From 9355d88aae6c2cc82cac1c18ec0625466c6178d3 Mon Sep 17 00:00:00 2001
From: sin <sin@2f30.org>
Date: Thu, 19 Feb 2015 11:24:28 +0000
Subject: [PATCH] Add COLUMNS support to cols(1)

First attempt to see if COLUMNS is set, if that fails an ioctl()
is issued to find the width of the output device.  If that fails
as well, we default to 65 chars per line.
---
 cols.1 | 18 +++++++++++++-----
 cols.c |  6 ++++--
 2 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/cols.1 b/cols.1
index c027118..179ff0a 100644
--- a/cols.1
+++ b/cols.1
@@ -1,4 +1,4 @@
-.Dd February 1, 2015
+.Dd February 19, 2015
 .Dt COLS 1
 .Os sbase
 .Sh NAME
@@ -20,16 +20,24 @@ character columns. If no
 is given,
 .Nm
 reads from stdin.
+.Pp
+By default
+.Nm cols
+tries to figure out the width of the output
+device. If that fails, it defaults to 65 chars.
 .Sh OPTIONS
 .Bl -tag -width Ds
 .It Fl c Ar chars
 Set the maximum number of character columns to use
 (unless the input contains lines longer than
 .Ar num
-characters). By default
-.Nm cols
-tries to figure out the width of the output
-device. If that fails, it defaults to 65 chars.
+characters).
+.El
+.Sh ENVIRONMENT
+.Bl -tag -width COLUMNS
+.It COLUMNS
+If this variable is set, the value is used as the
+width of the output device.
 .El
 .Sh HISTORY
 .Nm
diff --git a/cols.c b/cols.c
index 572dbe0..a48c576 100644
--- a/cols.c
+++ b/cols.c
@@ -31,6 +31,7 @@ main(int argc, char *argv[])
 	size_t i, l, col, len, bytes, maxlen = 0;
 	struct winsize w;
 	FILE *fp;
+	char *p;
 
 	ARGBEGIN {
 	case 'c':
@@ -42,8 +43,9 @@ main(int argc, char *argv[])
 	} ARGEND;
 
 	if (cflag == 0) {
-		ioctl(STDOUT_FILENO, TIOCGWINSZ, &w);
-		if (w.ws_col != 0)
+		if ((p = getenv("COLUMNS")))
+			chars = estrtonum(p, 1, MIN(LLONG_MAX, SIZE_MAX));
+		else if (!ioctl(STDOUT_FILENO, TIOCGWINSZ, &w) && w.ws_col > 0)
 			chars = w.ws_col;
 	}