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authorbrooks <brooks@FreeBSD.org>2017-05-15 22:50:54 +0000
committerbrooks <brooks@FreeBSD.org>2017-05-15 22:50:54 +0000
commit55f52c0df184d00af839c0781e20e389b1fb1d65 (patch)
treee9b08c17737ec3e3f734a9793f494b514786b0b5 /lib
parent60604a2c5e0a093503dd49542afcf9e3b586ea7c (diff)
downloadFreeBSD-src-55f52c0df184d00af839c0781e20e389b1fb1d65.zip
FreeBSD-src-55f52c0df184d00af839c0781e20e389b1fb1d65.tar.gz
MFC r317845-r317846
r317845: Provide a freebsd32 implementation of sigqueue() The previous misuse of sys_sigqueue() was sending random register or stack garbage to 64-bit targets. The freebsd32 implementation preserves the sival_int member of value when signaling a 64-bit process. Document the mixed ABI implementation of union sigval and the incompability of sival_ptr with pointer integrity schemes. Reviewed by: kib, wblock Sponsored by: DARPA, AFRL Differential Revision: https://reviews.freebsd.org/D10605 r317846: Regen post r317845. MFC with: r317845 Sponsored by: DARPA, AFRL
Diffstat (limited to 'lib')
-rw-r--r--lib/libc/sys/sigqueue.218
1 files changed, 16 insertions, 2 deletions
diff --git a/lib/libc/sys/sigqueue.2 b/lib/libc/sys/sigqueue.2
index 04e101b..8377c67 100644
--- a/lib/libc/sys/sigqueue.2
+++ b/lib/libc/sys/sigqueue.2
@@ -27,7 +27,7 @@
.\"
.\" $FreeBSD$
.\"
-.Dd March 10, 2012
+.Dd May 5, 2017
.Dt SIGQUEUE 2
.Os
.Sh NAME
@@ -129,7 +129,6 @@ does not exist.
.Xr kill 2 ,
.Xr sigaction 2 ,
.Xr sigpending 2 ,
-.Xr sigqueue 2 ,
.Xr sigsuspend 2 ,
.Xr sigtimedwait 2 ,
.Xr sigwait 2 ,
@@ -147,3 +146,18 @@ Support for
.Tn POSIX
realtime signal queue first appeared in
.Fx 7.0 .
+.Sh CAVEATS
+When using
+.Nm
+to send signals to a process which might have a different ABI
+(for instance, one is 32-bit and the other 64-bit),
+the
+.Va sival_int
+member of
+.Fa value
+can be delivered reliably, but the
+.Va sival_ptr
+may be truncated in endian dependent ways and must not be relied on.
+Further, many pointer integrity schemes disallow sending pointers to other
+processes, and this technique should not be used in programs intended to
+be portable.
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