Description: Make program compile on Debian.
Author: Michael Meskes <meskes@debian.org>

--- bsd/freebsd/write/write.c	2009-10-29 14:01:40.000000000 +0100
+++ bsdmainutils/usr.bin/write/write.c	2009-10-29 14:11:53.000000000 +0100
@@ -47,7 +47,6 @@
 #endif
 
 #include <sys/cdefs.h>
-__FBSDID("$FreeBSD$");
 
 #include <sys/param.h>
 #include <sys/signal.h>
@@ -65,6 +64,21 @@
 #include <unistd.h>
 #include <utmp.h>
 
+#include <errno.h>
+#include <time.h>
+#define HAVE_GETUTENT
+/* for Hurd */
+#ifndef MAXPATHLEN
+#  define MAXPATHLEN 4096
+#endif
+#ifndef MAXHOSTNAMELEN
+#  define MAXHOSTNAMELEN 255
+#endif
+#ifdef __GLIBC__
+#  undef __unused
+#  define __unused __attribute__((__unused__))
+#endif
+
 void done(int);
 void do_write(char *, char *, uid_t);
 static void usage(void);
@@ -95,14 +109,20 @@
 		myttyfd = fileno(stdout);
 	else if (isatty(fileno(stderr)))
 		myttyfd = fileno(stderr);
-	else
-		errx(1, "can't find your tty");
-	if (!(mytty = ttyname(myttyfd)))
-		errx(1, "can't find your tty's name");
-	if (!strncmp(mytty, _PATH_DEV, strlen(_PATH_DEV)))
-		mytty += strlen(_PATH_DEV);
-	if (term_chk(mytty, &msgsok, &atime, 1))
-		exit(1);
+	else {
+		mytty = "(none)";
+                msgsok = 1;
+	}
+
+	if (!mytty) {
+		if (!(mytty = ttyname(myttyfd)))
+			errx(1, "can't find your tty's name");
+		if (!strncmp(mytty, _PATH_DEV, strlen(_PATH_DEV)))
+			mytty += strlen(_PATH_DEV);
+		if (term_chk(mytty, &msgsok, &atime, 1))
+			exit(1);
+	}
+
 	if (!msgsok)
 		errx(1, "you have write permission turned off");
 
@@ -146,6 +166,15 @@
 int
 utmp_chk(char *user, char *tty)
 {
+#ifdef HAVE_GETUTENT
+        struct utmp *u;
+
+        while ((u = getutent()) != (struct utmp*) 0)
+                if (u->ut_type == USER_PROCESS &&
+                    strncmp(user, u->ut_name, sizeof(u->ut_name)) == 0 &&
+                    strncmp(tty, u->ut_line, sizeof(u->ut_line)) == 0)
+                        return(0);
+#else
 	struct utmp u;
 	int ufd;
 
@@ -160,6 +189,7 @@
 		}
 
 	(void)close(ufd);
+#endif
 	return(1);
 }
 
@@ -177,21 +207,37 @@
 void
 search_utmp(char *user, char *tty, char *mytty, uid_t myuid)
 {
+#ifdef HAVE_GETUTENT
+        struct utmp *u;
+#else
 	struct utmp u;
+#endif
 	time_t bestatime, atime;
 	int ufd, nloggedttys, nttys, msgsok, user_is_me;
 	char atty[UT_LINESIZE + 1];
 
+#ifdef HAVE_GETUTENT
+        setutent();
+#else
 	if ((ufd = open(_PATH_UTMP, O_RDONLY)) < 0)
 		err(1, "utmp");
+#endif
 
 	nloggedttys = nttys = 0;
 	bestatime = 0;
 	user_is_me = 0;
+#ifdef HAVE_GETUTENT
+        while ((u = getutent()) != (struct utmp*) 0)
+                if (strncmp(user, u->ut_name, sizeof(u->ut_name)) == 0
+                    && u->ut_type == USER_PROCESS) {
+                        ++nloggedttys;
+                        (void)strncpy(atty, u->ut_line, UT_LINESIZE);
+#else
 	while (read(ufd, (char *) &u, sizeof(u)) == sizeof(u))
 		if (strncmp(user, u.ut_name, sizeof(u.ut_name)) == 0) {
 			++nloggedttys;
 			(void)strncpy(atty, u.ut_line, UT_LINESIZE);
+#endif
 			atty[UT_LINESIZE] = '\0';
 			if (term_chk(atty, &msgsok, &atime, 0))
 				continue;	/* bad term? skip */
@@ -202,13 +248,27 @@
 				continue;	/* don't write to yourself */
 			}
 			++nttys;
+#ifdef HAVE_GETUTENT
+/*
+ * If this is a newly created tty (eg fresh xterm), then user will not have
+ * typed at it, and the atime will be way in the past.
+ * So, if the atime is < utmp creation time, use the utmp time.
+ */
+                        if (atime < u->ut_time)
+                                atime = u->ut_time;
+#endif
+
 			if (atime > bestatime) {
 				bestatime = atime;
 				(void)strcpy(tty, atty);
 			}
 		}
 
+#ifdef HAVE_GETUTENT
+        endutent();
+#else
 	(void)close(ufd);
+#endif
 	if (nloggedttys == 0)
 		errx(1, "%s is not logged in", user);
 	if (nttys == 0) {
@@ -263,6 +323,20 @@
 			login = "???";
 	}
 
+	/* got the utmp entry: ensure it matches the uid */
+	if ((pwd = getpwnam(login)) == NULL)
+		/* claimed utmp entry isn't in the password file */
+		errx(1, "you're %s, eh? Never heard of you.", login);
+	if (myuid != pwd->pw_uid) {
+		/* uid of logname in utmp is different from our uid,
+		   eg su'ed in someone else's login */
+		if (myuid != 0)
+			errx(1, "you are uid %d, but your login is as uid %d",
+			    myuid, pwd->pw_uid);
+		else
+		    warnx("warning: write will appear from %s", login);
+	}
+
 	(void)snprintf(path, sizeof(path), "%s%s", _PATH_DEV, tty);
 	if ((freopen(path, "w", stdout)) == NULL)
 		err(1, "%s", path);