On 26/05/10 02:01, Pádraig Brady wrote:
> On 25/05/10 15:32, Richard W.M. Jones wrote:
>> The manpage for truncate says:
>>
>> Note that the -r and -s options are mutually exclusive.
>>
>> and indeed you cannot have both:
>>
>> $ truncate -r /tmp/ref -s +10M /tmp/new
>> truncate: you must specify one of `--size' or `--reference'
>>
>> We suggest using the 'truncate' command in the 'virt-resize'
>> documentation[1]. We want users to create a file which is the size of
>> an existing file + some extra amount. Naturally this would be:
>>
>> truncate -r old-disk.img -s +1G new-disk.img
>>
>> but this does not work and we have to suggest that users use two
>> separate 'truncate' commands[2].
>
> That seems like a worthwhile change.
> I.E. allow relative --size with -r.
> I'll cook up a patch in the morning
Attached.
>> Related to this feature request, it would be nice if you could suffix
>> a size with a % sign to indicate that you want to increase a file by a
>> certain percentage of the old or reference size, eg:
>>
>> truncate -r old-disk.img -s +10% new-disk.img
>>
>> truncate -r old-disk.img -s 110% new-disk.img
>
> I'm a little less enthusiastic about the need for that.
> Given how awkward it is to achieve then I might do it
> (as a separate patch). Here's how you'd might do it
> handling overflow currently:
>
> truncate -s$(echo "$(stat --format %s file) * 1.1" | bc | cut -d. -f1) file
>
> I guess it would be OK to truncate the result
> rather than round to nearest?
With multi-precision expr now in fedora one could simplify to:
truncate -s$(expr $(stat --format %s file) '*' 110 / 100) file
I'm still not convinced it's worth bringing % calculations within truncate.
cheers,
Pádraig.
>From 63786cdaf2189d326d837a868d936e62e855abcc Mon Sep 17 00:00:00 2001
From: =?utf-8?q?P=C3=A1draig=20Brady?= <p...@draigbrady.com>
Date: Wed, 26 May 2010 09:27:53 +0100
Subject: [PATCH] truncate: support sizes relative to an existing file
* doc/coreutils.texi (truncate invocation): Mention that --reference
bases the --size rather than just setting it.
* src/truncate.c (usage): Likewise. Also remove the clause
describing --size and --reference as being mutually exclusive.
(do_truncate): Add an extra parameter to hold the size
of a referenced file, and use it if positive.
(main): Pass the size of a referenced file to do_truncate().
* tests/misc/truncate-parameters: Adjust for the new combinations.
* NEWS: Mention the change
Suggested by Richard W.M. Jones
---
NEWS | 1 +
doc/coreutils.texi | 4 ++--
src/truncate.c | 36 ++++++++++++++++++++++--------------
tests/misc/truncate-parameters | 12 +++++++++++-
4 files changed, 36 insertions(+), 17 deletions(-)
diff --git a/NEWS b/NEWS
index 19436fe..7a294f4 100644
--- a/NEWS
+++ b/NEWS
@@ -14,6 +14,7 @@ GNU coreutils NEWS -*- outline -*-
sort -g now uses long doubles for greater range and precision.
+ truncate now supports setting file sizes relative to a reference file.
* Noteworthy changes in release 8.5 (2010-04-23) [stable]
diff --git a/doc/coreutils.texi b/doc/coreutils.texi
index 115e5fb..d1c3085 100644
--- a/doc/coreutils.texi
+++ b/doc/coreutils.texi
@@ -10767,13 +10767,13 @@ Treat @var{size} as number of I/O blocks of the @var{file} rather than bytes.
@itemx --referen...@var{rfile}
@opindex -r
@opindex --reference
-Set the size of each @var{file} to the same size as @var{rfile}.
+Base the size of each @var{file} on the size of @var{rfile}.
@item -s @var{size}
@itemx --si...@var{size}
@opindex -s
@opindex --size
-Set the size of each @var{file} to this @var{size}.
+Set or adjust the size of each @var{file} according to @var{size}.
