NAME
_DIAGASSERT —
expression verification
macro
SYNOPSIS
#include <assert.h>
_DIAGASSERT(
expression);
DESCRIPTION
The
_DIAGASSERT() macro tests the given
expression and if it is false, one or more of the
following may occur:
- a diagnostic message may be logged to the system logger
with syslog(3). This is
default behaviour.
- a diagnostic message may be printed to the
stderr
stream.
- the calling process will be terminated by calling
abort(3).
This behaviour may be changed by setting the
LIBC_DIAGASSERT
environment variable (see below).
The diagnostic message consists of the text of the expression, the name of the
source file, the line number and the enclosing function.
If
expression is true, the
_DIAGASSERT()
macro does nothing.
The
_DIAGASSERT() macro is not compiled in by default, and
will only be compiled in with the
cc(1) option
-D_DIAGNOSTIC.
This macro is used in the various system libraries such as the
Standard C Library (libc, -lc) to ensure that various
library calls are invoked with valid arguments.
ENVIRONMENT
The
LIBC_DIAGASSERT
environment variable can be used to
modify the default behaviour of logging the assertion to the system logger.
LIBC_DIAGASSERT
may be set to one or more of the
following characters:
-
-
- a
- abort(3) once
any assertion messages have been logged and/or printed.
-
-
- A
- Opposite of “a”.
-
-
- e
- Print the assertion message to the
stderr
stream.
-
-
- E
- Opposite of “e”.
-
-
- l
- Log the assertion message with
syslog(3) to the facility
user.debug
.
-
-
- L
- Opposite of “l”.
DIAGNOSTICS
The diagnostic message has the following format:
"assertion \"%s\" failed: file \"%s\", line %d, function \"%s\"\n",
"expression", __FILE__, __LINE__, __func__
SEE ALSO
cc(1),
abort(3),
assert(3),
syslog(3)
HISTORY
The
_DIAGASSERT macro appeared in
NetBSD
1.5.