b6cbf7203b
This patch imports the unmodified current version of NetBSD libc. The NetBSD includes are in /nbsd_include, while the libc code itself is split between lib/nbsd_libc and common/lib/libc.
175 lines
4.7 KiB
Groff
175 lines
4.7 KiB
Groff
.\" $NetBSD: err.3,v 1.20 2010/03/22 19:30:53 joerg 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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.\" @(#)err.3 8.1 (Berkeley) 6/9/93
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.\"
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.Dd March 21, 2001
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.Dt ERR 3
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.Os
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.Sh NAME
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.Nm err ,
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.Nm verr ,
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.Nm errx ,
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.Nm verrx ,
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.Nm warn ,
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.Nm vwarn ,
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.Nm warnx ,
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.Nm vwarnx
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.Nd formatted error messages
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In err.h
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.Ft void
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.Fn err "int status" "const char *fmt" "..."
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.Ft void
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.Fn verr "int status" "const char *fmt" "va_list args"
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.Ft void
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.Fn errx "int status" "const char *fmt" "..."
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.Ft void
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.Fn verrx "int status" "const char *fmt" "va_list args"
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.Ft void
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.Fn warn "const char *fmt" "..."
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.Ft void
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.Fn vwarn "const char *fmt" "va_list args"
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.Ft void
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.Fn warnx "const char *fmt" "..."
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.Ft void
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.Fn vwarnx "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, a colon character,
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and a space are output.
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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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In the case of the
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.Fn err ,
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.Fn verr ,
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.Fn warn ,
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and
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.Fn vwarn
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functions, the error message string affiliated with the current value of
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the global variable
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.Va errno
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is output next, 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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In all cases, the output is followed by a newline character.
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The
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.Fn errx ,
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.Fn verrx ,
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.Fn warnx ,
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and
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.Fn vwarnx
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functions will not output this error message string.
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.Pp
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The
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.Fn err ,
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.Fn verr ,
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.Fn errx ,
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and
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.Fn verrx
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functions do not return, but instead cause the program to terminate
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with the status value given by the argument
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.Fa status .
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It is often appropriate to use the value
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.Dv EXIT_FAILURE ,
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defined in
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.In stdlib.h ,
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as the
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.Fa status
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argument given to these functions.
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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 terminate with status indicating failure:
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.Bd -literal -offset indent
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if ((p = malloc(size)) == NULL)
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err(EXIT_FAILURE, NULL);
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if ((fd = open(file_name, O_RDONLY, 0)) == -1)
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err(EXIT_FAILURE, "%s", file_name);
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.Ed
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.Pp
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Display an error message and terminate with status indicating failure:
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.Bd -literal -offset indent
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if (tm.tm_hour \*[Lt] START_TIME)
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errx(EXIT_FAILURE, "too early, wait until %s",
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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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warn("%s", block_device);
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.Ed
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.Sh SEE ALSO
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.Xr exit 3 ,
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.Xr getprogname 3 ,
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.Xr strerror 3
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.Sh HISTORY
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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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functions first appeared in
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.Bx 4.4 .
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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 your stack,
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leading to a possible security hole.
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This holds true even if you have built the string
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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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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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err(1, "%s", string);
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.Ed
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