Patchwork [17/25] Don’t include sys/select.h from sys/types.h.

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Submitter Zack Weinberg
Date June 26, 2019, 5:50 p.m.
Message ID <20190626175029.4699-8-zackw@panix.com>
Download mbox | patch
Permalink /patch/33439/
State New
Headers show

Comments

Zack Weinberg - June 26, 2019, 5:50 p.m.
This is supposedly present for BSD compatibility, but the current
generation of BSDs is not consistent about it: FreeBSD does, OpenBSD
doesn’t, NetBSD exposes only fd_set and the FD_* macros.  Programs
that need to wait for any of multiple I/O events have several
alternatives to select nowadays, so I think it makes sense to expose
select only to programs that specifically want it.

Only a few places within our own code are affected.  A few test
programs need to include sys/select.h explicitly, as does rpc/svc.h.
sysdeps/nptl/thread_db.h needs to declare sigset_t, and
sysdeps/unix/sysv/linux/pselect.c was including sys/poll.h instead of
sys/select.h, which is probably a copy-and-paste error.  sys/socket.h
needs to forward-declare struct timespec under __USE_GNU, because
recvmmsg has a struct timespec * argument; I’m open to the possibility
of having it fully declare struct timespec.

I considered taking sys/select.h out of sys/time.h as well, but POSIX
not only explicitly allows this inclusion, it requires sys/time.h to
declare almost everything that sys/select.h declares.  It doesn’t seem
worth creating another bits header just to prevent sys/time.h from
declaring pselect, sigset_t, and struct timespec.

Not including sys/select.h from sys/types.h means that sys/types.h
also no longer defines anything from sys/time.h, and a couple of files
were relying on that.  (pthread_join_common.c should be using
clock_gettime instead of gettimeofday, but that's out of scope for
this patch series.)

	* posix/sys/types.h: Don’t include sys/select.h.
	* scripts/check-obsolete-constructs.py: Remove whitelist entry
	for sys/types.h -> sys/select.h.  Adjust commentary re
	sys/time.h -> sys/select.h.

	* socket/sys/socket.h: When __USE_GNU, forward-declare struct timespec.
	* misc/tst-fdset.c, nptl/tst-cancel4.c, scripts/check-c++-types.sh
	* sunrpc/rpc/svc.h: Include sys/select.h.
	* sysdeps/nptl/thread_db.h: Include bits/types/sigset_t.h.
	* sysdeps/unix/sysv/linux/pselect.c: Include sys/select.h,
	not sys/poll.h.
	* nptl/pthread_join_common.c, sysdeps/unix/sysv/linux/dl-vdso.h:
	Include sys/time.h.
---
 misc/tst-fdset.c                     | 2 +-
 nptl/pthread_join_common.c           | 2 ++
 nptl/tst-cancel4.c                   | 1 +
 posix/sys/types.h                    | 3 ---
 scripts/check-c++-types.sh           | 1 +
 scripts/check-obsolete-constructs.py | 6 +++---
 socket/sys/socket.h                  | 4 ++++
 sunrpc/rpc/svc.h                     | 1 +
 sysdeps/nptl/thread_db.h             | 2 +-
 sysdeps/unix/sysv/linux/dl-vdso.h    | 6 ++++++
 sysdeps/unix/sysv/linux/pselect.c    | 2 +-
 11 files changed, 21 insertions(+), 9 deletions(-)

Patch

diff --git a/misc/tst-fdset.c b/misc/tst-fdset.c
index 70b7028dad..956e371746 100644
--- a/misc/tst-fdset.c
+++ b/misc/tst-fdset.c
@@ -18,7 +18,7 @@ 
    <http://www.gnu.org/licenses/>.  */
 
 #include <stdio.h>
-#include <sys/types.h>
+#include <sys/select.h>
 
 static int
 do_test (void)
diff --git a/nptl/pthread_join_common.c b/nptl/pthread_join_common.c
index 5224ee2110..b8b016ccb7 100644
--- a/nptl/pthread_join_common.c
+++ b/nptl/pthread_join_common.c
@@ -20,6 +20,8 @@ 
 #include <atomic.h>
 #include <stap-probe.h>
 
+#include <sys/time.h>
+
 static void
 cleanup (void *arg)
 {
diff --git a/nptl/tst-cancel4.c b/nptl/tst-cancel4.c
index 60a965d23a..dce93dc03a 100644
--- a/nptl/tst-cancel4.c
+++ b/nptl/tst-cancel4.c
@@ -24,6 +24,7 @@ 
 #include <stdlib.h>
 #include <string.h>
 #include <sys/types.h>
+#include <sys/select.h>
 #include <sys/socket.h>
 #include <sys/un.h>
 #include <sys/ipc.h>
diff --git a/posix/sys/types.h b/posix/sys/types.h
index 08305cf812..9381695548 100644
--- a/posix/sys/types.h
+++ b/posix/sys/types.h
@@ -93,9 +93,6 @@  __BEGIN_DECLS
 
