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Re: Improved tail patch
|
From: |
Paul Eggert |
|
Subject: |
Re: Improved tail patch |
|
Date: |
Fri, 23 Jul 2004 16:14:44 -0700 |
|
User-agent: |
Gnus/5.1006 (Gnus v5.10.6) Emacs/21.3 (gnu/linux) |
I installed the following patch to fix the rest of the problem that
you noted with "tail -f" and fifos. It turns out that using "select"
helps only in the case where there are two or more input files, at
least one of which is a fifo. Optimizing this case would complicate
the code (and it's already too complicated, as you may be able to tell
by reading the patch :-) so I left out all uses of 'select' for now.
2004-07-23 Paul Eggert <address@hidden>
Fix bug with "tail -f" reported by Rob Holland in
<http://lists.gnu.org/archive/html/bug-coreutils/2004-07/msg00054.html>.
Also, remove the undocumented and unsupported-since-2000
--max-consecutive-size-changes options. Fix another related bug:
"tail" got confused if stdin, stdout, or stderr were closed.
Also, use output buffering even with "tail -f".
* NEWS: Document this, plus yesterday's patch.
* doc/coreutils.texi (tail invocation): "size has remained the same"
-> "file has not changed", which is more accurate for fifos.
* lib/Makefile.am (libfetish_a_SOURCES): Add fcntl-safer.h,
open-safer.c.
* src/tail.c: Include fcntl-safer.h.
(COPY_TO_EOF): Set to UINTMAX_MAX, not OFF_T_MAX (which was wrong).
(COPY_A_BUFFER): New macro.
(struct File_spec): New members mtime, mode, blocking.
Remove member n_consecutive_size_changes.
(DEFAULT_MAX_N_CONSECUTIVE_SIZE_CHANGES,
max_n_consecutive_size_changes_between_opens,
MAX_CONSECUTIVE_SIZE_CHANGES_OPTION): Remove.
(long_options, tail_forever, parse_options):
Remove (non-)support for --max-consecutive-size-changes.
(record_open_fd): New function.
(recheck, tail_file): Use it. Don't assume that stdin is open.
(dump_remainder): Add support for new COPY_A_BUFFER special value.
Treat errno==EAGAIN like EOF, since it might be a nonblocking read.
(recheck): New arg BLOCKING, specifying whether to use blocking reads.
All uses changed.
(n_live_files): Remove, replacing with...
(any_live_files): New function. All uses changed.
(tail_forever): Use nonblocking I/O unless we know that blocking I/O
is safe; this avoids some hangs when reading from a fifo.
Avoid invoking fstat or sleep when using blocking I/O.
Do not check for changes to size if the file is not a regular file,
as the size is undefined in that case.
Check for changes to mtime or mode, too; this works for non-regular
files.
(tail_forever, main): Redo fflush strategy to work even when input
is nonblocking. Don't use unbuffered output; just flush when needed.
* lib/fcntl-safer.h, open-safer.c: New files.
* m4/prereq.m4 (gl_PREREQ): Add gl_FCNTL_SAFER.
* m4/fcntl-safer.m4: New file.
Index: NEWS
===================================================================
RCS file: /home/eggert/coreutils/cu/NEWS,v
retrieving revision 1.224
retrieving revision 1.225
diff -p -u -r1.224 -r1.225
--- NEWS 8 Jul 2004 14:03:45 -0000 1.224
+++ NEWS 23 Jul 2004 22:11:15 -0000 1.225
@@ -38,6 +38,9 @@ GNU coreutils NEWS
rm no longer requires read access to the current directory.
+ tail -f no longer mishandles pipes and fifos. With no operands,
+ tail now ignores -f if standard input is a pipe, as POSIX requires.
+
For some types of errors (e.g., read-only file system, I/O error)
when first encountering a directory, `rm -r' would mistakenly fail
to remove files under that directory.
