w: use environment to set user and from/host column widths

A patch from Debian.

Bug-Debian: http://bugs.debian.org/396423
Bug-Debian: http://bugs.debian.org/341439
Backported-by: Sami Kerola <kerolasa@iki.fi>

w.1

@@ -1,6 +1,6 @@
 .\"             -*-Nroff-*-
 .\"
-.TH W 1 "8 Dec 1993 " " " "Linux User's Manual"
+.TH W 1 "5 October 2009 " " " "Linux User's Manual"
 .SH NAME
 w \- Show who is logged on and what they are doing.
 .SH SYNOPSIS
@@ -61,6 +61,14 @@ Old style output. Prints blank space for idle times less than one minute.
 .B "user "
 Show information about the specified user only.
 
+.SH ENVIRONMENT
+.TP
+PROCPS_USERLEN
+Override the default width of the username column. Defaults to 8.
+.TP
+PROCPS_FROMLEN
+Override the default width of the from column. Defaults to 16.
+
 .SH FILES
 .TP
 .I /var/run/utmp

w.c

@@ -45,20 +45,19 @@ typedef struct utmp utmp_t;
 /* Uh... same thing as UT_NAMESIZE */
 #define USERSZ (sizeof u->ut_user)
 
+/* Arbitary setting, not too big for the screen, max host size */
+#define HOSTSZ 40
+
 
 /* This routine is careful since some programs leave utmp strings
- * unprintable.  Always outputs at least 16 chars padded with spaces
+ * unprintable.  Always outputs at least fromlen chars padded with spaces
  * on the right if necessary.
  */
-static void print_host(const char *restrict host, int len) {
+static void print_host(const char *restrict host, int len, const int fromlen) {
     const char *last;
     int width = 0;
 
-    /* FIXME: there should really be a way to configure this... */
+    if (len > fromlen) len = fromlen;
-    /* for now, we'll just limit it to the 16 that the libc5 version
-     * of utmp uses.
-     */
-    if (len > 16) len = 16;
     last = host + len;
     for ( ; host < last ; host++){
         if (isprint(*host) && *host != ' ') {
@@ -69,7 +68,8 @@ static void print_host(const char *restrict host, int len) {
 	}
     }
     // space-fill, and a '-' too if needed to ensure the column exists
-    if(width < 16) fputs("-               "+width, stdout);
+	while(width++ < fromlen)
+	  fputc(' ',stdout);
 }
 
 /***** compact 7 char format for time intervals (belongs in libproc?) */
@@ -181,7 +181,7 @@ static const proc_t *getproc(const utmp_t *restrict const u, const char *restric
 
 
 /***** showinfo */
-static void showinfo(utmp_t *u, int formtype, int maxcmd, int from) {
+static void showinfo(utmp_t *u, int formtype, int maxcmd, int from, const int userlen, const int fromlen) {
     unsigned long long jcpu;
     int ut_pid_found;
     unsigned i;
@@ -206,9 +206,9 @@ static void showinfo(utmp_t *u, int formtype, int maxcmd, int from) {
 
     strncpy(uname, u->ut_user, USERSZ);		/* force NUL term for printf */
     if (formtype) {
-	printf("%-9.8s%-9.8s", uname, u->ut_line);
+	printf("%-*.*s%-9.8s", userlen+1, userlen, uname, u->ut_line);
 	if (from)
-	    print_host(u->ut_host, sizeof u->ut_host);
+	    print_host(u->ut_host, sizeof u->ut_host, fromlen);
 	print_logintime(u->ut_time, stdout);
 	if (*u->ut_line == ':')			/* idle unknown for xdm logins */
 	    printf(" ?xdm? ");
@@ -221,9 +221,9 @@ static void showinfo(utmp_t *u, int formtype, int maxcmd, int from) {
 	} else
 	    printf("   ?   ");
     } else {
-	printf("%-9.8s%-9.8s", u->ut_user, u->ut_line);
+	printf("%-*.*s%-9.8s", userlen+1, userlen, u->ut_user, u->ut_line);
 	if (from)
-	    print_host(u->ut_host, sizeof u->ut_host);
+	    print_host(u->ut_host, sizeof u->ut_host, fromlen);
 	if (*u->ut_line == ':')			/* idle unknown for xdm logins */
 	    printf(" ?xdm? ");
 	else
@@ -246,6 +246,9 @@ int main(int argc, char **argv) {
     utmp_t *u;
     struct winsize win;
     int header=1, longform=1, from=1, args, maxcmd=80, ch;
+    int userlen = 8;
+    int fromlen = 16;
+    char *env_var;
 
 #ifndef W_SHOWFROM
     from = 0;
@@ -276,6 +279,22 @@ int main(int argc, char **argv) {
     if ((argv[optind]))
 	user = (argv[optind]);
 
+	/* Get user field length from environment */
+	if ( (env_var = getenv("PROCPS_USERLEN")) != NULL) {
+        userlen = atoi(env_var);
+        if (userlen < 8 || userlen > USERSZ) {
+            fprintf(stderr, "User length environment PROCPS_USERLEN must be between 8 and %d, ignoring.\n", USERSZ);
+			userlen=8;
+        }
+	}
+	/* Get from field length from environment */
+	if ( (env_var = getenv("PROCPS_FROMLEN")) != NULL) {
+        fromlen = atoi(env_var);
+        if (fromlen < 8 || fromlen > HOSTSZ) {
+            fprintf(stderr, "From length environment PROCPS_FROMLEN must be between 8 and %d, ignoring.\n", HOSTSZ);
+			fromlen=16;
+        }
+	}
     if (ioctl(1, TIOCGWINSZ, &win) != -1 && win.ws_col > 0)
 	maxcmd = win.ws_col;
     else if (p = getenv("COLUMNS"))
@@ -286,7 +305,7 @@ int main(int argc, char **argv) {
 	fprintf(stderr, "%d column window is too narrow\n", maxcmd);
 	exit(1);
     }
-    maxcmd -= 29 + (from ? 16 : 0) + (longform ? 20 : 0);
+    maxcmd -= 21 + userlen + (from ? fromlen : 0) + (longform ? 20 : 0);
     if (maxcmd < 3)
 	fprintf(stderr, "warning: screen width %d suboptimal.\n", win.ws_col);
 
@@ -294,7 +313,7 @@ int main(int argc, char **argv) {
 
     if (header) {				/* print uptime and headers */
 	print_uptime();
-	printf("USER     TTY      ");
+	printf("%-*s TTY      ",userlen,"USER");
 	if (from)
 	    printf("FROM            ");
 	if (longform)
@@ -310,14 +329,14 @@ int main(int argc, char **argv) {
 	    u = getutent();
 	    if (unlikely(!u)) break;
 	    if (u->ut_type != USER_PROCESS) continue;
- 	    if (!strncmp(u->ut_user, user, USERSZ)) showinfo(u, longform, maxcmd, from);
+ 	    if (!strncmp(u->ut_user, user, USERSZ)) showinfo(u, longform, maxcmd, from, userlen, fromlen);
 	}
     } else {
 	for (;;) {
 	    u = getutent();
 	    if (unlikely(!u)) break;
 	    if (u->ut_type != USER_PROCESS) continue;
- 	    if (*u->ut_user) showinfo(u, longform, maxcmd, from);
+ 	    if (*u->ut_user) showinfo(u, longform, maxcmd, from, userlen, fromlen);
 	}
     }
     endutent();