 17/40 tag.c: use ref transactions when doing updatesRonnie Sahlberg, Jun 6, 2014
  24. 18/40 replace.c: use the ref transaction functions for updatesRonnie Sahlberg, Jun 6, 2014
  25. 19/40 commit.c: use ref transactions for updatesRonnie Sahlberg, Jun 6, 2014
  26. 20/40 sequencer.c: use ref transactions for all ref updatesRonnie Sahlberg, Jun 6, 2014
  27. 21/40 fast-import.c: change update_branch to use ref transactionsRonnie Sahlberg, Jun 6, 2014
  28. 22/40 branch.c: use ref transaction for all ref updatesRonnie Sahlberg, Jun 6, 2014
  29. 23/40 refs.c: change update_ref to use a transactionRonnie Sahlberg, Jun 6, 2014
  30. 24/40 receive-pack.c: use a reference transaction for updating the refsRonnie Sahlberg, Jun 6, 2014
  31. Jonathan NiederJun 10, 2014
  32. Ronnie SahlbergJun 11, 2014
  33. 25/40 fast-import.c: use a ref transaction when dumping tagsRonnie Sahlberg, Jun 6, 2014
  34. Jonathan NiederJun 10, 2014
  35. 26/40 walker.c: use ref transaction for ref updatesRonnie Sahlberg, Jun 6, 2014
  36. Jonathan NiederJun 10, 2014
  37. 27/40 refs.c: make lock_ref_sha1 staticRonnie Sahlberg, Jun 6, 2014
  38. 28/40 refs.c: remove the update_ref_lock functionRonnie Sahlberg, Jun 6, 2014
  39. 29/40 refs.c: remove the update_ref_write functionRonnie Sahlberg, Jun 6, 2014
  40. 30/40 refs.c: remove lock_ref_sha1Ronnie Sahlberg, Jun 6, 2014
  41. 31/40 refs.c: make prune_ref use a transaction to delete the refRonnie Sahlberg, Jun 6, 2014
  42. Jonathan NiederJun 10, 2014
  43. 32/40 refs.c: make delete_ref use a transactionRonnie Sahlberg, Jun 6, 2014
  44. 33/40 refs.c: pass the ref log message to _create/delete/update instead of _commitRonnie Sahlberg, Jun 6, 2014
  45. 34/40 refs.c: pass NULL as *flags to read_ref_fullRonnie Sahlberg, Jun 6, 2014
  46. 35/40 refs.c: move the check for valid refname to lock_ref_sha1_basicRonnie Sahlberg, Jun 6, 2014
  47. 36/40 refs.c: call lock_ref_sha1_basic directly from commitRonnie Sahlberg, Jun 6, 2014
  48. 37/40 refs.c: pass a skip list to name_conflict_fnRonnie Sahlberg, Jun 6, 2014
  49. 38/40 refs.c: propagate any errno==ENOTDIR from _commit back to the callersRonnie Sahlberg, Jun 6, 2014
  50. 39/40 fetch.c: change s_update_ref to use a ref transactionRonnie Sahlberg, Jun 6, 2014
  51. 40/40 refs.c: make write_ref_sha1 staticRonnie Sahlberg, Jun 6, 2014

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