Update.cvs/libc-ud-970810

1997-08-10 18:48  Ulrich Drepper  <drepper@cygnus.com>

	* Makeconfig: Define build-programs to no if not set and $(config-os)
	is none.
	* Makerules (+depfiles): Don't add $(others) if not build-programs.
	* Rules (others): Don't depend on $(install-bin), $(install-rootbin)
	and $(install-sbin) if not build-programs.
	* Makefile (subdirs): Remove login.
	* sysdeps/mach/hurd/Subdirs: Add login.
	* sysdeps/unix/Subdirs: Add login.

	* sysdeps/generic/sys/mman.h: Test feature macros before defining
	non-POSIX things.  Add MAP_FAILED.
	* sysdeps/unix/bsd/osf/sys/mman.h: Likewise.
	* sysdeps/unix/bsd/sun/sunos4/sys/mman.h: Likewise.
	* sysdeps/unix/bsd/ultrix4/sys/mman.h: Likewise.
	* sysdeps/unix/sysv/irix4/sys/mman.h: Likewise.
	* sysdeps/unix/sysv/linux/sys/mman.h: Rewrite to not use kernel header
	but bits/mman.h.  Test feature macros before definitions non-POSIX
	functions.
	* sysdeps/unix/sysv/linux/alpha/bits/mman.h: New file.
	* sysdeps/unix/sysv/linux/i386/bits/mman.h: New file.
	* sysdeps/unix/sysv/linux/m68k/bits/mman.h: New file.
	* sysdeps/unix/sysv/linux/mips/bits/mman.h: New file.
	* sysdeps/unix/sysv/linux/powerpc/bits/mman.h: New file.
	* sysdeps/unix/sysv/linux/sparc/bits/mman.h: New file.
	* sysdeps/unix/sysv/linux/sparc64/bits/mman.h: New file.
	* sysdeps/unix/sysv/linux/alpha/Dist: Add bits/mman.h.
	* sysdeps/unix/sysv/linux/i386/Dist: Likewise.
	* sysdeps/unix/sysv/linux/m68k/Dist: Likewise.
	* sysdeps/unix/sysv/linux/mips/Dist: Likewise.
	* sysdeps/unix/sysv/linux/powerpc/Dist: Likewise.
	* sysdeps/unix/sysv/linux/sparc/Dist: Likewise.
	* sysdeps/unix/sysv/linux/sparc64/Dist: New file.  Likewise.

	* catgets/open_catalog.c (__open_catalog): Compare result of mmap
	with MAP_FAILED and not -1.
	* elf/dl-load.c (_dl_map_object_from_fd): Likewise.
	* elf/dl-minimal.c (malloc): Likewise.
	* elf/dl-misc.c (_dl_sysdep_read_whole_file): Likewise.
	* locale/loadlocale.c (_nl_load_locale): Likewise.
	* locale/programs/localedef.c: Likewise.
	* malloc/malloc.c (mmap_chunk): Likewise.
	(new_heap): Likewise.
	* string/stratcliff.c: Likewise.
	* string/tester.c: Add tests for stpcpy.

	* gmon/gmon.c (__monstartup): Use calloc instead of malloc+memset.

	* gmon/sys/gmon.h: Add prototype for write_profiling.

	* elf/dl-profile.c: Add decsriptions and implement reading of
	existing data in profiling file.
	* gmon/sys/gmon_out.h (GMON_SHOBJ_VERSION): New macro for shared
	lib profiling data.

	* sysdeps/stub/bits/libc-lock.h (__libc_once_define): Add new first
	parameter for class.

	* inet/inet_ntoa.c: Make once control variable static.
	Correctly handle case where key cannot be retrieved.
	* inet/Makefile (tests): Add tst-ntoa.
	* inet/tst-ntoa.c: New file.

	* manual/time.texi: Document localtime_r, gmtime_r, asctime_r, and
	ctime_r.
	Mention that tzname values must not be changed.