 /* In BSD <sys/types.h> is expected to define BYTE_ORDER.  */
 # include <endian.h>
-
-/* It also defines `fd_set' and the FD_* macros for `select'.  */
-# include <sys/select.h>
 #endif /* Use misc.  */
 
 __END_DECLS
diff --git a/scripts/check-c++-types.sh b/scripts/check-c++-types.sh
index a8f3cfff7b..141ddf7440 100755
--- a/scripts/check-c++-types.sh
+++ b/scripts/check-c++-types.sh
@@ -46,6 +46,7 @@  while read t; do
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <sys/resource.h>
+#include <sys/select.h>
 #include <unistd.h>
 void foo ($t) { }
 EOF
diff --git a/scripts/check-obsolete-constructs.py b/scripts/check-obsolete-constructs.py
index bd5a97f76b..a051d4e845 100755
--- a/scripts/check-obsolete-constructs.py
+++ b/scripts/check-obsolete-constructs.py
@@ -530,13 +530,13 @@  HEADER_ALLOWED_INCLUDES = {
     # mandated: sys/msg.h -> sys/ipc.h
     #           sys/sem.h -> sys/ipc.h
     #           sys/shm.h -> sys/ipc.h
-    # allowed:  sys/time.h -> sys/select.h
-    #           sys/wait.h -> signal.h
+    #           sys/time.h -> sys/select.h (effectively)
+    # allowed:  sys/wait.h -> signal.h
     "sys/msg.h":                   [ "sys/ipc.h" ],
     "sys/sem.h":                   [ "sys/ipc.h" ],
     "sys/shm.h":                   [ "sys/ipc.h" ],
     "sys/time.h":                  [ "sys/select.h" ],
-    "sys/types.h":                 [ "endian.h", "sys/select.h" ],
+    "sys/types.h":                 [ "endian.h" ],
     "sys/uio.h":                   [ "sys/types.h" ],
     "sys/un.h":                    [ "string.h" ],
     "sys/wait.h":                  [ "signal.h" ],
diff --git a/socket/sys/socket.h b/socket/sys/socket.h
index 1bb90ed67c..ce793dc3e2 100644
--- a/socket/sys/socket.h
+++ b/socket/sys/socket.h
@@ -35,6 +35,10 @@  __BEGIN_DECLS
 # include <bits/types/struct_osockaddr.h>
 #endif
 
+#ifdef __USE_GNU
+struct timespec;
+#endif
+
 /* The following constants should be used for the second parameter of
    `shutdown'.  */
 enum
diff --git a/sunrpc/rpc/svc.h b/sunrpc/rpc/svc.h
index 85d0183d48..c77dcf0c4a 100644
--- a/sunrpc/rpc/svc.h
+++ b/sunrpc/rpc/svc.h
@@ -53,6 +53,7 @@ 
 
 #include <features.h>
 #include <rpc/rpc_msg.h>
+#include <sys/select.h>
 
 __BEGIN_DECLS
 
diff --git a/sysdeps/nptl/thread_db.h b/sysdeps/nptl/thread_db.h
index d134acaa24..4d949b0c37 100644
--- a/sysdeps/nptl/thread_db.h
+++ b/sysdeps/nptl/thread_db.h
@@ -26,7 +26,7 @@ 
 #include <stdint.h>
 #include <sys/types.h>
 #include <sys/procfs.h>
-
+#include <bits/types/sigset_t.h>
 
 /* Error codes of the library.  */
 typedef enum
diff --git a/sysdeps/unix/sysv/linux/dl-vdso.h b/sysdeps/unix/sysv/linux/dl-vdso.h
index 9e61ca7423..edecf5faf4 100644
--- a/sysdeps/unix/sysv/linux/dl-vdso.h
+++ b/sysdeps/unix/sysv/linux/dl-vdso.h
@@ -23,6 +23,12 @@ 
 #include <ldsodefs.h>
 #include <dl-hash.h>
 
+/* This header must declare all functions that might be looked up
+   in the vDSO by code fragments generated by make-syscalls.sh.
+   At present the only such function that isn't covered by the above
+   headers is gettimeofday.  */
+#include <sys/time.h>
+
 /* Create version number record for lookup.  */
 #define PREPARE_VERSION(var, vname, vhash) \
   struct r_found_version var;						      \
diff --git a/sysdeps/unix/sysv/linux/pselect.c b/sysdeps/unix/sysv/linux/pselect.c
index c9406cac09..d1106e9b18 100644
--- a/sysdeps/unix/sysv/linux/pselect.c
+++ b/sysdeps/unix/sysv/linux/pselect.c
@@ -19,7 +19,7 @@ 
 #include <errno.h>
 #include <signal.h>
 #include <time.h>
-#include <sys/poll.h>
+#include <sys/select.h>
 #include <kernel-features.h>
 #include <sysdep-cancel.h>