Add support for a new archive format "empty" that reads empty files.

6 files changed, 109 insertions, 11 deletions

diff --git a/lib/libarchive/Makefile b/lib/libarchive/Makefile
index 3a5651c..3c4170d 100644
--- a/lib/libarchive/Makefile
+++ b/lib/libarchive/Makefile
@@ -60,6 +60,7 @@ SRCS=	archive.h					\
 	archive_read_support_compression_none.c		\
 	archive_read_support_format_all.c		\
 	archive_read_support_format_cpio.c		\
+	archive_read_support_format_empty.c		\
 	archive_read_support_format_iso9660.c		\
 	archive_read_support_format_tar.c		\
 	archive_read_support_format_zip.c		\
diff --git a/lib/libarchive/archive.h.in b/lib/libarchive/archive.h.in
index 3ef335e..cdcc21f 100644
--- a/lib/libarchive/archive.h.in
+++ b/lib/libarchive/archive.h.in
@@ -157,6 +157,7 @@ typedef int	archive_close_callback(struct archive *, void *_client_data);
 #define	ARCHIVE_FORMAT_ISO9660			0x40000
 #define	ARCHIVE_FORMAT_ISO9660_ROCKRIDGE	(ARCHIVE_FORMAT_ISO9660 | 1)
 #define	ARCHIVE_FORMAT_ZIP			0x50000
+#define	ARCHIVE_FORMAT_EMPTY			0x60000
 
 /*-
  * Basic outline for reading an archive:
@@ -187,6 +188,7 @@ int		 archive_read_support_compression_none(struct archive *);
 
 int		 archive_read_support_format_all(struct archive *);
 int		 archive_read_support_format_cpio(struct archive *);
+int		 archive_read_support_format_empty(struct archive *);
 int		 archive_read_support_format_gnutar(struct archive *);
 int		 archive_read_support_format_iso9660(struct archive *);
 int		 archive_read_support_format_tar(struct archive *);
diff --git a/lib/libarchive/archive_read.3 b/lib/libarchive/archive_read.3
index daa3c84..f968238 100644
--- a/lib/libarchive/archive_read.3
+++ b/lib/libarchive/archive_read.3
@@ -36,6 +36,7 @@
 .Nm archive_read_support_compression_none ,
 .Nm archive_read_support_format_all ,
 .Nm archive_read_support_format_cpio ,
+.Nm archive_read_support_format_empty ,
 .Nm archive_read_support_format_iso9660 ,
 .Nm archive_read_support_format_tar ,
 .Nm archive_read_support_format_zip ,
@@ -75,6 +76,8 @@
 .Ft int
 .Fn archive_read_support_format_cpio "struct archive *"
 .Ft int
+.Fn archive_read_support_format_empty "struct archive *"
+.Ft int
 .Fn archive_read_support_format_iso9660 "struct archive *"
 .Ft int
 .Fn archive_read_support_format_tar "struct archive *"
@@ -135,7 +138,7 @@ is always enabled by default.
 For convenience,
 .Fn archive_read_support_compression_all
 enables all available decompression code.
-.It Fn archive_read_support_format_all , Fn archive_read_support_format_cpio , Fn archive_read_support_format_iso9660 , Fn archive_read_support_format_tar, Fn archive_read_support_format_zip
+.It Fn archive_read_support_format_all , Fn archive_read_support_format_cpio , Fn archive_read_support_format_empty , Fn archive_read_support_format_iso9660 , Fn archive_read_support_format_tar, Fn archive_read_support_format_zip
 Enables support---including auto-detection code---for the
 specified archive format.
 For example,
@@ -539,3 +542,14 @@ or before calling
 you may confuse the permission-setting logic with
 the result that directory permissions are restored
 incorrectly.
+.Pp
+Many traditional archiver programs treat
+empty files as valid empty archives.
+For example, many implementations of
+.Xr tar 1
+allow you to append entries to an empty file.
+Of course, it is impossible to determine the format of an empty file
+by inspecting the contents, so this library treats empty files as
+having a special
+.Dq empty
+format.
diff --git a/lib/libarchive/archive_read.c b/lib/libarchive/archive_read.c
index 9e5acab..c24f139 100644
--- a/lib/libarchive/archive_read.c
+++ b/lib/libarchive/archive_read.c
@@ -172,16 +172,6 @@ archive_read_open2(struct archive *a, void *client_data,
 		return (ARCHIVE_FATAL);
 	}
 
