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Zack Weinberg 2cc7bad0ae [BZ 1190] Make EOF sticky in stdio.
C99 specifies that the EOF condition on a file is "sticky": once EOF
has been encountered, all subsequent reads should continue to return
EOF until the file is closed or something clears the "end-of-file
indicator" (e.g. fseek, clearerr).  This is arguably a change from
C89, where the wording was ambiguous; the BSDs always had sticky EOF,
but the System V lineage would attempt to read from the underlying fd
again.  GNU libc has followed System V for as long as we've been
using libio, but nowadays C99 conformance and BSD compatibility are
more important than System V compatibility.

You might wonder if changing the _underflow impls is sufficient to
apply the C99 semantics to all of the many stdio functions that
perform input.  It should be enough to cover all paths to _IO_SYSREAD,
and the only other functions that call _IO_SYSREAD are the _seekoff
impls, which is OK because seeking clears EOF, and the _xsgetn impls,
which, as far as I can tell, are unused within glibc.

The test programs in this patch use a pseudoterminal to set up the
necessary conditions.  To facilitate this I added a new test-support
function that sets up a pair of pty file descriptors for you; it's
almost the same as BSD openpty, the only differences are that it
allocates the optionally-returned tty pathname with malloc, and that
it crashes if anything goes wrong.

	[BZ #1190]
        [BZ #19476]
	* libio/fileops.c (_IO_new_file_underflow): Return EOF immediately
	if the _IO_EOF_SEEN bit is already set; update commentary.
	* libio/oldfileops.c (_IO_old_file_underflow): Likewise.
	* libio/wfileops.c (_IO_wfile_underflow): Likewise.

	* support/support_openpty.c, support/tty.h: New files.
	* support/Makefile (libsupport-routines): Add support_openpty.

