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Subject: Re: handling of closed file descriptors
To: Bruno Haible <bruno@HIDDEN>
References: <6639990.yRvKeTYcJc@omega> <2095398.ToFATaR5yE@omega>
<e44b73f3-60dc-11cb-1187-5a5b76816881@HIDDEN> <2029673.eREQEScGAn@omega>
From: Paul Eggert <eggert@HIDDEN>
Organization: UCLA Computer Science Department
Message-ID: <568450be-5ebc-b52b-f824-696aa9dc782d@HIDDEN>
Date: Sun, 6 Jan 2019 17:47:34 -0800
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Thanks for the xstdopen module; it simplifies diffutils and I installed the
attached patches there for it.
--------------B073A92927AA86D4E38598FF
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name="0001-build-update-gnulib-submodule-to-latest.patch"
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From 86ece0ee216910bce0dbceb60b98190bf8f93702 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@HIDDEN>
Date: Sun, 6 Jan 2019 17:15:06 -0800
Subject: [PATCH 1/2] build: update gnulib submodule to latest
---
gnulib | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/gnulib b/gnulib
index 10652b5..8089c00 160000
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 10652b56fe5b76370187a06296168cff9cffb730
+Subproject commit 8089c00979a5b089cff592c6b91420e595657167
--
2.17.1
--------------B073A92927AA86D4E38598FF
Content-Type: text/x-patch;
name="0002-diff-use-xstdopen-not-stdopen.patch"
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filename="0002-diff-use-xstdopen-not-stdopen.patch"
From db6d5f7240c8a743aebb3def80b3e3fabf05f0c1 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@HIDDEN>
Date: Sun, 6 Jan 2019 17:22:37 -0800
Subject: [PATCH 2/2] diff: use xstdopen, not stdopen
* bootstrap.conf (gnulib_modules):
* src/cmp.c, src/diff.c, src/diff3.c, src/sdiff.c (main):
Use xstdopen, not stdopen.
---
bootstrap.conf | 2 +-
src/cmp.c | 6 ++----
src/diff.c | 6 ++----
src/diff3.c | 6 ++----
src/sdiff.c | 6 ++----
5 files changed, 9 insertions(+), 17 deletions(-)
diff --git a/bootstrap.conf b/bootstrap.conf
index 0c9fbfe..4671349 100644
--- a/bootstrap.conf
+++ b/bootstrap.conf
@@ -67,7 +67,6 @@ stat
stat-macros
stat-time
stdint
-stdopen
strcase
strftime
strptime
@@ -85,6 +84,7 @@ wcwidth
xalloc
xfreopen
xreadlink
+xstdopen
xstrtoumax
xvasprintf
'
diff --git a/src/cmp.c b/src/cmp.c
index 811d039..ce2bdb5 100644
--- a/src/cmp.c
+++ b/src/cmp.c
@@ -31,11 +31,11 @@
#include <hard-locale.h>
#include <inttostr.h>
#include <progname.h>
-#include <stdopen.h>
#include <unlocked-io.h>
#include <version-etc.h>
#include <xalloc.h>
#include <binary-io.h>
+#include <xstdopen.h>
#include <xstrtol.h>
/* The official name of this program (e.g., no 'g' prefix). */
@@ -210,9 +210,7 @@ main (int argc, char **argv)
bindtextdomain (PACKAGE, LOCALEDIR);
textdomain (PACKAGE);
c_stack_action (0);
- int stdopen_errno = stdopen ();
- if (stdopen_errno != 0)
- error (EXIT_TROUBLE, stdopen_errno, _("standard file descriptors"));
+ xstdopen ();
/* Parse command line options. */
diff --git a/src/diff.c b/src/diff.c
index 541d912..e9c2b11 100644
--- a/src/diff.c
+++ b/src/diff.c
@@ -37,11 +37,11 @@
#include <progname.h>
#include <sh-quote.h>
#include <stat-time.h>
-#include <stdopen.h>
#include <timespec.h>
#include <version-etc.h>
#include <xalloc.h>
#include <xreadlink.h>
+#include <xstdopen.h>
#include <binary-io.h>
/* The official name of this program (e.g., no 'g' prefix). */
@@ -298,9 +298,7 @@ main (int argc, char **argv)
re_set_syntax (RE_SYNTAX_GREP | RE_NO_POSIX_BACKTRACKING);
excluded = new_exclude ();
presume_output_tty = false;
- int stdopen_errno = stdopen ();
- if (stdopen_errno != 0)
- error (EXIT_TROUBLE, stdopen_errno, _("standard file descriptors"));
+ xstdopen ();
/* Decode the options. */
diff --git a/src/diff3.c b/src/diff3.c
index 8ce1a3d..037df25 100644
--- a/src/diff3.c
+++ b/src/diff3.c
@@ -30,11 +30,11 @@
#include <file-type.h>
#include <getopt.h>
#include <progname.h>
-#include <stdopen.h>
#include <system-quote.h>
#include <version-etc.h>
#include <xalloc.h>
#include <xfreopen.h>
+#include <xstdopen.h>
/* The official name of this program (e.g., no 'g' prefix). */
#define PROGRAM_NAME "diff3"
@@ -273,9 +273,7 @@ main (int argc, char **argv)
bindtextdomain (PACKAGE, LOCALEDIR);
textdomain (PACKAGE);
c_stack_action (0);
- int stdopen_errno = stdopen ();
- if (stdopen_errno != 0)
- error (EXIT_TROUBLE, stdopen_errno, _("standard file descriptors"));
+ xstdopen ();
while ((c = getopt_long (argc, argv, "aeimvx3AEL:TX", longopts, 0)) != -1)
{
diff --git a/src/sdiff.c b/src/sdiff.c
index 605fd33..2ef83da 100644
--- a/src/sdiff.c
+++ b/src/sdiff.c
@@ -32,10 +32,10 @@
#include <file-type.h>
#include <getopt.h>
#include <progname.h>
-#include <stdopen.h>
#include <system-quote.h>
#include <version-etc.h>
#include <xalloc.h>
+#include <xstdopen.h>
/* The official name of this program (e.g., no 'g' prefix). */
#define PROGRAM_NAME "sdiff"
@@ -456,9 +456,7 @@ main (int argc, char *argv[])
bindtextdomain (PACKAGE, LOCALEDIR);
textdomain (PACKAGE);
c_stack_action (cleanup);
- int stdopen_errno = stdopen ();
- if (stdopen_errno != 0)
- error (EXIT_TROUBLE, stdopen_errno, _("standard file descriptors"));
+ xstdopen ();
prog = getenv ("EDITOR");
if (prog)
--
2.17.1
--------------B073A92927AA86D4E38598FF--
bug-diffutils@HIDDEN:bug#33965; Package diffutils.
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From debbugs-submit-bounces <at> debbugs.gnu.org Sat Jan 05 23:07:04 2019
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Subject: Re: bug#33965: handling of closed file descriptors
To: Bruno Haible <bruno@HIDDEN>
References: <6639990.yRvKeTYcJc@omega> <1742217.p5sQxCVaLy@omega>
<d4d28d01-5433-4d39-a723-c41ae9edb1cb@HIDDEN> <2095398.ToFATaR5yE@omega>
From: Paul Eggert <eggert@HIDDEN>
Organization: UCLA Computer Science Department
Message-ID: <e44b73f3-60dc-11cb-1187-5a5b76816881@HIDDEN>
Date: Sat, 5 Jan 2019 20:06:51 -0800
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Bruno Haible wrote:
>> The feature is not portable to POSIX
>> platforms. Besides, I doubt whether anybody is using the feature anyway.
>
> OK, if you question the "feature" as a whole,
Sorry, I was referring only to the never-used feature of diffutils, where "-" in
a command-line argument stands for a missing file if stdin is closed (only in
some cases, e.g., -N). I think nobody uses this feature or will miss it if it's
removed, and anyway it can't work on some POSIX-conforming platforms. I put the
feature into diffutils in many years ago, but it's now clear that the test case
that is exercising it is a mistake and that the feature itself was mistaken.
But to broaden this to the more-general issue of whether kernels should force
stdin/stdout/stderr to be open after an exec:
> I predict that this "simple change to the kernel" will not make it into
> the majority of the operating systems in the next 10 years. (But you
> could start lobbying for it among the OpenBSD people. They would be the
> most likely to adopt it, I guess.)
OpenBSD has already adopted it for setuid and setgid executables, as has
FreeBSD, NetBSD, and SELinux. I imagine this feature is reasonably common
elsewhere, at least for setuid (I haven't checked carefully). As far as I know
only HP-UX does it for non-setuid/gid executables.
