[PATCH] maint: ftruncate is always available, even without gnulib

[Jim Meyering]

FYI, I'll push this later today.
In case you don't read the URL thread, note that for more than 3 years,
anyone who builds coreutils on a system without ftruncate would get this
message along with a failed configure:

    Your system lacks the ftruncate function.
    Please report this, along with the output of "uname -a", to the
    bug-coreut...@gnu.org mailing list.  To continue past this point,
    rerun configure with SKIP_FTRUNCATE_CHECK=yes.
    E.g., ./configure SKIP_FTRUNCATE_CHECK=yes

The only report I've seen was due to MinGW, and that was 3 years ago.
Newer (as in 2004 or newer) versions do provide ftruncate.


>From ef5758c3282b3325340d8b601deed5ab5e7ade64 Mon Sep 17 00:00:00 2001
From: Jim Meyering <meyer...@redhat.com>
Date: Fri, 9 Apr 2010 10:49:38 +0200
Subject: [PATCH] maint: ftruncate is always available, even without gnulib

Now that even MinGW provides ftruncate, we know that all
reasonable portability targets provide this function.
Remove the workaround code.  We nearly removed the gnulib
module three years ago:
  http://thread.gmane.org/gmane.comp.lib.gnulib.bugs/9203
and it is now officially "obsolete".
* bootstrap.conf (gnulib_modules): Remove ftruncate.
* src/copy.c (copy_reg): Remove use of HAVE_FTRUNCATE and its
no-longer-used workaround code.
* src/truncate.c: Remove a comment about handling missing ftruncate.
---
 bootstrap.conf |    1 -
 src/copy.c     |   10 ++--------
 src/truncate.c |    7 +------
 3 files changed, 3 insertions(+), 15 deletions(-)

diff --git a/bootstrap.conf b/bootstrap.conf
index 9cdf984..ad7d6d5 100644
--- a/bootstrap.conf
+++ b/bootstrap.conf
@@ -97,7 +97,6 @@ gnulib_modules="
   fsusage
   fsync
   ftello
-  ftruncate
   fts
   getdate
   getgroups
diff --git a/src/copy.c b/src/copy.c
index 29f37c9..3c32fa3 100644
--- a/src/copy.c
+++ b/src/copy.c
@@ -798,15 +798,9 @@ copy_reg (char const *src_name, char const *dst_name,

       if (last_write_made_hole)
         {
-          if (HAVE_FTRUNCATE
-              ? /* ftruncate sets the file size,
-                   so there is no need for a write.  */
-              ftruncate (dest_desc, n_read_total) < 0
-              : /* Seek backwards one character and write a null.  */
-              (lseek (dest_desc, (off_t) -1, SEEK_CUR) < 0L
-               || full_write (dest_desc, "", 1) != 1))
+          if (ftruncate (dest_desc, n_read_total) < 0)
             {
-              error (0, errno, _("writing %s"), quote (dst_name));
+              error (0, errno, _("truncating %s"), quote (dst_name));
               return_val = false;
               goto close_src_and_dst_desc;
             }
diff --git a/src/truncate.c b/src/truncate.c
index 70573cc..ece52ee 100644
--- a/src/truncate.c
+++ b/src/truncate.c
@@ -18,12 +18,7 @@

    This is backwards compatible with the FreeBSD utility, but is more
    flexible wrt the size specifications and the use of long options,
-   to better fit the "GNU" environment.
-
-   Note if !defined(HAVE_FTRUNCATE) then the --skip-ftruncate configure flag
-   was specified or we're in a mingw environment. In these cases gnulib
-   emulation will be used and GNULIB_FTRUNCATE is defined. Note if emulation
-   can't even be provided ftruncate() will return EIO.  */
+   to better fit the "GNU" environment.  */

 #include <config.h>             /* sets _FILE_OFFSET_BITS=64 etc. */
 #include <stdio.h>
--
1.7.1.rc0.239.g8b27e