@@ -156,6 +159,10 @@ GNU coreutils NEWS
The stat option --filesystem has been renamed to --file-system, for
consistency with POSIX "file system" and with cp and du --one-file-system.
+
+** Removed features
+
+ tail's undocumented --max-consecutive-size-changes option has been removed.
* Major changes in release 5.2.1 (2004-03-12) [stable]
Index: doc/coreutils.texi
===================================================================
RCS file: /home/eggert/coreutils/cu/doc/coreutils.texi,v
retrieving revision 1.196
retrieving revision 1.197
diff -p -u -r1.196 -r1.197
--- doc/coreutils.texi 22 Jul 2004 20:54:33 -0000 1.196
+++ doc/coreutils.texi 23 Jul 2004 22:11:49 -0000 1.197
@@ -2509,7 +2509,7 @@ will print a warning if this is the case
@opindex --max-unchanged-stats
When tailing a file by name, if there have been @var{n} (default
address@hidden) consecutive
-iterations for which the size has remained the same, then
+iterations for which the file has not changed, then
@code{open}/@code{fstat} the file to determine if that file name is
still associated with the same device/inode-number pair as before.
When following a log file that is rotated, this is approximately the
Index: lib/Makefile.am
===================================================================
RCS file: /home/eggert/coreutils/cu/lib/Makefile.am,v
retrieving revision 1.189
retrieving revision 1.190
diff -p -u -r1.189 -r1.190
--- lib/Makefile.am 12 Jul 2004 06:29:59 -0000 1.189
+++ lib/Makefile.am 23 Jul 2004 22:33:23 -0000 1.190
@@ -57,6 +57,7 @@ libfetish_a_SOURCES = \
exclude.c exclude.h \
exit.h \
exitfail.c exitfail.h \
+ fcntl-safer.h \
filemode.c filemode.h \
file-type.c file-type.h \
fopen-safer.c \
@@ -87,6 +88,7 @@ libfetish_a_SOURCES = \
modechange.c modechange.h \
mountlist.h \
offtostr.c \
+ open-safer.c \
path-concat.c path-concat.h \
pathmax.h \
physmem.c physmem.h \
Index: m4/prereq.m4
===================================================================
RCS file: /home/eggert/coreutils/cu/m4/prereq.m4,v
retrieving revision 1.91
retrieving revision 1.92
diff -p -u -r1.91 -r1.92
--- m4/prereq.m4 12 Jul 2004 06:36:02 -0000 1.91
+++ m4/prereq.m4 23 Jul 2004 22:35:07 -0000 1.92
@@ -1,4 +1,4 @@
-#serial 41
+#serial 42
dnl We use gl_ for non Autoconf macros.
m4_pattern_forbid([^gl_[ABCDEFGHIJKLMNOPQRSTUVXYZ]])dnl
@@ -25,6 +25,7 @@ AC_DEFUN([gl_PREREQ],
AC_REQUIRE([gl_ERROR])
AC_REQUIRE([gl_EXCLUDE])
AC_REQUIRE([gl_EXITFAIL])
+ AC_REQUIRE([gl_FCNTL_SAFER])
AC_REQUIRE([gl_FILEBLOCKS])
AC_REQUIRE([gl_FILEMODE])
AC_REQUIRE([gl_FILE_TYPE])
Index: src/tail.c
===================================================================
RCS file: /home/eggert/coreutils/cu/src/tail.c,v
retrieving revision 1.224
retrieving revision 1.225
diff -p -u -r1.224 -r1.225
--- src/tail.c 22 Jul 2004 20:54:04 -0000 1.224
+++ src/tail.c 23 Jul 2004 22:33:51 -0000 1.225
@@ -35,6 +35,7 @@
#include "argmatch.h"
#include "c-strtod.h"
#include "error.h"
+#include "fcntl-safer.h"
#include "inttostr.h"
#include "posixver.h"
#include "quote.h"
@@ -58,8 +59,9 @@
/* Number of items to tail. */
#define DEFAULT_N_LINES 10
-/* A special value for dump_remainder's N_BYTES parameter. */
-#define COPY_TO_EOF OFF_T_MAX
+/* Special values for dump_remainder's N_BYTES parameter. */
+#define COPY_TO_EOF UINTMAX_MAX
+#define COPY_A_BUFFER (UINTMAX_MAX - 1)
/* FIXME: make Follow_name the default? */
#define DEFAULT_FOLLOW_MODE Follow_descriptor
@@ -99,12 +101,15 @@ struct File_spec
/* File descriptor on which the file is open; -1 if it's not open. */
int fd;
- /* The size of the file the last time we checked. */
+ /* Attributes of the file the last time we checked. */
