[preload-hacks] / uopen.1

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.TH uopen 1 "5 May 2005" "Straylight/Edgeware" "Preload hacks"
.SH NAME
uopen \- connect to Unix-domain sockets using open(2)
.SH SYNOPSIS
.B uopen
.RI [ command
.RI [ args ...]]
.SH DESCRIPTION
The
.B uopen
command runs
.I command
(by default, the calling user's shell, as determined by the
.B SHELL
environment variable) in an environment where an attempt by the program
to
.BR open (2)
a Unix-domain socket results in a connection being made to the socket.
.PP
This might be used to implement a signature server which chooses a
random signature for newly-written news and mail messages.  This can be
done by writing a simple program to choose and print a signature,
causing it to be invoked in response to connections to the socket
.B $HOME/.signature
(for example, by
.BR fw (1))
and running the message-drafting program under the control of
.BR uopen .
If we were willing to accept
.BR fortune (5)
as our signature generator, this can be done using, say
.VS
fw -d -p$HOME/.sigd.pid \e
  "from unix:$HOME/.signature to exec[fortune -s]"
uopen emacs -nw -f vm
.VE
.SH BUGS
.B uopen
is implemented as an
.B LD_PRELOAD
hack.  It won't work on setuid programs.
.PP
The code is needlessly Linux-specific in some places. 
.PP
It may not catch some uses of
.BR open (2)
or its friends from inside the Linux C library.  It's a strange and
murky world in there, and glibc does all manner of strange linker tricks
to stop you messing with
.BR open (2).
.SH SEE ALSO
.BR fw (1),
.BR ld.so (8),
.BR open (2).
.SH AUTHOR
Mark Wooding, <mdw@distorted.org.uk>
Commit	Line	Data
e4976bb0	1	.de VS
	2	.sp 1
	3	.RS
	4	.nf
	5	.ft B
	6	..
	7	.de VE
	8	.ft R
	9	.fi
	10	.RE
	11	.sp 1
	12	..
292b125f	13	.TH uopen 1 "5 May 2005" "Straylight/Edgeware" "Preload hacks"
e4976bb0	14	.SH NAME
	15	uopen \- connect to Unix-domain sockets using open(2)
	16	.SH SYNOPSIS
	17	.B uopen
	18	.RI [ command
	19	.RI [ args ...]]
	20	.SH DESCRIPTION
	21	The
	22	.B uopen
	23	command runs
	24	.I command
	25	(by default, the calling user's shell, as determined by the
	26	.B SHELL
	27	environment variable) in an environment where an attempt by the program
	28	to
	29	.BR open (2)
	30	a Unix-domain socket results in a connection being made to the socket.
	31	.PP
	32	This might be used to implement a signature server which chooses a
	33	random signature for newly-written news and mail messages. This can be
	34	done by writing a simple program to choose and print a signature,
	35	causing it to be invoked in response to connections to the socket
	36	.B $HOME/.signature
	37	(for example, by
	38	.BR fw (1))
	39	and running the message-drafting program under the control of
	40	.BR uopen .
	41	If we were willing to accept
	42	.BR fortune (5)
	43	as our signature generator, this can be done using, say
	44	.VS
	45	fw -d -p$HOME/.sigd.pid \e
	46	"from unix:$HOME/.signature to exec[fortune -s]"
	47	uopen emacs -nw -f vm
	48	.VE
	49	.SH BUGS
	50	.B uopen
	51	is implemented as an
	52	.B LD_PRELOAD
	53	hack. It won't work on setuid programs.
	54	.PP
	55	The code is needlessly Linux-specific in some places.
	56	.PP
	57	It may not catch some uses of
	58	.BR open (2)
	59	or its friends from inside the Linux C library. It's a strange and
	60	murky world in there, and glibc does all manner of strange linker tricks
	61	to stop you messing with
	62	.BR open (2).
	63	.SH SEE ALSO
	64	.BR fw (1),
	65	.BR ld.so (8),
	66	.BR open (2).
	67	.SH AUTHOR
a8be0591	68	Mark Wooding, <mdw@distorted.org.uk>