posix: Implement preadv2 and pwritev2

This patch adds support of preadv2 and pwritev2 which are similar to
preadv/pwritev but with an extra flag argument.  As for preadv/pwritev
both interfaces are added a non-standard GNU API.

For default 'posix' implementation trying to emulate the Linux supported
flags is troublesome:

   * We can not temporary change the file state of the O_DSYNC and O_SYNC
     flags to emulate RWF_{D}SYNC (attempts to change the state of using
     fcntl are silently ignored).

   * IOCB_HIPRI requires the file opened in O_DIRECT and uses an internal
     semantic not provided by any other flag (O_NONBLOCK for instance).

So default sysdeps/posix implementations fails with EOPNOTSUPP for any non
supported flag (which are none currently) calls generic preadv/pwritev.
Basically this implementation supports only preadv2 called as preadv (with
flags sets to 0).

The Linux one uses the preadv2/pwritev2 syscall if defined, otherwise it
call preadv/writev.  Instead of using the previous __ASSUME_* to
unconditionally issue the syscall (and avoid building the fallback routine),
it call pread/write if the preadv2/pwritev2 syscalls fails.  The idea
is just avoid adding another __ASSUME_* and checking each architecture
on every kernel bump and simplify code conditionals.

Checked on x86_64-linux-gnu and on i686-linux-gnu and a check with
run-built-tests=no on aarch64-linux-gnu, alpha-linux-gnu, arm-linux-gnueabihf,
ia64-linux-gnu, m68k-linux-gnu, microblaze-linux-gnu, mips{64,64n32}-linux-gnu,
nios2-linux-gnu, powerpc{64,64le}-linux-gnu, s390{x}-linux-gnu,
sparc{64,v9}-linux-gnu, tile{gx,pro}-linux-gnu, and sh4-linux-gnu (all using
gcc 6.3).

	* NEWS: Add note about pwritev2 and preadv2 inclusion.
	* misc/Makefile (routines): Add preadv2, preadv64v2, pwritev2, and
	pwritev64v2.
	(tests): Add tst-preadvwritev2 and tst-preadvwritev64v2.
	* misc/Versions (GLIBC_2.26): Add preadv2, preadv64v2, pwritev2, and
	pwritev64v2.
	* misc/preadv2.c: New file.
	* misc/preadv64v2.c: Likewise.
	* misc/pwritev2.c: Likewise.
	* misc/pwritev64v2.c: Likewise.
	* misc/tst-preadvwritev2.c: Likewise.
	* misc/tst-preadvwritev64v2.c: Likewise.
	* manual/llio.texi: Add preadv2 and pwritev2 documentation.
	* misc/sys/uio.h [__USE_GNU && !__USE_FILE_OFFSET64] (preadv2): New
	prototype.
	[__USE_GNU && !__USE_FILE_OFFSET64] (pwritev2):	Likewise.
	[__USE_GNU && __USE_FILE_OFFSET64] (preadv64v2): Likewise.
	[__USE_GNU && __USE_FILE_OFFSET64] (pwritev64v2): Likewise.
	* misc/tst-preadvwritev-common.c (PREADV): Define if not defined.
	(PWRITEV): Likewise.
	(do_test_with_offset): Use PREADV and PWRITEV macros and check for
	ENOSYS.
	* nptl/tst-cancel4.c (tf_pwritev2): New test.
	(tf_preadv2): Likewise.
	(tf_fsync): Add tf_pwritev2 and tf_preadv2.
	* sysdeps/posix/preadv2.c: Likewise.
	* sysdeps/posix/preadv64v2.c: Likewise.
	* sysdeps/posix/pwritev2.c: Likewise.
	* sysdeps/posix/pwritev64v2.c: Likewise.
	* sysdeps/unix/sysv/linux/kernel-features.h: Add comment for syscall
	support in kernel.
	* sysdeps/unix/sysv/linux/preadv2.c: Likewise.
	* sysdeps/unix/sysv/linux/preadv64v2.c: Likewise.
	* sysdeps/unix/sysv/linux/pwritev2.c: Likewise.
	* sysdeps/unix/sysv/linux/pwritev64v2.c: Likewise.
	* sysdeps/unix/sysv/linux/preadv.c (preadv): Add libc_hidden_def.
	* sysdeps/unix/sysv/linux/preadv64.c (preadv64): Likewise.
	* sysdeps/unix/sysv/linux/pwritev.c (pwritev): Likewise.
	* sysdeps/unix/sysv/linux/pwritev64.c (pwritev64): Likewise.
	* sysdeps/unix/sysv/linux/bits/uio.h: Add supported preadv2/pwritev2
	support flags on Linux.
	* sysdeps/unix/sysv/linux/aarch64/libc.abilist (GLIBC_2.26): Add
	preadv2, preadv64v2, pwritev2, pwritev64v2.
	* sysdeps/unix/sysv/linux/alpha/libc.abilist (GLIBC_2.26): Likewise.
	* sysdeps/unix/sysv/linux/arm/libc.abilist (GLIBC_2.26): Likewise.
	* sysdeps/unix/sysv/linux/hppa/libc.abilist (GLIBC_2.26): Likewise.
	* sysdeps/unix/sysv/linux/i386/libc.abilist (GLIBC_2.26): Likewise.
	* sysdeps/unix/sysv/linux/ia64/libc.abilist (GLIBC_2.26): Likewise.
	* sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist (GLIBC_2.26):
	Likewise.
	* sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist (GLIBC_2.26):
	Likewise.
	* sysdeps/unix/sysv/linux/microblaze/libc.abilist (GLIBC_2.26):
	Likewise.
	* sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist (GLIBC_2.26):
	Likewise.
	* sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist (GLIBC_2.26):
	Likewise.
	* sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist (GLIBC_2.26):
	Likewise.
	* sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist (GLIBC_2.26):
	Likewise.
	* sysdeps/unix/sysv/linux/nios2/libc.abilist (GLIBC_2.26): Likewise.
	* sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
	(GLIBC_2.26): Likewise.
	* sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
	(GLIBC_2.26): Likewise.
	* sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist (GLIBC_2.26):
	Likewise.
	* sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist
	(GLIBC_2.26): Likewise.
	* sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist (GLIBC_2.26):
	Likewise.
	* sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist (GLIBC_2.26):
	Likewise.
	* sysdeps/unix/sysv/linux/sh/libc.abilist (GLIBC_2.26): Likewise.
	* sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist (GLIBC_2.26):
	Likewise.
	* sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist (GLIBC_2.26):
	Likewise.
	* sysdeps/sysv/linux/tile/tilegx/tilegx32/libc.abilist (GLIBC_2.26):
	Likewise.
	* sysdeps/sysv/linux/tile/tilegx/tilegx64/libc.abilist (GLIBC_2.26):
	Likewise.
	* sysdeps/unix/sysv/linux/tile/tilepro/libc.abilist (GLIBC_2.26):
	Likewise.
	* sysdeps/unix/sysv/linux/x86_64/64/libc.abilist (GLIBC_2.26):
	Likewise.
	* sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist (GLIBC_2.26):
	Likewise.

