This is the mail archive of the
glibc-cvs@sourceware.org
mailing list for the glibc project.
GNU C Library master sources branch master updated. glibc-2.27.9000-190-g2cc7bad
- From: zack at sourceware dot org
- To: glibc-cvs at sourceware dot org
- Date: 13 Mar 2018 12:33:12 -0000
- Subject: GNU C Library master sources branch master updated. glibc-2.27.9000-190-g2cc7bad
This is an automated email from the git hooks/post-receive script. It was
generated because a ref change was pushed to the repository containing
the project "GNU C Library master sources".
The branch, master has been updated
via 2cc7bad0ae0a412e75270be5ed41d45c03e7a931 (commit)
from 778f1974863d63e858b6d0105e41d6f0c30732d3 (commit)
Those revisions listed above that are new to this repository have
not appeared on any other notification email; so we list those
revisions in full, below.
- Log -----------------------------------------------------------------
http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=2cc7bad0ae0a412e75270be5ed41d45c03e7a931
commit 2cc7bad0ae0a412e75270be5ed41d45c03e7a931
Author: Zack Weinberg <zackw@panix.com>
Date: Wed Feb 21 19:12:51 2018 -0500
[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.
diff --git a/ChangeLog b/ChangeLog
index 59ab3ef..203d274 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,20 @@
+2018-03-12 Zack Weinberg <zackw@panix.com>
+
+ [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.
+
2018-03-12 Dmitry V. Levin <ldv@altlinux.org>
* po/pt_BR.po: Update translations.
diff --git a/NEWS b/NEWS
index 60dd2f7..03330d4 100644
--- a/NEWS
+++ b/NEWS
@@ -28,6 +28,14 @@ Deprecated and removed features, and other changes affecting compatibility:
investigate using (f)getc_unlocked and (f)putc_unlocked, and, if
necessary, flockfile and funlockfile.
+ * All stdio functions now treat end-of-file as a sticky condition. If you
+ read from a file until EOF, and then the file is enlarged by another
+ process, you must call clearerr or another function with the same effect
+ (e.g. fseek, rewind) before you can read the additional data. This
+ corrects a longstanding C99 conformance bug. It is most likely to affect
+ programs that use stdio to read interactive input from a terminal.
+ (Bug #1190.)
+
* The macros 'major', 'minor', and 'makedev' are now only available from
the header <sys/sysmacros.h>; not from <sys/types.h> or various other
headers that happen to include <sys/types.h>. These macros are rarely
diff --git a/libio/Makefile b/libio/Makefile
index 3e08ed0..cbe14a8 100644
--- a/libio/Makefile
+++ b/libio/Makefile
@@ -64,7 +64,8 @@ tests = tst_swprintf tst_wprintf tst_swscanf tst_wscanf tst_getwc tst_putwc \
bug-memstream1 bug-wmemstream1 \
tst-setvbuf1 tst-popen1 tst-fgetwc bug-wsetpos tst-fseek \
tst-fwrite-error tst-ftell-partial-wide tst-ftell-active-handler \
- tst-ftell-append tst-fputws tst-bz22415
+ tst-ftell-append tst-fputws tst-bz22415 tst-fgetc-after-eof
+
ifeq (yes,$(build-shared))
