1 | /* |
---|
2 | * session_gate - Keeps session alive by continuing to run |
---|
3 | * |
---|
4 | * $Source: /afs/dev.mit.edu/source/repository/athena/etc/xdm/session_gate.c,v $ |
---|
5 | * $Header: /afs/dev.mit.edu/source/repository/athena/etc/xdm/session_gate.c,v 1.2 1990-11-18 18:39:21 mar Exp $ |
---|
6 | * $Author: mar $ |
---|
7 | */ |
---|
8 | |
---|
9 | #include <signal.h> |
---|
10 | #include <strings.h> |
---|
11 | #include <sys/file.h> |
---|
12 | #include <sys/types.h> |
---|
13 | #include <sys/stat.h> |
---|
14 | |
---|
15 | #define BUFSIZ 1024 |
---|
16 | #define MINUTE 60 |
---|
17 | #define PID_FILE_TEMPLATE "/tmp/session_gate_pid." |
---|
18 | |
---|
19 | static char filename[80]; |
---|
20 | |
---|
21 | void main( ); |
---|
22 | int itoa( ); |
---|
23 | void cleanup( ); |
---|
24 | void logout( ); |
---|
25 | time_t check_pid_file( ); |
---|
26 | time_t create_pid_file( ); |
---|
27 | time_t update_pid_file( ); |
---|
28 | void write_pid_to_file( ); |
---|
29 | |
---|
30 | |
---|
31 | void main(argc, argv) |
---|
32 | int argc; |
---|
33 | char **argv; |
---|
34 | { |
---|
35 | int pid; |
---|
36 | int parentpid; |
---|
37 | char buf[10]; |
---|
38 | time_t mtime; |
---|
39 | int dologout = 0; |
---|
40 | |
---|
41 | if (argc == 2 && !strcmp(argv[1], "-logout")) |
---|
42 | dologout = 1; |
---|
43 | |
---|
44 | pid = getpid(); |
---|
45 | parentpid = getppid(); |
---|
46 | |
---|
47 | /* Set up signal handlers for a clean exit */ |
---|
48 | |
---|
49 | if (dologout) { |
---|
50 | signal(SIGHUP, logout); |
---|
51 | signal(SIGINT, logout); |
---|
52 | signal(SIGQUIT, logout); |
---|
53 | signal(SIGTERM, logout); |
---|
54 | } else { |
---|
55 | signal(SIGHUP, cleanup); |
---|
56 | signal(SIGINT, cleanup); |
---|
57 | signal(SIGQUIT, cleanup); |
---|
58 | signal(SIGTERM, cleanup); |
---|
59 | } |
---|
60 | |
---|
61 | /* Figure out the filename */ |
---|
62 | |
---|
63 | strcpy(filename, PID_FILE_TEMPLATE); |
---|
64 | itoa(getuid(), buf); |
---|
65 | strcat(filename, buf); |
---|
66 | |
---|
67 | /* Put pid in file for the first time */ |
---|
68 | |
---|
69 | mtime = check_pid_file(filename, pid, (time_t)0); |
---|
70 | |
---|
71 | /* |
---|
72 | * Now sit and wait. If a signal occurs, catch it, cleanup, and exit. |
---|
73 | * Every minute, wake up and perform the following checks: |
---|
74 | * - If parent process does not exist, cleanup and exit. |
---|
75 | * - If pid file has been modified or is missing, refresh it. |
---|
76 | */ |
---|
77 | |
---|
78 | while (1) |
---|
79 | { |
---|
80 | sleep(MINUTE); |
---|
81 | if (parentpid != getppid()) |
---|
82 | cleanup(); |
---|
83 | mtime = check_pid_file(filename, pid, mtime); |
---|
84 | } |
---|
85 | } |
---|
86 | |
---|
87 | |
---|
88 | static powers[] = {100000, 10000,1000,100,10,1}; |
---|
89 | |
---|
90 | int itoa(x, buf) |
---|
91 | int x; |
---|
92 | char *buf; |
---|
93 | { |
---|
94 | int i; |
---|
95 | int pos=0; |
---|
96 | int digit; |
---|
97 | |
---|
98 | for (i = 0; i < 5; i++) |
---|
99 | { |
---|
100 | digit = (x/powers[i]) % 10; |
---|
101 | if ((pos > 0) || (digit != 0) || (i == 4)) |
---|
102 | buf[pos++] = '0' + (char) digit; |
---|
103 | } |
---|
104 | buf[pos] = '\0'; |