1 files changed, 71 insertions, 0 deletions

diff --git a/nptl/tst-cancel4.c b/nptl/tst-cancel4.c
index e66961f9a8..7a560a1dda 100644
--- a/nptl/tst-cancel4.c
+++ b/nptl/tst-cancel4.c
@@ -1079,6 +1079,75 @@ tf_pwritev (void *arg)
 }
 
 static void *
+tf_pwritev2 (void *arg)
+{
+  int fd;
+
+  if (arg == NULL)
+    /* XXX If somebody can provide a portable test case in which pwritev2
+       blocks we can enable this test to run in both rounds.  */
+    abort ();
+
+  errno = 0;
+
+  char fname[] = "/tmp/tst-cancel4-fd-XXXXXX";
+  tempfd = fd = mkstemp (fname);
+  if (fd == -1)
+    FAIL_EXIT1 ("mkstemp: %m");
+  unlink (fname);
+
+  xpthread_barrier_wait (&b2);
+
+  xpthread_barrier_wait (&b2);
+
+  ssize_t s;
+  pthread_cleanup_push (cl, NULL);
+
+  char buf[WRITE_BUFFER_SIZE];
+  memset (buf, '\0', sizeof (buf));
+  struct iovec iov[1] = { [0] = { .iov_base = buf, .iov_len = sizeof (buf) } };
+  s = pwritev2 (fd, iov, 1, 0, 0);
+
+  pthread_cleanup_pop (0);
+
+  FAIL_EXIT1 ("pwritev2 returns with %zd", s);
+}
+
+static void *
+tf_preadv2 (void *arg)
+{
+  int fd;
+
+  if (arg == NULL)
+    /* XXX If somebody can provide a portable test case in which preadv2
+       blocks we can enable this test to run in both rounds.  */
+    abort ();
+
+  errno = 0;
+
+  char fname[] = "/tmp/tst-cancel4-fd-XXXXXX";
+  tempfd = fd = mkstemp (fname);
+  if (fd == -1)
+    FAIL_EXIT1 ("mkstemp failed: %m");
+  unlink (fname);
+
+  xpthread_barrier_wait (&b2);
+
+  xpthread_barrier_wait (&b2);
+
+  ssize_t s;
+  pthread_cleanup_push (cl, NULL);
+
+  char buf[100];
+  struct iovec iov[1] = { [0] = { .iov_base = buf, .iov_len = sizeof (buf) } };
+  s = preadv2 (fd, iov, 1, 0, 0);
+
+  pthread_cleanup_pop (0);
+
+  FAIL_EXIT1 ("preadv2 returns with %zd", s);
+}
+
+static void *
 tf_fsync (void *arg)
 {
   if (arg == NULL)
@@ -1473,7 +1542,9 @@ struct cancel_tests tests[] =
   ADD_TEST (recvfrom, 2, 0),
   ADD_TEST (recvmsg, 2, 0),
   ADD_TEST (preadv, 2, 1),
+  ADD_TEST (preadv2, 2, 1),
   ADD_TEST (pwritev, 2, 1),
+  ADD_TEST (pwritev2, 2, 1),
   ADD_TEST (open, 2, 1),
   ADD_TEST (close, 2, 1),
   ADD_TEST (pread, 2, 1),