Abstract native file-locking and directory detection/creation to portable classes LockFile and FileSysDir; resolves QPID-1148

git-svn-id: https://svn.apache.org/repos/asf/incubator/qpid/trunk/qpid@702513 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 89 insertions, 0 deletions

diff --git a/cpp/src/qpid/sys/posix/LockFile.cpp b/cpp/src/qpid/sys/posix/LockFile.cpp
new file mode 100755
index 0000000000..af9ecd7d66
--- /dev/null
+++ b/cpp/src/qpid/sys/posix/LockFile.cpp
@@ -0,0 +1,89 @@
+/*
+ *
+ * Copyright (c) 2008 The Apache Software Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#include "qpid/sys/LockFile.h"
+
+#include <string>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+#include "check.h"
+
+namespace qpid {
+namespace sys {
+
+class LockFilePrivate {
+    friend class LockFile;
+
+    int fd;
+
+public:
+    LockFilePrivate(int f) : fd(f) {}
+};
+
+LockFile::LockFile(const std::string& path_, bool create)
+  : path(path_), created(create) {
+   
+    errno = 0;
+    int flags=create ? O_WRONLY|O_CREAT|O_NOFOLLOW : O_RDWR;
+    int fd = ::open(path.c_str(), flags, 0644);
+    if (fd < 0) throw ErrnoException("Cannot open " + path, errno);
+    if (::lockf(fd, F_TLOCK, 0) < 0) {
+        ::close(fd);
+        throw ErrnoException("Cannot lock " + path, errno);
+    }
+    impl.reset(new LockFilePrivate(fd));
+}
+
+LockFile::~LockFile() {
+    if (impl) {
+        int f = impl->fd;
+        if (f >= 0) {
+            (void) ::lockf(f, F_ULOCK, 0); // Suppress warnings about ignoring return value.
+            ::close(f);
+            impl->fd = -1;
+        }
+    }
+}
+
+pid_t LockFile::readPid(void) const {
+    if (!impl)
+        throw Exception("Lock file not open");
+
+    pid_t pid;
+    int desired_read = sizeof(pid_t);
+    if (desired_read > ::read(impl->fd, &pid, desired_read) ) {
+        throw Exception("Cannot read lock file " + path);
+    }
+    return pid;
+}
+
+void LockFile::writePid(void) {
+    if (!impl)
+        throw Exception("Lock file not open");
+
+    pid_t pid = getpid();
+    int desired_write = sizeof(pid_t);
+    if (desired_write > ::write(impl->fd, &pid, desired_write)) {
+        throw Exception("Cannot write lock file " + path);
+    }
+}
+ 
+}}  /* namespace qpid::sys */