Fix S1751: Rule shouldn't raise on exceptions within while loops

[jcurl]

Description

See GitHub issue #590 . The following code snippet results in S1751 on the return statement. As the catch contains a way out, the loop exits and will reenter the while loop.

protected virtual FileStream CreateLock(string lockFileName, bool retries)
{
    if (retries) ResetRetryTimeout();
    FileStream filelock = null;
    while (true) {
        try {
            filelock = new FileStream(lockFileName,
                FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.None, 8, FileOptions.DeleteOnClose);
            return filelock;
        } catch (Exception e) {
            int code = System.Runtime.InteropServices.Marshal.GetHRForException(e);
            if (code == unchecked((int)0x80070020) ||
                code == unchecked((int)0x80070021)) {
                // Sharing violation
                if (!retries) return null;
                if (!WaitRetryTimeout()) throw;
            } else {
                // All others are considered an error and we don't retry
                throw;
            }
        }
    };
}

Repro steps

See the code snippet above.

Expected behavior

Rule S1751 should not be raised

Actual behavior

S1751 is being raised as a false positive.

Known workarounds

None

Related information

• SonarC# Version 3.4.0.1732 (10/Aug/2017)
• Visual Studio Version VS2015 Enterprise

[Evangelink]

Hi @jcurl. Thanks for the feedback, we will have a look at this soon.