pstree uses COLUMNS environement variable

pstree previously only used the window size for determining number of
columns, then a default of 132. With this change, pstree now checks
the COLUMNS environment variable first and uses that if valid.

env checking code nicked from top.c, by Jim Warner.

Bug-Debian: http://bugs.debian.org/717017

3 files changed, 30 insertions, 9 deletions

diff --git a/ChangeLog b/ChangeLog
index d29569d..d9e2db0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,6 +1,7 @@
 Changes in 22.21
 ================
 	* Missing comma in fuser(1) added Debian #702391
+	* pstree uses COLUMN env variable Debian #717017
 
 Changes in 22.20
 ================
diff --git a/doc/pstree.1 b/doc/pstree.1
index fea80b6..6a9c3a8 100644
--- a/doc/pstree.1
+++ b/doc/pstree.1
@@ -1,12 +1,12 @@
 .\"
 .\" Copyright 1993-2002 Werner Almesberger
-.\"           2002-2012 Craig Small
+.\"           2002-2013 Craig Small
 .\" This program is free software; you can redistribute it and/or modify
 .\" it under the terms of the GNU General Public License as published by
 .\" the Free Software Foundation; either version 2 of the License, or
 .\" (at your option) any later version.
 .\"
-.TH PSTREE 1 "2012-07-28" "psmisc" "User Commands"
+.TH PSTREE 1 "2013-07-16" "psmisc" "User Commands"
 .SH NAME
 pstree \- display a tree of processes
 .SH SYNOPSIS
@@ -115,9 +115,9 @@ parentheses after each process name.
 implicitly disables compaction.  If both PIDs and PGIDs are displayed
 then PIDs are shown first.
 .IP \fB\-l\fP
-Display long lines.  By default, lines are truncated to the display
-width or 132 if output is sent to a non-tty or if the display width is
-unknown.
+Display long lines.  By default, lines are truncated to either the COLUMNS
+environment variable or the display width.  If neither of these methods work,
+the default of 132 columns is used.
 .IP \fB\-n\fP
 Sort processes with the same ancestor by PID instead of by name. 
 (Numeric sort.)
diff --git a/src/pstree.c b/src/pstree.c
index b9a01cf..4eab5dd 100644
--- a/src/pstree.c
+++ b/src/pstree.c
@@ -139,6 +139,29 @@ static int dumped = 0;                /* used by dump_by_user */
 static int charlen = 0;                /* length of character */
 
 static void fix_orphans(security_context_t scontext);
+
+/*
+ * Determine the correct output width, what we use is:
+ */
+static int get_output_width(void)
+{
+    char *ep, *env_columns;
+    struct winsize winsz;
+
+    env_columns = getenv("COLUMNS");
+    if (env_columns && *env_columns) {
+	long t;
+	t = strtol(env_columns, &ep, 0);
+	if (!*ep && (t > 0) && (t < 0x7fffffffL))
+	    return (int)t;
+    }
+    if (ioctl(1, TIOCGWINSZ, &winsz) >= 0)
+        if (winsz.ws_col)
+            return winsz.ws_col;
+    return 132;
+
+}
+
 /*
  * Allocates additional buffer space for width and more as needed.
  * The first call will allocate the first buffer.
@@ -814,7 +837,6 @@ void print_version()
 int main(int argc, char **argv)
 {
     PROC *current;
-    struct winsize winsz;
     const struct passwd *pw;
     pid_t pid, highlight;
     char termcap_area[1024];
@@ -842,9 +864,7 @@ int main(int argc, char **argv)
         { 0, 0, 0, 0 }
     };
 
-    if (ioctl(1, TIOCGWINSZ, &winsz) >= 0)
-        if (winsz.ws_col)
-            output_width = winsz.ws_col;
+    output_width = get_output_width();
     pid = ROOT_PID;
     highlight = 0;
     pw = NULL;