@node Running self-tests under valgrind
@section Running self-tests under valgrind

@cindex valgrind

For projects written in C or similar languages, running the self-tests
under Valgrind can reveal hard to find memory issues.  Gnulib supports
two ways to make use of Valgrind: one that enables use of Valgrind at
configure time, when @code{configure} found it to be present; and one
at the discretion of the developer.

@menu
* Using valgrind automatically::
* Valgrind options::
* Using valgrind manually::
* Valgrind and shell scripts::
@end menu

@node Using valgrind automatically
@subsection Using valgrind without developer intervention

The @code{valgrind-tests} module searches for Valgrind at configure time
and declares the @code{LOG_VALGRIND} automake variable for use with
automake's @code{LOG_COMPILER}.

After importing the @code{valgrind-tests} module to your project, you
use it by adding the following to the @code{Makefile.am} that runs the
self-tests:

@smallexample
LOG_COMPILER = $(LOG_VALGRIND)
@end smallexample

This will run all self-checks under valgrind.

Replace @code{LOG_COMPILER} with @code{TESTS_ENVIRONMENT} if you are
using the old serial test harness.  The parallel test harness has been
the default in automake since version 1.11.3, but if you are using an
older automake, or put @samp{serial-tests} in
@samp{AM_INIT_AUTOMAKE}/@samp{AUTOMAKE_OPTIONS} you would still be using
the serial test harness.

If you desire a project-wide decision that valgrind is not enabled by
default, but still allow users to enable it with
@code{--enable-valgrind-tests} you may put the following in configure.ac
before gl_INIT.

@smallexample
gl_VALGRIND_TESTS_DEFAULT_NO
@end smallexample

@node Valgrind options
@subsection Valgrind options

The @code{VALGRIND} variable holds the name of the valgrind binary and
some options passed to valgrind.  You may provide additional options
that are passed to valgrind using the @samp{VALGRINDFLAGS} variable, for
example:

@smallexample
./configure VALGRINDFLAGS="--suppressions=~/local.supp"
@end smallexample

Alternatively during build phase:

@smallexample
make check VALGRINDFLAGS="--suppressions=~/local.supp"
@end smallexample

This is useful if you have a valgrind suppression files that are needed
to avoid triggering errors for known errors, typically in system
libraries.

The @code{VALGRIND} variable include options that are useful when
valgrind is run non-interactively through the test harness.  The default
parameters are @code{-q} to silence the output,
@code{--error-exitcode=1} to cause valgrind errors to be treated as
fatal errors, and @code{--leak-check=full} to check for memory leaks.

These options can be controlled through the @code{DEFAULT_VALGRINDFLAGS}
variable.  For example, when configuring the package:

@smallexample
./configure DEFAULT_VALGRINDFLAGS="--quiet"
@end smallexample

Alternatively, during the build phase:

@smallexample
make check DEFAULT_VALGRINDFLAGS="--quiet"
@end smallexample

That would have the effect of removing @code{--error-exitcode=1} and
@code{--leak-check=full} from the default options, thus causing any
valgrind errors to be silently ignored, instead of causing fatal test
failures.

As a developer you may use the variables in @code{configure.ac} before
calling @code{gl_INIT}, like this if your program has deeply-nested call
chains:

@smallexample
gl_EARLY
...
VALGRINDFLAGS="$VALGRINDFLAGS --num-callers=42"
...
gl_INIT
@end smallexample

Note that any user-supplied @code{VALGRINDFLAGS} value is preserved,
which is usually what you want.

Finally, as a developer you may want to provide additional per-directory
options to valgrind and the @code{AM_VALGRINDFLAGS} variable can be used
for this.  For example:

@smallexample
AM_VALGRINDFLAGS = --suppressions=$(srcdir)/local-valgrind.supp
LOG_COMPILER = $(LOG_VALGRIND)
@end smallexample

@node Using valgrind manually
@subsection Using valgrind at the developer's discretion

In this approach, you define a @code{Makefile.am} variable @samp{VALGRIND}
(or, more abstractly, @samp{CHECKER}), that is usually set to empty.
When you have configured and built the package and you decide that you want
to run the tests with valgrind, you do so by modifying the definition of
@samp{VALGRIND} in the Makefile.

@node Valgrind and shell scripts
@subsection How to use Valgrind with shell scripts

It is not desirable to apply valgrind to shell scripts or other non-binaries,
because
@itemize @bullet
@item
It is wasteful, and you usually don't want to look for memory leaks in bash.
@item
On a bi-arch system, you may get an error message such as
"valgrind: wrong executable class (eg. 32-bit instead of 64-bit)".
@end itemize

There are two ways to avoid this:

@itemize @bullet
@item
Using the Automake parallel-tests feature, you can use the following instead:

@smallexample
TEST_EXTENSIONS = .pl .sh
LOG_COMPILER = $(LOG_VALGRIND)
@end smallexample

Then valgrind will only be used for the non-.sh and non-.pl tests.

For old automake (before 1.11.3), you will need @code{AUTOMAKE_OPTIONS =
parallel-tests} to enable the parallel test harness.

@item
You can make use of the @code{build-aux/run-test} script from Gnulib.
Add these lines to your @code{Makefile.am}:

@smallexample
LOG_COMPILER += $(SHELL) $(top_srcdir)/build-aux/run-test '$(LOG_VALGRIND)'
@end smallexample

Replace @code{LOG_COMPILER} with @code{TESTS_ENVIRONMENT} if you use the
old serial test harness.
@end itemize

However, with this measure in place, binaries invoked through scripts will
not be invoked under valgrind.  This can be solved by defining environment
variables in the @code{TESTS_ENVIRONMENT} variable that are then used by the
shell scripts.  For example, add the following:

@smallexample
TESTS_ENVIRONMENT = VALGRIND='$(LOG_VALGRIND)'
@end smallexample

And then modify the shell scripts to invoke the binary prefixed with
@code{$VALGRIND}.