linux: Add pidfd_send_signal

This was added on Linux 5.1(3eb39f47934f9d5a3027fe00d906a45fe3a15fad)
as a way to avoid the race condition of using kill (where PID might be
reused by the kernel between between obtaining the pid and sending the
signal).

If the siginfo_t argument is NULL then pidfd_send_signal is equivalent
to kill.  If it is not NULL pidfd_send_signal is equivalent to
rt_sigqueueinfo.

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

37 files changed, 46 insertions, 3 deletions

diff --git a/NEWS b/NEWS
index 278288f768..ad0c08d8ca 100644
--- a/NEWS
+++ b/NEWS
@@ -16,9 +16,9 @@ Major new features:
   -z pack-relative-relocs option, which is supported for some targets
   in recent binutils versions.  Lazy binding doesn't apply to DT_RELR.
 
-* On Linux, the pidfd_open and pidfd_getfd functions have been added.
-  The pidfd functionality provides access to a process while avoiding
-  the issue of PID reuse on tranditional Unix systems.
+* On Linux, the pidfd_open, pidfd_getfd, and pidfd_send_signal functions
+  have been added.  The pidfd functionality provides access to a process
+  while avoiding the issue of PID reuse on tranditional Unix systems.
 
 Deprecated and removed features, and other changes affecting compatibility:
 
