1 files changed, 132 insertions, 0 deletions
diff --git a/src/lib/log/interprocess/interprocess_sync_file.cc b/src/lib/log/interprocess/interprocess_sync_file.cc
new file mode 100644
index 0000000..ed6a5b7
--- /dev/null
+++ b/src/lib/log/interprocess/interprocess_sync_file.cc
@@ -0,0 +1,132 @@
+// Copyright (C) 2012-2015 Internet Systems Consortium, Inc. ("ISC")
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+// This file requires LOCKFILE_DIR to be defined. It points to the default
+// directory where lockfile will be created.
+
+#include <config.h>
+
+#include <log/interprocess/interprocess_sync_file.h>
+
+#include <string>
+#include <cerrno>
+#include <cstring>
+#include <sstream>
+#include <iostream>
+
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+namespace isc {
+namespace log {
+namespace interprocess {
+
+InterprocessSyncFile::~InterprocessSyncFile() {
+    if (fd_ != -1) {
+        // This will also release any applied locks.
+        close(fd_);
+        // The lockfile will continue to exist, and we must not delete
+        // it.
+    }
+}
+
+bool
+InterprocessSyncFile::do_lock(int cmd, short l_type) {
+    // Open lock file only when necessary (i.e., here). This is so that
+    // if a default InterprocessSync object is replaced with another
+    // implementation, it doesn't attempt any opens.
+    if (fd_ == -1) {
+        std::string lockfile_path = LOCKFILE_DIR;
+
+        const char* const env = getenv("KEA_LOCKFILE_DIR");
+        if (env != NULL) {
+            lockfile_path = env;
+        }
+
+        lockfile_path += "/" + task_name_ + "_lockfile";
+
+        // Open the lockfile in the constructor so it doesn't do the access
+        // checks every time a message is logged.
+        const mode_t mode = umask(S_IXUSR | S_IXGRP | S_IXOTH); // 0111
+        fd_ = open(lockfile_path.c_str(), O_CREAT | O_RDWR,
+                   S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP); // 0660
+        umask(mode);
+
+        if (fd_ == -1) {
+            std::stringstream tmp;
+
+            // We failed to create a lockfile. This means that the logging
+            // system is unusable. We need to report the issue using plain
+            // print to stderr.
+            tmp << "Unable to use interprocess sync lockfile ("
+                << std::strerror(errno) << "): " << lockfile_path;
+            std::cerr << tmp.str() << std::endl;
+
+            // And then throw exception as usual.
+            isc_throw(InterprocessSyncFileError, tmp.str());
+        }
+    }
+
+    struct flock lock;
+
+    memset(&lock, 0, sizeof (lock));
+    lock.l_type = l_type;
+    lock.l_whence = SEEK_SET;
+    lock.l_start = 0;
+    lock.l_len = 1;
+
+    return (fcntl(fd_, cmd, &lock) == 0);
+}
+
+bool
+InterprocessSyncFile::lock() {
+    if (is_locked_) {
+        return (true);
+    }
+
+    if (do_lock(F_SETLKW, F_WRLCK)) {
+        is_locked_ = true;
+        return (true);
+    }
+
+    return (false);
+}
+
+bool
+InterprocessSyncFile::tryLock() {
+    if (is_locked_) {
+        return (true);
+    }
+
+    if (do_lock(F_SETLK, F_WRLCK)) {
+        is_locked_ = true;
+        return (true);
+    }
+
+    return (false);
+}
+
+bool
+InterprocessSyncFile::unlock() {
+    if (!is_locked_) {
+        return (true);
+    }
+
+    if (do_lock(F_SETLKW, F_UNLCK)) {
+        is_locked_ = false;
+        return (true);
+    }
+
+    return (false);
+}
+
+} // namespace interprocess
+} // namespace log
+} // namespace isc