Update.

1998-07-31 17:59  Ulrich Drepper  <drepper@cygnus.com>

	* sysdeps/generic/bits/byteswap.h: Fix problems with side effects.

	* manual/filesys.texi: Document truncate and ftruncate.
	Patch by Michael Deutschmann <michael@talamasca.wkpowerlink.com>.

	* shadow/putspent.c: Lock stream while generating the output.

	* sunrpc/clnt_unix.c: Use ucred instead of cmsgcred again.
	(__msgwrite): Rewrite accordingly.
	* sunrpc/svc_unix.c: Likewise.
	* sysdeps/unix/sysv/linux/Dist: Remove __recvmsg.S and __sendmsg.S.
	* sysdeps/unix/sysv/linux/Makefile [$(subdir)==socket]
	(sysdep_routines): Remove __sendmsg and __recvmsg.
	* sysdeps/unix/sysv/linux/__recvmsg.S: Removed.
	* sysdeps/unix/sysv/linux/__sendmsg.S: Removed.
	* sysdeps/unix/sysv/linux/recvmsg.c: Removed.
	* sysdeps/unix/sysv/linux/sendmsg.c: Removed.
	* sysdeps/unix/sysv/linux/recvmsg.S: New file.
	* sysdeps/unix/sysv/linux/sendmsg.S: New file.
	* sysdeps/unix/sysv/linux/bits/socket.h: Define SCM_CREDENTIALS and
	struct ucred.  Remove struct cmsgcred.
	Patches by Thorsten Kukuk.

1998-08-03  Andreas Jaeger  <aj@arthur.rhein-neckar.de>

	* inet/rcmd.c (__ivaliduser): Allow '#' as comment character.

1998-08-08 14:42  Ulrich Drepper  <drepper@cygnus.com>

	* argp/argp-help.c: Prepare to be used outside glibc without gcc by
	adding usual alloca cruft.
	Reported by Eleftherios Gkioulekas <lf@amath.washington.edu>.

1998-04-05  Jim Meyering  <meyering@ascend.com>

	* lib/regex.c (WIDE_CHAR_SUPPORT): Define.
	This now depends on HAVE_BTOWC so systems that lack btowc (like
	solaris-2.5.1) don't lose.

1998-08-07  Mark Kettenis  <kettenis@phys.uva.nl>

	* sysdeps/generic/bits/sigaction.h: Remove definition of SA_DISABLE.
	* sysdeps/generic/bits/sigstack.h: Define SS_DISABLE, SS_ONSTACK,
	MINSIGSTKZ and SIGSTKSZ.  Definitions match BSD.
	* hurd/sigunwind.c (_hurdsig_longjmp_from_handler): Use SS_ONSTACK
	instead of SA_ONSTACK.
	* sysdeps/mach/hurd/sigaltstack.c (__sigaltstack): Renamed from
	sigaltstack, and created a weak alias.  Use SS_DISABLE and
	SS_ONSTACK instead of SA_DISABLE and SA_ONSTACK.
	* sysdeps/mach/hurd/sigstack.c (sigstack): Use SS_ONSTACK instead
	of SA_ONSTACK.  Call __sigaltstack instead of sigaltstack.
	* sysdeps/mach/hurd/i386/sigreturn.c (__sigreturn): Use SS_ONSTACK
	instead of SA_ONSTACK.
	* sysdeps/mach/hurd/alpha/sigreturn.c (__sigreturn): Likewise.
	* sysdeps/mach/hurd/mips/sigreturn.c (__sigreturn): Likewise.
	* sysdeps/mach/hurd/i386/trampoline.c (_hurd_setup_sighandler):
	Use SS_DISABLE instead of SA_DISABLE.  Use SS_ONSTACK instead of
	SA_ONSTACK where appropriate.
	* sysdeps/mach/hurd/alpha/trampoline.c (_hurd_setup_sighandler):
	Likewise.
	* sysdeps/mach/hurd/hppa/trampoline.c (_hurd_setup_sighandler):
	Likewise.
	* sysdeps/mach/hurd/mips/trampoline.c (_hurd_setup_sighandler):
	Likewise.
	* manual/signal.texi (Signal Stack): Talk about SS_DISABLE and
	SS_ONSTACK instead of SA_DISABLE and SA_ONSTACK in discussion of
	the `ss_flags' member of `struct sigaltstack'.

