Merge pull request #314 from iovisor/map_unshare

Close fd and unshare when public map is destructed

src/cc/bpf_module.cc

@@ -49,6 +49,7 @@
 #include "frontends/clang/b_frontend_action.h"
 #include "bpf_module.h"
 #include "kbuild_helper.h"
+#include "shared_table.h"
 #include "libbpf.h"
 
 namespace ebpf {
@@ -113,6 +114,10 @@ BPFModule::~BPFModule() {
   engine_.reset();
   rw_engine_.reset();
   ctx_.reset();
+  for (auto table : *tables_) {
+    if (table.is_shared)
+      SharedTables::instance()->remove_fd(table.name);
+  }
 }
 
 static void debug_printf(Module *mod, IRBuilder<> &B, const string &fmt, vector<Value *> args) {

src/cc/frontends/clang/b_frontend_action.cc

@@ -599,6 +599,7 @@ bool BTypeVisitor::VisitVarDecl(VarDecl *Decl) {
         C.getDiagnostics().Report(Decl->getLocStart(), diag_id) << table.name << "already in use";
         return false;
       }
+      table_it->is_shared = true;
       return true;
     }
 

src/cc/shared_table.cc

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include <unistd.h>
+
 #include "shared_table.h"
 
 namespace ebpf {
@@ -43,4 +45,13 @@ bool SharedTables::insert_fd(const string &name, int fd) {
   return true;
 }
 
+bool SharedTables::remove_fd(const string &name) {
+  auto table = tables_.find(name);
+  if (table == tables_.end())
+    return false;
+  close(table->second);
+  tables_.erase(table);
+  return true;
+}
+
 }

src/cc/shared_table.h

@@ -30,6 +30,8 @@ class SharedTables {
   bool insert_fd(const std::string &name, int fd);
   // lookup an fd in the shared table, or -1 if not found
   int lookup_fd(const std::string &name) const;
+  // close and remove a shared fd. return true if the value was found
+  bool remove_fd(const std::string &name);
  private:
   static SharedTables *instance_;
   std::map<std::string, int> tables_;

src/cc/table_desc.h

@@ -38,6 +38,7 @@ struct TableDesc {
   llvm::Function *leaf_sscanf;
   llvm::Function *key_snprintf;
   llvm::Function *leaf_snprintf;
+  bool is_shared;
 };
 
 }  // namespace ebpf