QPID-1148 - from Manuel Tiera

Lock file abstraction in sys/ with implementation portable to Linux and Solaris.

Changes by myself:
 - Makefile.am - must be updated for any new/renamed/removed source files.
 - Exception.h, Daemon.h, LockFile.h: Replaced throwIf() with if (...) throw ErrnoException(...)

The idiom throwIf(call-system-function(), "msg", errno) is incorret
(my fault, not Manuels). It assumes the first argument that makes a
system call call will be evaluated before the last one which fetches
errno. This may not be true on some compilers/platforms.


git-svn-id: https://svn.apache.org/repos/asf/incubator/qpid/trunk/qpid@674865 13f79535-47bb-0310-9956-ffa450edef68

3 files changed, 94 insertions, 14 deletions

diff --git a/cpp/src/qpid/sys/LockFile.h b/cpp/src/qpid/sys/LockFile.h
new file mode 100644
index 0000000000..f06cd6a47d
--- /dev/null
+++ b/cpp/src/qpid/sys/LockFile.h
@@ -0,0 +1,27 @@
+#ifndef _sys_LockFile_h
+#define _sys_LockFile_h
+
+/*
+ *
+ * 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 "posix/LockFile.h"
+
+#endif /*!_sys_LockFile_h*/
+
+
+       
diff --git a/cpp/src/qpid/sys/posix/Fork.cpp b/cpp/src/qpid/sys/posix/Fork.cpp
index 78017a5f91..ec3af620ef 100644
--- a/cpp/src/qpid/sys/posix/Fork.cpp
+++ b/cpp/src/qpid/sys/posix/Fork.cpp
@@ -32,27 +32,22 @@ namespace sys {
 using namespace std;
 
 namespace {
-/** Throw an exception containing msg and strerror if condition is true. */
-void throwIf(bool condition, const string& msg) {
-    if (condition) 
-        throw Exception(msg + (errno? ": "+strError(errno) : string()) + ".");
-}
 
 void writeStr(int fd, const std::string& str) {
     const char* WRITE_ERR = "Error writing to parent process";
     int size = str.size();
-    throwIf(int(sizeof(size)) > ::write(fd, &size, sizeof(size)), WRITE_ERR);
-    throwIf(size > ::write(fd, str.data(), size), WRITE_ERR);
+    if (int(sizeof(size)) > ::write(fd, &size, sizeof(size))) throw ErrnoException(WRITE_ERR);
+    if (size > ::write(fd, str.data(), size)) throw ErrnoException(WRITE_ERR);
 }
 
 string readStr(int fd) {
     string value;
     const char* READ_ERR = "Error reading from forked process";
     int size;
-    throwIf(int(sizeof(size)) > ::read(fd, &size, sizeof(size)), READ_ERR);
+    if (int(sizeof(size)) > ::read(fd, &size, sizeof(size))) throw ErrnoException(READ_ERR);
     if (size > 0) {          // Read string message
         value.resize(size);
-        throwIf(size > ::read(fd, const_cast<char*>(value.data()), size), READ_ERR);
+        if (size > ::read(fd, const_cast<char*>(value.data()), size)) throw ErrnoException(READ_ERR);
     }
     return value;
 }
@@ -64,7 +59,7 @@ Fork::~Fork() {}
 
 void Fork::fork() {
     pid_t pid = ::fork();
-    throwIf(pid < 0, "Failed to fork the process");
+    if (pid < 0) throw ErrnoException("Failed to fork the process");
     if (pid == 0) child();
     else parent(pid);
 }
@@ -80,9 +75,9 @@ struct AutoCloseFd {
 };
 
 void ForkWithMessage::fork() {
-    throwIf(::pipe(pipeFds) < 0, "Can't create pipe");
+    if(::pipe(pipeFds) < 0) throw ErrnoException("Can't create pipe");
     pid_t pid = ::fork();
-    throwIf(pid < 0, "Fork fork failed");
+    if(pid < 0) throw ErrnoException("Fork fork failed");
     if (pid == 0) {             // Child
         AutoCloseFd ac(pipeFds[1]); // Write side.
         ::close(pipeFds[0]); // Read side
@@ -113,8 +108,8 @@ string ForkWithMessage::wait(int timeout) { // parent waits for child.
     FD_ZERO(&fds);
     FD_SET(pipeFds[0], &fds);
     int n=select(FD_SETSIZE, &fds, 0, 0, &tv);
-    throwIf(n==0, "Timed out waiting for fork");
-    throwIf(n<0, "Error waiting for fork");
+    if(n<0) throw ErrnoException("Error waiting for fork");
+    if (n==0) throw Exception("Timed out waiting for fork");
 
     string error = readStr(pipeFds[0]);
     if (error.empty()) return readStr(pipeFds[0]);
diff --git a/cpp/src/qpid/sys/posix/LockFile.h b/cpp/src/qpid/sys/posix/LockFile.h
new file mode 100644
index 0000000000..a8fbb678b8
--- /dev/null
+++ b/cpp/src/qpid/sys/posix/LockFile.h
@@ -0,0 +1,58 @@
+#ifndef _sys_posix_LockFile_h
+#define _sys_posix_LockFile_h
+
+#include "check.h"
+
+#include <boost/noncopyable.hpp>
+#include <string>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+/*
+ *
+ * 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.
+ *
+ */
+namespace qpid {
+namespace sys {
+    
+class LockFile : private boost::noncopyable {
+public:
+    LockFile(const std::string& path_, bool create):
+        path(path_), fd(-1), created(create) {
+        errno = 0;
+        int flags=create ? O_WRONLY|O_CREAT|O_NOFOLLOW : O_RDWR;
+        fd = ::open(path.c_str(), flags, 0644);
+        if (fd < 0) throw ErrnoException("Cannot open " + path, errno);
+        if (::lockf(fd, F_TLOCK, 0) < 0) throw ErrnoException("Cannot lock " + path, errno);
+    }
+
+    ~LockFile() {
+        if (fd >= 0) {
+            ::lockf(fd, F_ULOCK, 0);
+            ::close(fd);
+        }
+    }
+
+    std::string path;
+    int fd;
+    bool created;
+};
+ 
+}
+}
+#endif /*!_sys_posix_LockFile_h*/