Re: [Bug-tar] FeatureRequest: add K, M, G, T tags to the -L option

[Sergey Poznyakoff]

Hello,

My apologies for not being able to respond earlier.

> I'd like to ask for a feature. It should be easier and more precise if
> you could use the following tags on a -L option:
> K = kilobytes
> M = Megabytes
> G = Gigabytes
> T = Terabytes

Yes, that's reasonable.  I have installed the attached patch.  It allows
for using suffix prefixes with -L and --record-size options.  Notice,
that if the argument to -L has no size suffix, it is still treated as
kilobytes.

> Also, auto-renaming would be awesome so I didn't have to type n
> newname2.tar.lzma. It should handle this for itself, no?

It can be done using the --new-volume-script option with the
script from subsection 9.6.1 of the Tar Manual[1].

Regards,
Sergey

[1] 
http://www.gnu.org/software/tar/manual/html_node/Multi_002dVolume-Archives.html

>From c1b30c268f8517bfe61fe253a34613584351efc0 Mon Sep 17 00:00:00 2001
From: Sergey Poznyakoff <address@hidden>
Date: Sat, 17 Jul 2010 11:38:08 +0300
Subject: [PATCH] Allow for size suffixes in -L and --record-size options.

* src/tar.c (TAR_SIZE_SUFFIXES): New define.
(parse_opt): Allow for size suffixes in arguments to
-L and --record-size options.
* NEWS, doc/tar.texi: Update.
---
 NEWS         |    7 +++++-
 doc/tar.texi |   61 ++++++++++++++++++++++++++++++++++++++++++++++-----------
 src/tar.c    |   14 ++++++++++--
 3 files changed, 66 insertions(+), 16 deletions(-)

diff --git a/NEWS b/NEWS
index 11d3fa0..a84873d 100644
--- a/NEWS
+++ b/NEWS
@@ -1,4 +1,4 @@
-GNU tar NEWS - User visible changes. 2010-03-28
+GNU tar NEWS - User visible changes. 2010-07-16
 Please send GNU tar bug reports to <address@hidden>
 
 
@@ -48,6 +48,11 @@ update of an archive:
 
 This did not work in previous versions, in spite of what the docs said.  
 
+** --record-size and --tape-length (-L) options
+
+Usual size suffixes are allowed for these options.  For example,
+-L10k stands for a 10 kilobyte tape length. 
+
 ** Fix dead loop on extracting existing symlinks with the -k option.
 
 
diff --git a/doc/tar.texi b/doc/tar.texi
index 30fa61f..52b774c 100644
--- a/doc/tar.texi
+++ b/doc/tar.texi
@@ -3153,10 +3153,13 @@ Specifies that @command{tar} should reblock its input, 
for reading
 from pipes on systems with buggy implementations.  @xref{Reading}.
 
 @opsummary{record-size}
address@hidden address@hidden
address@hidden address@hidden@var{suf}]
 
 Instructs @command{tar} to use @var{size} bytes per record when accessing the
-archive.  @xref{Blocking Factor}.
+archive.  The argument can be suffixed with a @dfn{size suffix}, e.g.
address@hidden for 10 Kilobytes.  @xref{size-suffixes},
+for a list of valid suffixes.   @xref{Blocking Factor}, for a detailed
+description of this option.
 
 @opsummary{recursion}
 @item --recursion
@@ -3306,11 +3309,15 @@ Alters the suffix @command{tar} uses when backing up 
files from the default
 @samp{~}.  @xref{backup}.
 
 @opsummary{tape-length}
address@hidden address@hidden
address@hidden -L @var{num}
address@hidden address@hidden@var{suf}]
address@hidden -L @address@hidden
 
 Specifies the length of tapes that @command{tar} is writing as being
address@hidden@var{num} x 1024} bytes long.  @xref{Using Multiple Tapes}.
address@hidden@var{num} x 1024} bytes long.  If optional @var{suf} is given, it
+specifies a multiplicative factor to be used instead of 1024.  For
+example, @samp{-L2M} means 2 megabytes.  @xref{size-suffixes}, for a
+list of allowed suffixes.  @xref{Using Multiple Tapes}, for a detailed
+discussion of this option.
 
 @opsummary{test-label}
 @item --test-label
@@ -10345,8 +10352,27 @@ that may be larger than will fit on the medium used to 
hold it.
 
