File glibc-2.26-Assume-that-pipe2-is-always-available.patch of Package glibc.29706
From 46d8874d5b2fcb7831dd84c5e2f6df51922a7936 Mon Sep 17 00:00:00 2001
From: Florian Weimer <fweimer@redhat.com>
Date: Tue, 18 Apr 2017 14:09:01 +0200
Subject: [PATCH] Assume that pipe2 is always available
The Debian patches for Hurd (which are already required to build
glibc before this commit) contain an implementation of pipe2.
---
include/unistd.h | 1 -
libio/iopopen.c | 80 ++++++++-----------------------
posix/wordexp.c | 32 ++-----------
socket/have_sock_cloexec.c | 4 --
sysdeps/unix/sysv/linux/kernel-features.h | 1 -
6 files changed, 32 insertions(+), 96 deletions(-)
Index: glibc-2.22/include/unistd.h
===================================================================
--- glibc-2.22.orig/include/unistd.h
+++ glibc-2.22/include/unistd.h
@@ -171,7 +171,6 @@ extern int __libc_pause (void);
extern int __pause_nocancel (void) attribute_hidden;
extern int __have_sock_cloexec attribute_hidden;
-extern int __have_pipe2 attribute_hidden;
extern int __have_dup3 attribute_hidden;
extern int __getlogin_r_loginuid (char *name, size_t namesize)
Index: glibc-2.22/libio/iopopen.c
===================================================================
--- glibc-2.22.orig/libio/iopopen.c
+++ glibc-2.22/libio/iopopen.c
@@ -143,29 +143,17 @@ _IO_new_proc_open (fp, command, mode)
if (_IO_file_is_open (fp))
return NULL;
-#ifdef O_CLOEXEC
-# ifndef __ASSUME_PIPE2
- if (__have_pipe2 >= 0)
-# endif
- {
- int r = __pipe2 (pipe_fds, O_CLOEXEC);
-# ifndef __ASSUME_PIPE2
- if (__have_pipe2 == 0)
- __have_pipe2 = r != -1 || errno != ENOSYS ? 1 : -1;
-
- if (__have_pipe2 > 0)
-# endif
- if (r < 0)
- return NULL;
- }
-#endif
-#ifndef __ASSUME_PIPE2
-# ifdef O_CLOEXEC
- if (__have_pipe2 < 0)
-# endif
- if (__pipe (pipe_fds) < 0)
- return NULL;
-#endif
+ /* Atomically set the O_CLOEXEC flag for the pipe end used by the
+ child process (to avoid leaking the file descriptor in case of a
+ concurrent fork). This is later reverted in the child process.
+ When popen returns, the parent pipe end can be O_CLOEXEC or not,
+ depending on the 'e' open mode, but there is only one flag which
+ controls both descriptors. The parent end is adjusted below,
+ after creating the child process. (In the child process, the
+ parent end should be closed on execve, so O_CLOEXEC remains set
+ there.) */
+ if (__pipe2 (pipe_fds, O_CLOEXEC) < 0)
+ return NULL;
if (do_read)
{
@@ -186,27 +174,13 @@ _IO_new_proc_open (fp, command, mode)
int child_std_end = do_read ? 1 : 0;
struct _IO_proc_file *p;
-#ifndef __ASSUME_PIPE2
- /* If we have pipe2 the descriptor is marked for close-on-exec. */
- _IO_close (parent_end);
-#endif
if (child_end != child_std_end)
- {
- _IO_dup2 (child_end, child_std_end);
-#ifndef __ASSUME_PIPE2
- _IO_close (child_end);
-#endif
- }
+ _IO_dup2 (child_end, child_std_end);
#ifdef O_CLOEXEC
else
- {
- /* The descriptor is already the one we will use. But it must
