https://blog.thameera.com Tue, 17 Sep 2013 18:24:38 +0000 en-US hourly 1 https://wordpress.org/?v=6.8.12 139676693 https://blog.thameera.com/embarassing-bugs-in-open-source-cc-projects/ https://blog.thameera.com/embarassing-bugs-in-open-source-cc-projects/#comments thameera Tue, 17 Sep 2013 18:24:38 +0000 Uncategorized bugs c++ chromium clang open-source winmerge http://blog.thameera.com/?p=1166 Viva64 develops PVS-Studio, which is a static code analyzer for C/C++/C++11. But their popularity has come from the fact that they run this software on quite a few major open source projects around the internet and post the results. They hit the mark of 1000 error samples yesterday. Their bug database is a treasure trove.…<p><a class="more-link" href="https://blog.thameera.com/embarassing-bugs-in-open-source-cc-projects/" title="Continue reading ‘Embarassing bugs in open source C/C++ projects’">Continue reading <span class="meta-nav">→</span></a></p> <p><a href="http://www.viva64.com/">Viva64</a> develops <a href="http://www.viva64.com/en/pvs-studio/">PVS-Studio</a>, which is a static code analyzer for C/C++/C++11. But their popularity has come from the fact that they run this software on quite a few major open source projects around the internet and post the results. They hit the mark of <a href="http://www.viva64.com/en/n/0098/">1000 error samples</a> yesterday.</p> <p>Their <a href="http://www.viva64.com/en/examples/">bug database</a> is a treasure trove. For one they expose bugs in open source projects that may not be easily seen by the naked eye. And it’s a great learning resource to see common pitfalls.</p> <p>This bug from the Chromium project is obviously a hapless victim of copy-pasting:</p> <pre class="brush: cpp; gutter: true; first-line: 1; highlight: []; html-script: false"> bool AutoFillProfileHasName(const AutoFillProfile&amp; profile) { return !profile.GetFieldText(AutofillType(NAME_FIRST)).empty() || !profile.GetFieldText(AutofillType(NAME_MIDDLE)).empty() || !profile.GetFieldText(AutofillType(NAME_MIDDLE)).empty(); } </pre> <p>Most probably the programmer intended to put <code>NAME_LAST</code> at the end.</p> <p>Dereferencing a null pointer in Clang. Ouch.</p> <pre class="brush: cpp; gutter: true; first-line: 1; highlight: []; html-script: false"> void MatcherGen::EmitLeafMatchCode(const TreePatternNode *N) { ... if (DI == 0) { errs() &lt;&lt; "Unknown leaf kind: " &lt;&lt; *DI &lt;&lt; "\n"; abort(); } ... } </pre> <p>And in this snippet from WinMerge, it might not be clear what the programmer has intended at first.</p> <pre class="brush: cpp; gutter: true; first-line: 1; highlight: []; html-script: false"> void CDirView::GetItemFileNames(int sel, String&amp; strLeft, String&amp; strRight) const { UINT_PTR diffpos = GetItemKey(sel); if (diffpos == (UINT_PTR)SPECIAL_ITEM_POS) { strLeft.empty(); strRight.empty(); } else { ... } } </pre> <p>It turns out that the intention was to clear the string. Actually it should’ve been <code>strLeft.clear();</code> and <code>strRight.clear();</code>. The static analyzer has caught the issue because the return value of <code>empty()</code> is required to be utilized, which is not done here.</p> https://blog.thameera.com/embarassing-bugs-in-open-source-cc-projects/feed/ 2 1166