off_t size;
-
- /* The device and inode of the file the last time we checked. */
+ struct timespec mtime;
dev_t dev;
ino_t ino;
+ mode_t mode;
+
+ /* 1 if O_NONBLOCK is clear, 0 if set, -1 if not known. */
+ int blocking;
/* The specified name initially referred to a directory or some other
type for which tail isn't meaningful. Unlike for a permission problem
@@ -114,9 +119,6 @@ struct File_spec
/* See description of DEFAULT_MAX_N_... below. */
unsigned int n_unchanged_stats;
- /* See description of DEFAULT_MAX_N_... below. */
- unsigned int n_consecutive_size_changes;
-
/* A file is tailable if it exists, is readable, and is of type
IS_TAILABLE_FILE_TYPE. */
int tailable;
@@ -154,7 +156,7 @@ enum header_mode
};
/* When tailing a file by name, if there have been this many consecutive
- iterations for which the size has remained the same, then open/fstat
+ iterations for which the file has not changed, then open/fstat
the file to determine if that file name is still associated with the
same device/inode-number pair as before. This option is meaningful only
when following by name. --max-unchanged-stats=N */
@@ -162,16 +164,6 @@ enum header_mode
static unsigned long max_n_unchanged_stats_between_opens =
DEFAULT_MAX_N_UNCHANGED_STATS_BETWEEN_OPENS;
-/* This variable is used to ensure that a file that is unlinked or moved
- aside, yet always growing will be recognized as having been renamed.
- After detecting this many consecutive size changes for a file, open/fstat
- the file to determine if that file name is still associated with the
- same device/inode-number pair as before. This option is meaningful only
- when following by name. --max-consecutive-size-changes=N */
-#define DEFAULT_MAX_N_CONSECUTIVE_SIZE_CHANGES 200
-static unsigned long max_n_consecutive_size_changes_between_opens =
- DEFAULT_MAX_N_CONSECUTIVE_SIZE_CHANGES;
-
/* The name this program was run with. */
char *program_name;
@@ -194,11 +186,6 @@ enum
RETRY_OPTION = CHAR_MAX + 1,
ALLOW_MISSING_OPTION, /* deprecated, FIXME: remove in late 2004 */
MAX_UNCHANGED_STATS_OPTION,
-
- /* FIXME: remove this in 2001, unless someone can show a good
- reason to keep it. */
- MAX_CONSECUTIVE_SIZE_CHANGES_OPTION,
-
PID_OPTION,
PRESUME_INPUT_PIPE_OPTION,
LONG_FOLLOW_OPTION
@@ -212,8 +199,6 @@ static struct option const long_options[
{"follow", optional_argument, NULL, LONG_FOLLOW_OPTION},
{"lines", required_argument, NULL, 'n'},
{"max-unchanged-stats", required_argument, NULL, MAX_UNCHANGED_STATS_OPTION},
- {"max-consecutive-size-changes", required_argument, NULL,
- MAX_CONSECUTIVE_SIZE_CHANGES_OPTION},
{"pid", required_argument, NULL, PID_OPTION},
{"presume-input-pipe", no_argument, NULL,
PRESUME_INPUT_PIPE_OPTION}, /* do not document */
@@ -327,6 +312,28 @@ xwrite (int fd, char const *buffer, size
error (EXIT_FAILURE, errno, _("write error"));
}
+/* Record a file F with descriptor FD, size SIZE, status ST, and
+ blocking status BLOCKING. */
+
+static void
+record_open_fd (struct File_spec *f, int fd,
+ off_t size, struct stat const *st,
+ int blocking)
+{
+ f->fd = fd;
+ f->size = size;
+ f->mtime.tv_sec = st->st_mtime;
+ f->mtime.tv_nsec = TIMESPEC_NS (st->st_mtim);
+ f->dev = st->st_dev;
+ f->ino = st->st_ino;
+ f->mode = st->st_mode;
+ f->blocking = blocking;
+ f->n_unchanged_stats = 0;
+ f->ignore = 0;
+}
+
+/* Close the file with descriptor FD and name FILENAME. */
+
static void
close_fd (int fd, const char *filename)
{
@@ -347,6 +354,7 @@ write_header (const char *pretty_filenam
/* Read and output N_BYTES of file PRETTY_FILENAME starting at the current
position in FD. If N_BYTES is COPY_TO_EOF, then copy until end of file.
