autoconfiguration test whether less(1) supports the -T option;

needed for Alpine Linux because it uses busybox less(1) by default;
based on a patch from Daniel Sabogal explained to me by Natanael Copa

3 files changed, 24 insertions, 3 deletions

diff --git a/configure b/configure
index 5dca7ad8..5300ef20 100755
--- a/configure
+++ b/configure
@@ -1,6 +1,6 @@
 #!/bin/sh
 #
-# $Id: configure,v 1.68 2019/03/04 13:01:57 schwarze Exp $
+# $Id: configure,v 1.69 2019/03/06 10:18:58 schwarze Exp $
 #
 # Copyright (c) 2014-2019 Ingo Schwarze <schwarze@openbsd.org>
 #
@@ -65,6 +65,7 @@ HAVE_FTS_COMPARE_CONST=
 HAVE_GETLINE=
 HAVE_GETSUBOPT=
 HAVE_ISBLANK=
+HAVE_LESS_T=
 HAVE_MKDTEMP=
 HAVE_NANOSLEEP=
 HAVE_NTOHL=
@@ -334,6 +335,20 @@ else
 	runtest fts FTS || true
 fi
 
+if ismanual "less -T" LESS_T ${HAVE_LESS_T}; then
+	:
+elif less -ET /dev/null test-noop.c 1>/dev/null 2>&3; then
+	HAVE_LESS_T=1
+	echo "tested less -T: yes" 1>&2
+	echo "tested less -T: yes" 1>&3
+	echo 1>&3
+else
+	HAVE_LESS_T=0
+	echo "tested less -T: no" 1>&2
+	echo "tested less -T: no" 1>&3
+	echo 1>&3
+fi
+
 # --- wide character and locale support ---
 if get_locale; then
 	singletest wchar WCHAR -DUTF8_LOCALE=\"${UTF8_LOCALE}\" || \
@@ -462,6 +477,7 @@ cat << __HEREDOC__
 #define HAVE_GETLINE ${HAVE_GETLINE}
 #define HAVE_GETSUBOPT ${HAVE_GETSUBOPT}
 #define HAVE_ISBLANK ${HAVE_ISBLANK}
+#define HAVE_LESS_T ${HAVE_LESS_T}
 #define HAVE_MKDTEMP ${HAVE_MKDTEMP}
 #define HAVE_NTOHL ${HAVE_NTOHL}
 #define HAVE_PLEDGE ${HAVE_PLEDGE}
diff --git a/configure.local.example b/configure.local.example
index c56cdaa5..4a456aad 100644
--- a/configure.local.example
+++ b/configure.local.example
@@ -1,4 +1,4 @@
-# $Id: configure.local.example,v 1.35 2019/03/04 13:01:57 schwarze Exp $
+# $Id: configure.local.example,v 1.36 2019/03/06 10:18:58 schwarze Exp $
 #
 # Copyright (c) 2014-2019 Ingo Schwarze <schwarze@openbsd.org>
 #
@@ -304,6 +304,7 @@ HAVE_FTS_COMPARE_CONST=0  # Setting this implies HAVE_FTS=1.
 HAVE_GETLINE=0
 HAVE_GETSUBOPT=0
 HAVE_ISBLANK=0
+HAVE_LESS_T=0
 HAVE_MKDTEMP=0
 HAVE_NTOHL=0
 HAVE_O_DIRECTORY=0
diff --git a/main.c b/main.c
index ae3a6320..b91c1586 100644
--- a/main.c
+++ b/main.c
@@ -1,4 +1,4 @@
-/*	$Id: main.c,v 1.321 2019/03/04 18:15:06 schwarze Exp $ */
+/*	$Id: main.c,v 1.322 2019/03/06 10:18:58 schwarze Exp $ */
 /*
  * Copyright (c) 2008-2012 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010-2012, 2014-2019 Ingo Schwarze <schwarze@openbsd.org>
@@ -1161,7 +1161,9 @@ spawn_pager(struct tag_files *tag_files)
 	char		*argv[MAX_PAGER_ARGS];
 	const char	*pager;
 	char		*cp;
+#if HAVE_LESS_T
 	size_t		 cmdlen;
+#endif
 	int		 argc, use_ofn;
 	pid_t		 pager_pid;
 
@@ -1193,6 +1195,7 @@ spawn_pager(struct tag_files *tag_files)
 	/* For less(1), use the tag file. */
 
 	use_ofn = 1;
+#if HAVE_LESS_T
 	if ((cmdlen = strlen(argv[0])) >= 4) {
 		cp = argv[0] + cmdlen - 4;
 		if (strcmp(cp, "less") == 0) {
@@ -1205,6 +1208,7 @@ spawn_pager(struct tag_files *tag_files)
 			}
 		}
 	}
+#endif
 	if (use_ofn)
 		argv[argc++] = tag_files->ofn;
 	argv[argc] = NULL;