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99320b9168
This way we do not depend on the installed groff being new enough. Signed-off-by: Guillem Jover <guillem@hadrons.org>
181 lines
4.8 KiB
Plaintext
181 lines
4.8 KiB
Plaintext
.\" $OpenBSD: err.3,v 1.20 2014/04/23 16:26:33 jmc Exp $
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.\"
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.\" Copyright (c) 1993
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.\" The Regents of the University of California. 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, are 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, 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. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.Dd $Mdocdate: April 23 2014 $
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.Dt ERRC 3bsd
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.Os
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.Sh NAME
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.Nm errc ,
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.Nm verrc ,
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.Nm warnc ,
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.Nm vwarnc
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.Nd formatted error messages
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.Sh LIBRARY
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.ds str-Lb-libbsd Utility functions from BSD systems (libbsd, \-lbsd)
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.ds doc-str-Lb-libbsd \*[str-Lb-libbsd]
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.Lb libbsd
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.Sh SYNOPSIS
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.In err.h
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(See
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.Xr libbsd 7
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for include usage.)
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.Ft void
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.Fn errc "int status" "int code" "const char *fmt" "..."
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.Ft void
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.Fn verrc "int status" "int code" "const char *fmt" "va_list args"
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.Ft void
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.Fn warnc "int code" "const char *fmt" "..."
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.Ft void
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.Fn vwarnc "int code" "const char *fmt" "va_list args"
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.Sh DESCRIPTION
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The
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.Fn err
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and
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.Fn warn
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family of functions display a formatted error message on the standard
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error output.
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In all cases, the last component of the program name, followed by
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a colon
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.Pq Sq \&:
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character and a space, are output.
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The text that follows depends on the function being called.
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The
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.Fa fmt
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specification (and associated arguments) may be any format allowed by
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.Xr printf 3
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or
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.Dv NULL .
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If the
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.Fa fmt
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argument is not
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.Dv NULL ,
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the formatted error message is output.
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.Pp
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The functions all output an error message string affiliated with
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an error value (see
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.Xr strerror 3 ) ,
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preceded by a colon character and a space if
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.Fa fmt
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is not
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.Dv NULL .
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That is, the output is as follows:
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.Bd -literal -offset indent
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progname: fmt: error message string
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.Ed
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.Pp
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if
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.Fa fmt
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is not
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.Dv NULL ,
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or:
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.Bd -literal -offset indent
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progname: error message string
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.Ed
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.Pp
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if it is.
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.Pp
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The argument
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.Fa code
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is used as the error value instead of the current value of the global variable
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.Va errno .
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.Pp
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In all cases, the output is followed by a newline character.
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.Pp
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The
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.Fn errc ,
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and
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.Fn verrc
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functions do not return, but exit with the value of the argument
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.Fa status .
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.Sh EXAMPLES
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Display the current
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.Va errno
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information string and exit:
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.Bd -literal -offset indent
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if ((p = malloc(size)) == NULL)
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err(1, NULL);
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if ((fd = open(file_name, O_RDONLY, 0)) == -1)
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err(1, "%s", file_name);
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.Ed
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.Pp
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Display an error message and exit:
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.Bd -literal -offset indent
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if (tm.tm_hour < START_TIME)
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errx(1, "too early, wait until %s", start_time_string);
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.Ed
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.Pp
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Warn of an error:
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.Bd -literal -offset indent
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if ((fd = open(raw_device, O_RDONLY, 0)) == -1)
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warnx("%s: %s: trying the block device",
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raw_device, strerror(errno));
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if ((fd = open(block_device, O_RDONLY, 0)) == -1)
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err(1, "%s", block_device);
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.Ed
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.Sh SEE ALSO
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.Xr err 3
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.Xr exit 3 ,
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.Xr perror 3 ,
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.Xr printf 3 ,
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.Xr strerror 3
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.Sh HISTORY
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.ds doc-operating-system-NetBSD-7.0 7.0
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The functions
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.Fn errc ,
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.Fn verrc ,
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.Fn warnc ,
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and
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.Fn vwarnc
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first appeared in
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.Fx 3.0 ,
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.Nx 7.0
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and
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.Ox 5.6 .
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.Sh CAVEATS
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It is important never to pass a string with user-supplied data as a
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format without using
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.Ql %s .
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An attacker can put format specifiers in the string to mangle the stack,
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leading to a possible security hole.
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This holds true even if the string has been built
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.Dq by hand
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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 the
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.Fn err
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and
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.Fn warn
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family of functions.
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.Pp
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Always be sure to use the proper secure idiom:
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.Bd -literal -offset indent
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errc(1, 0, "%s", string);
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.Ed
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