@multiplierSuffixesNoBlocks{size}
@var{size} may also be prefixed by one of the following to adjust
diff --git a/src/truncate.c b/src/truncate.c
index ece52ee..08090ab 100644
--- a/src/truncate.c
+++ b/src/truncate.c
@@ -115,8 +115,8 @@ Mandatory arguments to long options are mandatory for short options too.\n\
-o, --io-blocks treat SIZE as number of IO blocks instead of bytes\n\
"), stdout);
fputs (_("\
- -r, --reference=FILE use this FILE's size\n\
- -s, --size=SIZE use this SIZE\n"), stdout);
+ -r, --reference=RFILE base size on RFILE\n\
+ -s, --size=SIZE set or adjust the file size by SIZE\n"), stdout);
fputs (HELP_OPTION_DESCRIPTION, stdout);
fputs (VERSION_OPTION_DESCRIPTION, stdout);
emit_size_note ();
@@ -124,10 +124,6 @@ Mandatory arguments to long options are mandatory for short options too.\n\
SIZE may also be prefixed by one of the following modifying characters:\n\
`+' extend by, `-' reduce by, `<' at most, `>' at least,\n\
`/' round down to multiple of, `%' round up to multiple of.\n"), stdout);
- fputs (_("\
-\n\
-Note that the -r and -s options are mutually exclusive.\n\
-"), stdout);
emit_ancillary_info ();
}
exit (status);
@@ -135,12 +131,13 @@ Note that the -r and -s options are mutually exclusive.\n\
/* return 1 on error, 0 on success */
static int
-do_ftruncate (int fd, char const *fname, off_t ssize, rel_mode_t rel_mode)
+do_ftruncate (int fd, char const *fname, off_t ssize, off_t rsize,
+ rel_mode_t rel_mode)
{
struct stat sb;
off_t nsize;
- if ((block_mode || rel_mode) && fstat (fd, &sb) != 0)
+ if ((block_mode || (rel_mode && rsize < 0)) && fstat (fd, &sb) != 0)
{
error (0, errno, _("cannot fstat %s"), quote (fname));
return 1;
@@ -161,9 +158,9 @@ do_ftruncate (int fd, char const *fname, off_t ssize, rel_mode_t rel_mode)
}
if (rel_mode)
{
- uintmax_t const fsize = sb.st_size;
+ uintmax_t const fsize = rsize < 0 ? sb.st_size : rsize;
- if (sb.st_size < 0)
+ if (rsize < 0 && sb.st_size < 0)
{
/* Complain only for a regular file, a directory,
or a shared memory object, as POSIX 1003.1-2004 specifies
@@ -248,6 +245,7 @@ main (int argc, char **argv)
{
bool got_size = false;
off_t size IF_LINT (= 0);
+ off_t rsize = -1;
rel_mode_t rel_mode = rm_abs;
mode_t omode;
int c, errors = 0, fd = -1, oflags;
@@ -335,9 +333,16 @@ main (int argc, char **argv)
argc -= optind;
/* must specify either size or reference file */
- if ((ref_file && got_size) || (!ref_file && !got_size))
+ if (!ref_file && !got_size)
+ {
+ error (0, 0, _("you must specify either %s or %s"),
+ quote_n (0, "--size"), quote_n (1, "--reference"));
+ usage (EXIT_FAILURE);
+ }
+ /* must specify a relative size with a reference file */
+ if (ref_file && got_size && !rel_mode)
{
- error (0, 0, _("you must specify one of %s or %s"),
+ error (0, 0, _("you must specify a relative %s with %s"),
quote_n (0, "--size"), quote_n (1, "--reference"));
usage (EXIT_FAILURE);
}
@@ -360,7 +365,10 @@ main (int argc, char **argv)
struct stat sb;
if (stat (ref_file, &sb) != 0)
error (EXIT_FAILURE, errno, _("cannot stat %s"), quote (ref_file));
- size = sb.st_size;
+ if (!got_size)
+ size = sb.st_size;
+ else
+ rsize = sb.st_size;
}
oflags = O_WRONLY | (no_create ? 0 : O_CREAT) | O_NONBLOCK;
@@ -397,7 +405,7 @@ main (int argc, char **argv)
if (fd != -1)
{
- errors += do_ftruncate (fd, fname, size, rel_mode);
+ errors += do_ftruncate (fd, fname, size, rsize, rel_mode);
if (close (fd) != 0)
{
error (0, errno, _("closing %s"), quote (fname));
diff --git a/tests/misc/truncate-parameters b/tests/misc/truncate-parameters
index 6524070..c2f7019 100755
--- a/tests/misc/truncate-parameters
+++ b/tests/misc/truncate-parameters
@@ -30,7 +30,7 @@ truncate --size=0 && fail=1
# must specify size. don't default to 0
truncate file && fail=1
-# mixture of size & reference not allowed
+# mixture of absolute size & reference not allowed
truncate --size=0 --reference=file file && fail=1
# blocks without size is not valid
@@ -45,4 +45,14 @@ truncate --size=" >1" file || fail=1 #file now 1
truncate --size=" +1" file || fail=1 #file now 2
test $(stat --format %s file) = 2 || fail=1
+# reference allowed with relative size
+truncate --size=" +1" -r file file || fail=1 #file now 3
+test $(stat --format %s file) = 3 || fail=1
+
+# reference allowed alone also
+truncate -r file file || fail=1 #file still 3
+test $(stat --format %s file) = 3 || fail=1
+truncate -r file file2 || fail=1 #file2 now 3
+test $(stat --format %s file2) = 3 || fail=1
+
Exit $fail
--
1.6.2.5
