78f89679fc
Some applications, notably PostgreSQL, want to call setproctitle() very often. It's slow. Provide an alternative cheap way of updating process titles without making any syscalls, instead requiring other processes (top, ps etc) to do a bit more work to retrieve the data. This uses a pre-existing code path inherited from ancient BSD, which always did it that way. Submitted by: Thomas Munro MFC after: 2 weeks Differential revision: https://reviews.freebsd.org/D16111
134 lines
3.5 KiB
Groff
134 lines
3.5 KiB
Groff
.\" Copyright (c) 1995 Peter Wemm <peter@FreeBSD.org>
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, is permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice immediately at the beginning of the file, without modification,
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.\" this list of conditions, and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. This work was done expressly for inclusion into FreeBSD. Other use
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.\" is permitted provided this notation is included.
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.\" 4. Absolutely no warranty of function or purpose is made by the author
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.\" Peter Wemm.
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.\" 5. Modifications may be freely made to this file providing the above
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.\" conditions are met.
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.\"
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.\" $FreeBSD$
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.\"
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.\" The following requests are required for all man pages.
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.Dd July 4, 2018
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.Dt SETPROCTITLE 3
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.Os
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.Sh NAME
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.Nm setproctitle
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.Nd set process title
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.Sh SYNOPSIS
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.In sys/types.h
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.In unistd.h
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.Ft void
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.Fn setproctitle "const char *fmt" "..."
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.Ft void
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.Fn setproctitle_fast "const char *fmt" "..."
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.Sh DESCRIPTION
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The
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.Fn setproctitle
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library routine sets the process title that appears on the
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.Xr ps 1
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command.
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The
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.Fn setproctitle_fast
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variant is optimized for high frequency updates, but may make the
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.Xr ps 1
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command slightly slower by not updating the kernel cache of the program
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arguments.
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.Pp
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The title is set from the executable's name, followed by the
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result of a
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.Xr printf 3
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style expansion of the arguments as specified by the
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.Va fmt
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argument.
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If the
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.Va fmt
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argument begins with a
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.Dq -
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character, the executable's name is skipped.
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.Pp
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If
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.Va fmt
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is NULL, the process title is restored.
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.Sh EXAMPLES
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To set the title on a daemon to indicate its activity:
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.Bd -literal -offset indent
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setproctitle("talking to %s", inet_ntoa(addr));
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.Ed
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.Sh SEE ALSO
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.Xr ps 1 ,
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.Xr w 1 ,
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.Xr kvm 3 ,
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.Xr kvm_getargv 3 ,
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.Xr printf 3
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.Sh STANDARDS
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The
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.Fn setproctitle
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function
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is implicitly non-standard.
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Other methods of causing the
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.Xr ps 1
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command line to change, including copying over the argv[0] string are
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also implicitly non-portable.
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It is preferable to use an operating system
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supplied
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.Fn setproctitle
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if present.
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.Pp
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Unfortunately, it is possible that there are other calling conventions
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to other versions of
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.Fn setproctitle ,
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although none have been found by the author as yet.
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This is believed to be
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the predominant convention.
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.Pp
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It is thought that the implementation is compatible with other systems,
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including
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.Nx
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and
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.Bsx .
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.Sh HISTORY
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The
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.Fn setproctitle
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function
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first appeared in
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.Fx 2.2 .
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The
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.Fn setproctitle_fast
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function first appeared in
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.Fx 12 .
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Other operating systems have
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similar functions.
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.Sh AUTHORS
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.An -nosplit
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.An Peter Wemm Aq Mt peter@FreeBSD.org
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stole the idea from the
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.Sy "Sendmail 8.7.3"
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source code by
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.An Eric Allman Aq Mt eric@sendmail.org .
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.Sh BUGS
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Never pass a string with user-supplied data as a format without using
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.Ql %s .
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An attacker can put format specifiers in the string to mangle your stack,
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leading to a possible security hole.
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This holds true even if the string was built using a function like
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.Fn snprintf ,
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as the resulting string may still contain user-supplied conversion specifiers
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for later interpolation by
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.Fn setproctitle .
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.Pp
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Always use the proper secure idiom:
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.Pp
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.Dl setproctitle("%s", string);
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