> In the mean time, the remaining options I can see are:
>
> (a) Keep using the *-safer Gnulib modules.
>
> (b) Introduce a sanity_check_file_descriptors() function
> ...
> void
> sanity_check_file_descriptors (void)
> {
> int fd;
> for (fd = 0; fd <= 2; fd++)
> if (fcntl (fd, F_GETFD, NULL) < 0 && errno == EBADF)
> exit (125);
> }
> ...
> (b) surely is simpler than (a).
I suggest instead a third option (c) that was formerly used in Coreutils, which
is that the program makes sure that stdin/stdout/stderr are open before doing
anything that creates a file descriptor. As I understand it Coreutils moved away
from that approach primarily because it was redundant if the (earlier) *-safer
modules are also used. However, in hindsight perhaps Coreutils should have
stopped using the *-safer modules and just used method (c); it's a lot simpler
and less intrusive.
I resurrected and refreshed that old Coreutils code and put it into a new Gnulib
module stdopen, adjusted Gnulib's xfreopen module in a couple of minor ways
(only diffutils uses xfreopen as far as I know) so that it no longer requires
freopen-safer, and installed the first four attached patches into Gnulib. I then
propagated this into diffutils and removed the unportable feature by installing
the last three attached patches into diffutils.
As a result of these changes, diffutils no longer uses the *-safer modules (it
uses the new stdopen module instead), it no longer supports the unportable
feature in question, and it no longer mishandles some obscure situations where
stdin, stdout, or stderr are closed.
--------------34E9D1D1F5454BCC79E8AA56
Content-Type: text/x-patch;
name="0001-stdopen-copy-from-last-use-in-coreutils.patch"
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From 14e1f1c39766bcb3fe4d6ec975ecac4058d11d98 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@HIDDEN>
Date: Sat, 5 Jan 2019 11:02:51 -0800
Subject: [PATCH 1/4] stdopen: copy from last use in coreutils
* lib/stdopen.c, lib/stdopen.h, m4/stdopen.m4:
New files, taken from their last commit in coreutils
2007-07-23T12:35:58Z!jim@HIDDEN
71aa3ea88084d17bcb4fc1031ad7b66f8647115e.
---
ChangeLog | 8 ++++++
lib/stdopen.c | 74 +++++++++++++++++++++++++++++++++++++++++++++++++++
lib/stdopen.h | 16 +++++++++++
m4/stdopen.m4 | 13 +++++++++
4 files changed, 111 insertions(+)
create mode 100644 lib/stdopen.c
create mode 100644 lib/stdopen.h
create mode 100644 m4/stdopen.m4
diff --git a/ChangeLog b/ChangeLog
index d05cd8453..72d75ef26 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2019-01-05 Paul Eggert <eggert@HIDDEN>
+
+ stdopen: copy from last use in coreutils
+ * lib/stdopen.c, lib/stdopen.h, m4/stdopen.m4:
+ New files, taken from their last commit in coreutils
+ 2007-07-23T12:35:58Z!jim@HIDDEN
+ 71aa3ea88084d17bcb4fc1031ad7b66f8647115e.
+
2019-01-05 Bruno Haible <bruno@HIDDEN>
argp: Don't pass an invalid argument to dgettext().
diff --git a/lib/stdopen.c b/lib/stdopen.c
new file mode 100644
index 000000000..e9b554485
--- /dev/null
+++ b/lib/stdopen.c
@@ -0,0 +1,74 @@
+/* stdopen.c - ensure that the three standard file descriptors are in use
+
+ Copyright (C) 2005, 2006 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 3 of the License, 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, see <http://www.gnu.org/licenses/>. */
+
+/* Written by Paul Eggert and Jim Meyering. */
+
+#include <config.h>
+
+#include "stdopen.h"
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+
+/* Try to ensure that all of the standard file numbers (0, 1, 2)
+ are in use. Without this, each application would have to guard
+ every call to open, dup, fopen, etc. with tests to ensure they
+ don't use one of the special file numbers when opening a file.
+ Return false if at least one of the file descriptors is initially
+ closed and an attempt to reopen it fails. Otherwise, return true. */
+bool
+stdopen (void)
+{
+ int fd;
+ bool ok = true;
+
+ for (fd = 0; fd <= 2; fd++)
+ {
+ if (fcntl (fd, F_GETFD) < 0)
+ {
+ if (errno != EBADF)
+ ok = false;
+ else
+ {
+ static const int contrary_mode[]
+ = { O_WRONLY, O_RDONLY, O_RDONLY };
+ int mode = contrary_mode[fd];
+ int new_fd;
+ /* Open /dev/null with the contrary mode so that the typical
+ read (stdin) or write (stdout, stderr) operation will fail.
+ With descriptor 0, we can do even better on systems that
+ have /dev/full, by opening that write-only instead of
+ /dev/null. The only drawback is that a write-provoked
+ failure comes with a misleading errno value, ENOSPC. */
+ if (mode == O_RDONLY
+ || (new_fd = open ("/dev/full", mode) != fd))
+ new_fd = open ("/dev/null", mode);
+ if (new_fd != fd)
+ {
+ if (0 <= new_fd)
+ close (new_fd);
+ ok = false;
+ }
+ }
+ }
+ }
+
+ return ok;
+}
diff --git a/lib/stdopen.h b/lib/stdopen.h
new file mode 100644
index 000000000..d54e5f135
--- /dev/null
+++ b/lib/stdopen.h
@@ -0,0 +1,16 @@
+#ifndef STDOPEN_H
+# define STDOPEN_H 1
+
+# include <stdbool.h>
+
+# ifdef __cplusplus
+extern "C" {
+# endif
+
+bool stdopen (void);
+
+# ifdef __cplusplus
+}
+# endif
+
+#endif
diff --git a/m4/stdopen.m4 b/m4/stdopen.m4
new file mode 100644
index 000000000..b18c22ddf
--- /dev/null
+++ b/m4/stdopen.m4
@@ -0,0 +1,13 @@
+#serial 1
+dnl Copyright (C) 2005 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_STDOPEN],
+[
+ AC_LIBSOURCES([stdopen.c, stdopen.h])
+ AC_LIBOBJ([stdopen])
+
+ dnl Prerequisites.
+])
--
2.20.1
--------------34E9D1D1F5454BCC79E8AA56
Content-Type: text/x-patch;
name="0002-stdopen-modernize-and-simplify.patch"
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From a4015f0453aeb60cfa70dcdfbd78db62b3a79b62 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@HIDDEN>
Date: Sat, 5 Jan 2019 18:02:32 -0800
Subject: [PATCH 2/4] stdopen: modernize and simplify
* lib/stdopen.c: Update copyright date
Do not include sys/types.h; no longer needed these days.
(stdopen): Use C99-style decl in loop. Return int errno
value, rather than just a bool. Do not worry about fd mismatches,
since the caller cares only if 0, 1, 2 are occupied.
* lib/stdopen.h: No need to include <stdbool.h>.
* m4/stdopen.m4: Remove.
* modules/stdopen: New file.
---
ChangeLog | 10 ++++++++
lib/stdopen.c | 63 +++++++++++++++++++++----------------------------
lib/stdopen.h | 4 +---
m4/stdopen.m4 | 13 ----------
modules/stdopen | 24 +++++++++++++++++++
5 files changed, 62 insertions(+), 52 deletions(-)
delete mode 100644 m4/stdopen.m4
create mode 100644 modules/stdopen
diff --git a/ChangeLog b/ChangeLog
index 72d75ef26..16ad6f169 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,15 @@
2019-01-05 Paul Eggert <eggert@HIDDEN>
+ stdopen: modernize and simplify
+ * lib/stdopen.c: Update copyright date
+ Do not include sys/types.h; no longer needed these days.
+ (stdopen): Use C99-style decl in loop. Return int errno
+ value, rather than just a bool. Do not worry about fd mismatches,
+ since the caller cares only if 0, 1, 2 are occupied.
+ * lib/stdopen.h: No need to include <stdbool.h>.
+ * m4/stdopen.m4: Remove.
+ * modules/stdopen: New file.
+
stdopen: copy from last use in coreutils
* lib/stdopen.c, lib/stdopen.h, m4/stdopen.m4:
New files, taken from their last commit in coreutils
diff --git a/lib/stdopen.c b/lib/stdopen.c
index e9b554485..3903224e6 100644
--- a/lib/stdopen.c
+++ b/lib/stdopen.c
@@ -1,6 +1,6 @@
/* stdopen.c - ensure that the three standard file descriptors are in use
- Copyright (C) 2005, 2006 Free Software Foundation, Inc.