1998-08-05  Andreas Schwab  <schwab@issan.informatik.uni-dortmund.de>

	* libio/Makefile (routines) [$(versioning)=yes]: Add oldtmpfile.
	(shared-only-routines): Likewise.
	* libio/oldtmpfile.c: New file
	* stdio-common/tmpfile.c: Use __fdopen and __close.
	[USE_IN_LIBIO]: Use _IO_fdopen instead of _IO_new_fdopen.  Put
	tmpfile on symbol version GLIBC_2.1.
	* stdio-common/tmpfile64.c: Use __fdopen and __close.
	[USE_IN_LIBIO]: Use _IO_fdopen instead of _IO_new_fdopen.
	* stdio-common/Version [GLIBC_2.1]: Add tmpfile.
	* stdio-common/tempnam.c: Use __strdup instead of strdup.
	* sysdeps/posix/fdopen.c: Define __fdopen and make fdopen weak
	alias.
	* sysdeps/generic/fdopen.c: Likewise.
	* sysdeps/mach/hurd/fdopen.c: Likewise.
	* stdio/stdio.h: Declare __fdopen.
	* sunrpc/openchild.c: Use __fdopen instead of fdopen.
	[USE_IN_LIBIO]: Map __fdopen to _IO_fdopen.
	* sysdeps/posix/tempname.c (__gen_tempname): Don't bother checking
	__stub_open64, it is never defined.

1998-08-05  Andreas Schwab  <schwab@issan.informatik.uni-dortmund.de>

	* libio/iofopen64.c: Fix typo.  Avoid unnessary casts.
	* libio/iopopen.c: Unlink file before freeing it if command
	creation failed.  Avoid unnessary casts.
	* libio/iofdopen.c:  Avoid unnecessary cast.
	* pwd/fgetpwent_r.c [USE_IN_LIBIO]: Map funlockfile to
	_IO_funlockfile.
	* pwd/fgetspent_r.c [USE_IN_LIBIO]: Likewise.

1998-08-06  Andreas Schwab  <schwab@issan.informatik.uni-dortmund.de>

	* grp/grp.h, pwd/pwd.h: Don't declare __grpopen, __grpread,
	__grpalloc, __grpscan and the corresponding pwd functions, they
	were removed long ago.

1998-08-06  Andreas Schwab  <schwab@issan.informatik.uni-dortmund.de>

	* math/libm-test.c (csqrt_test): Adjust epsilons.
	(casinh_test): Likewise.

1998-08-06  Andreas Schwab  <schwab@issan.informatik.uni-dortmund.de>

	* posix/globtest.sh: Fix typo.  Remove second test output file.

1998-08-07  Cristian Gafton  <gafton@redhat.com>

	* pwd/putpwent.c (putpwent): Avoid writting (none) in the passwd file.
	* shadow/putspent.c (putspent): Likewise.
	* grp/putgrent.c: New file.
	* grp/Makefile (routines): Add putgrent.
	* grp/Versions [GLIBC_2.1]: Add putgrent.
	* grp/grp.h: Add putgrent prototype.

1998-08-04 19:33  Ulrich Drepper  <drepper@cygnus.com>

	* elf/elf.h: More ELF definitions.

1 files changed, 143 insertions, 0 deletions

diff --git a/manual/filesys.texi b/manual/filesys.texi
index 5d6df0a..302010f 100644
--- a/manual/filesys.texi
+++ b/manual/filesys.texi
@@ -1308,6 +1308,7 @@ modify these attributes of files.
 * Testing File Access::         How to find out if your process can
                                  access a file.
 * File Times::                  About the time attributes of a file.
+* File Size::			Manually changing the size of a file.
 @end menu
 
 @node Attribute Meanings
@@ -2502,6 +2503,148 @@ The return values and error conditions are the same as for the @code{utime}
 function.
 @end deftypefun
 
