Valgrind HOWTO and Examples

This repository contains several examples of Valgrind Memcheck usage. Everything is made for my own education, but you might find the examples and the infrastructure useful.

Valgrind sometimes gets things wrong and generates false-positives. To suppress the warnings about those, Valgrind uses suppression files. In this repository, those are named with a .sup extension and live in test/ directory.

How to build sample programs

Just type make:

make

You'll get a lot of programs named with .prog extension. Sample output:

cc -Wall -pedantic -std=c99 -g -ggdb -O0 empty.c -o empty.prog
cc -Wall -pedantic -std=c99 -g -ggdb -O0 fscanf.c -o fscanf.prog
cc -Wall -pedantic -std=c99 -g -ggdb -O0 fscanf_many.c -o fscanf_many.prog
cc -Wall -pedantic -std=c99 -g -ggdb -O0 printf.c -o printf.prog
cc -Wall -pedantic -std=c99 -g -ggdb -O0 vprintf_warn.c -o vprintf_warn.prog

You can run each .prog file and see its result.

How to run Valgrind checking

Just tyoe:

make check

Sample output:

valgrind -v --tool=memcheck --gen-suppressions=all --suppressions=data/empty.memcheck.sup --log-file=empty.memcheck --track-origins=yes ./empty.prog
valgrind -v --tool=memcheck --gen-suppressions=all --suppressions=data/fscanf.memcheck.sup --log-file=fscanf.memcheck --track-origins=yes ./fscanf.prog
valgrind -v --tool=memcheck --gen-suppressions=all --suppressions=data/fscanf_many.memcheck.sup --log-file=fscanf_many.memcheck --track-origins=yes ./fscanf_many.prog
valgrind -v --tool=memcheck --gen-suppressions=all --suppressions=data/printf.memcheck.sup --log-file=printf.memcheck --track-origins=yes ./printf.prog
tab_size: 20
valgrind -v --tool=memcheck --gen-suppressions=all --suppressions=data/vprintf_warn.memcheck.sup --log-file=vprintf_warn.memcheck --track-origins=yes ./vprintf_warn.prog
Going to read: 1 elements

Output sits in .memcheck files. They have a Valgrind output. Passed flags mean verbose output (-v), use default Memcheck tool (--tool=memcheck), generate suppressions without asking (--gen-suppressions=all), use not only default, but also additional suppression file (--suppressions) log output to the file (--log-file) and in case of memory problems, show exactly where they're coming from (--track-origin).

Author

• Wojciech Adam Koszek, wojciech@koszek.com
• http://www.koszek.com