+ Copyright (C) 2005-2006, 2019 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
@@ -21,7 +21,6 @@
#include "stdopen.h"
-#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
@@ -31,44 +30,36 @@
are in use. Without this, each application would have to guard
every call to open, dup, fopen, etc. with tests to ensure they
don't use one of the special file numbers when opening a file.
- Return false if at least one of the file descriptors is initially
- closed and an attempt to reopen it fails. Otherwise, return true. */
-bool
+ Return zero if successful, an errno value if at least one of
+ the file descriptors is initially closed and could not be opened. */
+
+int
stdopen (void)
{
- int fd;
- bool ok = true;
-
- for (fd = 0; fd <= 2; fd++)
+ for (int fd = STDIN_FILENO; fd <= STDERR_FILENO; fd++)
{
if (fcntl (fd, F_GETFD) < 0)
- {
- if (errno != EBADF)
- ok = false;
- else
- {
- static const int contrary_mode[]
- = { O_WRONLY, O_RDONLY, O_RDONLY };
- int mode = contrary_mode[fd];
- int new_fd;
- /* Open /dev/null with the contrary mode so that the typical
- read (stdin) or write (stdout, stderr) operation will fail.
- With descriptor 0, we can do even better on systems that
- have /dev/full, by opening that write-only instead of
- /dev/null. The only drawback is that a write-provoked
- failure comes with a misleading errno value, ENOSPC. */
- if (mode == O_RDONLY
- || (new_fd = open ("/dev/full", mode) != fd))
- new_fd = open ("/dev/null", mode);
- if (new_fd != fd)
- {
- if (0 <= new_fd)
- close (new_fd);
- ok = false;
- }
- }
- }
+ {
+ /* Open /dev/null with the contrary mode so that the typical
+ read (stdin) or write (stdout, stderr) operation will fail.
+ With descriptor 0, we can do even better on systems that
+ have /dev/full, by opening that write-only instead of
+ /dev/null. The only drawback is that a write-provoked
+ failure comes with a misleading errno value, ENOSPC. */
+ int mode = fd == STDIN_FILENO ? O_WRONLY : O_RDONLY;
+ int full_fd = fd == STDIN_FILENO ? open ("/dev/full", mode) : -1;
+ int new_fd = full_fd < 0 ? open ("/dev/null", mode) : full_fd;
+ if (new_fd < 0)
+ return errno;
+ if (STDERR_FILENO < new_fd)
+ {
+ /* 0, 1, and 2 are already open somehow.
+ Our is not to reason why. */
+ close (new_fd);
+ return 0;
+ }
+ }
}
- return ok;
+ return 0;
}
diff --git a/lib/stdopen.h b/lib/stdopen.h
index d54e5f135..27901d397 100644
--- a/lib/stdopen.h
+++ b/lib/stdopen.h
@@ -1,13 +1,11 @@
#ifndef STDOPEN_H
# define STDOPEN_H 1
-# include <stdbool.h>
-
# ifdef __cplusplus
extern "C" {
# endif
-bool stdopen (void);
+int stdopen (void);
# ifdef __cplusplus
}
diff --git a/m4/stdopen.m4 b/m4/stdopen.m4
deleted file mode 100644
index b18c22ddf..000000000
--- a/m4/stdopen.m4
+++ /dev/null
@@ -1,13 +0,0 @@
-#serial 1
-dnl Copyright (C) 2005 Free Software Foundation, Inc.
-dnl This file is free software; the Free Software Foundation
-dnl gives unlimited permission to copy and/or distribute it,
-dnl with or without modifications, as long as this notice is preserved.
-
-AC_DEFUN([gl_STDOPEN],
-[
- AC_LIBSOURCES([stdopen.c, stdopen.h])
- AC_LIBOBJ([stdopen])
-
- dnl Prerequisites.
-])
diff --git a/modules/stdopen b/modules/stdopen
new file mode 100644
index 000000000..81de5765b
--- /dev/null
+++ b/modules/stdopen
@@ -0,0 +1,24 @@
+Description:
+Arrange for stdin/stdout/stderr to be open.
+
+Files:
+lib/stdopen.c
+lib/stdopen.h
+
+Depends-on:
+fcntl
+unistd
+
+configure.ac:
+
+Makefile.am:
+lib_SOURCES += stdopen.c
+
+Include:
+"stdopen.h"
+
+License:
+GPL
+
+Maintainer:
+all
--
2.20.1
--------------34E9D1D1F5454BCC79E8AA56
Content-Type: text/x-patch;
name="0003-xfreopen-need-not-depend-on-freopen-safer.patch"
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
filename="0003-xfreopen-need-not-depend-on-freopen-safer.patch"
From f9d6fc71e4ebc142410352253fb1db337f530bdf Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@HIDDEN>
Date: Sat, 5 Jan 2019 18:03:10 -0800
Subject: [PATCH 3/4] xfreopen need not depend on freopen-safer
* modules/xfreopen (Depends-on):
Depend on freopen, not freopen-safer.
---
ChangeLog | 4 ++++
modules/xfreopen | 2 +-
2 files changed, 5 insertions(+), 1 deletion(-)
diff --git a/ChangeLog b/ChangeLog
index 16ad6f169..a88a52083 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,9 @@
2019-01-05 Paul Eggert <eggert@HIDDEN>
+ xfreopen need not depend on freopen-safer
+ * modules/xfreopen (Depends-on):
+ Depend on freopen, not freopen-safer.
+
stdopen: modernize and simplify
* lib/stdopen.c: Update copyright date
Do not include sys/types.h; no longer needed these days.
diff --git a/modules/xfreopen b/modules/xfreopen
index dcc48e0ac..850446d7a 100644
--- a/modules/xfreopen
+++ b/modules/xfreopen
@@ -8,7 +8,7 @@ lib/xfreopen.h
Depends-on:
error
exitfail
-freopen-safer
+freopen
quote
configure.ac:
--
2.20.1
--------------34E9D1D1F5454BCC79E8AA56
Content-Type: text/x-patch;
name="0004-xfreopen-need-not-include-stdio-.h.patch"
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
filename="0004-xfreopen-need-not-include-stdio-.h.patch"
From 10652b56fe5b76370187a06296168cff9cffb730 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@HIDDEN>
Date: Sat, 5 Jan 2019 18:55:19 -0800
Subject: [PATCH 4/4] xfreopen need not include stdio--.h
* lib/xfreopen.c: Do not include stdio--.h.
---
ChangeLog | 3 +++
lib/xfreopen.c | 1 -
2 files changed, 3 insertions(+), 1 deletion(-)
diff --git a/ChangeLog b/ChangeLog
index a88a52083..73a86f29a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,8 @@
2019-01-05 Paul Eggert <eggert@HIDDEN>
+ xfreopen need not include stdio--.h
+ * lib/xfreopen.c: Do not include stdio--.h.
+
xfreopen need not depend on freopen-safer
* modules/xfreopen (Depends-on):
Depend on freopen, not freopen-safer.
diff --git a/lib/xfreopen.c b/lib/xfreopen.c
index 32a38d444..46a7c92a5 100644
--- a/lib/xfreopen.c
+++ b/lib/xfreopen.c
@@ -21,7 +21,6 @@
#include "error.h"
#include "exitfail.h"
#include "quote.h"
-#include "stdio--.h"
#include "gettext.h"
#define _(msgid) gettext (msgid)
--
2.20.1
--------------34E9D1D1F5454BCC79E8AA56
Content-Type: text/x-patch;
name="0001-build-update-gnulib-submodule-to-latest.patch"
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
filename="0001-build-update-gnulib-submodule-to-latest.patch"
From 1104d026514014808629f28f2e6c787bf3c520c4 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@HIDDEN>
Date: Sat, 5 Jan 2019 18:05:33 -0800
Subject: [PATCH 1/3] build: update gnulib submodule to latest
---
gnulib | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/gnulib b/gnulib
index 4652c7b..10652b5 160000
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 4652c7bafa60332145f1e05a7de5f48e1bc56226
+Subproject commit 10652b56fe5b76370187a06296168cff9cffb730
--
2.17.1
--------------34E9D1D1F5454BCC79E8AA56
Content-Type: text/x-patch;
name="0002-diff-remove-unportable-diff-N-f-feature.patch"
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
filename="0002-diff-remove-unportable-diff-N-f-feature.patch"
From 2c9d956aacdfddbb87334c985cd995d75102f789 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@HIDDEN>
Date: Sat, 5 Jan 2019 19:20:11 -0800
Subject: [PATCH 2/3] =?UTF-8?q?diff:=20remove=20unportable=20=E2=80=98diff?=
=?UTF-8?q?=20-N=20-=20f=20<&-=E2=80=99=20feature?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
* NEWS: Mention this.