	* manual/users.texi: Document UTMP/WTMP handling functions.
	Mainly written by Mark Kettenis.

	* math/libm-test.c (cbrt_test): Add test for number with aboslute
	value < 1.0.

	* nss/nss_files/files-XXX.c (internal_setent): If opening of file
	failed with EGAIN return NSS_STATUS_TRYAGAIN.
	* nss/nss_files/files-alias.c (internal_setent): Likewise.

	* sysdeps/generic/bits/utmp.h: Pretty print.

	* sysdeps/i386/i586/strcpy.S: New file.  Much faster implementation.
	* sysdeps/i386/i586/stpcpy.S: New file.
	* sysdeps/i386/i686/Implies: Don't fall back on i586 versions since
	these are less efficient than i486/i386 versions.

	* sysdeps/libm-i387/e_rem_pio2.c: Add empty file to prevent the
	version from libm-ieee754 be compiled since the later is not needed.
	* sysdeps/libm-i387/e_rem_pio2f.c: Likewise.
	* sysdeps/libm-i387/e_rem_pio2l.c: Likewise.
	* sysdeps/libm-i387/k_rem_pio2.c: Likewise.
	* sysdeps/libm-i387/k_rem_pio2f.c: Likewise.
	* sysdeps/libm-i387/k_rem_pio2l.c: Likewise.
	* sysdeps/m68k/fpu/e_rem_pio2.c: Likewise.
	* sysdeps/m68k/fpu/e_rem_pio2f.c: Likewise.
	* sysdeps/m68k/fpu/e_rem_pio2l.c: Likewise.
	* sysdeps/m68k/fpu/k_rem_pio2.c: Likewise.
	* sysdeps/m68k/fpu/k_rem_pio2f.c: Likewise.
	* sysdeps/m68k/fpu/k_rem_pio2l.c: Likewise.

	* sysdeps/libm-i387/s_cbrt.S: Fix several bugs.
	* sysdeps/libm-i387/s_cbrtf.S: Likewise.
	* sysdeps/libm-i387/s_cbrtl.S: Likewise.

	* sysdeps/unix/sysv/linux/if_index.c (if_indextoname): Correct
	little bug.

	* sysdeps/unix/sysv/linux/bits/socket.h (struct msghdr): Make field
	msg_iovlen of type int.

	* time/tzfile.c: Change return type of __tzstring to char *.
	* time/tzset.c: Likewise.  Change definition of __tzstring.

	* time/tzset.c: Interpret no DST information in user provided time
	zone specification as it is meant: no DST.
	Patch by Paul Eggert <eggert@twinsun.com>.

1997-07-20 03:01  Geoff Keating  <geoffk@ozemail.com.au>

	* sysdeps/elf/dl-load.c (add_name_to_object): New procedure.
	(_dl_map_object_from_fd): Use add_name_to_object.
	(_dl_map_object): If an object's SONAME is used to resolve a
	dependency, add it to the list of the object's names.

	* inet/getnameinfo.c: Make `domain' non-const.

	* sysdeps/unix/sysv/linux/powerpc/kernel_termios.c: Clean up.

	* math/test-fenv.c (feenv_nomask_test): Don't execute if
	FE_NOMASK_ENV is not defined, or if fesetenv(FE_NOMASK_ENV)
	sets errno to ENOSYS.

	* sysdeps/powerpc/dl-machine.h: Print proper error message on
	unknown reloc type (rather than using assert).

	* sysdeps/unix/sysv/linux/powerpc/profil-counter.h: New file.
	* sysdeps/unix/sysv/linux/powerpc/profil.c: Deleted.

1997-07-16 12:47  Geoff Keating  <geoffk@ozemail.com.au>

	* sysdeps/powerpc/bits/fenv.h (feraiseexcept): New optimising macro.
	(feclearexcept): New optimising macro.
	(FE_NOMASK_ENV): Change to procedure so it can enable exceptions.
	(FE_ENABLED_ENV): Add.
	(FE_NONIEEE_ENV): Add.
	* sysdeps/powerpc/bits/fenv_const.c: Add __fe_enabled_env,
	__fe_nonieee_env; delete __fe_nomask_env.
	* sysdeps/powerpc/bits/fe_nomask.c: New file (stub warning until it
	gets implemented in the kernel).

