Lock file for accessing the video directory

HISTORY

@@ -786,3 +786,8 @@ Video Disk Recorder Revision History
   at the expected time).
 - Made the volume, mute and power keys work when a menu is active, too (thanks
   to Matthias Weingart).
+
+2001-09-30: Version 0.97
+
+- Implemented a lock file to prevent more than one instance of VDR from removing
+  files from the video directory at the same time.

config.h

@@ -4,7 +4,7 @@
  * See the main source file 'vdr.c' for copyright information and
  * how to reach the author.
  *
- * $Id: config.h 1.81 2001/09/22 13:37:05 kls Exp $
+ * $Id: config.h 1.82 2001/09/30 10:37:18 kls Exp $
  */
 
 #ifndef __CONFIG_H
@@ -19,7 +19,7 @@
 #include "eit.h"
 #include "tools.h"
 
-#define VDRVERSION "0.96"
+#define VDRVERSION "0.97"
 
 #define MAXPRIORITY 99
 #define MAXLIFETIME 99

recording.c

@@ -4,7 +4,7 @@
  * See the main source file 'vdr.c' for copyright information and
  * how to reach the author.
  *
- * $Id: recording.c 1.37 2001/09/23 13:43:29 kls Exp $
+ * $Id: recording.c 1.38 2001/09/30 10:29:11 kls Exp $
  */
 
 #define _GNU_SOURCE
@@ -45,6 +45,10 @@ void RemoveDeletedRecordings(void)
 {
   static time_t LastRemoveCheck = 0;
   if (time(NULL) - LastRemoveCheck > REMOVECHECKDELTA) {
+     // Make sure only one instance of VDR does this:
+     cLockFile LockFile(VideoDirectory);
+     if (!LockFile.Lock())
+        return;
      // Remove the oldest file that has been "deleted":
      cRecordings Recordings;
      if (Recordings.Load(true)) {
@@ -74,6 +78,10 @@ void AssertFreeDiskSpace(int Priority)
   static time_t LastFreeDiskCheck = 0;
   if (time(NULL) - LastFreeDiskCheck > DISKCHECKDELTA) {
      if (!VideoFileSpaceAvailable(MINDISKSPACE)) {
+        // Make sure only one instance of VDR does this:
+        cLockFile LockFile(VideoDirectory);
+        if (!LockFile.Lock())
+           return;
         // Remove the oldest file that has been "deleted":
         cRecordings Recordings;
         if (Recordings.Load(true)) {

tools.c

@@ -4,7 +4,7 @@
  * See the main source file 'vdr.c' for copyright information and
  * how to reach the author.
  *
- * $Id: tools.c 1.46 2001/09/22 12:13:40 kls Exp $
+ * $Id: tools.c 1.47 2001/09/30 10:36:40 kls Exp $
  */
 
 #define _GNU_SOURCE
@@ -590,6 +590,72 @@ bool cSafeFile::Close(void)
   return result;
 }
 
+// --- cLockFile -------------------------------------------------------------
+
+#define LOCKFILENAME      ".lock-vdr"
+#define LOCKFILESTALETIME 600 // seconds before considering a lock file "stale"
+
+cLockFile::cLockFile(const char *Directory)
+{
+  fileName = NULL;
+  f = -1;
+  if (DirectoryOk(Directory))
+     asprintf(&fileName, "%s/%s", Directory, LOCKFILENAME);
+}
+
+cLockFile::~cLockFile()
+{
+  Unlock();
+  delete fileName;
+}
+
+bool cLockFile::Lock(int WaitSeconds)
+{
+  if (f < 0 && fileName) {
+     time_t Timeout = time(NULL) + WaitSeconds;
+     do {
+        f = open(fileName, O_WRONLY | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
+        if (f < 0) {
+           if (errno == EEXIST) {
+              struct stat fs;
+              if (stat(fileName, &fs) == 0) {
+                 if (time(NULL) - fs.st_mtime > LOCKFILESTALETIME) {
+                    esyslog(LOG_ERR, "ERROR: removing stale lock file '%s'", fileName);
+                    if (remove(fileName) < 0) {
+                       LOG_ERROR_STR(fileName);
+                       break;
+                       }
+                    continue;
+                    }
+                 }
+              else if (errno != ENOENT) {
+                 LOG_ERROR_STR(fileName);
+                 break;
+                 }
+              }
+           else {
+              LOG_ERROR_STR(fileName);
+              break;
+              }
+           if (WaitSeconds)
+              sleep(1);
+           }
+        } while (f < 0 && time(NULL) < Timeout);
+     }
+  return f >= 0;
+}
+
+void cLockFile::Unlock(void)
+{
+  if (f >= 0) {
+     close(f);
+     remove(fileName);
+     f = -1;
+     }
+  else
+     esyslog(LOG_ERR, "ERROR: attempt to unlock %s without holding a lock!", fileName);
+}
+
 // --- cListObject -----------------------------------------------------------
 
 cListObject::cListObject(void)

tools.h

@@ -4,7 +4,7 @@
  * See the main source file 'vdr.c' for copyright information and
  * how to reach the author.
  *
- * $Id: tools.h 1.35 2001/09/22 12:12:55 kls Exp $
+ * $Id: tools.h 1.36 2001/09/30 10:20:59 kls Exp $
  */
 
 #ifndef __TOOLS_H
@@ -97,6 +97,17 @@ public:
   bool Close(void);
   };
 
+class cLockFile {
+private:
+  char *fileName;
+  int f;
+public:
+  cLockFile(const char *Directory);
+  ~cLockFile();
+  bool Lock(int WaitSeconds = 0);
+  void Unlock(void);
+  };
+
 class cListObject {
 private:
   cListObject *prev, *next;