+ If N_BYTES is COPY_A_BUFFER, then copy at most one buffer's worth.
Return the number of bytes read from the file. */
static uintmax_t
@@ -362,13 +370,22 @@ dump_remainder (const char *pretty_filen
size_t n = MIN (n_remaining, BUFSIZ);
size_t bytes_read = safe_read (fd, buffer, n);
if (bytes_read == SAFE_READ_ERROR)
- error (EXIT_FAILURE, errno, _("error reading %s"),
- quote (pretty_filename));
+ {
+ if (errno != EAGAIN)
+ error (EXIT_FAILURE, errno, _("error reading %s"),
+ quote (pretty_filename));
+ break;
+ }
if (bytes_read == 0)
break;
xwrite (STDOUT_FILENO, buffer, bytes_read);
- n_remaining -= bytes_read;
n_written += bytes_read;
+ if (n_bytes != COPY_TO_EOF)
+ {
+ n_remaining -= bytes_read;
+ if (n_remaining == 0 || n_bytes == COPY_A_BUFFER)
+ break;
+ }
}
return n_written;
@@ -822,21 +839,21 @@ start_lines (const char *pretty_filename
/* FIXME: describe */
static void
-recheck (struct File_spec *f)
+recheck (struct File_spec *f, bool blocking)
{
/* open/fstat the file and announce if dev/ino have changed */
struct stat new_stats;
- int fd;
int fail = 0;
int is_stdin = (STREQ (f->name, "-"));
int was_tailable = f->tailable;
int prev_errnum = f->errnum;
int new_file;
+ int fd = (is_stdin
+ ? STDIN_FILENO
+ : open_safer (f->name, O_RDONLY | (blocking ? 0 : O_NONBLOCK)));
assert (valid_file_spec (f));
- fd = (is_stdin ? STDIN_FILENO : open (f->name, O_RDONLY));
-
/* If the open fails because the file doesn't exist,
then mark the file as not tailable. */
f->tailable = !(reopen_inaccessible_files && fd == -1);
@@ -931,32 +948,24 @@ recheck (struct File_spec *f)
if (new_file)
{
- /* Record new file info in f. */
- f->fd = fd;
- f->size = 0; /* Start at the beginning of the file... */
- f->dev = new_stats.st_dev;
- f->ino = new_stats.st_ino;
- f->n_unchanged_stats = 0;
- f->n_consecutive_size_changes = 0;
- f->ignore = 0;
- xlseek (f->fd, f->size, SEEK_SET, pretty_name (f));
+ /* Start at the beginning of the file. */
+ record_open_fd (f, fd, 0, &new_stats, (is_stdin ? -1 : blocking));
+ xlseek (fd, 0, SEEK_SET, pretty_name (f));
}
}
-/* FIXME: describe */
+/* Return true if any of the N_FILES files in F are live, i.e., have
+ open file descriptors. */
-static unsigned int
-n_live_files (const struct File_spec *f, int n_files)
+static bool
+any_live_files (const struct File_spec *f, int n_files)
{
int i;
- unsigned int n_live = 0;
for (i = 0; i < n_files; i++)
- {
- if (f[i].fd >= 0)
- ++n_live;
- }
- return n_live;
+ if (0 <= f[i].fd)
+ return true;
+ return false;
}
/* Tail NFILES files forever, or until killed.
