From da579f5153f7fa1108091fc18b0761e7a0581c33 Mon Sep 17 00:00:00 2001
From: Andreas Baumann <mail@andreasbaumann.cc>
Date: Thu, 7 May 2015 15:22:28 +0200
Subject: fixed the rename problem (EEXIST if the destination file exists is
 wrong, the destination file should get all data and metadata from the source
 file)

---
 pgfuse.c       | 17 +++++++++++---
 pgsql.c        | 72 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 pgsql.h        |  2 ++
 tests/Makefile |  6 +++++
 4 files changed, 94 insertions(+), 3 deletions(-)

diff --git a/pgfuse.c b/pgfuse.c
index c77d70f..c4e0ebd 100644
--- a/pgfuse.c
+++ b/pgfuse.c
@@ -1346,9 +1346,20 @@ static int pgfuse_rename( const char *from, const char *to )
 				PSQL_ROLLBACK( conn ); RELEASE( conn );
 				return 0;
 			} else {
-				/* otherwise bail out */
-				PSQL_ROLLBACK( conn ); RELEASE( conn );
-				return -EEXIST;
+				/* otherwise make source file disappear and
+				 * destination file contain the same data
+				 * as the source one (preferably atomic because
+				 * of rename/lockfile tricks)
+				 */
+				res = psql_rename_to_existing_file( conn, from_id, to_id, from, to );
+				if( res < 0 ) {
+					PSQL_ROLLBACK( conn ); RELEASE( conn );
+					return res;
+				}
+
+				PSQL_COMMIT( conn ); RELEASE( conn );
+
+				return res;
 			}
 		}
 		/* TODO: handle all other cases */
diff --git a/pgsql.c b/pgsql.c
index 0022603..bfa14d6 100644
--- a/pgsql.c
+++ b/pgsql.c
@@ -846,6 +846,78 @@ int psql_rollback( PGconn *conn )
 	return 0;
 }
 
+int psql_rename_to_existing_file( PGconn *conn, const int64_t from_id, const int64_t to_id, const char *from_path, const char *to_path )
+{
+	int64_t param1 = htobe64( to_id );
+	int64_t param2 = htobe64( from_id );
+	const char *values[2] = { (char *)&param1, (char *)&param2 };
+	int lengths[2] = { sizeof( param1 ), sizeof( param2 ) };
+	int binary[2] = { 1, 1 };
+	PGresult *res;
+
+	/* first delete the data of the destination file */
+	res = PQexecParams( conn, "DELETE FROM data WHERE dir_id=$1::bigint",
+		1, NULL, values, lengths, binary, 1 );
+
+	if( PQresultStatus( res ) != PGRES_COMMAND_OK ) {
+		syslog( LOG_ERR, "Error in psql_rename_to_existing_file to remove data of the destination file '%s': %s",
+			to_path, PQerrorMessage( conn ) );
+		PQclear( res );
+		return -EIO;
+	}
+
+	/* the destination file should inherit the data from the source file,
+	   avoid copying stupidly here */
+	res = PQexecParams( conn, "UPDATE data SET dir_id=$1::bigint WHERE dir_id=$2::bigint",
+		2, NULL, values, lengths, binary, 1 );
+
+	if( PQresultStatus( res ) != PGRES_COMMAND_OK ) {
+		syslog( LOG_ERR, "Error in psql_rename_to_existing_file to move data from '%s' to '%s': %s",
+			from_path, to_path, PQerrorMessage( conn ) );
+		PQclear( res );
+		return -EIO;
+	}
+
+	PQclear( res );
+
+	/* We inherit automatically all metadata from the source
+	   file for the destination file. But we would like to
+	   have the new filename of the destination file. */
+	values[0] = (char *)&param2;
+	values[1] = to_path;
+	lengths[1] = strlen( to_path );
+	binary[1] = 0;
+
+	res = PQexecParams( conn, "UPDATE dir SET name=$2::varchar WHERE id=$1::bigint",
+		2, NULL, values, lengths, binary, 1 );
+
+	if( PQresultStatus( res ) != PGRES_COMMAND_OK ) {
+		syslog( LOG_ERR, "Error in psql_rename_to_existing_file to set new name for '%s' to '%s': %s",
+			from_path, to_path, PQerrorMessage( conn ) );
+		PQclear( res );
+		return -EIO;
+	}
+
+	PQclear( res );
+
+	/* finally we delete the inode entry for the source file */
+
+	values[0] = (char *)&param2;
+	res = PQexecParams( conn, "DELETE FROM dir where id=$1::bigint",
+		1, NULL, values, lengths, binary, 1 );
+
+	if( PQresultStatus( res ) != PGRES_COMMAND_OK ) {
+		syslog( LOG_ERR, "Error in psql_renamc_existing_file when deleting dir entry for path '%s': %s",
+			from_path, PQerrorMessage( conn ) );
+		PQclear( res );
+		return -EIO;
+	}
+
+	PQclear( res );
+
+	return 0;
+}
+
 int psql_rename( PGconn *conn, const int64_t from_id, const int64_t from_parent_id, const int64_t to_parent_id, const char *rename_to, const char *from, const char *to )
 {
 	PgMeta from_parent_meta;
diff --git a/pgsql.h b/pgsql.h
index abb58ec..918d818 100644
--- a/pgsql.h
+++ b/pgsql.h
@@ -96,6 +96,8 @@ int psql_truncate( PGconn *conn, const size_t block_size, const int64_t id, cons
 
 int psql_rename( PGconn *conn, const int64_t from_id, const int64_t from_parent_id, const int64_t to_parent_id, const char *rename_to, const char *from, const char *to );
 
+int psql_rename_to_existing_file( PGconn *conn, const int64_t from_id, const int64_t to_id, const char *from_path, const char *to_path );
+
 size_t psql_get_block_size( PGconn *conn, const size_t block_size );
 
 int64_t psql_get_fs_blocks_used( PGconn *conn );
diff --git a/tests/Makefile b/tests/Makefile
index 9170e79..21dedca 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -66,6 +66,12 @@ test: testfsync testpgsql testtypes testbigfile testopen
 	-df -i mnt
 	# test open/creat and flags
 	-./testopen
+	# move test
+	-echo "afile" > mnt/afile
+	-echo "bfile" > mnt/bfile
+	-mv mnt/afile mnt/bfile
+	-cat mnt/bfile
+	-rm mnt/bfile
 	# END: unmount FUSE file system
 	fusermount -u mnt
 
-- 
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