Document the 'v7' tar format support.

diff --git a/libarchive/libarchive-formats.5 b/libarchive/libarchive-formats.5
index 4a709b33c949c3aa3aeb1525796bcc5f9f9f6272..43c37785e8dd5b9386fdd293d4ce85cecfd57b66 100644 (file)
--- a/libarchive/libarchive-formats.5
+++ b/libarchive/libarchive-formats.5
@@ -55,7 +55,7 @@ It can write POSIX-standard
 .Dq ustar
 and
 .Dq pax interchange
-formats and a subset of the legacy GNU tar format.
+formats as well as v7 tar format and a subset of the legacy GNU tar format.
 .Pp
 All tar formats store each entry in one or more 512-byte records.
 The first record is used for file metadata, including filename,
@@ -151,6 +151,31 @@ Note that the pax interchange format has none of these restrictions.
 The ustar format is old and widely supported.
 It is recommended when compatibility is the primary concern.
 .El
+.It Cm v7
+The libarchive library can read and write the legacy v7 tar format.
+This format has the following limitations:
+.Bl -bullet -compact
+.It
+Only regular files, directories, and symbolic links can be archived.
+Block and character device nodes, FIFOs, and sockets cannot be archived.
+.It
+Path names in the archive are limited to 100 bytes.
+.It
+Symbolic links and hard links are stored in the archive with
+the name of the referenced file.
+This name is limited to 100 bytes.
+.It
+User and group information are stored as numeric IDs; there
+is no provision for storing user or group names.
+.It
+Extended attributes, file flags, and other extended
+security information cannot be stored.
+.It
+Archive entries are limited to 8 gigabytes in size.
+.El
+Generally, users should prefer the ustar format for portability
+as the v7 tar format is both less useful and less portable.
+.El
 .Pp
 The libarchive library also reads a variety of commonly-used extensions to
 the basic tar format.