# Add test-fopenloc only if shared library is enabled since it depends on
# shared localedata objects.
diff --git a/libio/fileops.c b/libio/fileops.c
index 79ad153..c9c5cbc 100644
--- a/libio/fileops.c
+++ b/libio/fileops.c
@@ -468,11 +468,10 @@ int
_IO_new_file_underflow (FILE *fp)
{
ssize_t count;
-#if 0
- /* SysV does not make this test; take it out for compatibility */
+
+ /* C99 requires EOF to be "sticky". */
if (fp->_flags & _IO_EOF_SEEN)
- return (EOF);
-#endif
+ return EOF;
if (fp->_flags & _IO_NO_READS)
{
diff --git a/libio/oldfileops.c b/libio/oldfileops.c
index 7997ddf..5e60c8c 100644
--- a/libio/oldfileops.c
+++ b/libio/oldfileops.c
@@ -294,11 +294,10 @@ attribute_compat_text_section
_IO_old_file_underflow (FILE *fp)
{
ssize_t count;
-#if 0
- /* SysV does not make this test; take it out for compatibility */
+
+ /* C99 requires EOF to be "sticky". */
if (fp->_flags & _IO_EOF_SEEN)
- return (EOF);
-#endif
+ return EOF;
if (fp->_flags & _IO_NO_READS)
{
diff --git a/libio/tst-fgetc-after-eof.c b/libio/tst-fgetc-after-eof.c
new file mode 100644
index 0000000..81c9cc9
--- /dev/null
+++ b/libio/tst-fgetc-after-eof.c
@@ -0,0 +1,109 @@
+/* Bug 1190: EOF conditions are supposed to be sticky.
+ Copyright (C) 2018 Free Software Foundation.
+ Copying and distribution of this file, with or without modification,
+ are permitted in any medium without royalty provided the copyright
+ notice and this notice are preserved. This file is offered as-is,
+ without any warranty. */
+
+/* ISO C1999 specification of fgetc:
+
+ #include <stdio.h>
+ int fgetc (FILE *stream);
+
+ Description
+
+ If the end-of-file indicator for the input stream pointed to by
+ stream is not set and a next character is present, the fgetc
+ function obtains that character as an unsigned char converted to
+ an int and advances the associated file position indicator for
+ the stream (if defined).
+
+ Returns
+
+ If the end-of-file indicator for the stream is set, or if the
+ stream is at end-of-file, the end-of-file indicator for the
+ stream is set and the fgetc function returns EOF. Otherwise, the
+ fgetc function returns the next character from the input stream
+ pointed to by stream. If a read error occurs, the error indicator
+ for the stream is set and the fgetc function returns EOF.
+
+ The requirement to return EOF "if the end-of-file indicator for the
+ stream is set" was new in C99; the language in the 1989 edition of
+ the standard was ambiguous. Historically, BSD-derived Unix always
+ had the C99 behavior, whereas in System V fgetc would attempt to
+ call read() again before returning EOF again. Prior to version 2.28,
+ glibc followed the System V behavior even though this does not
+ comply with C99.
+
+ See
+ <https://sourceware.org/bugzilla/show_bug.cgi?id=1190>,
+ <https://sourceware.org/bugzilla/show_bug.cgi?id=19476>,
+ and the thread at
+ <https://sourceware.org/ml/libc-alpha/2012-09/msg00343.html>
+ for more detail. */
+
+#include <support/tty.h>
+#include <support/check.h>
+
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#define XWRITE(fd, s, msg) do { \
+ if (write (fd, s, sizeof s - 1) != sizeof s - 1) \
+ { \
+ perror ("write " msg); \
+ return 1; \
+ } \
+ } while (0)
+
+int
+do_test (void)
+{
+ /* The easiest way to set up the conditions under which you can
+ notice whether the end-of-file indicator is sticky, is with a
+ pseudo-tty. This is also the case which applications are most
+ likely to care about. And it avoids any question of whether and
+ how it is legitimate to access the same physical file with two
+ independent FILE objects. */
+ int outer_fd, inner_fd;
+ FILE *fp;
+
+ support_openpty (&outer_fd, &inner_fd, 0, 0, 0);
+ fp = fdopen (inner_fd, "r+");
+ if (!fp)
+ {
+ perror ("fdopen");
+ return 1;
+ }
+
+ XWRITE (outer_fd, "abc\n\004", "first line + EOF");
