lib/colors: use libtinfo to check terminal capability

The current implementation assumes that all terminals supports colors
and users are forcet to use terminal-colors.d/ to disable colors for
some terminals.

This patch checks for maximal supported colors for the current
terminal and colors are automatically disabled for terminals like
vt100.

The patch moves lib/colors.c from libcommon.la to libtcolors.la to
avoid collisions with another utils.

Signed-off-by: Karel Zak <kzak@redhat.com>

1 files changed, 32 insertions, 3 deletions

diff --git a/lib/colors.c b/lib/colors.c
index 2e5af48d9..da5a3e1f4 100644
--- a/lib/colors.c
+++ b/lib/colors.c
@@ -10,6 +10,10 @@
 #include <sys/types.h>
 #include <dirent.h>
 #include <ctype.h>
+#ifdef HAVE_LIBTINFO
+# include <curses.h>
+# include <term.h>
+#endif
 
 #include "c.h"
 #include "colors.h"
@@ -664,6 +668,31 @@ static void termcolors_init_debug(void)
 	__UL_INIT_DEBUG(termcolors, TERMCOLORS_DEBUG_, 0, TERMINAL_COLORS_DEBUG);
 }
 
+static int colors_terminal_is_ready(void)
+{
+	int ncolors = -1;
+
+	if (isatty(STDOUT_FILENO) != 1)
+		goto none;
+
+#ifdef HAVE_LIBTINFO
+	{
+		int ret;
+
+		if (setupterm(NULL, STDOUT_FILENO, &ret) != OK || ret != 1)
+			goto none;
+		ncolors = tigetnum("colors");
+		if (ncolors <= 2)
+			goto none;
+	}
+#endif
+	DBG(CONF, ul_debug("terminal is ready (supports %d colors)", ncolors));
+	return 1;
+none:
+	DBG(CONF, ul_debug("terminal is NOT ready"));
+	return 0;
+}
+
 /**
  * colors_init:
  * @mode: UL_COLORMODE_*
@@ -676,7 +705,7 @@ static void termcolors_init_debug(void)
  */
 int colors_init(int mode, const char *name)
 {
-	int atty = -1;
+	int ready = -1;
 	struct ul_color_ctl *cc = &ul_colors;
 
 	cc->utilname = name;
@@ -684,7 +713,7 @@ int colors_init(int mode, const char *name)
 
 	termcolors_init_debug();
 
-	if (mode == UL_COLORMODE_UNDEF && (atty = isatty(STDOUT_FILENO))) {
+	if (mode == UL_COLORMODE_UNDEF && (ready = colors_terminal_is_ready())) {
 		int rc = colors_read_configuration(cc);
 		if (rc)
 			cc->mode = UL_COLORMODE_DEFAULT;
@@ -703,7 +732,7 @@ int colors_init(int mode, const char *name)
 
 	switch (cc->mode) {
 	case UL_COLORMODE_AUTO:
-		cc->has_colors = atty == -1 ? isatty(STDOUT_FILENO) : atty;
+		cc->has_colors = ready == -1 ? colors_terminal_is_ready() : ready;
 		break;
 	case UL_COLORMODE_ALWAYS:
 		cc->has_colors = 1;