	* sysdeps/powerpc/fraiseenv.c: Deal with chips that don't have
	FE_INVALID_SOFTWARE implemented. Use macros for bit names for clarity.
	* sysdeps/powerpc/fsetexcptflag.c: Likewise.

	* io/ftw.c: Don't compare holes in structures.
	* sysdeps/unix/sysv/linux/sys/sysmacros.h: Cast the result of the
	macros to `int', because otherwise it might be `long long' which
	the calling code is probably not expecting.

	* sysdeps/libm-ieee754/s_lround.c [NO_LONG_DOUBLE]: Fix a few bugs,
	document the existence of some more.

	* sysdeps/powerpc/s_llrint.c: New file.
	* sysdeps/powerpc/s_lrint.c: New file.
	* sysdeps/powerpc/s_llround.c: New file.
	* sysdeps/powerpc/s_lround.c: New file.

	* sysdeps/powerpc/s_sqrt.c: New file.
	* sysdeps/powerpc/s_sqrtf.c: New file.
	* sysdeps/powerpc/w_sqrt.s: New empty file.
	* sysdeps/powerpc/w_sqrtf.s: New empty file.
	* sysdeps/powerpc/t_sqrt.c: New file.
	* sysdeps/powerpc/test-arithf.c: New file.
	* sysdeps/powerpc/Makefile [subdir=math]: Add t_sqrt to support
	routines.  Add test-arithf to test programs.

	* sysdeps/powerpc/bits/mathdef.h: Add FP_ILOGB0, FP_ILOGBNAN.

	* sysdeps/powerpc/strcmp.s: Simplify drastically. Now much neater,
	and possibly faster (or possibly slower, depending on input).

1997-06-08 22:55  Geoff Keating  <geoffk@ozemail.com.au>

	* sysdeps/powerpc/fenvbits.h: Correct FE_DFL_ENV and FE_NOMASK_ENV
	macros.
	* sysdeps/powerpc/s_rint.c: New file.

1997-05-22 08:47  Geoff Keating  <geoffk@ozemail.com.au>

	* sysdeps/powerpc/Makefile [subdir=math]: Add q_* routines.
	* sysdeps/powerpc/Dist: Add quad_float.h.
	* sysdeps/powerpc/q_dtoq.c: New file.
	* sysdeps/powerpc/q_itoq.c: New file.
	* sysdeps/powerpc/q_lltoq.c: New file.
	* sysdeps/powerpc/q_neg.c: New file.
	* sysdeps/powerpc/q_qtoi.c: New file.
	* sysdeps/powerpc/q_qtoll.c: New file.
	* sysdeps/powerpc/q_qtos.c: New file.
	* sysdeps/powerpc/q_qtou.c: New file.
	* sysdeps/powerpc/q_qtoull.c: New file.
	* sysdeps/powerpc/q_stoq.c: New file.
	* sysdeps/powerpc/q_ulltoq.c: New file.
	* sysdeps/powerpc/q_utoq.c: New file.
	* sysdeps/powerpc/quad_float.h: New file.
	* sysdeps/powerpc/test-arith.c: New file.

	* sysdeps/powerpc/fpu_control.h: Fix _FPU_GETCW.
	* sysdeps/powerpc/fegetround.c: Use mcrfs to be faster and not
	require a stack frame.
	* sysdeps/powerpc/bits/fenv.h: Include inline macro for fegetround.

