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1.1 root 1: static char *sccsid = "@(#)write.c 4.2 (Berkeley) 11/10/80";
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 <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: char *argv[];
35: {
36: struct stat stbuf;
37: register i;
38: register FILE *uf;
39: int c1, c2;
40: long clock = time( 0 );
41: struct tm *localtime();
42: struct tm *localclock = localtime( &clock );
43:
44: if(argc < 2) {
45: printf("usage: write user [ttyname]\n");
46: exit(1);
47: }
48: him = argv[1];
49: if(argc > 2)
50: histtya = argv[2];
51: if ((uf = fopen("/etc/utmp", "r")) == NULL) {
52: printf("cannot open /etc/utmp\n");
53: goto cont;
54: }
55: mytty = ttyname(2);
56: if (mytty == NULL) {
57: printf("Can't find your tty\n");
58: exit(1);
59: }
60: mytty = rindex(mytty, '/') + 1;
61: if (histtya) {
62: strcpy(histty, "/dev/");
63: strcat(histty, histtya);
64: }
65: while (fread((char *)&ubuf, sizeof(ubuf), 1, uf) == 1) {
66: if (ubuf.ut_name[0] == '\0')
67: continue;
68: if (strcmp(ubuf.ut_line, mytty)==0) {
69: for(i=0; i<NMAX; i++) {
70: c1 = ubuf.ut_name[i];
71: if(c1 == ' ')
72: c1 = 0;
73: me[i] = c1;
74: if(c1 == 0)
75: break;
76: }
77: }
78: if(him[0] != '-' || him[1] != 0)
79: for(i=0; i<NMAX; i++) {
80: c1 = him[i];
81: c2 = ubuf.ut_name[i];
82: if(c1 == 0)
83: if(c2 == 0 || c2 == ' ')
84: break;
85: if(c1 != c2)
86: goto nomat;
87: }
88: logcnt++;
89: if (histty[0]==0) {
90: strcpy(histty, "/dev/");
91: strcat(histty, ubuf.ut_line);
92: }
93: nomat:
94: ;
95: }
96: cont:
97: if (logcnt==0 && histty[0]=='\0') {
98: printf("%s not logged in.\n", him);
99: exit(1);
100: }
101: fclose(uf);
102: if (histtya==0 && logcnt > 1) {
103: printf("%s logged more than once\nwriting to %s\n", him, histty+5);
104: }
105: if(histty[0] == 0) {
106: printf(him);
107: if(logcnt)
108: printf(" not on that tty\n"); else
109: printf(" not logged in\n");
110: exit(1);
111: }
112: if (access(histty, 0) < 0) {
113: printf("No such tty\n");
114: exit(1);
115: }
116: signal(SIGALRM, timout);
117: alarm(5);
118: if ((tf = fopen(histty, "w")) == NULL)
119: goto perm;
120: alarm(0);
121: if (fstat(fileno(tf), &stbuf) < 0)
122: goto perm;
123: if ((stbuf.st_mode&02) == 0)
124: goto perm;
125: sigs(eof);
126: fprintf(tf, "\r\nMessage from ");
127: #ifdef interdata
128: fprintf(tf, "(Interdata) " );
129: #endif
130: fprintf(tf, "%s on %s at %d:%02d ...\r\n"
131: , me, mytty , localclock -> tm_hour , localclock -> tm_min );
132: fflush(tf);
133: for(;;) {
134: char buf[128];
135: i = read(0, buf, 128);
136: if(i <= 0)
137: eof();
138: if(buf[0] == '!') {
139: buf[i] = 0;
140: ex(buf);
141: continue;
142: }
143: write(fileno(tf), buf, i);
144: if ( buf[ i - 1 ] == '\n' )
145: write( fileno( tf ) , "\r" , 1 );
146: }
147:
148: perm:
149: printf("Permission denied\n");
150: exit(1);
151: }
152:
153: timout()
154: {
155:
156: printf("Timeout opening their tty\n");
157: exit(1);
158: }
159:
160: eof()
161: {
162:
163: fprintf(tf, "EOF\r\n");
164: exit(0);
165: }
166:
167: ex(bp)
168: char *bp;
169: {
170: register i;
171:
172: sigs(SIG_IGN);
173: i = fork();
174: if(i < 0) {
175: printf("Try again\n");
176: goto out;
177: }
178: if(i == 0) {
179: sigs((int (*)())0);
180: execl(getenv("SHELL") ? getenv("SHELL") : "/bin/sh", "sh", "-c", bp+1, 0);
181: exit(0);
182: }
183: while(wait((int *)NULL) != i)
184: ;
185: printf("!\n");
186: out:
187: sigs(eof);
188: }
189:
190: sigs(sig)
191: int (*sig)();
192: {
193: register i;
194:
195: for(i=0;signum[i];i++)
196: signal(signum[i],sig);
197: }
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