| 1 | /* |
| 2 | Copyright (C) Andrew Tridgell 1998 |
| 3 | |
| 4 | This program is free software; you can redistribute it and/or modify |
| 5 | it under the terms of the GNU General Public License as published by |
| 6 | the Free Software Foundation; either version 2 of the License, or |
| 7 | (at your option) any later version. |
| 8 | |
| 9 | This program is distributed in the hope that it will be useful, |
| 10 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 12 | GNU General Public License for more details. |
| 13 | |
| 14 | You should have received a copy of the GNU General Public License |
| 15 | along with this program; if not, write to the Free Software |
| 16 | Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. |
| 17 | */ |
| 18 | |
| 19 | /* support the max connections option */ |
| 20 | #include "rsync.h" |
| 21 | |
| 22 | int yield_connection(char *fname, int max_connections) |
| 23 | { |
| 24 | int fd, i; |
| 25 | pid_t mypid=getpid(), pid=0; |
| 26 | |
| 27 | if (max_connections <= 0) |
| 28 | return 1; |
| 29 | |
| 30 | fd = open(fname,O_RDWR); |
| 31 | if (fd == -1) { |
| 32 | rprintf(FERROR,"Couldn't open lock file %s (%s)\n",fname,strerror(errno)); |
| 33 | return 0; |
| 34 | } |
| 35 | |
| 36 | if (!lock_file(fd)) { |
| 37 | rprintf(FERROR,"failed to lock %s\n", fname); |
| 38 | close(fd); |
| 39 | return 0; |
| 40 | } |
| 41 | |
| 42 | /* find the right spot */ |
| 43 | for (i=0;i<max_connections;i++) { |
| 44 | if (read(fd, &pid, sizeof(pid)) != sizeof(pid)) { |
| 45 | unlock_file(fd); |
| 46 | close(fd); |
| 47 | return 0; |
| 48 | } |
| 49 | if (pid == mypid) break; |
| 50 | } |
| 51 | |
| 52 | if (i == max_connections) { |
| 53 | rprintf(FERROR,"Entry not found in lock file %s\n",fname); |
| 54 | unlock_file(fd); |
| 55 | close(fd); |
| 56 | return 0; |
| 57 | } |
| 58 | |
| 59 | pid = 0; |
| 60 | |
| 61 | /* remove our mark */ |
| 62 | if (lseek(fd,i*sizeof(pid),SEEK_SET) != i*sizeof(pid) || |
| 63 | write(fd, &pid,sizeof(pid)) != sizeof(pid)) { |
| 64 | rprintf(FERROR,"Couldn't update lock file %s (%s)\n",fname,strerror(errno)); |
| 65 | unlock_file(fd); |
| 66 | close(fd); |
| 67 | return 0; |
| 68 | } |
| 69 | |
| 70 | unlock_file(fd); |
| 71 | close(fd); |
| 72 | return 1; |
| 73 | } |
| 74 | |
| 75 | |
| 76 | /**************************************************************************** |
| 77 | simple routine to do connection counting |
| 78 | ****************************************************************************/ |
| 79 | int claim_connection(char *fname,int max_connections) |
| 80 | { |
| 81 | int fd, i; |
| 82 | pid_t pid; |
| 83 | |
| 84 | if (max_connections <= 0) |
| 85 | return 1; |
| 86 | |
| 87 | fd = open(fname,O_RDWR|O_CREAT, 0600); |
| 88 | |
| 89 | if (fd == -1) { |
| 90 | return 0; |
| 91 | } |
| 92 | |
| 93 | if (!lock_file(fd)) { |
| 94 | rprintf(FERROR,"failed to lock %s\n", fname); |
| 95 | close(fd); |
| 96 | return 0; |
| 97 | } |
| 98 | |
| 99 | /* find a free spot */ |
| 100 | for (i=0;i<max_connections;i++) { |
| 101 | if (read(fd,&pid,sizeof(pid)) != sizeof(pid)) break; |
| 102 | if (pid == 0 || !process_exists(pid)) break; |
| 103 | } |
| 104 | |
| 105 | if (i == max_connections) { |
| 106 | unlock_file(fd); |
| 107 | close(fd); |
| 108 | return 0; |
| 109 | } |
| 110 | |
| 111 | pid = getpid(); |
| 112 | |
| 113 | if (lseek(fd,i*sizeof(pid),SEEK_SET) != i*sizeof(pid) || |
| 114 | write(fd, &pid,sizeof(pid)) != sizeof(pid)) { |
| 115 | unlock_file(fd); |
| 116 | close(fd); |
| 117 | return 0; |
| 118 | } |
| 119 | |
| 120 | unlock_file(fd); |
| 121 | close(fd); |
| 122 | return 1; |
| 123 | } |