diff --git a/project/common.mk b/project/common.mk
index 8bc157e..e569cbd 100644
--- a/project/common.mk
+++ b/project/common.mk
@@ -5,6 +5,7 @@ API_SRCS = \
 	src/helper/tpax_path_copy.c \
 	src/helper/tpax_stat_compare.c \
 	src/logic/tpax_archive_append.c \
+	src/logic/tpax_archive_write.c \
 	src/logic/tpax_init_ustar_header.c \
 	src/logic/tpax_file_create_memory_snapshot.c \
 	src/logic/tpax_file_create_tmpfs_snapshot.c \
diff --git a/src/logic/tpax_archive_append.c b/src/logic/tpax_archive_append.c
index 5083344..e2536e1 100644
--- a/src/logic/tpax_archive_append.c
+++ b/src/logic/tpax_archive_append.c
@@ -22,33 +22,6 @@
 #include "tpax_tmpfile_impl.h"
 #include "tpax_errinfo_impl.h"
 
-#ifndef ssizeof
-#define ssizeof(x) (ssize_t)(sizeof(x))
-#endif
-
-static int tpax_archive_append_memory_data(
-	int                             fdout,
-	void *                          buf,
-	ssize_t                         nbytes)
-{
-	ssize_t ret;
-	char  * ch;
-
-	for (ch=buf; nbytes; ch+=ret) {
-		ret = write(fdout,ch,nbytes);
-
-		while ((ret < 0) && (errno == EINTR))
-			ret = write(fdout,ch,nbytes);
-
-		if (ret < 0)
-			return ret;
-
-		nbytes -= ret;
-	}
-
-	return 0;
-}
-
 static char * tpax_append_prefix_item(
 	const struct tpax_driver_ctx *  dctx,
 	const char *                    prefix)
@@ -110,33 +83,6 @@ static char * tpax_append_prefix_item_from_path(
 	return tpax_append_prefix_item(dctx,pathbuf);
 }
 
-static int tpax_archive_append_pad(
-	const struct tpax_driver_ctx *  dctx,
-	int                             fdout,
-	const struct stat *             st)
-{
-	int     ret;
-	off_t   cpos;
-	ssize_t nbytes;
-	char    buf[512];
-
-	nbytes  = st->st_size;
-	nbytes += 0x1ff;
-	nbytes |= 0x1ff;
-	nbytes ^= 0x1ff;
-	nbytes -= st->st_size;
-
-	memset(buf,0,nbytes);
-
-	cpos  = tpax_get_driver_cpos(dctx);
-	cpos += st->st_size + nbytes;
-
-	if (!(ret = tpax_archive_append_memory_data(fdout,buf,nbytes)))
-		tpax_set_driver_cpos(dctx,cpos);
-
-	return ret;
-}
-
 static struct tpax_dirent_buffer * tpax_dirent_buf_first_alloc(
 	const struct tpax_driver_ctx * dctx)
 {
@@ -524,49 +470,5 @@ int tpax_archive_append_item(
 		cdent = cnext;
 	}
 
