added two new options "max connections" and "lock file"

[rsync/rsync.git] / connection.c

diff --git a/connection.c b/connection.c
new file mode 100644 (file)
index 0000000..fc7c666
--- /dev/null
+++ b/connection.c
@@ -0,0 +1,123 @@
+/* 
+   Copyright (C) Andrew Tridgell 1998
+   
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+   
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+   
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
+/* support the max connections option */
+#include "rsync.h"
+
+int yield_connection(char *fname, int max_connections)
+{
+       int fd, i;
+       pid_t mypid=getpid(), pid=0;
+
+       if (max_connections <= 0)
+               return 1;
+
+       fd = open(fname,O_RDWR);
+       if (fd == -1) {
+               rprintf(FERROR,"Couldn't open lock file %s (%s)\n",fname,strerror(errno));
+               return 0;
+       }
+
+       if (!lock_file(fd)) {
+               rprintf(FERROR,"failed to lock %s\n", fname);
+               close(fd);
+               return 0;
+       }
+
+       /* find the right spot */
+       for (i=0;i<max_connections;i++) {
+               if (read(fd, &pid, sizeof(pid)) != sizeof(pid)) {
+                       unlock_file(fd);
+                       close(fd);
+                       return 0;
+               }
+               if (pid == mypid) break;
+       }
+
+       if (i == max_connections) {
+               rprintf(FERROR,"Entry not found in lock file %s\n",fname);
+               unlock_file(fd);
+               close(fd);
+               return 0;
+       }
+
+       pid = 0;
+  
+       /* remove our mark */
+       if (lseek(fd,i*sizeof(pid),SEEK_SET) != i*sizeof(pid) ||
+           write(fd, &pid,sizeof(pid)) != sizeof(pid)) {
+               rprintf(FERROR,"Couldn't update lock file %s (%s)\n",fname,strerror(errno));
+               unlock_file(fd);
+               close(fd);
+               return 0;
+       }
+
+       unlock_file(fd);
+       close(fd);
+       return 1;
+}
+
+
+/****************************************************************************
+simple routine to do connection counting
+****************************************************************************/
+int claim_connection(char *fname,int max_connections)
+{
+       int fd, i;
+       pid_t pid;
+
+       if (max_connections <= 0)
+               return 1;
+       
+       fd = open(fname,O_RDWR|O_CREAT, 0600);
+
+       if (fd == -1) {
+               return 0;
+       }
+
+       if (!lock_file(fd)) {
+               rprintf(FERROR,"failed to lock %s\n", fname);
+               close(fd);
+               return 0;
+       }
+
+       /* find a free spot */
+       for (i=0;i<max_connections;i++) {
+               if (read(fd,&pid,sizeof(pid)) != sizeof(pid)) break;
+               if (pid == 0 || !process_exists(pid)) break;
+       }               
+
+       if (i == max_connections) {
+               unlock_file(fd);
+               close(fd);
+               return 0;
+       }
+
+       pid = getpid();
+
+       if (lseek(fd,i*sizeof(pid),SEEK_SET) != i*sizeof(pid) ||
+           write(fd, &pid,sizeof(pid)) != sizeof(pid)) {
+               unlock_file(fd);
+               close(fd);
+               return 0;
+       }
+
+       unlock_file(fd);
+       close(fd);
+       return 1;
+}