* bootstrap.conf (gnulib_modules): Add stdopen.
* doc/diffutils.texi (Comparing Directories):
Do not document behavior if stdin is closed.
* src/diff.c: Include stdopen.h.
(main): Call stdopen early.
(compare_files) [__hpux]: Remove recently-introduced
special case for HP-UX exec with stdin closed.
* tests/new-file: Remove tests of the removed feature.
---
NEWS | 9 +++++++++
bootstrap.conf | 1 +
doc/diffutils.texi | 3 +--
src/diff.c | 11 ++++-------
tests/new-file | 14 --------------
5 files changed, 15 insertions(+), 23 deletions(-)
diff --git a/NEWS b/NEWS
index d45d0fc..af675da 100644
--- a/NEWS
+++ b/NEWS
@@ -2,6 +2,15 @@ GNU diffutils NEWS -*- outline -*-
* Noteworthy changes in release ?.? (????-??-??) [?]
+** Incompatible changes
+
+ diff no longer treats a closed stdin as representing an absent file
+ in usage like 'diff --new-file - foo <&-'. This feature was rarely
+ if ever used and was not portable to POSIX platforms that reopen
+ stdin on exec, such as SELinux if the process underwent an AT_SECURE
+ transition, or HP-UX even if not setuid.
+ [bug#33965 introduced in 2.8]
+
* Noteworthy changes in release 3.7 (2018-12-31) [stable]
diff --git a/bootstrap.conf b/bootstrap.conf
index 48cadd4..0c9fbfe 100644
--- a/bootstrap.conf
+++ b/bootstrap.conf
@@ -67,6 +67,7 @@ stat
stat-macros
stat-time
stdint
+stdopen
strcase
strftime
strptime
diff --git a/doc/diffutils.texi b/doc/diffutils.texi
index 42d3abd..3a780db 100644
--- a/doc/diffutils.texi
+++ b/doc/diffutils.texi
@@ -1796,8 +1796,7 @@ second position.) To do this, use the @option{--new-file}
(@option{-N}) option. This option affects command-line arguments as
well as files found via directory traversal; for example, @samp{diff
-N a b} treats @file{a} as empty if @file{a} does not exist but
-@file{b} does, and similarly @samp{diff -N - b} treats standard input
-as empty if it is closed but @file{b} exists.
+@file{b} does.
If the older directory contains large files that are not in
the newer directory, you can make the patch smaller by using the
diff --git a/src/diff.c b/src/diff.c
index 2ed3ae5..a5ec7f4 100644
--- a/src/diff.c
+++ b/src/diff.c
@@ -37,6 +37,7 @@
#include <progname.h>
#include <sh-quote.h>
#include <stat-time.h>
+#include <stdopen.h>
#include <timespec.h>
#include <version-etc.h>
#include <xalloc.h>
@@ -297,6 +298,9 @@ main (int argc, char **argv)
re_set_syntax (RE_SYNTAX_GREP | RE_NO_POSIX_BACKTRACKING);
excluded = new_exclude ();
presume_output_tty = false;
+ int stdopen_errno = stdopen ();
+ if (stdopen_errno != 0)
+ error (EXIT_TROUBLE, stdopen_errno, "standard file descriptors");
/* Decode the options. */
@@ -1172,13 +1176,6 @@ compare_files (struct comparison const *parent,
cmp.file[f].desc = STDIN_FILENO;
if (binary && ! isatty (STDIN_FILENO))
set_binary_mode (STDIN_FILENO, O_BINARY);
-#ifdef __hpux
- /* Recognize file descriptors closed by the parent on HP-UX. */
- int flags = fcntl (STDIN_FILENO, F_GETFL, NULL);
- if (flags >= 0 && (flags & FD_CLOEXEC) != 0)
- cmp.file[f].desc = ERRNO_ENCODE (EBADF);
- else
-#endif
if (fstat (STDIN_FILENO, &cmp.file[f].stat) != 0)
cmp.file[f].desc = ERRNO_ENCODE (errno);
else
diff --git a/tests/new-file b/tests/new-file
index 4400051..e3a61da 100755
--- a/tests/new-file
+++ b/tests/new-file
@@ -10,12 +10,6 @@ echo a > a || fail=1
echo '0a1
> a' > exp || fail=1
-returns_ 1 diff -N - a <&- > out || fail=1
-compare exp out || fail=1
-
-returns_ 1 diff --unidirectional-new-file - a <&- > out || fail=1
-compare exp out || fail=1
-
returns_ 1 diff -N b - < a > out || fail=1
compare exp out || fail=1
@@ -25,14 +19,6 @@ compare exp out || fail=1
echo '1d0
< a' > exp || fail=1
-returns_ 1 diff -N a - <&- > out || fail=1
-compare exp out || fail=1
-
-# With closed standard input, require an exit status of 2
-# and empty stdout.
-returns_ 2 diff --unidirectional-new-file a - <&- > out || fail=1
-compare /dev/null out || fail=1
-
returns_ 1 diff -N - b < a > out || fail=1
compare exp out || fail=1
--
2.17.1
--------------34E9D1D1F5454BCC79E8AA56
Content-Type: text/x-patch;
name="0003-diff-fix-cmp-diff3-sdiff-with-stdin-closed.patch"
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
filename="0003-diff-fix-cmp-diff3-sdiff-with-stdin-closed.patch"
From 601eceb57cfb87ded594701acc401277c53ff837 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@HIDDEN>
Date: Sat, 5 Jan 2019 19:55:08 -0800
Subject: [PATCH 3/3] diff: fix cmp, diff3, sdiff with stdin closed
* NEWS: Mention this.
* src/cmp.c, src/diff3.c, src/sdiff.c: Include stdopen.h.
(main): Call stdopen early.
* src/cmp.c (main): Simplify now that we need not worry about
stdin being closed.
* src/diff.c (main): Translate stdopen diagnostic.
---
NEWS | 8 ++++++++
src/cmp.c | 28 ++++++++++++++--------------
src/diff.c | 2 +-
src/diff3.c | 4 ++++
src/sdiff.c | 4 ++++
5 files changed, 31 insertions(+), 15 deletions(-)
diff --git a/NEWS b/NEWS
index af675da..9ab0748 100644
--- a/NEWS
+++ b/NEWS
@@ -11,6 +11,14 @@ GNU diffutils NEWS -*- outline -*-
transition, or HP-UX even if not setuid.
[bug#33965 introduced in 2.8]
+** Bug fixes
+
+ diff and related programs no longer get confused if stdin, stdout,
+ or stderr are closed. Previously, they sometimes opened files into
+ file descriptors 0, 1, or 2 and then mistakenly did I/O with them
+ that was intended for stdin, stdout, or stderr.
+ [bug#33965 present since "the beginning"]
+
* Noteworthy changes in release 3.7 (2018-12-31) [stable]
diff --git a/src/cmp.c b/src/cmp.c
index 53ff210..7bad6dd 100644
--- a/src/cmp.c
+++ b/src/cmp.c
@@ -31,6 +31,7 @@
#include <hard-locale.h>
#include <inttostr.h>
#include <progname.h>
+#include <stdopen.h>
#include <unlocked-io.h>
#include <version-etc.h>
#include <xalloc.h>
@@ -199,7 +200,7 @@ GB 1,000,000,000, G 1,073,741,824, and so on for T, P, E, Z, Y."),
int
main (int argc, char **argv)
{
- int c, f, exit_status;
+ int c, exit_status;
size_t words_per_buffer;
exit_failure = EXIT_TROUBLE;
@@ -209,6 +210,9 @@ main (int argc, char **argv)
bindtextdomain (PACKAGE, LOCALEDIR);
textdomain (PACKAGE);
c_stack_action (0);
+ int stdopen_errno = stdopen ();
+ if (stdopen_errno != 0)
+ error (EXIT_TROUBLE, stdopen_errno, _("standard file descriptors"));
/* Parse command line options. */
@@ -268,7 +272,7 @@ main (int argc, char **argv)
file[0] = argv[optind++];
file[1] = optind < argc ? argv[optind++] : "-";
- for (f = 0; f < 2 && optind < argc; f++)
+ for (int f = 0; f < 2 && optind < argc; f++)
{
char *arg = argv[optind++];
specify_ignore_initial (f, &arg, 0);
@@ -277,33 +281,29 @@ main (int argc, char **argv)
if (optind < argc)
try_help ("extra operand '%s'", argv[optind]);
- for (f = 0; f < 2; f++)
+ for (int f = 0; f < 2; f++)
{
- /* If file[1] is "-", treat it first; this avoids a misdiagnostic if
- stdin is closed and opening file[0] yields file descriptor 0. */
- int f1 = f ^ (STREQ (file[1], "-"));
-
/* Two files with the same name and offset are identical.