+@node File Size
+@subsection File Size
+
+Normally file sizes are maintained automatically.  A file begins with a
+size of @math{0} and is automatically extended when data is written
+past its end.  It is also possible to empty a file completely in an
+@code{open} or @code{fopen} call.
+
+However, sometimes it is neccessary to @emph{reduce} the size of a file.
+This can be done with the @code{truncate} and @code{ftruncate} functions.
+They were introduced in BSD Unix.  @code{ftruncate} was later added to
+POSIX.1.
+
+Some systems allow you to extend a file (creating holes) with these
+functions.  This is useful when using memory-mapped I/O
+(@pxref{Memory-mapped I/O}), where files are not automatically extended.
+However it is not portable but must be implemented if @code{mmap} allows
+mapping of files (i.e., @code{_POSIX_MAPPED_FILES} is defined).
+
+Using these functions on anything other than a regular file gives
+@emph{undefined} results.  On many systems, such a call will appear to
+succeed, without actually accomplishing anything.
+
+@deftypefun int truncate (const char *@var{filename}, off_t @var{length})
+
+The @code{truncate} function changes the size of @var{filename} to
+@var{length}.  If @var{length} is shorter than the previous length, data at
+the end will be lost.
+
+If @var{length} is longer, holes will be added to the end.  However, some
+systems do not support this feature and will leave the file unchanged.
+
+The return value is @math{0} for success, or @math{-1} for an error.  In
+addition to the usual file name errors, the following errors may occur:
+
+@table @code
+
+@item EACCES
+The file is a directory or not writable.
+
+@item EINVAL
+@var{length} is negative.
+
+@item EFBIG
+The operation would extend the file beyond the limits of the operating system.
+
+@item EIO
+A hardware I/O error occured.
+
+@item EPERM
+The file is "append-only" or "immutable".
+
+@item EINTR
+The operation was interrupted by a signal.
+
+@end table
+
+@end deftypefun
+
+@deftypefun int ftruncate (int @var{fd}, off_t @var{length})
+
+This is like @code{truncate}, but it works on a file descriptor @var{fd}.
+
+@code{ftruncate} is especially useful in combination with @code{mmap}.
+Since the mapped region must have a fixed size one cannot enlarge the
+file by writing something beyond the last mapped page.  Instead one has
+to enlarge the file itself and then remap the file with the new size.
+The example below shows how this works.
+
+The return value is @math{0} for success, or @math{-1} for an error.  The
+following errors may occur:
+
+@table @code
+
+@item EBADF
+@var{fd} does not correspond to an open file.
+
+@item EACCES
+@var{fd} is a directory or not open for write.
+
+@item EINVAL
+@var{length} is negative.
+
+@item EFBIG
+The operation would extend the file beyond the limits of the operating system.
+@c or the open() call -- with the not-yet-discussed feature of opening
+@c files with extra-large offsets.
+
+@item EIO
+A hardware I/O error occured.
+
+@item EPERM
+The file is "append-only" or "immutable".
+
+@item EINTR
+The operation was interrupted by a signal.
+
+@c ENOENT is also possible on Linux --- however it only occurs if the file
+@c descriptor has a `file' structure but no `inode' structure.  I'm not
+@c sure how such an fd could be created.  Perhaps it's a bug.
+
+@end table
+
+@end deftypefun
+
+As announced here is a little example how to use @code{ftruncate} in
+combination with @code{mmap}:
+
+@smallexample
+int fd;
+void *start;
+size_t len;
+
+int
+add (off_t at, void *block, size_t size)
+@{
+  if (at + size > len)
+    @{
+      /* Resize the file and remap.  */
+      size_t ps = sysconf (_SC_PAGESIZE);
+      size_t ns = (at + size + ps - 1) & ~(ps - 1);
+      void *np;
+      if (ftruncate (fd, ns) < 0)
+        return -1;
+      np = mmap (NULL, ns, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
+      if (np == MAP_FAILED)
+        return -1;
+      start = np;
+      len = ns;
+    @}
+  memcpy ((char *) start + at, block, size);
+  return 0;
+@}
+@end smallexample
+
+The function @code{add} allows to add at arbitrary positions in the file
+given blocks of memory.  If the current size of the file is too small it
+is extended.  Please note the it is extended in multiples of a pagesize.
+This is a requirement of @code{mmap}.  The program has to track the real
+size and once the program finished to work a final @code{ftruncate} call
+should set the real size of the file.
+
 @node Making Special Files
 @section Making Special Files
 @cindex creating special files