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.