	* libio/tst-fgetc-after-eof.c, wcsmbs/test-fgetwc-after-eof.c:
	New test cases.
	* libio/Makefile (tests): Add tst-fgetc-after-eof.
	* wcsmbs/Makefile (tests): Add tst-fgetwc-after-eof.
2018-03-13 08:31:56 -04:00
argp Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
assert Fix uninitialized variable in assert_perror (bug 22761) 2018-02-05 11:06:15 +01:00
benchtests benchtests: Don't benchmark 0 length calls for strncmp 2018-03-06 18:29:57 +05:30
bits hurd: Fix includability of <hurd/signal.h> in all standards 2018-03-05 22:50:29 +01:00
catgets intl/tst-gettext: fix failure with newest msgfmt 2018-02-18 18:16:05 +01:00
ChangeLog.old Add missing reference to bug 21654 2017-10-07 13:14:36 +02:00
conform Don't install libio.h or _G_config.h. 2018-02-07 10:07:31 -05:00
crypt crypt: Fix badsalttest test (Bug 22765) 2018-02-01 00:02:49 -08:00
csu Post-cleanup 2: minimize _G_config.h. 2018-02-07 10:10:32 -05:00
ctype Use libc_hidden_* for tolower, toupper (bug 15105). 2018-02-23 13:54:53 +00:00
debug Remove _IO_file_flags define. 2018-02-21 14:22:50 -05:00
dirent Define _DIRENT_MATCHES_DIRENT64 regardless 2018-03-05 18:10:04 -03:00
dlfcn Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
elf hurd: add gscope support 2018-03-11 13:06:33 +01:00
gmon Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
gnulib Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
grp Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
gshadow Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
hesiod Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
hurd hurd: Fix includability of <hurd/signal.h> in all standards 2018-03-05 22:50:29 +01:00
iconv Fix s390 -Os iconv build. 2018-03-05 21:46:55 +00:00
iconvdata Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
include Remove hidden __libc_longjmp 2018-03-10 09:27:20 -08:00
inet Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
intl intl/tst-gettext: fix failure with newest msgfmt 2018-02-18 18:16:05 +01:00
io Add missing start-of-file descriptive comment. 2018-03-06 09:21:04 +01:00
libidn Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
libio [BZ 1190] Make EOF sticky in stdio. 2018-03-13 08:31:56 -04:00
locale Fix two more -Os strcoll / wcscoll build failures. 2018-02-27 16:55:42 +00:00
localedata an_ES locale: update some locale data [BZ #22896] 2018-03-01 15:06:24 +01:00
login Update copyright dates not handled by scripts/update-copyrights. 2018-01-01 00:41:16 +00:00
mach hurd: Fix inclusion of mach headers in all standards 2018-03-04 02:53:09 +01:00
malloc malloc: Revert sense of prev_inuse in comments 2018-03-09 16:21:22 +01:00
manual manual: Update _DEFAULT_SOURCE. [BZ #22862] 2018-02-21 02:38:42 -08:00
math Remove mplog and mpexp 2018-02-15 12:41:05 +00:00
mathvec Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
misc Add missing start-of-file descriptive comment. 2018-03-06 09:21:04 +01:00
nis libnsl: Turn remaining symbols into compat symbols [BZ #22701] 2018-01-29 17:42:30 +01:00
nptl nptl: Fix tst-cancel4 sendto tests 2018-03-05 18:09:08 -03:00
nptl_db nptl_db: Remove stale match_pid' parameter from iterate_thread_list' 2018-03-01 16:10:05 +00:00
nscd Fix multiple definitions of __nss_*_database (bug 22918) 2018-03-03 17:44:24 +01:00
nss Fix multiple definitions of __nss_*_database (bug 22918) 2018-03-03 17:44:24 +01:00
po Update translations from the Translation Project 2018-03-12 13:24:46 +00:00
posix Fix multiple definitions of __nss_*_database (bug 22918) 2018-03-03 17:44:24 +01:00
pwd Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
resolv hurd: fix warning 2018-01-27 16:43:16 +01:00
resource resource/tst-getrlimit.c: Add copyright header 2018-01-05 20:34:10 +01:00
rt Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
scripts hurd: Fix inclusion of mach headers in all standards 2018-03-04 02:53:09 +01:00
setjmp Remove hidden __libc_longjmp 2018-03-10 09:27:20 -08:00
shadow Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
signal Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
socket Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
soft-fp Do not use packed structures in soft-fp. 2018-02-01 20:44:49 +00:00
stdio-common Remove miscellaneous debris from libio. 2018-02-21 14:39:54 -05:00
stdlib Separate out error_t definition 2018-03-04 17:27:58 +01:00
streams Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
string Fix another -Os strcoll build issue. 2018-02-26 18:38:01 +00:00
sunrpc Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
support [BZ 1190] Make EOF sticky in stdio. 2018-03-13 08:31:56 -04:00
sysdeps Lookup the startup server through /servers/startup 2018-03-12 00:24:31 +01:00
sysvipc Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
termios Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
time Fix -Os getc_unlocked linknamespace, localplt issues (bug 15105, bug 19463). 2018-02-21 18:01:11 +00:00
timezone Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
wcsmbs [BZ 1190] Make EOF sticky in stdio. 2018-03-13 08:31:56 -04:00
wctype Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
.gitattributes Assume __NR_openat is always defined 2016-03-23 23:35:08 +01:00
.gitignore Add *.pyc to .gitignore 2015-05-18 15:26:26 +05:30
abi-tags Remove the bulk of the NaCl port. 2017-05-20 08:09:10 -04:00
aclocal.m4 LIBC_SLIBDIR_RTLDDIR: substitute arguments in single quotes 2018-01-25 17:20:28 +01:00
ChangeLog [BZ 1190] Make EOF sticky in stdio. 2018-03-13 08:31:56 -04:00
config.h.in Add RISC-V entries to config.h.in 2018-01-29 10:24:57 -08:00
config.make.in Pass -no-pie to GCC only if GCC defaults to PIE [BZ #22614] 2017-12-18 12:24:38 -08:00
configure Pass -no-pie to GCC only if GCC defaults to PIE [BZ #22614] 2017-12-18 12:24:38 -08:00
configure.ac Pass -no-pie to GCC only if GCC defaults to PIE [BZ #22614] 2017-12-18 12:24:38 -08:00
COPYING Update to latest versions of GPL-2.0 and LGPL-2.1 2013-09-09 12:52:48 +10:00
COPYING.LIB Update to latest versions of GPL-2.0 and LGPL-2.1 2013-09-09 12:52:48 +10:00
extra-lib.mk Rename cppflags-iterator.mk to libof-iterator.mk, remove extra-modules.mk. 2017-05-09 07:06:29 -04:00
gen-locales.mk Improve gen-locales.mk and gen-locale.sh to make test files with @ options work 2018-02-27 17:01:57 +01:00
INSTALL Document use of CC and CFLAGS in more detail (bug 20980, bug 21234). 2018-02-15 23:48:47 +00:00
libc-abis A few more archs have IFUNC support. 2010-03-17 02:43:12 -07:00
libof-iterator.mk Rename cppflags-iterator.mk to libof-iterator.mk, remove extra-modules.mk. 2017-05-09 07:06:29 -04:00
LICENSES Expand LICENSES file. 2012-12-05 21:56:15 +00:00
MAINTAINERS Add MAINTAINERS 2017-05-11 13:38:30 -04:00
Makeconfig Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
Makefile Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
Makefile.in New make target to only build benchmark binaries 2016-04-20 10:23:28 +05:30
Makerules Define GEN_AS_CONST_HEADERS when generating header files [BZ #22792] 2018-02-23 11:29:39 -08:00
NEWS [BZ 1190] Make EOF sticky in stdio. 2018-03-13 08:31:56 -04:00
o-iterator.mk Fri Mar 17 12:58:37 1995 Roland McGrath <roland@churchy.gnu.ai.mit.edu> 1995-03-17 18:42:51 +00:00
README Skeleton documentation for the RISC-V port 2018-01-29 10:22:26 -08:00
Rules Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
shlib-versions Extend NSS test suite 2017-07-17 15:52:44 -04:00
test-skeleton.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
version.h Open master branch for glibc 2.28 development 2018-02-01 17:18:19 +00:00

