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1.1 root 1: static char *sccsid = "@(#)write.c 4.8 7/1/83";
2: /*
3: * write to another user
4: */
5:
6: #include <stdio.h>
7: #include <sys/types.h>
8: #include <sys/stat.h>
9: #include <signal.h>
10: #include <utmp.h>
11: #include <sys/time.h>
12:
13: #define NMAX sizeof(ubuf.ut_name)
14: #define LMAX sizeof(ubuf.ut_line)
15:
16: char *strcat();
17: char *strcpy();
18: struct utmp ubuf;
19: int signum[] = {SIGHUP, SIGINT, SIGQUIT, 0};
20: char me[10] = "???";
21: char *him;
22: char *mytty;
23: char histty[32];
24: char *histtya;
25: char *ttyname();
26: char *rindex();
27: int logcnt;
28: int eof();
29: int timout();
30: FILE *tf;
31: char *getenv();
32:
33: main(argc, argv)
34: int argc;
35: char *argv[];
36: {
37: struct stat stbuf;
38: register i;
39: register FILE *uf;
40: int c1, c2;
41: long clock = time(0);
42: struct tm *localtime();
43: struct tm *localclock = localtime( &clock );
44:
45: if (argc < 2) {
46: printf("usage: write user [ttyname]\n");
47: exit(1);
48: }
49: him = argv[1];
50: if (argc > 2)
51: histtya = argv[2];
52: if ((uf = fopen("/etc/utmp", "r")) == NULL) {
53: printf("cannot open /etc/utmp\n");
54: goto cont;
55: }
56: mytty = ttyname(2);
57: if (mytty == NULL) {
58: printf("Can't find your tty\n");
59: exit(1);
60: }
61: if (stat(mytty, &stbuf) < 0) {
62: printf("Can't stat your tty\n");
63: exit(1);
64: }
65: if ((stbuf.st_mode&02) == 0) {
66: printf("You have write permission turned off.\n");
67: exit(1);
68: }
69: mytty = rindex(mytty, '/') + 1;
70: if (histtya) {
71: strcpy(histty, "/dev/");
72: strcat(histty, histtya);
73: }
74: while (fread((char *)&ubuf, sizeof(ubuf), 1, uf) == 1) {
75: if (ubuf.ut_name[0] == '\0')
76: continue;
77: if (strcmp(ubuf.ut_line, mytty)==0) {
78: for (i=0; i<NMAX; i++) {
79: c1 = ubuf.ut_name[i];
80: if (c1 == ' ')
81: c1 = 0;
82: me[i] = c1;
83: if (c1 == 0)
84: break;
85: }
86: }
87: if (him[0] != '-' || him[1] != 0)
88: for (i=0; i<NMAX; i++) {
89: c1 = him[i];
90: c2 = ubuf.ut_name[i];
91: if (c1 == 0)
92: if (c2 == 0 || c2 == ' ')
93: break;
94: if (c1 != c2)
95: goto nomat;
96: }
97: logcnt++;
98: if (histty[0]==0) {
99: strcpy(histty, "/dev/");
100: strcat(histty, ubuf.ut_line);
101: }
102: nomat:
103: ;
104: }
105: cont:
106: if (logcnt==0 && histty[0]=='\0') {
107: printf("%s not logged in.\n", him);
108: exit(1);
109: }
110: fclose(uf);
111: if (histtya==0 && logcnt > 1) {
112: printf("%s logged more than once\nwriting to %s\n", him, histty+5);
113: }
114: if (histty[0] == 0) {
115: printf(him);
116: if (logcnt)
117: printf(" not on that tty\n"); else
118: printf(" not logged in\n");
119: exit(1);
120: }
121: if (access(histty, 0) < 0) {
122: printf("No such tty\n");
123: exit(1);
124: }
125: signal(SIGALRM, timout);
126: alarm(5);
127: if ((tf = fopen(histty, "w")) == NULL)
128: goto perm;
129: alarm(0);
130: if (fstat(fileno(tf), &stbuf) < 0)
131: goto perm;
132: if ((stbuf.st_mode&02) == 0)
133: goto perm;
134: sigs(eof);
135: { char hostname[32];
136: gethostname(hostname, sizeof (hostname));
137: fprintf(tf, "\r\nMessage from ");
138: fprintf(tf, "%s!%s on %s at %d:%02d ...\r\n\007\007\007",
139: hostname, me, mytty, localclock->tm_hour, localclock->tm_min);
140: }
141: fflush(tf);
142: for (;;) {
143: char buf[128];
144: i = read(0, buf, 128);
145: if (i <= 0)
146: eof();
147: if (buf[0] == '!') {
148: buf[i] = 0;
149: ex(buf);
150: continue;
151: }
152: if (write(fileno(tf), buf, i) != i) {
153: printf("\n\007Write failed (%s logged out?)\n", him);
154: exit(1);
155: }
156: if (buf[i-1] == '\n')
157: write(fileno(tf), "\r", 1);
158: }
159: perm:
160: printf("Permission denied\n");
161: exit(1);
162: }
163:
164: timout()
165: {
166:
167: printf("Timeout opening their tty\n");
168: exit(1);
169: }
170:
171: eof()
172: {
173:
174: fprintf(tf, "EOF\r\n");
175: exit(0);
176: }
177:
178: ex(bp)
179: char *bp;
180: {
181: register i;
182:
183: sigs(SIG_IGN);
184: i = fork();
185: if (i < 0) {
186: printf("Try again\n");
187: goto out;
188: }
189: if (i == 0) {
190: sigs((int (*)())0);
191: execl(getenv("SHELL") ?
192: getenv("SHELL") : "/bin/sh", "sh", "-c", bp+1, 0);
193: exit(0);
194: }
195: while (wait((int *)NULL) != i)
196: ;
197: printf("!\n");
198: out:
199: sigs(eof);
200: }
201:
202: sigs(sig)
203: int (*sig)();
204: {
205: register i;
206:
207: for (i=0; signum[i]; i++)
208: signal(signum[i], sig);
209: }
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