+ TEST_COMPARE (fgetc (fp), 'a');
+ TEST_COMPARE (fgetc (fp), 'b');
+ TEST_COMPARE (fgetc (fp), 'c');
+ TEST_COMPARE (fgetc (fp), '\n');
+ TEST_COMPARE (fgetc (fp), EOF);
+
+ TEST_VERIFY_EXIT (feof (fp));
+ TEST_VERIFY_EXIT (!ferror (fp));
+
+ XWRITE (outer_fd, "d\n", "second line");
+
+ /* At this point, there is a new full line of input waiting in the
+ kernelside input buffer, but we should still observe EOF from
+ stdio, because the end-of-file indicator has not been cleared. */
+ TEST_COMPARE (fgetc (fp), EOF);
+
+ /* Clearing EOF should reveal the next line of input. */
+ clearerr (fp);
+ TEST_COMPARE (fgetc (fp), 'd');
+ TEST_COMPARE (fgetc (fp), '\n');
+
+ fclose (fp);
+ close (outer_fd);
+ return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/libio/wfileops.c b/libio/wfileops.c
index 1dbf72f..63cb687 100644
--- a/libio/wfileops.c
+++ b/libio/wfileops.c
@@ -116,6 +116,10 @@ _IO_wfile_underflow (FILE *fp)
enum __codecvt_result status;
ssize_t count;
+ /* C99 requires EOF to be "sticky". */
+ if (fp->_flags & _IO_EOF_SEEN)
+ return WEOF;
+
if (__glibc_unlikely (fp->_flags & _IO_NO_READS))
{
fp->_flags |= _IO_ERR_SEEN;
diff --git a/support/Makefile b/support/Makefile
index 1bda81e..c632df6 100644
--- a/support/Makefile
+++ b/support/Makefile
@@ -52,6 +52,7 @@ libsupport-routines = \
support_format_hostent \
support_format_netent \
support_isolate_in_subprocess \
+ support_openpty \
support_record_failure \
support_run_diff \
support_shared_allocate \
diff --git a/support/support_openpty.c b/support/support_openpty.c
new file mode 100644
index 0000000..ac779ab
--- /dev/null
+++ b/support/support_openpty.c
@@ -0,0 +1,109 @@
+/* Open a pseudoterminal.
+ Copyright (C) 2018 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include <support/tty.h>
+#include <support/check.h>
+#include <support/support.h>
+
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <fcntl.h>
+#include <termios.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+
+/* As ptsname, but allocates space for an appropriately-sized string
+ using malloc. */
+static char *
+xptsname (int fd)
+{
+ int rv;
+ size_t buf_len = 128;
+ char *buf = xmalloc (buf_len);
+ for (;;)
+ {
+ rv = ptsname_r (fd, buf, buf_len);
+ if (rv)
+ FAIL_EXIT1 ("ptsname_r: %s", strerror (errno));
+
+ if (memchr (buf, '\0', buf_len))
+ return buf; /* ptsname succeeded and the buffer was not truncated */
+
+ buf_len *= 2;
+ buf = xrealloc (buf, buf_len);
+ }
+}
+
+void
+support_openpty (int *a_outer, int *a_inner, char **a_name,
+ const struct termios *termp,
+ const struct winsize *winp)
+{
+ int outer = -1, inner = -1;
+ char *namebuf = 0;
+
+ outer = posix_openpt (O_RDWR | O_NOCTTY);
+ if (outer == -1)
+ FAIL_EXIT1 ("posix_openpt: %s", strerror (errno));
+
+ if (grantpt (outer))
+ FAIL_EXIT1 ("grantpt: %s", strerror (errno));
+
+ if (unlockpt (outer))
+ FAIL_EXIT1 ("unlockpt: %s", strerror (errno));
+
+
+#ifdef TIOCGPTPEER
+ inner = ioctl (outer, TIOCGPTPEER, O_RDWR | O_NOCTTY);
+#endif
+ if (inner == -1)
+ {
+ /* The kernel might not support TIOCGPTPEER, fall back to open
+ by name. */
+ namebuf = xptsname (outer);
+ inner = open (namebuf, O_RDWR | O_NOCTTY);
+ if (inner == -1)
+ FAIL_EXIT1 ("%s: %s", namebuf, strerror (errno));
+ }
+
+ if (termp)
+ {
+ if (tcsetattr (inner, TCSAFLUSH, termp))
+ FAIL_EXIT1 ("tcsetattr: %s", strerror (errno));
+ }
+#ifdef TIOCSWINSZ
+ if (winp)
+ {
+ if (ioctl (inner, TIOCSWINSZ, winp))
+ FAIL_EXIT1 ("TIOCSWINSZ: %s", strerror (errno));
+ }
+#endif
+
+ if (a_name)
+ {
+ if (!namebuf)
+ namebuf = xptsname (outer);
+ *a_name = namebuf;
+ }
+ else
+ free (namebuf);
+ *a_outer = outer;
+ *a_inner = inner;
+}
diff --git a/support/tty.h b/support/tty.h
new file mode 100644
index 0000000..1d37c42
--- /dev/null
+++ b/support/tty.h
@@ -0,0 +1,45 @@
+/* Support functions related to (pseudo)terminals.