1997-05-18 05:55  Geoff Keating  <geoffk@ozemail.com.au>

	* sysdeps/powerpc/fenv_libc.h (fegetenv_register,
	fesetenv_register): Add 'volatile'.
	(set_fpscr_bit, reset_fpscr_bit): New macros, FPSCR_*
	constants to use with them.
	* sysdeps/powerpc/s_copysign.S: New file.
	* sysdeps/powerpc/s_copysignf.s: New file.
	* sysdeps/powerpc/s_fabs.S: New file.
	* sysdeps/powerpc/s_fabsf.s: New file.
	* sysdeps/powerpc/s_isnan.c: New file.
	* sysdeps/powerpc/s_isnanf.s: New file.
	* sysdeps/powerpc/s_rintf.c: New file.

	* sysdeps/powerpc/fenvbits.h: Make FE_INVALID the summary
	bit in the FPSCR, not the enable bit.
	* sysdeps/powerpc/fraiseexcpt.c: Consequent change to the above.
	* sysdeps/powerpc/fclrexcpt.c: Correct.
	* sysdeps/powerpc/fsetexcptflag.c: Correct.
	* sysdeps/powerpc/ftestexcpt.c: Is now much simpler.
	* sysdeps/powerpc/fgetexcptflg.c: Simplify.

	* sysdeps/powerpc/strlen.s: Schedule better, save 3 clocks :-).

	* sysdeps/powerpc/dl-machine.h (elf_machine_rela): Add comment
	explaining some reentrancy issues with lazy PLT entries.

1997-08-09 13:04  Mark Kettenis  <kettenis@phys.uva.nl>

	* login/logout.c (logout): utmpname returns -1 on error.

	* login/libutil.map: Remove updwtmp.

	* login/getutline.c: Rename getutline to __getutline and make
	getutline a weak alias.  Make getutxline a weak alias for
	__getutline.
	* login/getutid.c: Rename getutid to __getutid and make getutid a
	weak alias.  Make getutxid a weak alias for __getutid.
	* libc.map: Add getutxid, getutxline.

	* login/utmpname.c (__utmpname): Reset backend right after backend
	endutent call.
	* login/utmp_file.c: Reordered functions.  Remove unecessary
	header files.
	(getutent_r_file, pututline_file): Do not call setutent_file.  At this
	point the file is guaranteed to be open (assert!).
	(getutid_r_file, getutline_r_file): Remove check for validity of file
	descriptor.  At this point the file is guaranteed to be open.
	(getutent_r_file, internal_getut_r, getutline_r_file, pututline_file,
	updwtmp_file): Do not wait when unlocking file.
	* login/utmp_daemon.c: General cleanup and a bit of reordering.
	(getutent_r_daemon, pututline_daemon): Do not call setutent_daemon.
	At this point the socket is guaranteed to be open (assert!).
	(getutid_r_daemon, getutline_r_daemon): Do not check if daemon_sock is
	valid.  At this point the socket is guaranteed to be open (assert!).
	* login/getutline_r.c: Remove unnecessary header files.
	(__getutline_r): Do not call backend setutent.
	* login/getutid_r.c: Remove unnecessary header files.
	(__getutid_r): Do not call backend setutent.
	* login/getutent_r.c: Remove unneccesary header files.
	(__libc_utmp_unknown_functions): Added getutid_r_unknown,
	getutline_r_unknown.
	(setutent_unknown): Only set file backend if setutent for the file
	backend was successful.
	(getutent_r_unknown, pututline_unknown): Call setutent_unknown instead
	of __setutent.  Report failure if no backend was selected.
	(getutid_r_unknown): New function.
	(getutline_r_unknown): New function.
	(__endutent): Reset backend.  This makes sure all backends are checked
	on the next setutent call.

1997-08-08 20:20  Thorsten Kukuk  <kukuk@vt.uni-paderborn.de>

	* nis_cache.c: Replace dummy functions.

	* libc.map: Add xdr_sizeof symbol.

	* sunrpc/Makefile: Add xdr_sizeof to routines.
	* sunrpc/rpc/xdr.h: Add xdr_sizeof prototype.
	* sunrpc/xdr_sizeof.c: New, from tirpc 2.3.