@@ -969,6 +978,9 @@ n_live_files (const struct File_spec *f,
static void
tail_forever (struct File_spec *f, int nfiles, double sleep_interval)
{
+ /* Use blocking I/O as an optimization, when it's easy. */
+ bool blocking = (pid == 0 && follow_mode == Follow_descriptor
+ && nfiles == 1 && ! S_ISREG (f[0].mode));
int last;
int writer_is_dead = 0;
@@ -977,90 +989,110 @@ tail_forever (struct File_spec *f, int n
while (1)
{
int i;
- int any_changed;
+ bool any_input = false;
- any_changed = 0;
for (i = 0; i < nfiles; i++)
{
+ int fd;
+ char const *name;
+ mode_t mode;
struct stat stats;
+ uintmax_t bytes_read;
if (f[i].ignore)
continue;
if (f[i].fd < 0)
{
- recheck (&f[i]);
+ recheck (&f[i], blocking);
continue;
}
- if (fstat (f[i].fd, &stats) < 0)
+ fd = f[i].fd;
+ name = pretty_name (&f[i]);
+ mode = f[i].mode;
+
+ if (f[i].blocking != blocking)
{
- f[i].fd = -1;
- f[i].errnum = errno;
- error (0, errno, "%s", pretty_name (&f[i]));
- continue;
+ int old_flags = fcntl (fd, F_GETFL);
+ int new_flags = old_flags | (blocking ? 0 : O_NONBLOCK);
+ if (old_flags < 0
+ || (new_flags != old_flags
+ && fcntl (fd, F_SETFL, new_flags) == -1))
+ error (EXIT_FAILURE, errno,
+ _("%s: cannot change nonblocking mode"), name);
+ f[i].blocking = blocking;
}
- if (stats.st_size == f[i].size)
+ if (!blocking)
{
- f[i].n_consecutive_size_changes = 0;
- if ((max_n_unchanged_stats_between_opens
- <= f[i].n_unchanged_stats++)
- && follow_mode == Follow_name)
+ if (fstat (fd, &stats) != 0)
{
- recheck (&f[i]);
- f[i].n_unchanged_stats = 0;
+ f[i].fd = -1;
+ f[i].errnum = errno;
+ error (0, errno, "%s", name);
+ continue;
}
- continue;
- }
- /* Ensure that a file that's unlinked or moved aside, yet always
- growing will be recognized as having been renamed. */
- if ((max_n_consecutive_size_changes_between_opens
- <= f[i].n_consecutive_size_changes++)
- && follow_mode == Follow_name)
- {
- f[i].n_consecutive_size_changes = 0;
- recheck (&f[i]);
- continue;
- }
+ if ((! S_ISREG (stats.st_mode) || f[i].size == stats.st_size)
+ && f[i].mtime.tv_sec == stats.st_mtime
+ && f[i].mtime.tv_nsec == TIMESPEC_NS (stats.st_mtim)
+ && f[i].mode == stats.st_mode)
+ {
+ if ((max_n_unchanged_stats_between_opens
+ <= f[i].n_unchanged_stats++)
+ && follow_mode == Follow_name)
+ {
+ recheck (&f[i], blocking);
+ f[i].n_unchanged_stats = 0;
+ }
+ continue;
+ }
- /* This file has changed size. Print out what we can, and
- then keep looping. */
+ /* This file has changed. Print out what we can, and
+ then keep looping. */
- any_changed = 1;
+ f[i].mtime.tv_sec = stats.st_mtime;
+ f[i].mtime.tv_nsec = TIMESPEC_NS (stats.st_mtim);
+ f[i].mode = stats.st_mode;
- /* reset counter */
- f[i].n_unchanged_stats = 0;
+ /* reset counter */
+ f[i].n_unchanged_stats = 0;
- if (stats.st_size < f[i].size)
- {
- error (0, 0, _("%s: file truncated"), pretty_name (&f[i]));
- last = i;
- xlseek (f[i].fd, (off_t) stats.st_size, SEEK_SET,
