139 lines
3.6 KiB
Plaintext
139 lines
3.6 KiB
Plaintext
.\" Id: assertions.mdoc,v 1.3 2004/03/09 06:30:06 marka Exp
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.\"
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.\" Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
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.\" Copyright (c) 1997,1999 by Internet Software Consortium.
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.\"
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.\" Permission to use, copy, modify, and distribute this software for any
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.\" purpose with or without fee is hereby granted, provided that the above
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.\" copyright notice and this permission notice appear in all copies.
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.\"
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.\" THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
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.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR
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.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
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.\" OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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.\"
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.Dd November 17, 1997
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.Dt ASSERTIONS 3
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.Os ISC
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.Sh NAME
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.Nm REQUIRE ,
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.Nm REQUIRE_ERR ,
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.Nm ENSURE ,
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.Nm ENSURE_ERR ,
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.Nm INSIST ,
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.Nm INSIST_ERR ,
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.Nm INVARIANT ,
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.Nm INVARIANT_ERR ,
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.Nm set_assertion_failure_callback
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.Nd assertion system
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.Sh SYNOPSIS
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.Fd #include <isc/assertions.h>
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.Fo "typedef void (*assertion_failure_callback)"
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.Fa "char *filename"
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.Fa "int line"
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.Fa "assertion_type type"
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.Fa "char *condition"
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.Fa "int print_errno"
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.Fc
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.Fn REQUIRE "int boolean_expression"
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.Fn REQUIRE_ERR "int boolean_expression"
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.Fn ENSURE "int boolean_expression"
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.Fn ENSURE_ERR "int boolean_expression"
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.Fn INSIST "int boolean_expression"
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.Fn INSIST_ERR "int boolean_expression"
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.Fn INVARIANT "int boolean_expression"
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.Fn INVARIANT_ERR "int boolean_expression"
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.Ft void
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.Fn set_assertion_failure_callback "assertion_failure_callback callback"
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.Ft char *
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.Fn assertion_type_to_text "assertion_type type"
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.Sh DESCRIPTION
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The
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.Fn REQUIRE ,
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.Fn ENSURE ,
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.Fn INSIST ,
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and
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.Fn INVARIANT
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macros evaluate a boolean expression, and if it is false, they invoke the
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current assertion failure callback. The default callback will print a message
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to
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.Li stderr
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describing the failure, and then cause the program to dump core.
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If the
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.Dq Fn _ERR
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variant of the assertion is used, the callback will include
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.Fn strerror "errno"
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in its message.
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.Pp
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Each assertion type has an associated
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.Li CHECK
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macro. If this macro's value is
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.Dq 0
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when
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.Dq "<isc/assertions.h>"
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is included, then assertions of that type will not be checked. E.g.
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.Pp
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.Dl #define CHECK_ENSURE 0
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.Pp
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will disable checking of
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.Fn ENSURE
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and
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.Fn ENSURE_ERR .
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The macros
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.Li CHECK_ALL
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and
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.Li CHECK_NONE
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may also be used, respectively specifying that either all or none of the
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assertion types should be checked.
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.Pp
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.Fn set_assertion_failure_callback
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specifies the function to call when an assertion fails.
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.Pp
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When an
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.Fn assertion_failure_callback
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is called, the
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.Fa filename
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and
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.Fa line
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arguments specify the filename and line number of the failing assertion.
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The
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.Fa type
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is one of:
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.Bd -literal -offset indent
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assert_require
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assert_ensure
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assert_insist
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assert_invariant
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.Ed
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.Pp
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and may be used by the callback to determine the type of the failing
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assertion.
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.Fa condition
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is the literal text of the assertion that failed.
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.Fa print_errno
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will be non-zero if the callback should print
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.Fa strerror "errno"
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as part of its output.
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.Pp
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.Fn assertion_type_to_text
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returns a textual representation of
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.Fa type .
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For example,
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.Fn assertion_type_to_text "assert_require"
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returns the string
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.Dq REQUIRE .
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.Sh SEE ALSO
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.Rs
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.%A Bertrand Meyer
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.%B Object-Oriented Software Construction, 2nd edition
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.%Q Prentice\-Hall
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.%D 1997
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.%O ISBN 0\-13\-629155\-4
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.%P chapter 11
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.Re
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.Sh AUTHOR
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Bob Halley (ISC).
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