 @xopindex{tape-length, short description}
 @item -L @var{num}
address@hidden address@hidden
-Change tape after writing @var{num} x 1024 bytes.
address@hidden address@hidden@var{suf}]
+Change tape after writing @var{size} units of data.  Unless @var{suf} is
+given, @var{size} is treated as kilobytes, i.e. @address@hidden x
+1024} bytes.  The following suffixes alter this behavior:
+
address@hidden Table, size-suffixes
address@hidden Suffixes}
address@hidden @columnfractions 0.2 0.3 0.3
address@hidden Suffix @tab Units            @tab Byte Equivalent
address@hidden b          @tab Blocks           @tab @var{size} x 512
address@hidden B          @tab Kilobytes        @tab @var{size} x 1024
address@hidden c          @tab Bytes            @tab @var{size}
address@hidden G          @tab Gigabytes        @tab @var{size} x 1024^3
address@hidden K          @tab Kilobytes        @tab @var{size} x 1024
address@hidden k          @tab Kilobytes        @tab @var{size} x 1024
address@hidden M          @tab Megabytes        @tab @var{size} x 1024^2
address@hidden P          @tab Petabytes        @tab @var{size} x 1024^5
address@hidden T          @tab Terabytes        @tab @var{size} x 1024^4
address@hidden w          @tab Words            @tab @var{size} x 2
address@hidden multitable
address@hidden float
 
 This option might be useful when your tape drivers do not properly
 detect end of physical tapes.  By being slightly conservative on the
@@ -11154,15 +11180,26 @@ tape:
 @anchor{tape-length}
 @table @option
 @opindex tape-length
address@hidden address@hidden
address@hidden -L @var{size}
-Set maximum length of a volume.  The @var{size} argument should then
-be the usable size of the tape in units of 1024 bytes.  This option
-selects @option{--multi-volume} automatically.  For example:
address@hidden address@hidden@var{suf}]
address@hidden -L @address@hidden
+Set maximum length of a volume.  The @var{suf}, if given, specifies
+units in which @var{size} is expressed, e.g. @samp{2M} mean 2
+megabytes (@pxref{size-suffixes}, for a list of allowed size
+suffixes).  Without @var{suf}, units of 1024 bytes (kilobyte) are
+assumed.
+
+This option selects @option{--multi-volume} automatically.  For example:
 
 @smallexample
 $ @kbd{tar --create --tape-length=41943040 --file=/dev/tape @var{files}}
 @end smallexample
+
address@hidden
+or, which is equivalent:
+
address@hidden
+$ @kbd{tar --create --tape-length=4G --file=/dev/tape @var{files}}
address@hidden smallexample
 @end table
 
 @anchor{change volume prompt}
diff --git a/src/tar.c b/src/tar.c
index 5b61144..10ba8a9 100644
--- a/src/tar.c
+++ b/src/tar.c
@@ -1364,6 +1364,8 @@ expand_pax_option (struct tar_args *targs, const char 
*arg)
 }
 
 
+#define TAR_SIZE_SUFFIXES "bBcGgkKMmPTtw"
+
 static error_t
 parse_opt (int key, char *arg, struct argp_state *state)
 {
@@ -1506,10 +1508,15 @@ parse_opt (int key, char *arg, struct argp_state *state)
     case 'L':
       {
        uintmax_t u;
-       if (xstrtoumax (arg, 0, 10, &u, "") != LONGINT_OK)
+       char *p;
+       
+       if (xstrtoumax (arg, &p, 10, &u, TAR_SIZE_SUFFIXES) != LONGINT_OK)
          USAGE_ERROR ((0, 0, "%s: %s", quotearg_colon (arg),
                        _("Invalid tape length")));
-       tape_length_option = 1024 * (tarlong) u;
+       if (p > arg && !strchr (TAR_SIZE_SUFFIXES, p[-1]))
+         tape_length_option = 1024 * (tarlong) u;
+       else
+         tape_length_option = (tarlong) u;
        multi_volume_option = true;
       }
       break;
@@ -1961,7 +1968,8 @@ parse_opt (int key, char *arg, struct argp_state *state)
     case RECORD_SIZE_OPTION:
       {
        uintmax_t u;
-       if (! (xstrtoumax (arg, 0, 10, &u, "") == LONGINT_OK
+       
+       if (! (xstrtoumax (arg, NULL, 10, &u, TAR_SIZE_SUFFIXES) == LONGINT_OK
               && u == (size_t) u))
          USAGE_ERROR ((0, 0, "%s: %s", quotearg_colon (arg),
                        _("Invalid record size")));
-- 
1.6.0.3