-	(void)tpax_archive_append_pad;
-
-	return 0;
-}
-
-int tpax_archive_seal(const struct tpax_driver_ctx * dctx)
-{
-	int     fdout;
-	off_t   cpos;
-	ssize_t nbytes;
-	ssize_t nwritten;
-	ssize_t blksize;
-	char    buf[512];
-
-	blksize = tpax_get_archive_block_size(dctx);
-	cpos    = tpax_get_driver_cpos(dctx);
-
-	if (cpos % 512)
-		return TPAX_CUSTOM_ERROR(dctx,TPAX_ERR_FLOW_ERROR);
-
-	fdout = tpax_driver_fdout(dctx);
-	memset(buf,0,sizeof(buf));
-
-	switch (cpos % blksize) {
-		case 0:
-			nbytes = cpos + blksize;
-			break;
-
-		default:
-			nbytes  = cpos / blksize;
-			nbytes *= blksize;
-			nbytes += blksize;
-
-			if (nbytes-cpos == 512)
-				nbytes += blksize;
-	}
-
-	for (nwritten=cpos; nwritten<nbytes; nwritten+=512) {
-		if (tpax_archive_append_memory_data(fdout,buf,512) < 0)
-			return TPAX_SYSTEM_ERROR(dctx);
-
-		tpax_set_driver_cpos(dctx,nwritten);
-	}
-
 	return 0;
 }
diff --git a/src/logic/tpax_archive_write.c b/src/logic/tpax_archive_write.c
new file mode 100644
index 0000000..b4dcf2a
--- /dev/null
+++ b/src/logic/tpax_archive_write.c
@@ -0,0 +1,104 @@
+/**************************************************************/
+/*  tpax: a topological pax implementation                    */
+/*  Copyright (C) 2020--2024  SysDeer Technologies, LLC       */
+/*  Released under GPLv2 and GPLv3; see COPYING.TPAX.         */
+/**************************************************************/
+
+#include <tpax/tpax.h>
+#include "tpax_driver_impl.h"
+#include "tpax_errinfo_impl.h"
+#include "tpax_visibility_impl.h"
+
+static int tpax_archive_append_memory_data(
+	int                             fdout,
+	void *                          buf,
+	ssize_t                         nbytes)
+{
+	ssize_t ret;
+	char  * ch;
+
+	for (ch=buf; nbytes; ch+=ret) {
+		ret = write(fdout,ch,nbytes);
+
+		while ((ret < 0) && (errno == EINTR))
+			ret = write(fdout,ch,nbytes);
+
+		if (ret < 0)
+			return ret;
+
+		nbytes -= ret;
+	}
+
+	return 0;
+}
+
+static int tpax_archive_append_pad(
+	const struct tpax_driver_ctx *  dctx,
+	int                             fdout,
+	const struct stat *             st)
+{
+	int     ret;
+	off_t   cpos;
+	ssize_t nbytes;
+	char    buf[512];
+
+	nbytes  = st->st_size;
+	nbytes += 0x1ff;
+	nbytes |= 0x1ff;
+	nbytes ^= 0x1ff;
+	nbytes -= st->st_size;
+
+	memset(buf,0,nbytes);
+
+	cpos  = tpax_get_driver_cpos(dctx);
+	cpos += st->st_size + nbytes;
+
+	if (!(ret = tpax_archive_append_memory_data(fdout,buf,nbytes)))
+		tpax_set_driver_cpos(dctx,cpos);
+
+	return ret;
+}
+
+int tpax_archive_seal(const struct tpax_driver_ctx * dctx)
+{
+	int     fdout;
+	off_t   cpos;
+	ssize_t nbytes;
+	ssize_t nwritten;
+	ssize_t blksize;
+	char    buf[512];
+
+	blksize = tpax_get_archive_block_size(dctx);
+	cpos    = tpax_get_driver_cpos(dctx);
+
+	if (cpos % 512)
+		return TPAX_CUSTOM_ERROR(dctx,TPAX_ERR_FLOW_ERROR);
+
+	fdout = tpax_driver_fdout(dctx);
+	memset(buf,0,sizeof(buf));
+
+	switch (cpos % blksize) {
+		case 0:
+			nbytes = cpos + blksize;
+			break;
+
+		default:
+			nbytes  = cpos / blksize;
+			nbytes *= blksize;
+			nbytes += blksize;
+
+			if (nbytes-cpos == 512)
+				nbytes += blksize;
+	}
+
+	for (nwritten=cpos; nwritten<nbytes; nwritten+=512) {
+		if (tpax_archive_append_memory_data(fdout,buf,512) < 0)
+			return TPAX_SYSTEM_ERROR(dctx);
+
+		tpax_set_driver_cpos(dctx,nwritten);
+	}
+
+	(void)tpax_archive_append_pad;
+
+	return 0;
+}