But wait until we open the file once, for proper diagnostics. */
if (f && ignore_initial[0] == ignore_initial[1]
&& file_name_cmp (file[0], file[1]) == 0)
return EXIT_SUCCESS;
- if (STREQ (file[f1], "-"))
+ if (STREQ (file[f], "-"))
{
- file_desc[f1] = STDIN_FILENO;
+ file_desc[f] = STDIN_FILENO;
if (O_BINARY && ! isatty (STDIN_FILENO))
set_binary_mode (STDIN_FILENO, O_BINARY);
}
else
- file_desc[f1] = open (file[f1], O_RDONLY | O_BINARY, 0);
+ file_desc[f] = open (file[f], O_RDONLY | O_BINARY, 0);
- if (file_desc[f1] < 0 || fstat (file_desc[f1], stat_buf + f1) != 0)
+ if (file_desc[f] < 0 || fstat (file_desc[f], stat_buf + f) != 0)
{
- if (file_desc[f1] < 0 && comparison_type == type_status)
+ if (file_desc[f] < 0 && comparison_type == type_status)
exit (EXIT_TROUBLE);
else
- die (EXIT_TROUBLE, errno, "%s", file[f1]);
+ die (EXIT_TROUBLE, errno, "%s", file[f]);
}
}
@@ -361,7 +361,7 @@ main (int argc, char **argv)
exit_status = cmp ();
- for (f = 0; f < 2; f++)
+ for (int f = 0; f < 2; f++)
if (close (file_desc[f]) != 0)
die (EXIT_TROUBLE, errno, "%s", file[f]);
if (exit_status != EXIT_SUCCESS && comparison_type < type_no_stdout)
diff --git a/src/diff.c b/src/diff.c
index a5ec7f4..d54782c 100644
--- a/src/diff.c
+++ b/src/diff.c
@@ -300,7 +300,7 @@ main (int argc, char **argv)
presume_output_tty = false;
int stdopen_errno = stdopen ();
if (stdopen_errno != 0)
- error (EXIT_TROUBLE, stdopen_errno, "standard file descriptors");
+ error (EXIT_TROUBLE, stdopen_errno, _("standard file descriptors"));
/* Decode the options. */
diff --git a/src/diff3.c b/src/diff3.c
index c7b2840..36bf4a6 100644
--- a/src/diff3.c
+++ b/src/diff3.c
@@ -30,6 +30,7 @@
#include <file-type.h>
#include <getopt.h>
#include <progname.h>
+#include <stdopen.h>
#include <system-quote.h>
#include <version-etc.h>
#include <xalloc.h>
@@ -272,6 +273,9 @@ main (int argc, char **argv)
bindtextdomain (PACKAGE, LOCALEDIR);
textdomain (PACKAGE);
c_stack_action (0);
+ int stdopen_errno = stdopen ();
+ if (stdopen_errno != 0)
+ error (EXIT_TROUBLE, stdopen_errno, _("standard file descriptors"));
while ((c = getopt_long (argc, argv, "aeimvx3AEL:TX", longopts, 0)) != -1)
{
diff --git a/src/sdiff.c b/src/sdiff.c
index 25ce3fe..bbbe16c 100644
--- a/src/sdiff.c
+++ b/src/sdiff.c
@@ -32,6 +32,7 @@
#include <file-type.h>
#include <getopt.h>
#include <progname.h>
+#include <stdopen.h>
#include <system-quote.h>
#include <version-etc.h>
#include <xalloc.h>
@@ -455,6 +456,9 @@ main (int argc, char *argv[])
bindtextdomain (PACKAGE, LOCALEDIR);
textdomain (PACKAGE);
c_stack_action (cleanup);
+ int stdopen_errno = stdopen ();
+ if (stdopen_errno != 0)
+ error (EXIT_TROUBLE, stdopen_errno, _("standard file descriptors"));
prog = getenv ("EDITOR");
if (prog)
--
2.17.1
--------------34E9D1D1F5454BCC79E8AA56--
bug-diffutils@HIDDEN:bug#33965; Package diffutils.
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Sat, 5 Jan 2019 10:44:18 +0100 (CET)
From: Bruno Haible <bruno@HIDDEN>
To: Paul Eggert <eggert@HIDDEN>
Subject: Re: bug#33965: handling of closed file descriptors
Date: Sat, 05 Jan 2019 10:44:17 +0100
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[CCing bug-gnulib. This is a followup to
https://debbugs.gnu.org/cgi/bugreport.cgi?bug=33965 ]
Hi Paul,
> The feature is not portable to POSIX
> platforms. Besides, I doubt whether anybody is using the feature anyway.
OK, if you question the "feature" as a whole, then I'd say:
* Users don't *need* the "feature", in the sense that:
- The normal way of invoking a program is by providing arguments
and standard input/output streams. Users who want to invoke a program
are not actively looking for this contorted way to invoke a program.
- For most programs, equivalent functionality to the "feature" is available
by passing an empty string, a reference to an empty file, or /dev/null
as argument. If a program exists for which the equivalent functionality
is not available through the normal way of invocation, the developers
should better add it.
* But it's a security risk that a program can be invoked in ways in which it
was surely never tested. Anything can happen then - from overwriting precious
files of the user to endless loops.
* Therefore if you want to take out the "feature", you still have to think
about how to mitigate the security risks.
> Although the HP-UX solution to this problem may not be best, it's better
> than the traditional behavior as it is a simple change to the kernel
> that fixes the issue for all applications, as opposed to the
> more-complicated dances we do in openat-safer and friends.
Given
- the prevalent "worse is better" attitude,
- the "never break userland behaviour that programs may rely upon"
principle of the Linux kernel community,
- the fact that the glibc people looked at the problem and used the
HP-UX solution only for setuid programs,
I predict that this "simple change to the kernel" will not make it into
the majority of the operating systems in the next 10 years. (But you
could start lobbying for it among the OpenBSD people. They would be the
most likely to adopt it, I guess.)
In the mean time, the remaining options I can see are:
(a) Keep using the *-safer Gnulib modules.
(b) Introduce a sanity_check_file_descriptors() function that all programs
can invoke right at the beginning of main(), and that exits with an
exit code if it detects a closed fd.
void
sanity_check_file_descriptors (void)
{
int fd;
for (fd = 0; fd <= 2; fd++)
if (fcntl (fd, F_GETFD, NULL) < 0 && errno == EBADF)
exit (125);
}
On platforms like HP-UX, this code would not cause an exit, but
the exec() call has already provided substitutes for the closed fds;
this mitigates the security risks.
I would propose exit code 125, since 127 and 126 are already taken [1].
(b) surely is simpler than (a).
Bruno
[1] http://tldp.org/LDP/abs/html/exitcodes.html
bug-diffutils@HIDDEN:bug#33965; Package diffutils.