1997-08-08  Thomas Bushnell, n/BSG  <thomas@gnu.ai.mit.edu>

	* sysdeps/mach/bits/libc-lock.h (__libc_once): Define correctly.

1997-08-07  Thomas Bushnell, n/BSG  <thomas@gnu.ai.mit.edu>

	* sysdeps/mach/hurd/profil.c (fetch_samples): Put parens in the
	right place.

1997-08-06  Thomas Bushnell, n/BSG  <thomas@gnu.ai.mit.edu>

	* sysdeps/mach/hurd/profil.c (fetch_samples): Do arithmetic on
	PC's in long long to avoid overflow.

1997-08-07  Thomas Bushnell, n/BSG  <thomas@gnu.ai.mit.edu>

	* sysdeps/mach/bits/libc-lock.h (__libc_once, __libc_once_define):
	New macros.

1997-08-06  Andreas Jaeger  <aj@arthur.rhein-neckar.de>

	* nis/Makefile (headers): Remove bits/nislib.h.

1997-08-06 14:54  Ulrich Drepper  <drepper@cygnus.com>

	* sysdeps/mach/hurd/Subdirs: Add login.

1997-08-06 14:23  Klaus Espenlaub  <kespenla@hydra.informatik.uni-ulm.de>

	* db/hash/hash.c (init_hash): Don't use stat() if it doesn't provide
	the preferred block size.

	* login/programs/database.c (store_state_entry): Don't compile if
	there is no ut_type field.
	(store_state_entry, store_process_entry): Use the ut_tv field
	for timestamps if supported.

	* login/programs/utmpdump.c (print_entry): Always use ut_tv field.

	* login/programs/xtmp.c: Fix numerous xtmp/utmp typos.  Use the ut_tv
	field for timestamps if supported.

	* login/programs/xtmp.h: Fix xtmp/utmp typo.

	* sysdeps/posix/defs.c (stdstream): Change (PTR) to (void *).

	* sysdeps/stub/connect.c (connect): Change to __connect, add alias.
	* sysdeps/stub/send.c (send): Likewise.
	* sysdeps/stub/s_exp2f.c: Emit correct stub_warning().
	* sysdeps/stub/statfs.c: Move stub_warning() to the usual place.
	* sysdeps/stub/init-first.c: Add definition of __libc_pid.

1997-08-05 13:28  Philip Blundell  <pb@spring.nexus.co.uk>

	* sysdeps/standalone/arm/bits/errno.h: Add EISDIR, EOPNOTSUPP;
	tidy up formatting.

	* Makefile (subdirs): Remove `login'.
	* sysdeps/unix/Subdirs: New file; build `login' subdirectory
	for Unix systems.

1997-08-05  Andreas Schwab  <schwab@issan.informatik.uni-dortmund.de>

	* sysdeps/generic/bits/utmpx.h: New file.

	* sysdeps/mach/hurd/Dist: Add some files.
	* sysdeps/mips/Dist: Likewise.
	* sysdeps/mips/mips64/Dist: Likewise.
	* sysdeps/sparc/Dist: Likewise.
	* sysdeps/unix/sysv/linux/mips/Dist: Likewise.
	* sysdeps/unix/sysv/linux/sparc/Dist: Likewise.
	* sysdeps/mips/mipsel/Dist: New file.
	* sysdeps/sparc64/elf/Dist: New file.
	* sysdeps/unix/sysv/linux/sparc64/Dist: New file.

1997-08-05  Andreas Schwab  <schwab@issan.informatik.uni-dortmund.de>

	* libc.map: Add missing symbols.

1997-08-05  Andreas Jaeger  <aj@arthur.rhein-neckar.de>

	* manual/socket.texi: Correct typos.

	* manual/math.texi: Correct typos.

	* manual/time.texi (Formatting Date and Time): Likewise.

