Read Sharepoint Audit log reports

The audit log data enabled for a site collection can be read programmatically as follows:

SPSite siteCollection = SPContext.Current.Site;

SPAuditQuery wssQuery = new SPAuditQuery(siteCollection);

SPAuditEntryCollection auditCol;

auditCol = siteCollection.Audit.GetEntries(wssQuery);

// enumerate through audit log and read entries

foreach (SPAuditEntry entry in auditCol) {

    // inspect entry

}

Reading the log data can be a performance issue if all the entries are looped, so restrict the entries to either a list,listitem or a user using methods RestrictToList or ResstrictToListItem, RestrictToUser. SetRangeStart and SetRangeEnd methods on SPAuditQuery class can be used to get the logs for a limited period.