x/sys/unix: mkerrors.sh fails on linux/pidfd.h

[lmb]

What operating system and processor architecture are you using (go env)?

Linux on amd64

What did you do?

The following diff will make mkerrors.sh error out:

diff --git a/unix/mkerrors.sh b/unix/mkerrors.sh
index 0bcb8c3..e92d8d7 100755
--- a/unix/mkerrors.sh
+++ b/unix/mkerrors.sh
@@ -240,6 +240,7 @@ struct ltchars {
 #include <linux/nfc.h>
 #include <linux/nsfs.h>
 #include <linux/perf_event.h>
+#include <linux/pidfd.h>
 #include <linux/pps.h>
 #include <linux/ptrace.h>
 #include <linux/random.h>

Output:

----- GENERATING: 386 -----
configure: WARNING: minimum kernel version reset to 3.2.0
header files generated
zsysnum file generated
zsyscall file generated
ztypes file generated
In file included from /tmp/include/fcntl.h:35,
                 from /tmp/include/sys/file.h:24,
                 from /build/_const.go:180:
/tmp/include/bits/fcntl.h:35:8: error: redefinition of 'struct flock'
   35 | struct flock
      |        ^~~~~
In file included from /tmp/include/asm/fcntl.h:1,
                 from /tmp/include/linux/fcntl.h:5,
                 from /tmp/include/linux/pidfd.h:7,
                 from /build/_const.go:101:
/tmp/include/asm-generic/fcntl.h:196:8: note: originally defined here
  196 | struct flock {
      |        ^~~~~
In file included from /tmp/include/fcntl.h:35,
                 from /tmp/include/sys/file.h:24,
                 from /build/_const.go:180:
/tmp/include/bits/fcntl.h:50:8: error: redefinition of 'struct flock64'
   50 | struct flock64
      |        ^~~~~~~
In file included from /tmp/include/asm/fcntl.h:1,
                 from /tmp/include/linux/fcntl.h:5,
                 from /tmp/include/linux/pidfd.h:7,
                 from /build/_const.go:101:
/tmp/include/asm-generic/fcntl.h:211:8: note: originally defined here
  211 | struct flock64 {
      |        ^~~~~~~
/tmp/include/asm-generic/fcntl.h:152:21: error: expected identifier before numeric constant
  152 | #define F_OWNER_TID 0
      |                     ^
/tmp/include/bits/fcntl-linux.h:267:5: note: in expansion of macro 'F_OWNER_TID'
  267 |     F_OWNER_TID = 0,  /* Kernel thread.  */
      |     ^~~~~~~~~~~
In file included from /tmp/include/bits/fcntl.h:61,
                 from /tmp/include/fcntl.h:35,
                 from /tmp/include/sys/file.h:24,
                 from /build/_const.go:180:
/tmp/include/bits/fcntl-linux.h:274:8: error: redefinition of 'struct f_owner_ex'
  274 | struct f_owner_ex
      |        ^~~~~~~~~~
In file included from /tmp/include/asm/fcntl.h:1,
                 from /tmp/include/linux/fcntl.h:5,
                 from /tmp/include/linux/pidfd.h:7,
                 from /build/_const.go:101:
/tmp/include/asm-generic/fcntl.h:156:8: note: originally defined here
  156 | struct f_owner_ex {
      |        ^~~~~~~~~~
zerrors file generated
----- SUCCESS:    386 -----

<...>

There is source generated, but the diff is huge and it's not well formed Go.

[tklauser]

We occasionally run into this of problem when types (struct flock and struct flock64 in this case) are defined in both kernel headers and libc headers. The solution so far has usually been to add the respective include and definition to linux/type.go instead.

[ianlancetaylor]

Resolved by just adding a definition to linux/type.go.