+ Copyright (C) 2018 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#ifndef _SUPPORT_TTY_H
+#define _SUPPORT_TTY_H 1
+
+struct termios;
+struct winsize;
+
+/** Open a pseudoterminal pair. The outer fd is written to the address
+ A_OUTER and the inner fd to A_INNER.
+
+ If A_NAME is not NULL, it will be set to point to a string naming
+ the /dev/pts/NNN device corresponding to the inner fd; space for
+ this string is allocated with malloc and should be freed by the
+ caller when no longer needed. (This is different from the libutil
+ function 'openpty'.)
+
+ If TERMP is not NULL, the terminal parameters will be initialized
+ according to the termios structure it points to.
+
+ If WINP is not NULL, the terminal window size will be set
+ accordingly.
+
+ Terminates the process on failure (like xmalloc). */
+extern void support_openpty (int *a_outer, int *a_inner, char **a_name,
+ const struct termios *termp,
+ const struct winsize *winp);
+
+#endif
diff --git a/wcsmbs/Makefile b/wcsmbs/Makefile
index 3ee91d2..63a6fba 100644
--- a/wcsmbs/Makefile
+++ b/wcsmbs/Makefile
@@ -50,7 +50,7 @@ strop-tests := wcscmp wcsncmp wmemcmp wcslen wcschr wcsrchr wcscpy wcsnlen \
tests := tst-wcstof wcsmbs-tst1 tst-wcsnlen tst-btowc tst-mbrtowc \
tst-wcrtomb tst-wcpncpy tst-mbsrtowcs tst-wchar-h tst-mbrtowc2 \
tst-c16c32-1 wcsatcliff tst-wcstol-locale tst-wcstod-nan-locale \
- tst-wcstod-round test-char-types \
+ tst-wcstod-round test-char-types tst-fgetwc-after-eof \
$(addprefix test-,$(strop-tests))
include ../Rules
diff --git a/wcsmbs/tst-fgetwc-after-eof.c b/wcsmbs/tst-fgetwc-after-eof.c
new file mode 100644
index 0000000..9103529
--- /dev/null
+++ b/wcsmbs/tst-fgetwc-after-eof.c
@@ -0,0 +1,114 @@
+/* Bug 1190: EOF conditions are supposed to be sticky.
+ Copyright (C) 2018 Free Software Foundation.
+ Copying and distribution of this file, with or without modification,
+ are permitted in any medium without royalty provided the copyright
+ notice and this notice are preserved. This file is offered as-is,
+ without any warranty. */
+
+/* ISO C1999 specification of fgetwc:
+
+ #include <stdio.h>
+ #include <wchar.h>
+ wint_t fgetwc (FILE *stream);
+
+ Description
+
+ If the end-of-file indicator for the input stream pointed to by
+ stream is not set and a next wide character is present, the
+ fgetwc function obtains that wide character as a wchar_t
+ converted to a wint_t and advances the associated file position
+ indicator for the stream (if defined).
+
+ Returns
+
+ If the end-of-file indicator for the stream is set, or if the
+ stream is at end-of-file, the end- of-file indicator for the
+ stream is set and the fgetwc function returns WEOF. Otherwise,
+ the fgetwc function returns the next wide character from the
+ input stream pointed to by stream. If a read error occurs, the
+ error indicator for the stream is set and the fgetwc function
+ returns WEOF. If an encoding error occurs (including too few
+ bytes), the value of the macro EILSEQ is stored in errno and the
+ fgetwc function returns WEOF.
