Assorted cleanup of tar-related code.

Introduce TAR_BLOCK_SIZE and replace many instances of 512 with
the new constant. Introduce function tarPaddingBytesRequired
and use it to replace numerous repetitions of (x + 511) & ~511.

Add preprocessor guards against multiple inclusion to pgtar.h.

Reformat the prototype for tarCreateHeader so it doesn't extend
beyond 80 characters.

Discussion: http://postgr.es/m/CA+TgmobWbfReO9-XFk8urR1K4wTNwqoHx_v56t7=T8KaiEoKNw@mail.gmail.com

1 files changed, 21 insertions, 2 deletions

diff --git a/src/include/pgtar.h b/src/include/pgtar.h
index 0a875903a7..0f08dc0c2c 100644
--- a/src/include/pgtar.h
+++ b/src/include/pgtar.h
@@ -11,6 +11,10 @@
  *
  *-------------------------------------------------------------------------
  */
+#ifndef PG_TAR_H
+#define PG_TAR_H
+
+#define		TAR_BLOCK_SIZE	512
 
 enum tarError
 {
@@ -19,8 +23,23 @@ enum tarError
 	TAR_SYMLINK_TOO_LONG
 };
 
-extern enum tarError tarCreateHeader(char *h, const char *filename, const char *linktarget,
-									 pgoff_t size, mode_t mode, uid_t uid, gid_t gid, time_t mtime);
+extern enum tarError tarCreateHeader(char *h, const char *filename,
+									 const char *linktarget, pgoff_t size,
+									 mode_t mode, uid_t uid, gid_t gid,
+									 time_t mtime);
 extern uint64 read_tar_number(const char *s, int len);
 extern void print_tar_number(char *s, int len, uint64 val);
 extern int	tarChecksum(char *header);
+
+/*
+ * Compute the number of padding bytes required for an entry in a tar
+ * archive. We must pad out to a multiple of TAR_BLOCK_SIZE. Since that's
+ * a power of 2, we can use TYPEALIGN().
+ */
+static inline size_t
+tarPaddingBytesRequired(size_t len)
+{
+	return TYPEALIGN(TAR_BLOCK_SIZE, len) - len;
+}
+
+#endif