diff options
| -rw-r--r-- | lib/libc/stdlib/strtonum.3 | 92 |
1 files changed, 56 insertions, 36 deletions
diff --git a/lib/libc/stdlib/strtonum.3 b/lib/libc/stdlib/strtonum.3 index 763efc180f5..7a8d7faf6d7 100644 --- a/lib/libc/stdlib/strtonum.3 +++ b/lib/libc/stdlib/strtonum.3 @@ -1,35 +1,18 @@ -.\" Copyright (c) 1990, 1991 The Regents of the University of California. -.\" All rights reserved. +.\" $OpenBSD: strtonum.3,v 1.5 2004/05/06 06:19:01 tedu Exp $ .\" -.\" This code is derived from software contributed to Berkeley by -.\" Chris Torek and the American National Standards Committee X3, -.\" on Information Processing Systems. +.\" Copyright (c) 2004 Ted Unangst .\" -.\" Redistribution and use in source and binary forms, with or without -.\" modification, are permitted provided that the following conditions -.\" are met: -.\" 1. Redistributions of source code must retain the above copyright -.\" notice, this list of conditions and the following disclaimer. -.\" 2. Redistributions in binary form must reproduce the above copyright -.\" notice, this list of conditions and the following disclaimer in the -.\" documentation and/or other materials provided with the distribution. -.\" 3. Neither the name of the University nor the names of its contributors -.\" may be used to endorse or promote products derived from this software -.\" without specific prior written permission. +.\" Permission to use, copy, modify, and distribute this software for any +.\" purpose with or without fee is hereby granted, provided that the above +.\" copyright notice and this permission notice appear in all copies. .\" -.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND -.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE -.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE -.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE -.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL -.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS -.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) -.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT -.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY -.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF -.\" SUCH DAMAGE. -.\" -.\" $OpenBSD: strtonum.3,v 1.4 2004/05/06 04:20:20 deraadt Exp $ +.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES +.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF +.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR +.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES +.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN +.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF +.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. .\" .Dd April 29, 2004 .Dt STRTONUM 3 @@ -55,8 +38,15 @@ function converts the string in to an .Li unsigned long long value. -The conversion is done according to base 10. Negative values may be obtained by casting the result. +The +.Fn strtonum +function was designed to facilitate safe, robust programming +and overcome the shortcomings of the +.Xr atoi 3 +and +.Xr strtol 3 +family of interfaces. .Pp The string may begin with an arbitrary amount of whitespace (as determined by @@ -69,9 +59,7 @@ sign. .Pp The remainder of the string is converted to an .Li unsigned long long -value in the obvious manner, -stopping at the first character which is not a valid digit -in the given base. +value according to base 10. .Pp The value obtained is then checked against the provided .Fa minval @@ -89,14 +77,41 @@ indicating the failure. The .Fn strtonum function returns the result of the conversion, -unless the value would underflow or overflow. -On error, 0 is returned. +unless the value would exceed the provided bounds or is invalid. +On error, 0 is returned and +.Fa errstr +will point to an error message. +.Sh EXAMPLES +Using +.Fn strtonum +correctly is meant to be simpler than the alternative functions. +.Bd -literal -offset indent +int iterations; +const char *errstr; + +iterations = strtonum(optarg, 1, 64, &errstr); +if (errstr) + errx(1, "number of iterations is %s: %s", errstr, optarg); +.Ed +.Pp +The above example will guarantee that the value of iterations is between +1 and 64. .Sh ERRORS .Bl -tag -width Er .It Bq Er ERANGE The given string was out of range. .It Bq Er EINVAL -The given string did not consist solely of a valid number. +The given string did not consist solely of digit characters. +.El +.Pp +If an error occurs, errstr will be set to one of the following strings. +.Bl -tag -width "too large" +.It "too large" +The result was larger than the provided maximum value. +.It "too small" +The result was smaller than the provided minimum value. +.It "invalid" +The string did not consist solely of digit characters. .El .Sh SEE ALSO .Xr atof 3 , @@ -112,3 +127,8 @@ The given string did not consist solely of a valid number. is an .Ox extension. +The existing alternatives, such as +.Xr atoi 3 +and +.Xr strtol 3 +are either impossible or difficult to use safely. |