Full text available.Received: (at 33965) by debbugs.gnu.org; 5 Jan 2019 09:41:30 +0000 From debbugs-submit-bounces <at> debbugs.gnu.org Sat Jan 05 04:41:30 2019 Received: from localhost ([127.0.0.1]:47241 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from <debbugs-submit-bounces <at> debbugs.gnu.org>) id 1gfiSQ-0000YA-0U for submit <at> debbugs.gnu.org; Sat, 05 Jan 2019 04:41:30 -0500 Received: from mo4-p00-ob.smtp.rzone.de ([85.215.255.22]:18895) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from <bruno@HIDDEN>) id 1gfiSN-0000Xz-6r for 33965 <at> debbugs.gnu.org; Sat, 05 Jan 2019 04:41:28 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; t=1546681285; s=strato-dkim-0002; d=clisp.org; h=References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: X-RZG-CLASS-ID:X-RZG-AUTH:From:Subject:Sender; bh=yRwiNJEBgxBTEMLPMs3FMTpZgs78C0PCFq/AdqOFj+g=; b=UJRp/M1nR5Rkjn5nHM+Dv0B4mbYfZyw932kGM0aRGkNHUYTY2djIFb8wzRq2N/cH+c Ey6LffW3AMMBV4m25SKZVQ4NWkQgO+I34hklE/15FtNmTMFlAW7nZFWkjbJ2ZYP/TYhe NDjrZQpJ1K6Jov9NBbpmUaZXNW45tK+02PBhzNm5f6NohsUYZwZtu2BKMbu/5tgKjp7T DBR5z9NPta0JBKCNR9ysYYx5Egvm8Khhrt+YD/4bKflP55qkOvDmj2HL7rt/P4Gl+iRD dEk/ZpHwtb0gTrXDlWIdZMG8TKlt8zWNXFdcTuPvLQgwYP2iFsKmN/hSYblFBzhX6meK hkiA== X-RZG-AUTH: ":Ln4Re0+Ic/6oZXR1YgKryK8brlshOcZlIWs+iCP5vnk6shH+AHjwLuWOGKf2y/s=" X-RZG-CLASS-ID: mo00 Received: from bruno.haible.de by smtp.strato.de (RZmta 44.9 DYNA|AUTH) with ESMTPSA id v0a34ev059fK5mW (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (curve secp521r1 with 521 ECDH bits, eq. 15360 bits RSA)) (Client did not present a certificate); Sat, 5 Jan 2019 10:41:20 +0100 (CET) From: Bruno Haible <bruno@HIDDEN> To: Paul Eggert <eggert@HIDDEN> Subject: Re: [bug-diffutils] bug#33965: handling of closed file descriptors Date: Sat, 05 Jan 2019 10:41:20 +0100 Message-ID: <1637429.tjGFVHuugb@omega> User-Agent: KMail/5.1.3 (Linux/4.4.0-141-generic; KDE/5.18.0; x86_64; ; ) In-Reply-To: <d4d28d01-5433-4d39-a723-c41ae9edb1cb@HIDDEN> References: <6639990.yRvKeTYcJc@omega> <1742217.p5sQxCVaLy@omega> <d4d28d01-5433-4d39-a723-c41ae9edb1cb@HIDDEN> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Spam-Score: -0.0 (/) X-Debbugs-Envelope-To: 33965 Cc: 33965 <at> debbugs.gnu.org, jim@HIDDEN X-BeenThere: debbugs-submit <at> debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: <debbugs-submit.debbugs.gnu.org> List-Unsubscribe: <https://debbugs.gnu.org/cgi-bin/mailman/options/debbugs-submit>, <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=unsubscribe> List-Archive: <https://debbugs.gnu.org/cgi-bin/mailman/private/debbugs-submit/> List-Post: <mailto:debbugs-submit <at> debbugs.gnu.org> List-Help: <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=help> List-Subscribe: <https://debbugs.gnu.org/cgi-bin/mailman/listinfo/debbugs-submit>, <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=subscribe> Errors-To: debbugs-submit-bounces <at> debbugs.gnu.org Sender: "Debbugs-submit" <debbugs-submit-bounces <at> debbugs.gnu.org> X-Spam-Score: -1.0 (-) > > It is like saying that it would be OK for a program, when interrupted > > through Ctrl-Z and restarted through 'fg', to stop processing and exit > > with a message "read: Interrupted system call". ... > > POSIX allowed the kernel to return from a > > read() system call with errno = EINTR. But users don't want this. So it > > was seen as a bug in the program, and fixed. > > If by "users" you mean "programs that make system calls" By "users don't want this" I meant: Users don't want programs to terminate with an error message "read: Interrupted system call", just because they used the job control features of the shell. Bruno
bug-diffutils@HIDDEN:bug#33965; Package diffutils.
Full text available.Received: (at 33965) by debbugs.gnu.org; 5 Jan 2019 00:33:00 +0000 From debbugs-submit-bounces <at> debbugs.gnu.org Fri Jan 04 19:33:00 2019 Received: from localhost ([127.0.0.1]:47131 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from <debbugs-submit-bounces <at> debbugs.gnu.org>) id 1gfZtc-0001eY-5j for submit <at> debbugs.gnu.org; Fri, 04 Jan 2019 19:33:00 -0500 Received: from zimbra.cs.ucla.edu ([131.179.128.68]:57324) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from <eggert@HIDDEN>) id 1gfZta-0001eI-Ak for 33965 <at> debbugs.gnu.org; Fri, 04 Jan 2019 19:32:59 -0500 Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id 1DF0B160F47; Fri, 4 Jan 2019 16:32:52 -0800 (PST) Received: from zimbra.cs.ucla.edu ([127.0.0.1]) by localhost (zimbra.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id izH4715T2GGL; Fri, 4 Jan 2019 16:32:51 -0800 (PST) Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id 41AD5160F48; 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Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.3.1 MIME-Version: 1.0 In-Reply-To: <1742217.p5sQxCVaLy@omega> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Spam-Score: -2.3 (--) X-Debbugs-Envelope-To: 33965 Cc: 33965 <at> debbugs.gnu.org, jim@HIDDEN X-BeenThere: debbugs-submit <at> debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: <debbugs-submit.debbugs.gnu.org> List-Unsubscribe: <https://debbugs.gnu.org/cgi-bin/mailman/options/debbugs-submit>, <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=unsubscribe> List-Archive: <https://debbugs.gnu.org/cgi-bin/mailman/private/debbugs-submit/> List-Post: <mailto:debbugs-submit <at> debbugs.gnu.org> List-Help: <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=help> List-Subscribe: <https://debbugs.gnu.org/cgi-bin/mailman/listinfo/debbugs-submit>, <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=subscribe> Errors-To: debbugs-submit-bounces <at> debbugs.gnu.org Sender: "Debbugs-submit" <debbugs-submit-bounces <at> debbugs.gnu.org> X-Spam-Score: -3.3 (---) On 1/4/19 3:30 PM, Bruno Haible wrote: > >> the test case assumes more about the shell's "<&-" >> construct than what POSIX requires. > It is like saying that it would be OK for a program, when interrupted > through Ctrl-Z and restarted through 'fg', to stop processing and exit > with a message "read: Interrupted system call". I don't see the analogy at all. Currently diffutils has a test shell script that is not portable POSIX code. Although we've worked around the problem with HP-UX by hacking on 'diff' itself, there are plausible POSIX platforms where our current hack will not work. It's not unreasonable to expect that test scripts should limit themselves to POSIX features so that they are as portable as reasonably possible. > POSIX allowed the kernel to return from a > read() system call with errno = EINTR. But users don't want this. So it > was seen as a bug in the program, and fixed. If by "users" you mean "programs that make system calls", then many users *do* want that. Certainly Emacs does, and I imagine many other programs do too. If you meant something else by "users" then I'm not sure I'm following the analogy. For the stdin-is-closed situation, the users and developers of many (I would say most) applications do not want 'open' to hijack stdin. Although the HP-UX solution to this problem may not be best, it's better than the traditional behavior as it is a simple change to the kernel that fixes the issue for all applications, as opposed to the more-complicated dances we do in openat-safer and friends. After thinking about this a bit more, the message that I'm getting from all this is that we should change diffutils to no longer rely on the "feature" that stdin is closed, and remove the test cases that attempt to test for this "feature". The feature is not portable to POSIX platforms. Besides, I doubt whether anybody is using the feature anyway. I put the feature in many years ago, so I can take the blame for introducing the misguided feature and the responsibility for taking it out.
bug-diffutils@HIDDEN:bug#33965; Package diffutils.
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From: Bruno Haible <bruno@HIDDEN>
To: Paul Eggert <eggert@HIDDEN>
Subject: Re: [bug-diffutils] bug#33965: handling of closed file descriptors
Date: Sat, 05 Jan 2019 00:30:39 +0100
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Sorry, Paul, but I have to vehemently disagree here. You are mixing
two different questions:
(A) What is the best behaviour for a kernel?
(B) What is the best behaviour for a program?
About (A):
> We should encourage platforms like HP-UX that try to work around the
> trouble
The question is: Is it better for a kernel to be minimalist, hence
exec() does nothing special with the file descriptors? Or is it better
for a kernel to avoid pitfalls for programs, by protecting the first
3 file descriptors?
It is similar to the question: In the case of a signal delivery, should
a read() or write() system call return with a partial result or EINTR, or
should the kernel protect the programs from this knowledge and programming
overhead? This question was extensively discussed under the title
"worse is better", see
https://www.jwz.org/doc/worse-is-better.html
https://en.wikipedia.org/wiki/Worse_is_better
I have no personal opinion on this question.
About (B):
> I'd rather think of this as a bug in the test case, not a bug in 'diff'.
Here I disagree.
* The majority of the uses of 'diff' and coreutils is through shell scripts.
* <&- and >&- are POSIX-standardized syntaxes in shell scripts for a long
time.
* It is a goal to make the same shell script work the same way on different
platforms. The user gains nothing if you tell them "your shell script
works differently on Linux than on HP-UX because the kernel behaves
slightly differently".