-	/* An empty archive is a serious error. */
-	if (bytes_read == 0) {
-		archive_set_error(a, ARCHIVE_ERRNO_FILE_FORMAT,
-		    "Empty input file");
-		/* Close the empty file. */
-		if (client_closer)
-			(client_closer)(a, client_data);
-		return (ARCHIVE_FATAL);
-	}
-
 	/* Now that the client callbacks have worked, remember them. */
 	a->client_opener = client_opener; /* Do we need to remember this? */
 	a->client_reader = client_reader;
diff --git a/lib/libarchive/archive_read_support_format_all.c b/lib/libarchive/archive_read_support_format_all.c
index 6a7b880..df3a03f 100644
--- a/lib/libarchive/archive_read_support_format_all.c
+++ b/lib/libarchive/archive_read_support_format_all.c
@@ -32,6 +32,7 @@ int
 archive_read_support_format_all(struct archive *a)
 {
 	archive_read_support_format_cpio(a);
+	archive_read_support_format_empty(a);
 	archive_read_support_format_iso9660(a);
 	archive_read_support_format_tar(a);
 	archive_read_support_format_zip(a);
diff --git a/lib/libarchive/archive_read_support_format_empty.c b/lib/libarchive/archive_read_support_format_empty.c
new file mode 100644
index 0000000..2df2194
--- /dev/null
+++ b/lib/libarchive/archive_read_support_format_empty.c
@@ -0,0 +1,90 @@
+/*-
+ * Copyright (c) 2003-2007 Tim Kientzle
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "archive_platform.h"
+__FBSDID("$FreeBSD$");
+
+#include "archive.h"
+#include "archive_entry.h"
+#include "archive_private.h"
+
+static int	archive_read_format_empty_bid(struct archive *);
+static int	archive_read_format_empty_read_data(struct archive *,
+		    const void **, size_t *, off_t *);
+static int	archive_read_format_empty_read_header(struct archive *,
+		    struct archive_entry *);
+int
+archive_read_support_format_empty(struct archive *a)
+{
+	int r;
+
+	r = __archive_read_register_format(a,
+	    NULL,
+	    archive_read_format_empty_bid,
+	    archive_read_format_empty_read_header,
+	    archive_read_format_empty_read_data,
+	    NULL,
+	    NULL);
+
+	return (r);
+}
+
+
+static int
+archive_read_format_empty_bid(struct archive *a)
+{
+	int bytes_read;
+	const void *h;
+
+	bytes_read = (a->compression_read_ahead)(a, &h, 1);
+	if (bytes_read > 0)
+		return (-1);
+	return (1);
+}
+
+static int
+archive_read_format_empty_read_header(struct archive *a,
+    struct archive_entry *entry)
+{
+	(void)a; /* UNUSED */
+	(void)entry; /* UNUSED */
+
+	a->archive_format = ARCHIVE_FORMAT_EMPTY;
+	a->archive_format_name = "Empty file";
+
+	return (ARCHIVE_EOF);
+}
+
+static int
+archive_read_format_empty_read_data(struct archive *a,
+    const void **buff, size_t *size, off_t *offset)
+{
+	(void)a; /* UNUSED */
+	(void)buff; /* UNUSED */
+	(void)size; /* UNUSED */
+	(void)offset; /* UNUSED */
+
+	return (ARCHIVE_EOF);
+}