1 files changed, 107 insertions, 0 deletions
diff --git a/src/bin/pg_basebackup/walmethods.h b/src/bin/pg_basebackup/walmethods.h
new file mode 100644
index 0000000..76530dc
--- /dev/null
+++ b/src/bin/pg_basebackup/walmethods.h
@@ -0,0 +1,107 @@
+/*-------------------------------------------------------------------------
+ *
+ * walmethods.h
+ *
+ * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *		  src/bin/pg_basebackup/walmethods.h
+ *-------------------------------------------------------------------------
+ */
+
+#include "common/compression.h"
+
+typedef void *Walfile;
+
+typedef enum
+{
+	CLOSE_NORMAL,
+	CLOSE_UNLINK,
+	CLOSE_NO_RENAME
+} WalCloseMethod;
+
+/*
+ * A WalWriteMethod structure represents the different methods used
+ * to write the streaming WAL as it's received.
+ *
+ * All methods that have a failure return indicator will set state
+ * allowing the getlasterror() method to return a suitable message.
+ * Commonly, errno is this state (or part of it); so callers must take
+ * care not to clobber errno between a failed method call and use of
+ * getlasterror() to retrieve the message.
+ */
+typedef struct WalWriteMethod WalWriteMethod;
+struct WalWriteMethod
+{
+	/*
+	 * Open a target file. Returns Walfile, or NULL if open failed. If a temp
+	 * suffix is specified, a file with that name will be opened, and then
+	 * automatically renamed in close(). If pad_to_size is specified, the file
+	 * will be padded with NUL up to that size, if supported by the Walmethod.
+	 */
+	Walfile		(*open_for_write) (const char *pathname, const char *temp_suffix, size_t pad_to_size);
+
+	/*
+	 * Close an open Walfile, using one or more methods for handling automatic
+	 * unlinking etc. Returns 0 on success, other values for error.
+	 */
+	int			(*close) (Walfile f, WalCloseMethod method);
+
+	/* Check if a file exist */
+	bool		(*existsfile) (const char *pathname);
+
+	/* Return the size of a file, or -1 on failure. */
+	ssize_t		(*get_file_size) (const char *pathname);
+
+	/*
+	 * Return the name of the current file to work on in pg_malloc()'d string,
+	 * without the base directory.  This is useful for logging.
+	 */
+	char	   *(*get_file_name) (const char *pathname, const char *temp_suffix);
+
+	/* Returns the compression method */
+	pg_compress_algorithm (*compression_algorithm) (void);
+
+	/*
+	 * Write count number of bytes to the file, and return the number of bytes
+	 * actually written or -1 for error.
+	 */
+	ssize_t		(*write) (Walfile f, const void *buf, size_t count);
+
+	/* Return the current position in a file or -1 on error */
+	off_t		(*get_current_pos) (Walfile f);
+
+	/*
+	 * fsync the contents of the specified file. Returns 0 on success.
+	 */
+	int			(*sync) (Walfile f);
+
+	/*
+	 * Clean up the Walmethod, closing any shared resources. For methods like
+	 * tar, this includes writing updated headers. Returns true if the
+	 * close/write/sync of shared resources succeeded, otherwise returns false
+	 * (but the resources are still closed).
+	 */
+	bool		(*finish) (void);
+
+	/* Return a text for the last error in this Walfile */
+	const char *(*getlasterror) (void);
+};
+
+/*
+ * Available WAL methods:
+ *	- WalDirectoryMethod - write WAL to regular files in a standard pg_wal
+ *	- WalTarMethod       - write WAL to a tarfile corresponding to pg_wal
+ *						   (only implements the methods required for pg_basebackup,
+ *						   not all those required for pg_receivewal)
+ */
+WalWriteMethod *CreateWalDirectoryMethod(const char *basedir,
+										 pg_compress_algorithm compression_algo,
+										 int compression, bool sync);
+WalWriteMethod *CreateWalTarMethod(const char *tarbase,
+								   pg_compress_algorithm compression_algo,
+								   int compression, bool sync);
+
+/* Cleanup routines for previously-created methods */
+void		FreeWalDirectoryMethod(void);
+void		FreeWalTarMethod(void);