Linux: Add gettid system call wrapper [BZ #6399]

This commit adds gettid to <unistd.h> on Linux, and not to the
kernel-independent GNU API.

gettid is now supportable on Linux because too many things assume a
1:1 mapping between libpthread threads and kernel threads.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>

40 files changed, 388 insertions, 9 deletions

diff --git a/ChangeLog b/ChangeLog
index 20ff76ab62..78ea38a086 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,73 @@
+2019-01-31  Florian Weimer  <fweimer@redhat.com>
+
+	[BZ #6399]
+	Linux: Add gettid system call wrapper.
+	* posix/Makefile (headers): Add bits/unistd_ext.h.
+	* posix/bits/unistd_ext.h: New file.
+	* posix/unistd.h: Include it.
+	* manual/process.texi (Process Identification): Document gettid.
+	* sysdeps/unix/sysv/linux/Makefile [subdir == misc] (tests): Add
+	tst-gettid, tst-gettid-kill.
+	(tst-gettid): Link with $(shared-thread-library).
+	* sysdeps/unix/sysv/linux/Version (GLIBC_2.30): Export gettid.
+	* sysdeps/unix/sysv/linux/bits/unistd_ext.h: New file.
+	* sysdeps/unix/sysv/linux/bits/syscalls.list (gettid): Add.
+	* sysdeps/unix/sysv/linux/bits/tst-gettid.c: New file.
+	* sysdeps/unix/sysv/linux/bits/tst-gettid-kill.c: Likewise.
+	* sysdeps/unix/sysv/linux/aarch64/libc.abilist (GLIBC_2.30):
+	Add gettid.
+	* sysdeps/unix/sysv/linux/alpha/libc.abilist (GLIBC_2.30):
+	Likewise.
+	* sysdeps/unix/sysv/linux/arm/libc.abilist (GLIBC_2.30): Likewise.
+	* sysdeps/unix/sysv/linux/csky/libc.abilist (GLIBC_2.30):
+	Likewise.
+	* sysdeps/unix/sysv/linux/hppa/libc.abilist (GLIBC_2.30):
+	Likewise.
+	* sysdeps/unix/sysv/linux/i386/libc.abilist (GLIBC_2.30):
+	Likewise.
+	* sysdeps/unix/sysv/linux/ia64/libc.abilist (GLIBC_2.30):
+	Likewise.
+	* sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist (GLIBC_2.30):
+	Likewise.
+	* sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist (GLIBC_2.30):
+	Likewise.
+	* sysdeps/unix/sysv/linux/microblaze/libc.abilist (GLIBC_2.30):
+	Likewise.
+	* sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
+	(GLIBC_2.30): Likewise.
+	* sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
+	(GLIBC_2.30): Likewise.
+	* sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
+	(GLIBC_2.30): Likewise.
+	* sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
+	(GLIBC_2.30): Likewise.
+	* sysdeps/unix/sysv/linux/nios2/libc.abilist (GLIBC_2.30):
+	Likewise.
+	* sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
+	(GLIBC_2.30): Likewise.
+	* sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
+	(GLIBC_2.30): Likewise.
+	* sysdeps/unix/sysv/linux/powerpc/powerpc64/be/libc.abilist
+	(GLIBC_2.30): Likewise.
+	* sysdeps/unix/sysv/linux/powerpc/powerpc64/le/libc.abilist
+	(GLIBC_2.30): Likewise.
+	* sysdeps/unix/sysv/linux/riscv/rv64/libc.abilist (GLIBC_2.30):
+	Likewise.
+	* sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist (GLIBC_2.30):
+	Likewise.
+	* sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist (GLIBC_2.30):
+	Likewise.
+	* sysdeps/unix/sysv/linux/sh/libc.abilist (GLIBC_2.30): Likewise.
+	* sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist (GLIBC_2.30):
+	Likewise.
+	* sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist (GLIBC_2.30):
+	Likewise.
+	* sysdeps/unix/sysv/linux/x86_64/64/libc.abilist (GLIBC_2.30):
+	Likewise.
+	* sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist (GLIBC_2.30):
+	Likewise.
+	* sysdeps/unix/sysv/linux/tst-setgetname.c (gettid): Remove.
+
 2019-02-07  Florian Weimer  <fweimer@redhat.com>
 
 	* rt/clock-compat.c (COMPAT_REDIRECT): Turn librt forwarders into
diff --git a/NEWS b/NEWS
index 45792f62a9..0a3b6c7a5a 100644
--- a/NEWS
+++ b/NEWS
@@ -12,6 +12,8 @@ Major new features:
 * The dynamic linker accepts the --preload argument to preload shared
   objects, in addition to the LD_PRELOAD environment variable.
 
