From cd784246306174a3142d2af36852f845598605cc Mon Sep 17 00:00:00 2001
From: Bill Joy <bill@ucbvax.Berkeley.EDU>
Date: Thu, 2 Oct 1980 01:29:40 -0800
Subject: [PATCH] date and time created 80/10/01 17:29:40 by bill

SCCS-vsn: usr.bin/write/write.c 4.1
---
 usr/src/usr.bin/write/write.c | 195 ++++++++++++++++++++++++++++++++++
 1 file changed, 195 insertions(+)
 create mode 100644 usr/src/usr.bin/write/write.c

diff --git a/usr/src/usr.bin/write/write.c b/usr/src/usr.bin/write/write.c
new file mode 100644
index 0000000000..47d88b6e99
--- /dev/null
+++ b/usr/src/usr.bin/write/write.c
@@ -0,0 +1,195 @@
+static char *sccsid = "@(#)write.c	4.1 (Berkeley) %G%";
+/*
+ * write to another user
+ */
+
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <signal.h>
+#include <utmp.h>
+#include <time.h>
+
+#define NMAX sizeof(ubuf.ut_name)
+#define LMAX sizeof(ubuf.ut_line)
+
+char	*strcat();
+char	*strcpy();
+struct	utmp ubuf;
+int	signum[] = {SIGHUP, SIGINT, SIGQUIT, 0};
+char	me[10]	= "???";
+char	*him;
+char	*mytty;
+char	histty[32];
+char	*histtya;
+char	*ttyname();
+char	*rindex();
+int	logcnt;
+int	eof();
+int	timout();
+FILE	*tf;
+char	*getenv();
+
+main(argc, argv)
+char *argv[];
+{
+	struct stat stbuf;
+	register i;
+	register FILE *uf;
+	int c1, c2;
+	long	clock = time( 0 );
+	struct tm *localtime();
+	struct tm *localclock = localtime( &clock );
+
+	if(argc < 2) {
+		printf("usage: write user [ttyname]\n");
+		exit(1);
+	}
+	him = argv[1];
+	if(argc > 2)
+		histtya = argv[2];
+	if ((uf = fopen("/etc/utmp", "r")) == NULL) {
+		printf("cannot open /etc/utmp\n");
+		goto cont;
+	}
+	mytty = ttyname(2);
+	if (mytty == NULL) {
+		printf("Can't find your tty\n");
+		exit(1);
+	}
+	mytty = rindex(mytty, '/') + 1;
+	if (histtya) {
+		strcpy(histty, "/dev/");
+		strcat(histty, histtya);
+	}
+	while (fread((char *)&ubuf, sizeof(ubuf), 1, uf) == 1) {
+		if (strcmp(ubuf.ut_line, mytty)==0) {
+			for(i=0; i<NMAX; i++) {
+				c1 = ubuf.ut_name[i];
+				if(c1 == ' ')
+					c1 = 0;
+				me[i] = c1;
+				if(c1 == 0)
+					break;
+			}
+		}
+		if(him[0] != '-' || him[1] != 0)
+		for(i=0; i<NMAX; i++) {
+			c1 = him[i];
+			c2 = ubuf.ut_name[i];
+			if(c1 == 0)
+				if(c2 == 0 || c2 == ' ')
+					break;
+			if(c1 != c2)
+				goto nomat;
+		}
+		logcnt++;
+		if (histty[0]==0) {
+			strcpy(histty, "/dev/");
+			strcat(histty, ubuf.ut_line);
+		}
+	nomat:
+		;
+	}
+cont:
+	if (logcnt==0 && histty[0]=='\0') {
+		printf("%s not logged in.\n", him);
+		exit(1);
+	}
+	fclose(uf);
+	if (histtya==0 && logcnt > 1) {
+		printf("%s logged more than once\nwriting to %s\n", him, histty+5);
+	}
+	if(histty[0] == 0) {
+		printf(him);
+		if(logcnt)
+			printf(" not on that tty\n"); else
+			printf(" not logged in\n");
+		exit(1);
+	}
+	if (access(histty, 0) < 0) {
+		printf("No such tty\n");
+		exit(1);
+	}
+	signal(SIGALRM, timout);
+	alarm(5);
+	if ((tf = fopen(histty, "w")) == NULL)
+		goto perm;
+	alarm(0);
+	if (fstat(fileno(tf), &stbuf) < 0)
+		goto perm;
+	if ((stbuf.st_mode&02) == 0)
+		goto perm;
+	sigs(eof);
+	fprintf(tf, "\r\nMessage from ");
+#ifdef interdata
+	fprintf(tf, "(Interdata) " );
+#endif
+	fprintf(tf, "%s on %s at %d:%02d ...\r\n"
+	       , me, mytty , localclock -> tm_hour , localclock -> tm_min );
+	fflush(tf);
+	for(;;) {
+		char buf[128];
+		i = read(0, buf, 128);
+		if(i <= 0)
+			eof();
+		if(buf[0] == '!') {
+			buf[i] = 0;
+			ex(buf);
+			continue;
+		}
+		write(fileno(tf), buf, i);
+		if ( buf[ i - 1 ] == '\n' )
+		    write( fileno( tf ) , "\r" , 1 );
+	}
+
+perm:
+	printf("Permission denied\n");
+	exit(1);
+}
+
+timout()
+{
+
+	printf("Timeout opening their tty\n");
+	exit(1);
+}
+
+eof()
+{
+
+	fprintf(tf, "EOF\r\n");
+	exit(0);
+}
+
+ex(bp)
+char *bp;
+{
+	register i;
+
+	sigs(SIG_IGN);
+	i = fork();
+	if(i < 0) {
+		printf("Try again\n");
+		goto out;
+	}
+	if(i == 0) {
+		sigs((int (*)())0);
+		execl(getenv("SHELL") ? getenv("SHELL") : "/bin/sh", "sh", "-c", bp+1, 0);
+		exit(0);
+	}
+	while(wait((int *)NULL) != i)
+		;
+	printf("!\n");
+out:
+	sigs(eof);
+}
+
+sigs(sig)
+int (*sig)();
+{
+	register i;
+
+	for(i=0;signum[i];i++)
+		signal(signum[i],sig);
+}
-- 
2.20.1