+
+ The requirement to return WEOF "if the end-of-file indicator for the
+ stream is set" was new in C99; the language in the 1995 edition of
+ the standard was ambiguous. Historically, BSD-derived Unix always
+ had the C99 behavior, whereas in System V fgetwc would attempt to
+ call read() again before returning EOF again. Prior to version 2.28,
+ glibc followed the System V behavior even though this does not
+ comply with C99.
+
+ See
+ <https://sourceware.org/bugzilla/show_bug.cgi?id=1190>,
+ <https://sourceware.org/bugzilla/show_bug.cgi?id=19476>,
+ and the thread at
+ <https://sourceware.org/ml/libc-alpha/2012-09/msg00343.html>
+ for more detail. */
+
+#include <support/tty.h>
+#include <support/check.h>
+
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <wchar.h>
+
+#define XWRITE(fd, s, msg) do { \
+ if (write (fd, s, sizeof s - 1) != sizeof s - 1) \
+ { \
+ perror ("write " msg); \
+ return 1; \
+ } \
+ } while (0)
+
+int
+do_test (void)
+{
+ /* The easiest way to set up the conditions under which you can
+ notice whether the end-of-file indicator is sticky, is with a
+ pseudo-tty. This is also the case which applications are most
+ likely to care about. And it avoids any question of whether and
+ how it is legitimate to access the same physical file with two
+ independent FILE objects. */
+ int outer_fd, inner_fd;
+ FILE *fp;
+
+ support_openpty (&outer_fd, &inner_fd, 0, 0, 0);
+ fp = fdopen (inner_fd, "r+");
+ if (!fp)
+ {
+ perror ("fdopen");
+ return 1;
+ }
+
+ XWRITE (outer_fd, "abc\n\004", "first line + EOF");
+ TEST_COMPARE (fgetwc (fp), L'a');
+ TEST_COMPARE (fgetwc (fp), L'b');
+ TEST_COMPARE (fgetwc (fp), L'c');
+ TEST_COMPARE (fgetwc (fp), L'\n');
+ TEST_COMPARE (fgetwc (fp), WEOF);
+
+ TEST_VERIFY_EXIT (feof (fp));
+ TEST_VERIFY_EXIT (!ferror (fp));
+
+ XWRITE (outer_fd, "d\n", "second line");
+
+ /* At this point, there is a new full line of input waiting in the
+ kernelside input buffer, but we should still observe EOF from
+ stdio, because the end-of-file indicator has not been cleared. */
+ TEST_COMPARE (fgetwc (fp), WEOF);
+
+ /* Clearing EOF should reveal the next line of input. */
+ clearerr (fp);
+ TEST_COMPARE (fgetwc (fp), L'd');
+ TEST_COMPARE (fgetwc (fp), L'\n');
+
+ fclose (fp);
+ close (outer_fd);
+ return 0;
+}
+
+#include <support/test-driver.c>
-----------------------------------------------------------------------
Summary of changes:
ChangeLog | 17 ++++++
NEWS | 8 +++
libio/Makefile | 3 +-
libio/fileops.c | 7 +--
libio/oldfileops.c | 7 +--
libio/tst-fgetc-after-eof.c | 109 +++++++++++++++++++++++++++++++++++++++
libio/wfileops.c | 4 ++
support/Makefile | 1 +
support/support_openpty.c | 109 +++++++++++++++++++++++++++++++++++++++
support/tty.h | 45 ++++++++++++++++
wcsmbs/Makefile | 2 +-
wcsmbs/tst-fgetwc-after-eof.c | 114 +++++++++++++++++++++++++++++++++++++++++
12 files changed, 416 insertions(+), 10 deletions(-)
create mode 100644 libio/tst-fgetc-after-eof.c
create mode 100644 support/support_openpty.c
create mode 100644 support/tty.h
create mode 100644 wcsmbs/tst-fgetwc-after-eof.c
hooks/post-receive
--
GNU C Library master sources