- pretty_name (&f[i]));
- f[i].size = stats.st_size;
- continue;
- }
+ if (S_ISREG (mode) && stats.st_size < f[i].size)
+ {
+ error (0, 0, _("%s: file truncated"), name);
+ last = i;
+ xlseek (fd, stats.st_size, SEEK_SET, name);
+ f[i].size = stats.st_size;
+ continue;
+ }
- if (i != last)
- {
- if (print_headers)
- write_header (pretty_name (&f[i]));
- last = i;
+ if (i != last)
+ {
+ if (print_headers)
+ write_header (name);
+ last = i;
+ }
}
- f[i].size += dump_remainder (pretty_name (&f[i]), f[i].fd,
- COPY_TO_EOF);
+
+ bytes_read = dump_remainder (name, fd,
+ blocking ? COPY_A_BUFFER : COPY_TO_EOF);
+ any_input |= (bytes_read != 0);
+ f[i].size += bytes_read;
}
- if (n_live_files (f, nfiles) == 0 && ! reopen_inaccessible_files)
+ if (! any_live_files (f, nfiles) && ! reopen_inaccessible_files)
{
error (0, 0, _("no files remaining"));
break;
}
- /* If none of the files changed size, sleep. */
- if (!any_changed)
+ if ((!any_input | blocking) && fflush (stdout) != 0)
+ error (EXIT_FAILURE, errno, _("write error"));
+
+ /* If nothing was read, sleep and/or check for dead writers. */
+ if (!any_input)
{
if (writer_is_dead)
break;
@@ -1189,8 +1221,8 @@ tail_lines (const char *pretty_filename,
which lseek (... SEEK_END) works. */
if ( ! presume_input_pipe
&& S_ISREG (stats.st_mode)
- && (start_pos = lseek (fd, (off_t) 0, SEEK_CUR)) != -1
- && start_pos < (end_pos = lseek (fd, (off_t) 0, SEEK_END)))
+ && (start_pos = lseek (fd, 0, SEEK_CUR)) != -1
+ && start_pos < (end_pos = lseek (fd, 0, SEEK_END)))
{
*read_pos = end_pos;
if (end_pos != 0 && file_lines (pretty_filename, fd, n_lines,
@@ -1250,7 +1282,7 @@ tail_file (struct File_spec *f, uintmax_
}
else
{
- fd = open (f->name, O_RDONLY);
+ fd = open_safer (f->name, O_RDONLY);
}
f->tailable = !(reopen_inaccessible_files && fd == -1);
@@ -1310,17 +1342,10 @@ tail_file (struct File_spec *f, uintmax_
}
else
{
- f->fd = fd;
-
/* Note: we must use read_pos here, not stats.st_size,
to avoid a race condition described by Ken Raeburn:
http://mail.gnu.org/archive/html/bug-textutils/2003-05/msg00007.html */
- f->size = read_pos;
- f->dev = stats.st_dev;
- f->ino = stats.st_ino;
- f->n_unchanged_stats = 0;
- f->n_consecutive_size_changes = 0;
- f->ignore = 0;
+ record_open_fd (f, fd, read_pos, &stats, (is_stdin ? -1 : 1));
}
}
else
@@ -1553,18 +1578,6 @@ parse_options (int argc, char **argv,
}
break;
- case MAX_CONSECUTIVE_SIZE_CHANGES_OPTION:
- /* --max-consecutive-size-changes=N */
- if (xstrtoul (optarg, NULL, 10,
- &max_n_consecutive_size_changes_between_opens, "")
- != LONGINT_OK)
- {
- error (EXIT_FAILURE, 0,
- _("%s: invalid maximum number of consecutive size changes"),
- optarg);
- }
- break;
-
case PID_OPTION:
{
strtol_error s_err;
@@ -1729,14 +1742,7 @@ main (int argc, char **argv)
exit_status |= tail_file (&F[i], n_units);
if (forever)
- {
- /* This fflush appears to be required only on Solaris 5.7. */
- if (fflush (stdout) < 0)