This directory contains the sources of the GNU C Library.
See the file "version.h" for what release version you have.

The GNU C Library is the standard system C library for all GNU systems,
and is an important part of what makes up a GNU system.  It provides the
system API for all programs written in C and C-compatible languages such
as C++ and Objective C; the runtime facilities of other programming
languages use the C library to access the underlying operating system.

In GNU/Linux systems, the C library works with the Linux kernel to
implement the operating system behavior seen by user applications.
In GNU/Hurd systems, it works with a microkernel and Hurd servers.

The GNU C Library implements much of the POSIX.1 functionality in the
GNU/Hurd system, using configurations i[4567]86-*-gnu.  The current
GNU/Hurd support requires out-of-tree patches that will eventually be
incorporated into an official GNU C Library release.

When working with Linux kernels, this version of the GNU C Library
requires Linux kernel version 3.2 or later.

Also note that the shared version of the libgcc_s library must be
installed for the pthread library to work correctly.

The GNU C Library supports these configurations for using Linux kernels:

	aarch64*-*-linux-gnu
	alpha*-*-linux-gnu
	arm-*-linux-gnueabi
	hppa-*-linux-gnu
	i[4567]86-*-linux-gnu
	x86_64-*-linux-gnu	Can build either x86_64 or x32
	ia64-*-linux-gnu
	m68k-*-linux-gnu
	microblaze*-*-linux-gnu
	mips-*-linux-gnu
	mips64-*-linux-gnu
	powerpc-*-linux-gnu	Hardware or software floating point, BE only.
	powerpc64*-*-linux-gnu	Big-endian and little-endian.
	s390-*-linux-gnu
	s390x-*-linux-gnu
	riscv64-*-linux-gnu
	sh[34]-*-linux-gnu
	sparc*-*-linux-gnu
	sparc64*-*-linux-gnu
	tilegx-*-linux-gnu

If you are interested in doing a port, please contact the glibc
maintainers; see http://www.gnu.org/software/libc/ for more
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See the file INSTALL to find out how to configure, build, and install
the GNU C Library.  You might also consider reading the WWW pages for
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The GNU C Library is (almost) completely documented by the Texinfo manual
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