[PATCH] libc-compat.h for <asm-generic/fcntl.h>

[Eric Neblock]

Hello everyone,
  I've done some kernel hacking and needed in some extra flags for
open(2). Although the kernel works, I could not access my changes in
userland. Adding in <asm-generic/fcntl.h> caused many redefinition
errors, and ignoring <fcntl.h> causes issues as flibc's <fcntl.h>
contains the prototype for open(2).

  As such, I've filed a feature request to glibc (20050) and have since
made a patch to help facilitate any changes other people may have. I've
also sent the glibc patch to libc-alpha.

  Attached is the patch that should make the changes, while not breaking
compatibility for those who do not need it.

  If there is any other information that I need to provide, then please
let me know.

  Finally, I'd like to be CC'd on this and future e-mails related to
this patch.

Regards,
Eric Neblock
Only in ./linux-4.5.2-CACS/: dest
diff -crB ./linux-4.5.2-CACS/include/uapi/asm-generic/fcntl.h ./linux-4.5.2/include/uapi/asm-generic/fcntl.h
*** ./linux-4.5.2-CACS/include/uapi/asm-generic/fcntl.h	2016-05-08 14:29:10.567043802 -0500
--- ./linux-4.5.2/include/uapi/asm-generic/fcntl.h	2016-04-20 01:46:35.000000000 -0500
***************
*** 1,7 ****
  #ifndef _ASM_GENERIC_FCNTL_H
  #define _ASM_GENERIC_FCNTL_H
  
- #include <linux/libc-compat.h>
  #include <linux/types.h>
  
  /*
--- 1,6 ----
***************
*** 16,29 ****
   * When introducing new O_* bits, please check its uniqueness in fcntl_init().
   */
  
- /* Make sure that we don't cause errors with libc */
- #if __UAPI_DEF_FCNTL_H
  #define O_ACCMODE	00000003
  #define O_RDONLY	00000000
  #define O_WRONLY	00000001
  #define O_RDWR		00000002
- #endif
- 
  #ifndef O_CREAT
  #define O_CREAT		00000100	/* not fcntl */
  #endif
--- 15,24 ----
***************
*** 93,116 ****
  #define __O_TMPFILE	020000000
  #endif
  
- #if __UAPI_DEF_FCNTL_H
  /* a horrid kludge trying to make sure that this will fail on old kernels */
  #define O_TMPFILE (__O_TMPFILE | O_DIRECTORY)
  #define O_TMPFILE_MASK (__O_TMPFILE | O_DIRECTORY | O_CREAT)      
- #endif
  
  #ifndef O_NDELAY
  #define O_NDELAY	O_NONBLOCK
  #endif
  
- #if __UAPI_DEF_FCNTL_H
  #define F_DUPFD		0	/* dup */
  #define F_GETFD		1	/* get close_on_exec */
  #define F_SETFD		2	/* set/clear close_on_exec */
  #define F_GETFL		3	/* get file->f_flags */
  #define F_SETFL		4	/* set file->f_flags */
- #endif
- 
  #ifndef F_GETLK
  #define F_GETLK		5
  #define F_SETLK		6
--- 88,106 ----
***************
*** 142,148 ****
  #define F_GETOWNER_UIDS	17
  #endif
  
- #if __UAPI_DEF_FCNTL_H
  /*
   * Open File Description Locks
   *
--- 132,137 ----
***************
*** 170,176 ****
  
  /* for F_[GET|SET]FL */
  #define FD_CLOEXEC	1	/* actually anything with low bit set goes */
- #endif /* __UAPI_DEF_FCNTL_H */
  
  /* for posix fcntl() and lockf() */
  #ifndef F_RDLCK
--- 159,164 ----
***************
*** 185,191 ****
  #define F_SHLCK		8	/* or 4 */
  #endif
  
- #if __UAPI_DEF_FCNTL_H
  /* operations for bsd flock(), also used by the kernel implementation */
  #define LOCK_SH		1	/* shared lock */
  #define LOCK_EX		2	/* exclusive lock */
--- 173,178 ----
***************
*** 200,209 ****
  
  #define F_LINUX_SPECIFIC_BASE	1024
  
- #endif
- 
- #if __UAPI_DEF_FCNTL_H
- 
  #ifndef HAVE_ARCH_STRUCT_FLOCK
  #ifndef __ARCH_FLOCK_PAD
  #define __ARCH_FLOCK_PAD
--- 187,192 ----
***************
*** 233,237 ****
  	__ARCH_FLOCK64_PAD
  };
  #endif
! #endif /* __UAPI_DEF_FCNTL_H */
  #endif /* _ASM_GENERIC_FCNTL_H */
--- 216,220 ----
  	__ARCH_FLOCK64_PAD
  };
  #endif
! 
  #endif /* _ASM_GENERIC_FCNTL_H */
diff -crB ./linux-4.5.2-CACS/include/uapi/linux/libc-compat.h ./linux-4.5.2/include/uapi/linux/libc-compat.h
*** ./linux-4.5.2-CACS/include/uapi/linux/libc-compat.h	2016-05-08 14:29:55.226333792 -0500
--- ./linux-4.5.2/include/uapi/linux/libc-compat.h	2016-04-20 01:46:35.000000000 -0500
***************
*** 20,26 ****
   *      e.g. #include <linux/libc-compat.h>
   *     This include must be as early as possible.
   *
!  * (b) In libc-compat.h add enough code to detect that the conflicting
   *     userspace libc header has been included first.
   *
   * (c) If the userspace libc header has been included first define a set of
--- 20,26 ----
   *      e.g. #include <linux/libc-compat.h>
   *     This include must be as early as possible.
   *
!  * (b) In libc-compat.h add enough code to detect that the comflicting
   *     userspace libc header has been included first.
   *
   * (c) If the userspace libc header has been included first define a set of
***************
*** 80,87 ****
  #define __UAPI_DEF_IN6_PKTINFO		0
  #define __UAPI_DEF_IP6_MTUINFO		0
  
- #define __UAPI_DEF_FCNTL_H 0
- 
  #else
  
  /* Linux headers included first, and we must define everything
--- 80,85 ----
***************
*** 140,147 ****
  /* Definitions for xattr.h */
  #define __UAPI_DEF_XATTR		1
  
- /* Definitions for fcntl.h */
- #define __UAPI_DEF_FCNTL_H 1
  #endif /* __GLIBC__ */
  
  #endif /* _UAPI_LIBC_COMPAT_H */
--- 138,143 ----

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