[glibc/release/2.36/master] include: isolate __O_CLOEXEC flag for sys/mount.h and fcntl.h

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=c13121204aea247799184590aafc28dbda0ccb39

commit c13121204aea247799184590aafc28dbda0ccb39
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)
    
    (Adjusted sysdeps/unix/sysv/linux/Makefile for lack of reformatting.)

Diff:
---
 io/fcntl.c                                   | 4 ++++
 sysdeps/unix/sysv/linux/Makefile             | 2 +-
 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(+), 5 deletions(-)

diff --git a/io/fcntl.c b/io/fcntl.c
index 491678bccc..d6e56629b8 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 d92ea7a1f3..80ad22259c 100644
--- a/sysdeps/unix/sysv/linux/Makefile
+++ b/sysdeps/unix/sysv/linux/Makefile
@@ -114,7 +114,7 @@ sysdep_headers += sys/mount.h sys/acct.h \
 		  bits/types/struct_shmid64_ds_helper.h \
 		  bits/pthread_stack_min.h bits/pthread_stack_min-dynamic.h \
 		  sys/rseq.h bits/rseq.h \
-		  sys/pidfd.h
+		  sys/pidfd.h bits/cloexec.h
 
 tests += tst-clone tst-clone2 tst-clone3 tst-fanotify tst-personality \
 	 tst-quota tst-sync_file_range tst-sysconf-iov_max tst-ttyname \
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 bfc674235d..b7d1ad99e2 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 19841d0738..4a65508a26 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 b6333a60e6..d5c844455c 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,