* Therefore the gnulib modules
dirent-safer
fcntl-safer
fopen-safer
freopen-safer
openat-safer
pipe2-safer
popen-safer
stdlib-safer
tmpfile-safer
unistd-safer
serve a good purpose. They make programs running on Linux and
programs running on HP-UX behave more similarly, which is a good thing.
> This is because the test case assumes more about the shell's "<&-"
> construct than what POSIX requires.
It is like saying that it would be OK for a program, when interrupted
through Ctrl-Z and restarted through 'fg', to stop processing and exit
with a message "read: Interrupted system call". That's indeed how some
programs behaved around 1992: POSIX allowed the kernel to return from a
read() system call with errno = EINTR. But users don't want this. So it
was seen as a bug in the program, and fixed.
Same here.
Bruno
bug-diffutils@HIDDEN:bug#33965; Package diffutils.
Full text available.Debbugs Internal Request <help-debbugs@HIDDEN>
to internal_control <at> debbugs.gnu.org.
Full text available.Received: (at 33965) by debbugs.gnu.org; 4 Jan 2019 22:42:32 +0000 From debbugs-submit-bounces <at> debbugs.gnu.org Fri Jan 04 17:42:32 2019 Received: from localhost ([127.0.0.1]:47102 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from <debbugs-submit-bounces <at> debbugs.gnu.org>) id 1gfYAi-0005EO-2d for submit <at> debbugs.gnu.org; Fri, 04 Jan 2019 17:42:32 -0500 Received: from zimbra.cs.ucla.edu ([131.179.128.68]:39778) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from <eggert@HIDDEN>) id 1gfYAf-0005E8-2k for 33965 <at> debbugs.gnu.org; Fri, 04 Jan 2019 17:42:30 -0500 Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id E7BAD160F5B; Fri, 4 Jan 2019 14:42:22 -0800 (PST) Received: from zimbra.cs.ucla.edu ([127.0.0.1]) by localhost (zimbra.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id 4lGmXO5PkIEK; Fri, 4 Jan 2019 14:42:22 -0800 (PST) Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id EBBAC160F5C; 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charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit I'd rather think of this as a bug in the test case, not a bug in 'diff'. This is because the test case assumes more about the shell's "<&-" construct than what POSIX requires. The bigger picture here is that invoking programs with stdin closed is trouble, and although Gnulib provides several modules to work around the trouble these modules are a hassle and many applications don't use them. We should encourage platforms like HP-UX that try to work around the trouble, instead of having diffutils attempt to simulate the traditional but inferior exec semantics. Although the Linux kernel currently implements the traditional semantics, in this particular case I think I'd rather have diffutils adjust to what the platform provides, rather than attempt to simulate Linux behavior even on non-Linux kernels. So I propose the attached further patch. --------------4C5C8295E10957DE69AEE802 Content-Type: text/plain; charset=UTF-8; name="0001-diff-move-HP-UX-workaround-into-test-case.txt" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="0001-diff-move-HP-UX-workaround-into-test-case.txt" RnJvbSBmZDNjOTc4ZGQ5Mjk0NTNkZmJlMGJmOGVhYTkyOTUzMjEyNzRiYTMzIE1vbiBTZXAg MTcgMDA6MDA6MDAgMjAwMQpGcm9tOiBQYXVsIEVnZ2VydCA8ZWdnZXJ0QGNzLnVjbGEuZWR1 PgpEYXRlOiBGcmksIDQgSmFuIDIwMTkgMTM6NDM6NTUgLTA4MDAKU3ViamVjdDogW1BBVENI XSBkaWZmOiBtb3ZlIEhQLVVYIHdvcmthcm91bmQgaW50byB0ZXN0IGNhc2UKTUlNRS1WZXJz aW9uOiAxLjAKQ29udGVudC1UeXBlOiB0ZXh0L3BsYWluOyBjaGFyc2V0PVVURi04CkNvbnRl bnQtVHJhbnNmZXItRW5jb2Rpbmc6IDhiaXQKCiogc3JjL2RpZmYuYyAoY29tcGFyZV9maWxl cykgW19faHB1eF06IFJlbW92ZSByZWNlbnRseS1pbnRyb2R1Y2VkCnNwZWNpYWwgY2FzZSBm b3IgSFAtVVggZXhlYyB3aXRoIHN0ZGluIGNsb3NlZC4KKiB0ZXN0cy9uZXctZmlsZTogRG9u 4oCZdCBhc3N1bWUgc3RkaW4gc3RheXMgY2xvc2VkIGFmdGVyIGEKc3VjY2Vzc2Z1bCBleGVj LCBhcyBQT1NJWCBkb2VzbuKAmXQgZ3VhcmFudGVlIHRoaXMgYW5kIGl0IGlzCm5vdCB0cnVl IG9uIEhQLVVYLgotLS0KIHNyYy9kaWZmLmMgICAgIHwgIDcgLS0tLS0tLQogdGVzdHMvbmV3 LWZpbGUgfCAzNCArKysrKysrKysrKysrKysrKysrKysrKy0tLS0tLS0tLS0tCiAyIGZpbGVz IGNoYW5nZWQsIDIzIGluc2VydGlvbnMoKyksIDE4IGRlbGV0aW9ucygtKQoKZGlmZiAtLWdp dCBhL3NyYy9kaWZmLmMgYi9zcmMvZGlmZi5jCmluZGV4IDJlZDNhZTUuLjZlOGM2YmUgMTAw NjQ0Ci0tLSBhL3NyYy9kaWZmLmMKKysrIGIvc3JjL2RpZmYuYwpAQCAtMTE3MiwxMyArMTE3 Miw2IEBAIGNvbXBhcmVfZmlsZXMgKHN0cnVjdCBjb21wYXJpc29uIGNvbnN0ICpwYXJlbnQs CiAJICAgICAgY21wLmZpbGVbZl0uZGVzYyA9IFNURElOX0ZJTEVOTzsKIAkgICAgICBpZiAo YmluYXJ5ICYmICEgaXNhdHR5IChTVERJTl9GSUxFTk8pKQogCQlzZXRfYmluYXJ5X21vZGUg KFNURElOX0ZJTEVOTywgT19CSU5BUlkpOwotI2lmZGVmIF9faHB1eAotCSAgICAgIC8qIFJl Y29nbml6ZSBmaWxlIGRlc2NyaXB0b3JzIGNsb3NlZCBieSB0aGUgcGFyZW50IG9uIEhQLVVY LiAgKi8KLQkgICAgICBpbnQgZmxhZ3MgPSBmY250bCAoU1RESU5fRklMRU5PLCBGX0dFVEZM LCBOVUxMKTsKLQkgICAgICBpZiAoZmxhZ3MgPj0gMCAmJiAoZmxhZ3MgJiBGRF9DTE9FWEVD KSAhPSAwKQotCQljbXAuZmlsZVtmXS5kZXNjID0gRVJSTk9fRU5DT0RFIChFQkFERik7Ci0J ICAgICAgZWxzZQotI2VuZGlmCiAJICAgICAgaWYgKGZzdGF0IChTVERJTl9GSUxFTk8sICZj bXAuZmlsZVtmXS5zdGF0KSAhPSAwKQogCQljbXAuZmlsZVtmXS5kZXNjID0gRVJSTk9fRU5D T0RFIChlcnJubyk7CiAJICAgICAgZWxzZQpkaWZmIC0tZ2l0IGEvdGVzdHMvbmV3LWZpbGUg Yi90ZXN0cy9uZXctZmlsZQppbmRleCA0NDAwMDUxLi45YjJhZGE0IDEwMDc1NQotLS0gYS90 ZXN0cy9uZXctZmlsZQorKysgYi90ZXN0cy9uZXctZmlsZQpAQCAtMTAsMTEgKzEwLDIxIEBA IGVjaG8gYSA+IGEgfHwgZmFpbD0xCiBlY2hvICcwYTEKID4gYScgPiBleHAgfHwgZmFpbD0x CiAKLXJldHVybnNfIDEgZGlmZiAtTiAtIGEgPCYtID4gb3V0IHx8IGZhaWw9MQotY29tcGFy ZSBleHAgb3V0IHx8IGZhaWw9MQotCi1yZXR1cm5zXyAxIGRpZmYgLS11bmlkaXJlY3Rpb25h bC1uZXctZmlsZSAtIGEgPCYtID4gb3V0IHx8IGZhaWw9MQotY29tcGFyZSBleHAgb3V0IHx8 IGZhaWw9MQorIyBQT1NJWCBhbGxvd3MgYSBjbG9zZWQgc3RkaW4gdG8gYmUgb3BlbmVkIGJ5 IHRoZSBrZXJuZWwgYWZ0ZXIgYW4gZXhlYywKKyMgc28gZG8gc29tZSB0ZXN0cyBvbmx5IG9u IHBsYXRmb3JtcyB3aGVyZSBzdGRpbiBzdGF5cyBjbG9zZWQgdGhlbi4KK2lmIHJldHVybnNf IDIgY21wIC0gLSA8Ji0gPi9kZXYvbnVsbCAyPiYxOyB0aGVuCisgIHN0ZGluX3N0YXlzX2Ns