Refactor pg_rewind for more clear decision making.

Deciding what to do with each file is now a separate step after all the
necessary information has been gathered. It is more clear that way.
Previously, the decision-making was divided between process_source_file()
and process_target_file(), and it was a bit hard to piece together what
the overall rules were.

Reviewed-by: Kyotaro Horiguchi, Soumyadeep Chakraborty
Discussion: https://www.postgresql.org/message-id/0c5b3783-af52-3ee5-f8fa-6e794061f70d%40iki.fi

1 files changed, 13 insertions, 3 deletions

diff --git a/src/bin/pg_rewind/file_ops.c b/src/bin/pg_rewind/file_ops.c
index 55439db20ba..ec37d0b2e0d 100644
--- a/src/bin/pg_rewind/file_ops.c
+++ b/src/bin/pg_rewind/file_ops.c
@@ -126,8 +126,9 @@ void
 remove_target(file_entry_t *entry)
 {
 	Assert(entry->action == FILE_ACTION_REMOVE);
+	Assert(entry->target_exists);
 
-	switch (entry->type)
+	switch (entry->target_type)
 	{
 		case FILE_TYPE_DIRECTORY:
 			remove_target_dir(entry->path);
@@ -140,6 +141,10 @@ remove_target(file_entry_t *entry)
 		case FILE_TYPE_SYMLINK:
 			remove_target_symlink(entry->path);
 			break;
+
+		case FILE_TYPE_UNDEFINED:
+			pg_fatal("undefined file type for \"%s\"", entry->path);
+			break;
 	}
 }
 
@@ -147,21 +152,26 @@ void
 create_target(file_entry_t *entry)
 {
 	Assert(entry->action == FILE_ACTION_CREATE);
+	Assert(!entry->target_exists);
 
-	switch (entry->type)
+	switch (entry->source_type)
 	{
 		case FILE_TYPE_DIRECTORY:
 			create_target_dir(entry->path);
 			break;
 
 		case FILE_TYPE_SYMLINK:
-			create_target_symlink(entry->path, entry->link_target);
+			create_target_symlink(entry->path, entry->source_link_target);
 			break;
 
 		case FILE_TYPE_REGULAR:
 			/* can't happen. Regular files are created with open_target_file. */
 			pg_fatal("invalid action (CREATE) for regular file");
 			break;
+
+		case FILE_TYPE_UNDEFINED:
+			pg_fatal("undefined file type for \"%s\"", entry->path);
+			break;
 	}
 }