1997-08-04 13:06  Thomas Bushnell, n/BSG  <thomas@gnu.ai.mit.edu>

	* gmon/gmon.c (write_gmon): New function; guts from _mcleanup.
	(_mcleanup): Use write_gmon.
	(write_profiling): This function can be safely called at any time
	to write a current histogram without interfering with ongoing
	profiling.

	* sysdeps/mach/hurd/profil.c (fetch_samples): Initialize NSAMPLES.

1997-08-01 17:53  Thomas Bushnell, n/BSG  <thomas@gnu.ai.mit.edu>

	* sysdeps/mach/hurd/profil.c (fetch_samples): Sample buffer need
	not be vm_deallocated; it's a stack buffer.
	(profil_vm_deallocate): Delete prototype.
	(#include <../mach/RPC_vm_deallocate_rpc.c>): Drop this
	inclusion.
	* sysdeps/mach/hurd/Makefile
	($(common-objpfx)hurd/../mach/RPC_vm_deallocate_rpc.c): Delete
	this rule.

	* sysdeps/mach/hurd/profil.c (fetch_samples): New function, guts
	from profile_waiter.
	(profile_waiter): Use fetch_samples.
	(profil): When turning off profiling, fetch the last bunch of
	samples before disabling PC sampling.
	(fetch_samples): Add prototype.

1997-07-30 12:53  Thomas Bushnell, n/BSG  <thomas@gnu.ai.mit.edu>

	* sysdeps/mach/hurd/Makefile: Give normal rules for the mach RPC
	source included by profil.c instead of trying to use
	before-compile grot.

1997-07-23 15:04  Thomas Bushnell, n/BSG  <thomas@gnu.ai.mit.edu>

	* sysdeps/mach/hurd/profil.c (profile_waiter): Do vm_deallocate
	after releasing lock.  Use special RPC stubs and avoid assert,
	thus making this function entirely independent of the threadvar
	mechanism and of cthreads.
	(lock): Convert to be a spin lock instead of a mutex, so that the
	waiter thread need not use cthreads.  Use a fork prepare hook
	instead of _hurd_fork_locks to make sure we are clean before
	forking.
	(fork_profil_child): Renamed from fork_profil.
	(profil_reply_port): New variable.
	(profil_vm_deallocate, profil_task_get_sampled_pcs): Special RPC
	stubs made by special hacks.
	* sysdeps/mach/hurd/Makefile (before-compile): Add the mach RPC
	source files that profil.c needs if we are in the gmon directory.

	* mach/setup-thread.c (__mach_setup_thread): Delete avoidance of a
	cthreads bug that hasn't existed for two years.

	* stdio-common/printf_fp.c (__printf_fp): Correct rounding of numbers
	* locale/programs/locale.c (print_escaped): New function.
	* time/australasia: Likewise.
	(open_database, synchronize_database, initialize_database):
	* nss/nss_files/files-netgrp.c (_nss_netgroup_parseline): Don't
	* Makerules (load-map-file): Currectly handle missing map file.
	cannot rely on M_SQRT2 being defined.
	(log1p): Use __M_SQRT2 not M_SQRT2.

1 files changed, 71 insertions, 1 deletions

diff --git a/manual/time.texi b/manual/time.texi
index 1022e1a..d711234 100644
--- a/manual/time.texi
+++ b/manual/time.texi
@@ -536,6 +536,26 @@ Calling @code{localtime} has one other effect: it sets the variable
 Zone Functions}.
 @end deftypefun
 