diff --git a/sysdeps/unix/sysv/linux/Versions b/sysdeps/unix/sysv/linux/Versions
index 78912c0484..694c64a5bc 100644
--- a/sysdeps/unix/sysv/linux/Versions
+++ b/sysdeps/unix/sysv/linux/Versions
@@ -302,6 +302,7 @@ libc {
   GLIBC_2.36 {
     pidfd_open;
     pidfd_getfd;
+    pidfd_send_signal;
   }
   GLIBC_PRIVATE {
     # functions used in other libraries
diff --git a/sysdeps/unix/sysv/linux/aarch64/libc.abilist b/sysdeps/unix/sysv/linux/aarch64/libc.abilist
index 1acaa31519..7602129631 100644
--- a/sysdeps/unix/sysv/linux/aarch64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/aarch64/libc.abilist
@@ -2618,3 +2618,4 @@ GLIBC_2.35 epoll_pwait2 F
 GLIBC_2.35 posix_spawn_file_actions_addtcsetpgrp_np F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
+GLIBC_2.36 pidfd_send_signal F
diff --git a/sysdeps/unix/sysv/linux/alpha/libc.abilist b/sysdeps/unix/sysv/linux/alpha/libc.abilist
index fa2018b88a..5b39d6023c 100644
--- a/sysdeps/unix/sysv/linux/alpha/libc.abilist
+++ b/sysdeps/unix/sysv/linux/alpha/libc.abilist
@@ -2715,6 +2715,7 @@ GLIBC_2.35 epoll_pwait2 F
 GLIBC_2.35 posix_spawn_file_actions_addtcsetpgrp_np F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
+GLIBC_2.36 pidfd_send_signal 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/arc/libc.abilist b/sysdeps/unix/sysv/linux/arc/libc.abilist
index 4ed3f76c4f..e413302f2e 100644
--- a/sysdeps/unix/sysv/linux/arc/libc.abilist
+++ b/sysdeps/unix/sysv/linux/arc/libc.abilist
@@ -2379,3 +2379,4 @@ GLIBC_2.35 epoll_pwait2 F
 GLIBC_2.35 posix_spawn_file_actions_addtcsetpgrp_np F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
+GLIBC_2.36 pidfd_send_signal F
diff --git a/sysdeps/unix/sysv/linux/arm/be/libc.abilist b/sysdeps/unix/sysv/linux/arm/be/libc.abilist
index edc7cf524e..ade1b93d13 100644
--- a/sysdeps/unix/sysv/linux/arm/be/libc.abilist
+++ b/sysdeps/unix/sysv/linux/arm/be/libc.abilist
@@ -498,6 +498,7 @@ GLIBC_2.35 epoll_pwait2 F
 GLIBC_2.35 posix_spawn_file_actions_addtcsetpgrp_np F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
+GLIBC_2.36 pidfd_send_signal 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/arm/le/libc.abilist b/sysdeps/unix/sysv/linux/arm/le/libc.abilist
index 6554476cd2..10e91537fa 100644
--- a/sysdeps/unix/sysv/linux/arm/le/libc.abilist
+++ b/sysdeps/unix/sysv/linux/arm/le/libc.abilist
@@ -495,6 +495,7 @@ GLIBC_2.35 epoll_pwait2 F
 GLIBC_2.35 posix_spawn_file_actions_addtcsetpgrp_np F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
+GLIBC_2.36 pidfd_send_signal 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/csky/libc.abilist b/sysdeps/unix/sysv/linux/csky/libc.abilist
index 201ec9a966..22618c7aaa 100644
--- a/sysdeps/unix/sysv/linux/csky/libc.abilist
+++ b/sysdeps/unix/sysv/linux/csky/libc.abilist
@@ -2654,3 +2654,4 @@ GLIBC_2.35 epoll_pwait2 F
 GLIBC_2.35 posix_spawn_file_actions_addtcsetpgrp_np F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
+GLIBC_2.36 pidfd_send_signal F
diff --git a/sysdeps/unix/sysv/linux/hppa/libc.abilist b/sysdeps/unix/sysv/linux/hppa/libc.abilist
index 116369f238..e2aea90c74 100644
--- a/sysdeps/unix/sysv/linux/hppa/libc.abilist
+++ b/sysdeps/unix/sysv/linux/hppa/libc.abilist
@@ -2603,6 +2603,7 @@ GLIBC_2.35 epoll_pwait2 F
 GLIBC_2.35 posix_spawn_file_actions_addtcsetpgrp_np F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
+GLIBC_2.36 pidfd_send_signal 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 2c5aea2d0d..29ecca26bb 100644
--- a/sysdeps/unix/sysv/linux/i386/libc.abilist
+++ b/sysdeps/unix/sysv/linux/i386/libc.abilist
@@ -2787,6 +2787,7 @@ GLIBC_2.35 epoll_pwait2 F
 GLIBC_2.35 posix_spawn_file_actions_addtcsetpgrp_np F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
+GLIBC_2.36 pidfd_send_signal 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 4bb67cc684..69a2ca2391 100644
--- a/sysdeps/unix/sysv/linux/ia64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/ia64/libc.abilist
@@ -2553,6 +2553,7 @@ GLIBC_2.35 epoll_pwait2 F
 GLIBC_2.35 posix_spawn_file_actions_addtcsetpgrp_np F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
+GLIBC_2.36 pidfd_send_signal 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/m68k/coldfire/libc.abilist b/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
index dbe82628b0..23cc4ddd8a 100644
--- a/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
+++ b/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
@@ -499,6 +499,7 @@ GLIBC_2.35 epoll_pwait2 F
 GLIBC_2.35 posix_spawn_file_actions_addtcsetpgrp_np F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
+GLIBC_2.36 pidfd_send_signal F
 GLIBC_2.4 _Exit F
 GLIBC_2.4 _IO_2_1_stderr_ D 0x98
 GLIBC_2.4 _IO_2_1_stdin_ D 0x98
diff --git a/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist b/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
index e42d47632e..2d1d8a3d0c 100644
--- a/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
+++ b/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