---|
105 | return pos; |
---|
106 | } |
---|
107 | |
---|
108 | |
---|
109 | void cleanup( ) |
---|
110 | { |
---|
111 | unlink(filename); |
---|
112 | exit(0); |
---|
113 | } |
---|
114 | |
---|
115 | void logout( ) |
---|
116 | { |
---|
117 | int f; |
---|
118 | |
---|
119 | unlink(filename); |
---|
120 | f = open(".logout", O_RDONLY, 0); |
---|
121 | if (f >= 0) { |
---|
122 | close(0); |
---|
123 | dup(f, 0); |
---|
124 | execl("/bin/csh", "logout", 0); |
---|
125 | } |
---|
126 | exit(0); |
---|
127 | } |
---|
128 | |
---|
129 | |
---|
130 | |
---|
131 | time_t check_pid_file(filename, pid, mtime) |
---|
132 | char* filename; |
---|
133 | int pid; |
---|
134 | time_t mtime; |
---|
135 | { |
---|
136 | struct stat st_buf; |
---|
137 | |
---|
138 | if (stat(filename, &st_buf) == -1) |
---|
139 | return create_pid_file(filename, pid); /* File gone: create */ |
---|
140 | else if (st_buf.st_mtime > mtime) |
---|
141 | return update_pid_file(filename, pid); /* File changed: update */ |
---|
142 | else |
---|
143 | return mtime; /* File unchanged */ |
---|
144 | } |
---|
145 | |
---|
146 | |
---|
147 | time_t create_pid_file(filename, pid) |
---|
148 | char* filename; |
---|
149 | int pid; |
---|
150 | { |
---|
151 | int fd; |
---|
152 | struct stat st_buf; |
---|
153 | |
---|
154 | if ((fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0)) >= 0) |
---|
155 | { |
---|
156 | write_pid_to_file(pid, fd); |
---|
157 | fchmod(fd, S_IREAD | S_IWRITE); /* set file mode 600 */ |
---|
158 | close(fd); |
---|
159 | } |
---|
160 | |
---|
161 | stat(filename, &st_buf); |
---|
162 | return st_buf.st_mtime; |
---|
163 | } |
---|
164 | |
---|
165 | |
---|
166 | time_t update_pid_file(filename, pid) |
---|
167 | char* filename; |
---|
168 | int pid; |
---|
169 | { |
---|
170 | int fd; |
---|
171 | char buf[BUFSIZ]; |
---|
172 | int count; |
---|
173 | char* start; |
---|
174 | char* end; |
---|
175 | struct stat st_buf; |
---|
176 | |
---|
177 | /* Determine if the file already contains the pid */ |
---|
178 | |
---|
179 | if ((fd = open(filename, O_RDONLY, 0)) >= 0) |
---|
180 | { |
---|
181 | if ((count = read(fd, buf, BUFSIZ-1)) > 0) |
---|
182 | { |
---|
183 | buf[count-1] = '\0'; |
---|
184 | start = buf; |
---|
185 | while ((end = index(start, '\n')) != 0) |
---|
186 | { |
---|
187 | *end = '\0'; |
---|
188 | if (atoi(start) == pid) |
---|
189 | { |
---|
190 | stat(filename, &st_buf); |
---|
191 | return st_buf.st_mtime; |
---|
192 | } |
---|
193 | start = end + 1; |
---|
194 | } |
---|
195 | } |
---|
196 | close(fd); |
---|
197 | } |
---|
198 | |
---|
199 | /* Append the pid to the file */ |
---|
200 | |
---|
201 | if ((fd = open(filename, O_WRONLY | O_APPEND, 0)) >= 0) |
---|
202 | { |
---|
203 | write_pid_to_file(pid, fd); |
---|
204 | close(fd); |
---|
205 | } |
---|
206 | |
---|
207 | stat(filename, &st_buf); |
---|
208 | return st_buf.st_mtime; |
---|
209 | } |
---|
210 | |
---|
211 | |
---|
212 | void write_pid_to_file(pid, fd) |
---|
213 | int pid; |
---|
214 | int fd; |
---|
215 | { |
---|
216 | char buf[10]; |
---|
217 | |
---|
218 | itoa(pid, buf); |
---|
219 | strcat(buf, "\n"); |
---|
220 | write(fd, buf, strlen(buf)); |
---|
221 | } |
---|