+Using the @code{localtime} function is a big problem in multi-threaded
+programs.  The result is returned in a static buffer and this is used in
+all threads.  POSIX.1c introduced a varient of this function.
+
+@comment time.h
+@comment POSIX.1c
+@deftypefun {struct tm *} localtime_r (const time_t *@var{time}, struct tm *@var{resultp})
+The @code{localtime_r} function works just like the @code{localtime}
+function.  It takes a pointer to a variable containing the calendar time
+and converts it to the broken-down time format.
+
+But the result is not placed in a static buffer.  Instead it is placed
+in the object of type @code{struct tm} to which the parameter
+@var{resultp} points.
+
+If the conversion is successful the function returns a pointer to the
+object the result was written into, i.e., it returns @var{resultp}.
+@end deftypefun
+
+
 @comment time.h
 @comment ISO
 @deftypefun {struct tm *} gmtime (const time_t *@var{time})
@@ -547,6 +567,21 @@ Recall that calendar times are @emph{always} expressed in coordinated
 universal time.
 @end deftypefun
 
+As for the @code{localtime} function we have the problem that the result
+is placed ina static variable.  POSIX.1c also provides a replacement for
+@code{gmtime}.
+
+@comment time.h
+@comment POSIX.1c
+@deftypefun {struct tm *} gmtime_r (const time_t *@var{time}, struct tm *@var{resultp})
+This function is similar to @code{localtime_r}, except that it converts
+just like @code{gmtime} the given time as Coordinated Universal Time.
+
+If the conversion is successful the function returns a pointer to the
+object the result was written into, i.e., it returns @var{resultp}.
+@end deftypefun
+
+
 @comment time.h
 @comment ISO
 @deftypefun time_t mktime (struct tm *@var{brokentime})
@@ -602,6 +637,20 @@ string.)
 @end deftypefun
 
 @comment time.h
+@comment POSIX.1c
+@deftypefun {char *} asctime_r (const struct tm *@var{brokentime}, char *@var{buffer})
+This function is similar to @code{asctime} but instead of placing the
+result in a static buffer it writes the string in the buffer pointed to
+by the parameter @var{buffer}.  This buffer should have at least room
+for 16 bytes.
+
+If no error occurred the function returns a pointer to the string the
+result was written into, i.e., it returns @var{buffer}.  Otherwise
+return @code{NULL}.
+@end deftypefun
+
+
+@comment time.h
 @comment ISO
 @deftypefun {char *} ctime (const time_t *@var{time})
 The @code{ctime} function is similar to @code{asctime}, except that the
@@ -617,6 +666,23 @@ does so.  @xref{Time Zone Functions}.
 @end deftypefun
 
 @comment time.h
+@comment POSIX.1c
+@deftypefun {char *} ctime_r (const time_t *@var{time}, char *@var{buffer})
+This function is similar to @code{ctime}, only that it places the result
+in the string pointed to by @var{buffer}.  It is equivalent to (written
+using gcc extensions, @xref{Statement Exprs,,,gcc,Porting and Using gcc}.):
+
+@smallexample
+(@{ struct tm tm; asctime_r (localtime_r (time, &tm), buf); @})
+@end smallexample
+
+If no error occurred the function returns a pointer to the string the
+result was written into, i.e., it returns @var{buffer}.  Otherwise
+return @code{NULL}.
+@end deftypefun
+
+
+@comment time.h
 @comment ISO
 @comment POSIX.2
 @deftypefun size_t strftime (char *@var{s}, size_t @var{size}, const char *@var{template}, const struct tm *@var{brokentime})
@@ -885,7 +951,7 @@ A literal @samp{%} character.
 The @var{size} parameter can be used to specify the maximum number of
 characters to be stored in the array @var{s}, including the terminating
 null character.  If the formatted time requires more than @var{size}
-characters, @code{strftime} return zero and the content of the array
+characters, @code{strftime} returns zero and the content of the array
 @var{s} is indetermined.  Otherwise the return value indicates the
 number of characters placed in the array @var{s}, not including the
 terminating null character.
@@ -1095,6 +1161,10 @@ GNU programs it is better to use the @code{tm_zone} member of the
 broken-down time structure, since @code{tm_zone} reports the correct
 abbreviation even when it is not the latest one.
 
+Though the strings are declared as @code{char *} the user must stay away
+from modifying these strings.  Modying the strings will almost certainly
+lead to trouble.
+
 @end deftypevar
 
 @comment time.h