@@ -2730,6 +2730,7 @@ GLIBC_2.35 epoll_pwait2 F
 GLIBC_2.35 posix_spawn_file_actions_addtcsetpgrp_np F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
+GLIBC_2.36 pidfd_send_signal 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/microblaze/be/libc.abilist b/sysdeps/unix/sysv/linux/microblaze/be/libc.abilist
index 0b79ff3a37..7b6e88bdb9 100644
--- a/sysdeps/unix/sysv/linux/microblaze/be/libc.abilist
+++ b/sysdeps/unix/sysv/linux/microblaze/be/libc.abilist
@@ -2703,3 +2703,4 @@ GLIBC_2.35 epoll_pwait2 F
 GLIBC_2.35 posix_spawn_file_actions_addtcsetpgrp_np F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
+GLIBC_2.36 pidfd_send_signal F
diff --git a/sysdeps/unix/sysv/linux/microblaze/le/libc.abilist b/sysdeps/unix/sysv/linux/microblaze/le/libc.abilist
index d2f0713d1f..155c974790 100644
--- a/sysdeps/unix/sysv/linux/microblaze/le/libc.abilist
+++ b/sysdeps/unix/sysv/linux/microblaze/le/libc.abilist
@@ -2700,3 +2700,4 @@ GLIBC_2.35 epoll_pwait2 F
 GLIBC_2.35 posix_spawn_file_actions_addtcsetpgrp_np F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
+GLIBC_2.36 pidfd_send_signal F
diff --git a/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
index 382852234f..7a811120ea 100644
--- a/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
@@ -2695,6 +2695,7 @@ GLIBC_2.35 epoll_pwait2 F
 GLIBC_2.35 posix_spawn_file_actions_addtcsetpgrp_np F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
+GLIBC_2.36 pidfd_send_signal 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/mips/mips32/nofpu/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
index cb02b6df77..7d28dca5c1 100644
--- a/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
@@ -2693,6 +2693,7 @@ GLIBC_2.35 epoll_pwait2 F
 GLIBC_2.35 posix_spawn_file_actions_addtcsetpgrp_np F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
+GLIBC_2.36 pidfd_send_signal 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/mips/mips64/n32/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
index 7e62a8b7fc..41790f0d63 100644
--- a/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
@@ -2701,6 +2701,7 @@ GLIBC_2.35 epoll_pwait2 F
 GLIBC_2.35 posix_spawn_file_actions_addtcsetpgrp_np F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
+GLIBC_2.36 pidfd_send_signal 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/mips/mips64/n64/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
index 63840726fe..9c15006c12 100644
--- a/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
@@ -2604,6 +2604,7 @@ GLIBC_2.35 epoll_pwait2 F
 GLIBC_2.35 posix_spawn_file_actions_addtcsetpgrp_np F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
+GLIBC_2.36 pidfd_send_signal 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/nios2/libc.abilist b/sysdeps/unix/sysv/linux/nios2/libc.abilist
index e4608208a8..27c0498b60 100644
--- a/sysdeps/unix/sysv/linux/nios2/libc.abilist
+++ b/sysdeps/unix/sysv/linux/nios2/libc.abilist
@@ -2742,3 +2742,4 @@ GLIBC_2.35 epoll_pwait2 F
 GLIBC_2.35 posix_spawn_file_actions_addtcsetpgrp_np F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
+GLIBC_2.36 pidfd_send_signal F
diff --git a/sysdeps/unix/sysv/linux/or1k/libc.abilist b/sysdeps/unix/sysv/linux/or1k/libc.abilist
index 97c37b3f52..e500d4756f 100644
--- a/sysdeps/unix/sysv/linux/or1k/libc.abilist
+++ b/sysdeps/unix/sysv/linux/or1k/libc.abilist
@@ -2125,3 +2125,4 @@ GLIBC_2.35 writev F
 GLIBC_2.35 wscanf F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
+GLIBC_2.36 pidfd_send_signal F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
index 0d017c3119..adb21db204 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
@@ -2757,6 +2757,7 @@ GLIBC_2.35 epoll_pwait2 F
 GLIBC_2.35 posix_spawn_file_actions_addtcsetpgrp_np F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
+GLIBC_2.36 pidfd_send_signal 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/powerpc/powerpc32/nofpu/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
index 5e61dfbd78..28a08c4afb 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
@@ -2790,6 +2790,7 @@ GLIBC_2.35 epoll_pwait2 F
 GLIBC_2.35 posix_spawn_file_actions_addtcsetpgrp_np F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
+GLIBC_2.36 pidfd_send_signal 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/powerpc/powerpc64/be/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc64/be/libc.abilist
index a7ddc5022e..98c5f3e61c 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/be/libc.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/be/libc.abilist
@@ -2512,6 +2512,7 @@ GLIBC_2.35 epoll_pwait2 F
 GLIBC_2.35 posix_spawn_file_actions_addtcsetpgrp_np F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
+GLIBC_2.36 pidfd_send_signal 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/powerpc/powerpc64/le/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc64/le/libc.abilist
index 78117f1dea..31e5aa90cd 100644
--- a/