- error (EXIT_FAILURE, errno, _("write error"));
-
- SETVBUF (stdout, NULL, _IONBF, 0);
- tail_forever (F, n_files, sleep_interval);
- }
+ tail_forever (F, n_files, sleep_interval);
if (have_read_stdin && close (STDIN_FILENO) < 0)
error (EXIT_FAILURE, errno, "-");
--- /dev/null 2003-03-18 13:55:57 -0800
+++ lib/fcntl-safer.h 2004-07-22 21:29:12 -0700
@@ -0,0 +1,21 @@
+/* Invoke fcntl functions, but avoid some glitches.
+
+ Copyright (C) 2004 Free Software Foundation, Inc.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2, or (at your option)
+ any later version.
+
+ This program 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 General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software Foundation,
+ Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
+
+/* Written by Paul Eggert. */
+
+int open_safer (char const *, int, ...);
--- /dev/null 2003-03-18 13:55:57 -0800
+++ lib/open-safer.c 2004-07-23 15:29:43 -0700
@@ -0,0 +1,75 @@
+/* Invoke open, but avoid some glitches.
+
+ Copyright (C) 2004 Free Software Foundation, Inc.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2, or (at your option)
+ any later version.
+
+ This program 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 General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software Foundation,
+ Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
+
+/* Written by Paul Eggert. */
+
+#if HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <fcntl-safer.h>
+
+#include <unistd-safer.h>
+
+#include <errno.h>
+#include <stdarg.h>
+
+#if HAVE_FCNTL_H
+# include <fcntl.h>
+#endif
+
+#if HAVE_UNISTD_H
+# include <unistd.h>
+#endif
+#ifndef STDERR_FILENO
+# define STDERR_FILENO 2
+#endif
+
+/* Like open, but do not return STDIN_FILENO, STDOUT_FILENO, or
+ STDERR_FILENO. */
+
+int
+open_safer (char const *file, int oflag, ...)
+{
+ int fd;
+ mode_t mode = 0;
+
+ if (oflag & O_CREAT)
+ {
+ va_list args;
+ va_start (args, oflag);
+ if (sizeof (int) <= sizeof (mode_t))
+ mode = va_arg (args, mode_t);
+ else
+ mode = va_arg (args, int);
+ va_end (args);
+ }
+
+ fd = open (file, oflag, mode);
+
+ if (0 <= fd && fd <= STDERR_FILENO)
+ {
+ int f = dup_safer (fd);
+ int e = errno;
+ close (fd);
+ errno = e;
+ fd = f;
+ }
+
+ return fd;
+}
--- /dev/null 2003-03-18 13:55:57 -0800
+++ m4/fcntl-safer.m4 2004-07-23 15:17:50 -0700
@@ -0,0 +1,29 @@
+# fcntl-safer.m4 serial 1
+
+# Copyright (C) 2004 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2, or (at your option)
+# any later version.
+
+# This program 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 General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software Foundation,
+# Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
+
+# Written by Paul Eggert.
+
+AC_DEFUN([gl_FCNTL_SAFER],
+[
+ gl_PREREQ_OPEN_SAFER
+])
+
+# Prerequisites of lib/open-safer.c.
+AC_DEFUN([gl_PREREQ_OPEN_SAFER], [
+ AC_CHECK_HEADERS_ONCE(fcntl.h unistd.h)
+])