b3NlZD10cnVlCitlbHNlCisgIHN0ZGluX3N0YXlzX2Nsb3NlZD1mYWxzZQorZmkKKworaWYg JHN0ZGluX3N0YXlzX2Nsb3NlZDsgdGhlbgorICByZXR1cm5zXyAxIGRpZmYgLU4gLSBhIDwm LSA+IG91dCB8fCBmYWlsPTEKKyAgY29tcGFyZSBleHAgb3V0IHx8IGZhaWw9MQorCisgIHJl dHVybnNfIDEgZGlmZiAtLXVuaWRpcmVjdGlvbmFsLW5ldy1maWxlIC0gYSA8Ji0gPiBvdXQg fHwgZmFpbD0xCisgIGNvbXBhcmUgZXhwIG91dCB8fCBmYWlsPTEKK2ZpCiAKIHJldHVybnNf IDEgZGlmZiAtTiBiIC0gPCBhID4gb3V0IHx8IGZhaWw9MQogY29tcGFyZSBleHAgb3V0IHx8 IGZhaWw9MQpAQCAtMjUsMTMgKzM1LDE1IEBAIGNvbXBhcmUgZXhwIG91dCB8fCBmYWlsPTEK IGVjaG8gJzFkMAogPCBhJyA+IGV4cCB8fCBmYWlsPTEKIAotcmV0dXJuc18gMSBkaWZmIC1O IGEgLSA8Ji0gPiBvdXQgfHwgZmFpbD0xCi1jb21wYXJlIGV4cCBvdXQgfHwgZmFpbD0xCitp ZiAkc3RkaW5fc3RheXNfY2xvc2VkOyB0aGVuCisgIHJldHVybnNfIDEgZGlmZiAtTiBhIC0g PCYtID4gb3V0IHx8IGZhaWw9MQorICBjb21wYXJlIGV4cCBvdXQgfHwgZmFpbD0xCiAKLSMg V2l0aCBjbG9zZWQgc3RhbmRhcmQgaW5wdXQsIHJlcXVpcmUgYW4gZXhpdCBzdGF0dXMgb2Yg MgotIyBhbmQgZW1wdHkgc3Rkb3V0LgotcmV0dXJuc18gMiBkaWZmIC0tdW5pZGlyZWN0aW9u YWwtbmV3LWZpbGUgYSAtIDwmLSA+IG91dCB8fCBmYWlsPTEKLWNvbXBhcmUgL2Rldi9udWxs IG91dCB8fCBmYWlsPTEKKyAgIyBXaXRoIGNsb3NlZCBzdGFuZGFyZCBpbnB1dCwgcmVxdWly ZSBhbiBleGl0IHN0YXR1cyBvZiAyCisgICMgYW5kIGVtcHR5IHN0ZG91dC4KKyAgcmV0dXJu c18gMiBkaWZmIC0tdW5pZGlyZWN0aW9uYWwtbmV3LWZpbGUgYSAtIDwmLSA+IG91dCB8fCBm YWlsPTEKKyAgY29tcGFyZSAvZGV2L251bGwgb3V0IHx8IGZhaWw9MQorZmkKIAogcmV0dXJu c18gMSBkaWZmIC1OIC0gYiA8IGEgPiBvdXQgfHwgZmFpbD0xCiBjb21wYXJlIGV4cCBvdXQg fHwgZmFpbD0xCi0tIAoyLjIwLjEKCg== --------------4C5C8295E10957DE69AEE802--
bug-diffutils@HIDDEN:bug#33965; Package diffutils.
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From: Jim Meyering <jim@HIDDEN>
Date: Thu, 3 Jan 2019 22:15:19 -0800
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Subject: Re: [bug-diffutils] bug#33965: handling of closed file descriptors
To: Bruno Haible <bruno@HIDDEN>
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On Thu, Jan 3, 2019 at 11:43 AM Bruno Haible <bruno@HIDDEN> wrote:
>
> There is a problem with the handling of closed file descriptors
> in diff-3.7: As mentioned in [1], the 'new-file' test fails on HP-UX.
> An investigation [2] shows that different coding techniques are needed,
> depending on the desired outcome for closed file descriptors.
>
> This patch uses a variant of (A) from [2]. Namely, the result of fcntl
> can apparently be used to distinguish the substitute file descriptor
> stuffed in by exec() from a regular open("/dev/null",O_RDONLY).
>
> [1] https://lists.gnu.org/archive/html/diffutils-devel/2018-12/msg00019.html
> [2] https://lists.gnu.org/archive/html/bug-gnulib/2019-01/msg00012.html
Thank you. I have just pushed that with one tweak to the log message:
s/parent parent/parent/.
Bruno Haible <bruno@HIDDEN>:Jim Meyering <jim@HIDDEN>:
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From: Bruno Haible <bruno@HIDDEN>
To: bug-diffutils@HIDDEN
Subject: Re: handling of closed file descriptors
Date: Thu, 03 Jan 2019 21:02:16 +0100
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I wrote:
> the result of fcntl
> can apparently be used to distinguish the substitute file descriptor
> stuffed in by exec() from a regular open("/dev/null",O_RDONLY).
Note that the code works for STDIN_FILENO, where fcntl(...) is 5 in one case
and 0 in the other case, and we use FD_CLOEXEC = 1 to distinguish the two.
For STDOUT_FILENO, fcntl(...) would be 5 in one case and 1 in the other case,
and the flag which allows to distinguish the two cases (4) is not listed in
<sys/fcntl.h>, therefore likely is a kernel-private flag.
Bruno
bug-diffutils@HIDDEN:bug#33965; Package diffutils.
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Thu, 3 Jan 2019 20:42:29 +0100 (CET)
From: Bruno Haible <bruno@HIDDEN>
To: bug-diffutils@HIDDEN
Subject: handling of closed file descriptors
Date: Thu, 03 Jan 2019 20:42:28 +0100
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There is a problem with the handling of closed file descriptors
in diff-3.7: As mentioned in [1], the 'new-file' test fails on HP-UX.
An investigation [2] shows that different coding techniques are needed,
depending on the desired outcome for closed file descriptors.
This patch uses a variant of (A) from [2]. Namely, the result of fcntl
can apparently be used to distinguish the substitute file descriptor
stuffed in by exec() from a regular open("/dev/null",O_RDONLY).
[1] https://lists.gnu.org/archive/html/diffutils-devel/2018-12/msg00019.html
[2] https://lists.gnu.org/archive/html/bug-gnulib/2019-01/msg00012.html
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From 288ddc7c18c022f39233ca78e78e49e02833966c Mon Sep 17 00:00:00 2001
From: Bruno Haible <bruno@HIDDEN>
Date: Thu, 3 Jan 2019 20:36:35 +0100
Subject: [PATCH] Recognize file descriptors closed by the parent process on
HP-UX.
* src/diff.c (compare_files): Use fcntl to distinguish a file descriptor closed
by the parent parent process from a file descriptor that references /dev/null.
---
src/diff.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/src/diff.c b/src/diff.c
index 6e8c6be..2ed3ae5 100644
--- a/src/diff.c
+++ b/src/diff.c
@@ -1172,6 +1172,13 @@ compare_files (struct comparison const *parent,
cmp.file[f].desc = STDIN_FILENO;
if (binary && ! isatty (STDIN_FILENO))
set_binary_mode (STDIN_FILENO, O_BINARY);
+#ifdef __hpux
+ /* Recognize file descriptors closed by the parent on HP-UX. */
+ int flags = fcntl (STDIN_FILENO, F_GETFL, NULL);
+ if (flags >= 0 && (flags & FD_CLOEXEC) != 0)
+ cmp.file[f].desc = ERRNO_ENCODE (EBADF);
+ else
+#endif
if (fstat (STDIN_FILENO, &cmp.file[f].stat) != 0)
cmp.file[f].desc = ERRNO_ENCODE (errno);
else
--
2.7.4
--nextPart8317215.dh2gXTNRMh--
Bruno Haible <bruno@HIDDEN>:bug-diffutils@HIDDEN.
Full text available.bug-diffutils@HIDDEN:bug#33965; Package diffutils.
Full text available.
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