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.Dd January 22, 2007 .Dt _DIAGASSERT 3 .Os .Sh NAME .Nm _DIAGASSERT .Nd expression verification macro .Sh SYNOPSIS n assert.h .Fn _DIAGASSERT expression .Sh DESCRIPTION The .Fn _DIAGASSERT macro tests the given .Ar expression and if it is false, one or more of the following may occur: l -bullet -offset indent t a diagnostic message may be logged to the system logger with .Xr syslog 3 . This is default behaviour. t a diagnostic message may be printed to the .Dv stderr stream. t the calling process will be terminated by calling .Xr abort 3 . .El
p This behaviour may be changed by setting the .Ev LIBC_DIAGASSERT environment variable (see below).
p The diagnostic message consists of the text of the expression, the name of the source file, the line number and the enclosing function.
p If .Ar expression is true, the .Fn _DIAGASSERT macro does nothing.
p The .Fn _DIAGASSERT macro is not compiled in by default, and will only be compiled in with the .Xr cc 1 option .Fl D_DIAGNOSTIC .
p This macro is used in the various system libraries such as the .Lb libc to ensure that various library calls are invoked with valid arguments. .Sh ENVIRONMENT The .Ev LIBC_DIAGASSERT environment variable can be used to modify the default behaviour of logging the assertion to the system logger.
p .Ev LIBC_DIAGASSERT may be set to one or more of the following characters: l -tag -width xxx -offset indent t a .Xr abort 3 once any assertion messages have been logged and/or printed. t A Opposite of .Dq a . t e Print the assertion message to the .Dv stderr stream. t E Opposite of .Dq e . t l Log the assertion message with .Xr syslog 3 to the facility .Dv user.debug . t L Opposite of .Dq l . .El .Sh DIAGNOSTICS The diagnostic message has the following format: d -literal -offset indent "assertion \e"%s\e" failed: file \e"%s\e", line %d, function \e"%s\e"\en", "expression", __FILE__, __LINE__, __func__ .Ed .Sh SEE ALSO .Xr cc 1 , .Xr abort 3 , .Xr assert 3 , .Xr syslog 3 .Sh HISTORY The .Nm _DIAGASSERT macro appeared in .Nx 1.5 .