- not be marked close-on-exec. Undo the effects. */
-# ifndef __ASSUME_PIPE2
- if (__have_pipe2 > 0)
-# endif
- __fcntl (child_end, F_SETFD, 0);
- }
+ /* The descriptor is already the one we will use. But it must
+ not be marked close-on-exec. Undo the effects. */
+ __fcntl (child_end, F_SETFD, 0);
#endif
/* POSIX.2: "popen() shall ensure that any streams from previous
popen() calls that remain open in the parent process are closed
@@ -232,26 +206,10 @@ _IO_new_proc_open (fp, command, mode)
return NULL;
}
- if (do_cloexec)
- {
-#ifndef __ASSUME_PIPE2
-# ifdef O_CLOEXEC
- if (__have_pipe2 < 0)
-# endif
- __fcntl (parent_end, F_SETFD, FD_CLOEXEC);
-#endif
- }
- else
- {
-#ifdef O_CLOEXEC
- /* Undo the effects of the pipe2 call which set the
- close-on-exec flag. */
-# ifndef __ASSUME_PIPE2
- if (__have_pipe2 > 0)
-# endif
- __fcntl (parent_end, F_SETFD, 0);
-#endif
- }
+ if (!do_cloexec)
+ /* Undo the effects of the pipe2 call which set the
+ close-on-exec flag. */
+ __fcntl (parent_end, F_SETFD, 0);
_IO_fileno (fp) = parent_end;
Index: glibc-2.22/posix/wordexp.c
===================================================================
--- glibc-2.22.orig/posix/wordexp.c
+++ glibc-2.22/posix/wordexp.c
@@ -836,10 +836,7 @@ exec_comm_child (char *comm, int *fildes
{
#ifdef O_CLOEXEC
/* Reset the close-on-exec flag (if necessary). */
-# ifndef __ASSUME_PIPE2
- if (__have_pipe2 > 0)
-# endif
- __fcntl (fildes[1], F_SETFD, 0);
+ __fcntl (fildes[1], F_SETFD, 0);
#endif
}
@@ -905,31 +902,8 @@ exec_comm (char *comm, char **word, size
if (!comm || !*comm)
return 0;
-#ifdef O_CLOEXEC
-# ifndef __ASSUME_PIPE2
- if (__have_pipe2 >= 0)
-# endif
- {
- int r = __pipe2 (fildes, O_CLOEXEC);
-# ifndef __ASSUME_PIPE2
- if (__have_pipe2 == 0)
- __have_pipe2 = r != -1 || errno != ENOSYS ? 1 : -1;
-
- if (__have_pipe2 > 0)
-# endif
- if (r < 0)
- /* Bad */
- return WRDE_NOSPACE;
- }
-#endif
-#ifndef __ASSUME_PIPE2
-# ifdef O_CLOEXEC
- if (__have_pipe2 < 0)
-# endif
- if (__pipe (fildes) < 0)
- /* Bad */
- return WRDE_NOSPACE;
-#endif
+ if (__pipe2 (fildes, O_CLOEXEC) < 0)
+ return WRDE_NOSPACE;
again:
if ((pid = __fork ()) < 0)
Index: glibc-2.22/socket/have_sock_cloexec.c
===================================================================
--- glibc-2.22.orig/socket/have_sock_cloexec.c
+++ glibc-2.22/socket/have_sock_cloexec.c
@@ -23,10 +23,6 @@
int __have_sock_cloexec;
#endif
-#if defined O_CLOEXEC && !defined __ASSUME_PIPE2
-int __have_pipe2;
-#endif
-
#if defined O_CLOEXEC && !defined __ASSUME_DUP3
int __have_dup3;
#endif
Index: glibc-2.22/sysdeps/unix/sysv/linux/kernel-features.h
===================================================================
--- glibc-2.22.orig/sysdeps/unix/sysv/linux/kernel-features.h
+++ glibc-2.22/sysdeps/unix/sysv/linux/kernel-features.h
@@ -90,7 +90,6 @@
2.6.27. */
#define __ASSUME_SOCK_CLOEXEC 1
#define __ASSUME_IN_NONBLOCK 1
-#define __ASSUME_PIPE2 1
#define __ASSUME_EVENTFD2 1
#define __ASSUME_SIGNALFD4 1
#define __ASSUME_DUP3 1