+* On Linux, the gettid function has been added.
+
 Deprecated and removed features, and other changes affecting compatibility:
 
 * The functions clock_gettime, clock_getres, clock_settime,
diff --git a/manual/process.texi b/manual/process.texi
index 652b0001b5..5728bde2cb 100644
--- a/manual/process.texi
+++ b/manual/process.texi
@@ -228,6 +228,17 @@ The @code{getppid} function returns the process ID of the parent of the
 current process.
 @end deftypefun
 
+@deftypefun pid_t gettid (void)
+@standards{Linux, unistd.h}
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
+The @code{gettid} function returns the thread ID of the current
+thread.  The returned value is obtained from the Linux kernel and is
+not subject to caching.  See the discussion of thread IDs above,
+especially regarding reuse of the IDs of threads which have exited.
+
+This function is specific to Linux.
+@end deftypefun
+
 @node Creating a Process
 @section Creating a Process
 
diff --git a/posix/Makefile b/posix/Makefile
index 873947f72e..93c3a290d7 100644
--- a/posix/Makefile
+++ b/posix/Makefile
@@ -31,7 +31,8 @@ headers	:= sys/utsname.h sys/times.h sys/wait.h sys/types.h unistd.h	      \
 	   bits/local_lim.h tar.h bits/utsname.h bits/confname.h	      \
 	   bits/waitflags.h bits/waitstatus.h sys/unistd.h sched.h	      \
 	   bits/sched.h bits/cpu-set.h re_comp.h wait.h bits/environments.h   \
-	   cpio.h spawn.h bits/unistd.h bits/types/struct_sched_param.h
+	   cpio.h spawn.h bits/unistd.h bits/types/struct_sched_param.h	      \
+	   bits/unistd_ext.h
 
 routines :=								      \
 	uname								      \
diff --git a/posix/bits/unistd_ext.h b/posix/bits/unistd_ext.h
new file mode 100644
index 0000000000..d6e88f3bd4
--- /dev/null
+++ b/posix/bits/unistd_ext.h
@@ -0,0 +1,21 @@
+/* System-specific extensions of <unistd.h>, generic version.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef _UNISTD_H
+# error "Never include <bits/unistd_ext.h> directly; use <unistd.h> instead."
+#endif
diff --git a/posix/unistd.h b/posix/unistd.h
index f67452122b..55a989f7bb 100644
--- a/posix/unistd.h
+++ b/posix/unistd.h
@@ -1166,6 +1166,9 @@ int getentropy (void *__buffer, size_t __length) __wur;
 # include <bits/unistd.h>
 #endif
 
+/* System-specific extensions.  */
+#include <bits/unistd_ext.h>
+
 __END_DECLS
 
 #endif /* unistd.h  */
diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
index 5f8c2c7c7d..52ac6ad484 100644
--- a/sysdeps/unix/sysv/linux/Makefile
+++ b/sysdeps/unix/sysv/linux/Makefile
@@ -53,10 +53,9 @@ sysdep_headers += sys/mount.h sys/acct.h sys/sysctl.h \
 tests += tst-clone tst-clone2 tst-clone3 tst-fanotify tst-personality \
 	 tst-quota tst-sync_file_range tst-sysconf-iov_max tst-ttyname \
 	 test-errno-linux tst-memfd_create tst-mlock2 tst-pkey \
-	 tst-rlimit-infinity tst-ofdlocks
+	 tst-rlimit-infinity tst-ofdlocks tst-gettid tst-gettid-kill
 tests-internal += tst-ofdlocks-compat
 
-
 # Generate the list of SYS_* macros for the system calls (__NR_*
 # macros).  The file syscall-names.list contains all possible system
 # call names, and the generated header file produces SYS_* macros for
@@ -114,6 +113,9 @@ $(objpfx)tst-mman-consts.out: ../sysdeps/unix/sysv/linux/tst-mman-consts.py
 					  $(CPPFLAGS))" \
 	< /dev/null > $@ 2>&1; $(evaluate-test)
 
+$(objpfx)tst-gettid: $(shared-thread-library)
+$(objpfx)tst-gettid-kill: $(shared-thread-library)
+
 endif # $(subdir) == misc
 
