[glibc/release/2.37/master] include: isolate __O_CLOEXEC flag for sys/mount.h and fcntl.h

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=e2aae832170ee060dda386a647e5fb242bbb6eec

commit e2aae832170ee060dda386a647e5fb242bbb6eec
Author: DJ Delorie <[email protected]>
Date:   Mon Jan 26 22:24:42 2026 -0500

    include: isolate __O_CLOEXEC flag for sys/mount.h and fcntl.h
    
    Including sys/mount.h should not implicitly include fcntl.h
    as that causes namespace pollution and conflicts with kernel
    headers.  It only needs O_CLOEXEC for OPEN_TREE_CLOEXEC
    (although it shouldn't need that, but it's defined that way)
    so we provide that define (via a private version) separately.
    
    Reviewed-by: Adhemerval Zanella  <[email protected]>
    Tested-by: Florian Weimer <[email protected]>
    (cherry picked from commit 419245719ccbc7dad6a97f24465e7f09c090327a)

Diff:
---
 io/fcntl.c                                   | 4 ++++
 sysdeps/unix/sysv/linux/Makefile             | 1 +
 sysdeps/unix/sysv/linux/alpha/bits/cloexec.h | 1 +
 sysdeps/unix/sysv/linux/bits/cloexec.h       | 1 +
 sysdeps/unix/sysv/linux/bits/fcntl-linux.h   | 4 +---
 sysdeps/unix/sysv/linux/hppa/bits/cloexec.h  | 1 +
 sysdeps/unix/sysv/linux/sparc/bits/cloexec.h | 1 +
 sysdeps/unix/sysv/linux/sys/mount.h          | 6 +++++-
 sysdeps/unix/sysv/linux/tst-mount.c          | 1 +
 9 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/io/fcntl.c b/io/fcntl.c
index 0d36a3caef..18f314c329 100644
--- a/io/fcntl.c
+++ b/io/fcntl.c
@@ -18,6 +18,10 @@
 #include <errno.h>
 #include <fcntl.h>
 
+#ifndef __O_CLOEXEC
+# error __O_CLOEXEC not defined by fcntl.h/cloexec.h
+#endif
+
 /* Perform file control operations on FD.  */
 int
 __fcntl (int fd, int cmd, ...)
diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
index 6acfd2cc48..3782c6c63b 100644
--- a/sysdeps/unix/sysv/linux/Makefile
+++ b/sysdeps/unix/sysv/linux/Makefile
@@ -119,6 +119,7 @@ CFLAGS-tst-writev.c += "-DARTIFICIAL_LIMIT=(0x80000000-sysconf(_SC_PAGESIZE))"
 
 sysdep_headers += \
   bits/a.out.h \
+  bits/cloexec.h \
   bits/epoll.h \
   bits/eventfd.h \
   bits/inotify.h \
diff --git a/sysdeps/unix/sysv/linux/alpha/bits/cloexec.h b/sysdeps/unix/sysv/linux/alpha/bits/cloexec.h
new file mode 100644
index 0000000000..f381f28a53
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/alpha/bits/cloexec.h
@@ -0,0 +1 @@
+#define __O_CLOEXEC 010000000
diff --git a/sysdeps/unix/sysv/linux/bits/cloexec.h b/sysdeps/unix/sysv/linux/bits/cloexec.h
new file mode 100644
index 0000000000..3059fb6473
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/bits/cloexec.h
@@ -0,0 +1 @@
+#define __O_CLOEXEC 02000000
diff --git a/sysdeps/unix/sysv/linux/bits/fcntl-linux.h b/sysdeps/unix/sysv/linux/bits/fcntl-linux.h
index 1babbdc84e..54915dad4c 100644
--- a/sysdeps/unix/sysv/linux/bits/fcntl-linux.h
+++ b/sysdeps/unix/sysv/linux/bits/fcntl-linux.h
@@ -81,9 +81,7 @@
 #ifndef __O_NOFOLLOW
 # define __O_NOFOLLOW	0400000
 #endif
-#ifndef __O_CLOEXEC
-# define __O_CLOEXEC   02000000
-#endif
+#include <bits/cloexec.h>
 #ifndef __O_DIRECT
 # define __O_DIRECT	 040000
 #endif
diff --git a/sysdeps/unix/sysv/linux/hppa/bits/cloexec.h b/sysdeps/unix/sysv/linux/hppa/bits/cloexec.h
new file mode 100644
index 0000000000..f381f28a53
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/hppa/bits/cloexec.h
@@ -0,0 +1 @@
+#define __O_CLOEXEC 010000000
diff --git a/sysdeps/unix/sysv/linux/sparc/bits/cloexec.h b/sysdeps/unix/sysv/linux/sparc/bits/cloexec.h
new file mode 100644
index 0000000000..6706eaa7d5
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/sparc/bits/cloexec.h
@@ -0,0 +1 @@
+#define __O_CLOEXEC 0x400000
diff --git a/sysdeps/unix/sysv/linux/sys/mount.h b/sysdeps/unix/sysv/linux/sys/mount.h
index c6da841d99..600ac455bc 100644
--- a/sysdeps/unix/sysv/linux/sys/mount.h
+++ b/sysdeps/unix/sysv/linux/sys/mount.h
@@ -21,7 +21,6 @@
 #ifndef _SYS_MOUNT_H
 #define _SYS_MOUNT_H	1
 
-#include <fcntl.h>
 #include <features.h>
 #include <stdint.h>
 #include <stddef.h>
@@ -263,6 +262,11 @@ enum fsconfig_command
 
 /* open_tree flags.  */
 #define OPEN_TREE_CLONE    1         /* Clone the target tree and attach the clone */
+#ifndef O_CLOEXEC
+# include <bits/cloexec.h>
+# define O_CLOEXEC __O_CLOEXEC
+#endif
+#undef  OPEN_TREE_CLOEXEC
 #define OPEN_TREE_CLOEXEC  O_CLOEXEC /* Close the file on execve() */
 
 
diff --git a/sysdeps/unix/sysv/linux/tst-mount.c b/sysdeps/unix/sysv/linux/tst-mount.c
index abf9761d4a..6ec433b62b 100644
--- a/sysdeps/unix/sysv/linux/tst-mount.c
+++ b/sysdeps/unix/sysv/linux/tst-mount.c
@@ -20,6 +20,7 @@
 #include <support/check.h>
 #include <support/xunistd.h>
 #include <support/namespace.h>
+#include <fcntl.h> /* For AT_ constants.  */
 #include <sys/mount.h>
 
 _Static_assert (sizeof (struct mount_attr) == MOUNT_ATTR_SIZE_VER0,