 ifeq ($(subdir),time)
diff --git a/sysdeps/unix/sysv/linux/Versions b/sysdeps/unix/sysv/linux/Versions
index f1e12d9c69..5166ccff25 100644
--- a/sysdeps/unix/sysv/linux/Versions
+++ b/sysdeps/unix/sysv/linux/Versions
@@ -174,6 +174,9 @@ libc {
   GLIBC_2.29 {
     getcpu;
   }
+  GLIBC_2.30 {
+    gettid;
+  }
   GLIBC_PRIVATE {
     # functions used in other libraries
     __syscall_rt_sigqueueinfo;
diff --git a/sysdeps/unix/sysv/linux/aarch64/libc.abilist b/sysdeps/unix/sysv/linux/aarch64/libc.abilist
index 9c330f325e..f3b44d723f 100644
--- a/sysdeps/unix/sysv/linux/aarch64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/aarch64/libc.abilist
@@ -2141,3 +2141,4 @@ GLIBC_2.28 thrd_yield F
 GLIBC_2.29 getcpu F
 GLIBC_2.29 posix_spawn_file_actions_addchdir_np F
 GLIBC_2.29 posix_spawn_file_actions_addfchdir_np F
+GLIBC_2.30 gettid F
diff --git a/sysdeps/unix/sysv/linux/alpha/libc.abilist b/sysdeps/unix/sysv/linux/alpha/libc.abilist
index f630fa4c6f..fe0de20b2b 100644
--- a/sysdeps/unix/sysv/linux/alpha/libc.abilist
+++ b/sysdeps/unix/sysv/linux/alpha/libc.abilist
@@ -2204,6 +2204,7 @@ GLIBC_2.3.4 setipv4sourcefilter F
 GLIBC_2.3.4 setsourcefilter F
 GLIBC_2.3.4 xdr_quad_t F
 GLIBC_2.3.4 xdr_u_quad_t F
+GLIBC_2.30 gettid F
 GLIBC_2.4 _IO_fprintf F
 GLIBC_2.4 _IO_printf F
 GLIBC_2.4 _IO_sprintf F
diff --git a/sysdeps/unix/sysv/linux/arm/libc.abilist b/sysdeps/unix/sysv/linux/arm/libc.abilist
index b96f45590f..f451fefac9 100644
--- a/sysdeps/unix/sysv/linux/arm/libc.abilist
+++ b/sysdeps/unix/sysv/linux/arm/libc.abilist
@@ -126,6 +126,7 @@ GLIBC_2.28 thrd_yield F
 GLIBC_2.29 getcpu F
 GLIBC_2.29 posix_spawn_file_actions_addchdir_np F
 GLIBC_2.29 posix_spawn_file_actions_addfchdir_np F
+GLIBC_2.30 gettid F
 GLIBC_2.4 _Exit F
 GLIBC_2.4 _IO_2_1_stderr_ D 0xa0
 GLIBC_2.4 _IO_2_1_stdin_ D 0xa0
diff --git a/sysdeps/unix/sysv/linux/bits/unistd_ext.h b/sysdeps/unix/sysv/linux/bits/unistd_ext.h
new file mode 100644
index 0000000000..0061172f23
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/bits/unistd_ext.h
@@ -0,0 +1,36 @@
+/* System-specific extensions of <unistd.h>, Linux version.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef _UNISTD_H
+# error "Never include <bits/unistd_ext.h> directly; use <unistd.h> instead."
+#endif
+
+#ifdef __USE_GNU
+
+/* Return the kernel thread ID (TID) of the current thread.  The
+   returned value is not subject to caching.  Most Linux system calls
+   accept a TID in place of a PID.  Using the TID to change properties
+   of a thread that has been created using pthread_create can lead to
+   undefined behavior (comparable to manipulating file descriptors
+   directly that have not been created explicitly).  Note that a TID
+   uniquely identifies a thread only while this thread is running; a
+   TID can be reused once a thread has exited, even if the thread is
+   not detached and has not been joined.  */
+extern __pid_t gettid (void) __THROW;
+
+#endif
diff --git a/sysdeps/unix/sysv/linux/csky/libc.abilist b/sysdeps/unix/sysv/linux/csky/libc.abilist
index 019044c3cd..018d02b414 100644
--- a/sysdeps/unix/sysv/linux/csky/libc.abilist
+++ b/sysdeps/unix/sysv/linux/csky/libc.abilist
@@ -2085,3 +2085,4 @@ GLIBC_2.29 xdrstdio_create F
 GLIBC_2.29 xencrypt F
 GLIBC_2.29 xprt_register F
 GLIBC_2.29 xprt_unregister F
+GLIBC_2.30 gettid F
diff --git a/sysdeps/unix/sysv/linux/hppa/libc.abilist b/sysdeps/unix/sysv/linux/hppa/libc.abilist
index 088a8ee369..fc3c5d5c27 100644
--- a/sysdeps/unix/sysv/linux/hppa/libc.abilist
+++ b/sysdeps/unix/sysv/linux/hppa/libc.abilist
@@ -2037,6 +2037,7 @@ GLIBC_2.3.4 setipv4sourcefilter F
 GLIBC_2.3.4 setsourcefilter F
 GLIBC_2.3.4 xdr_quad_t F
 GLIBC_2.3.4 xdr_u_quad_t F
+GLIBC_2.30 gettid F
 GLIBC_2.4 __confstr_chk F
 GLIBC_2.4 __fgets_chk F
 GLIBC_2.4 __fgets_unlocked_chk F
diff --git a/sysdeps/unix/sysv/linux/i386/libc.abilist b/sysdeps/unix/sysv/linux/i386/libc.abilist
index f7ff2c57b9..f2b04dbbff 100644
--- a/sysdeps/unix/sysv/linux/i386/libc.abilist
+++ b/sysdeps/unix/sysv/linux/i386/libc.abilist
@@ -2203,6 +2203,7 @@ GLIBC_2.3.4 setsourcefilter F
 GLIBC_2.3.4 vm86 F
 GLIBC_2.3.4 xdr_quad_t F
 GLIBC_2.3.4 xdr_u_quad_t F
+GLIBC_2.30 gettid F
 GLIBC_2.4 __confstr_chk F
 GLIBC_2.4 __fgets_chk F
 GLIBC_2.4 __fgets_unlocked_chk F
diff --git a/sysdeps/unix/sysv/linux/ia64/libc.abilist b/sysdeps/unix/sysv/linux/ia64/libc.abilist
index becd8b1033..10ecf2e47c 100644