lib/colors: add support for auto, always and never modes

... to implement --color[=<when>]

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

include/colors.h

@@ -38,8 +38,19 @@
 
 #define UL_COLOR_WHITE		"\033[1;37m"
 
+/* --color[=WHEN] */
+enum colortmode {
+	UL_COLORMODE_AUTO = 0,
+	UL_COLORMODE_NEVER,
+	UL_COLORMODE_ALWAYS,
+
+	__UL_NCOLORMODES	/* last */
+};
+
+extern int colormode_from_string(const char *str);
+
 /* Initialize the global variable OUT_IS_TERM */
-extern int colors_init(void);
+extern int colors_init(int mode);
 
 /* Set the color to CLR_SCHEME */
 extern void color_enable(const char *clr_scheme);

lib/Makemodule.am

@@ -45,6 +45,7 @@ check_PROGRAMS += \
 	test_at \
 	test_blkdev \
 	test_canonicalize \
+	test_colors \
 	test_fileutils \
 	test_ismounted \
 	test_mangle \
@@ -89,6 +90,9 @@ test_at_CFLAGS = -DTEST_PROGRAM_AT
 test_strutils_SOURCES = lib/strutils.c
 test_strutils_CFLAGS = -DTEST_PROGRAM
 
+test_colors_SOURCES = lib/colors.c
+test_colors_CFLAGS = -DTEST_PROGRAM
+
 test_randutils_SOURCES = lib/randutils.c
 test_randutils_CFLAGS = -DTEST_PROGRAM
 

lib/colors.c

@@ -4,14 +4,26 @@
  * This file may be distributed under the terms of the
  * GNU Lesser General Public License.
  */
+#include <c.h>
+#include <assert.h>
 
 #include "colors.h"
 
 static int ul_color_term_ok;
 
-int colors_init(void)
+int colors_init(int mode)
 {
-	ul_color_term_ok = isatty(STDOUT_FILENO);
+	switch (mode) {
+	case UL_COLORMODE_AUTO:
+		ul_color_term_ok = isatty(STDOUT_FILENO);
+		break;
+	case UL_COLORMODE_ALWAYS:
+		ul_color_term_ok = 1;
+		break;
+	case UL_COLORMODE_NEVER:
+	default:
+		ul_color_term_ok = 0;
+	}
 	return ul_color_term_ok;
 }
 
@@ -26,3 +38,61 @@ void color_disable(void)
 	if (ul_color_term_ok)
 		fputs(UL_COLOR_RESET, stdout);
 }
+
+int colormode_from_string(const char *str)
+{
+	size_t i;
+	static const char *modes[] = {
+		[UL_COLORMODE_AUTO]   = "auto",
+		[UL_COLORMODE_NEVER]  = "never",
+		[UL_COLORMODE_ALWAYS] = "always"
+	};
+
+	if (!str || !*str)
+		return -EINVAL;
+
+	assert(ARRAY_SIZE(modes) == __UL_NCOLORMODES);
+
+	for (i = 0; i < ARRAY_SIZE(modes); i++) {
+		if (strcasecmp(str, modes[i]) == 0)
+			return i;
+	}
+
+	return -EINVAL;
+}
+
+#ifdef TEST_PROGRAM
+# include <getopt.h>
+# include <err.h>
+
+int main(int argc, char *argv[])
+{
+	static const struct option longopts[] = {
+		{ "colors", optional_argument, 0, 'c' },
+		{ NULL, 0, 0, 0 }
+	};
+	int c, mode = UL_COLORMODE_NEVER;	/* default */
+
+	while ((c = getopt_long(argc, argv, "c::", longopts, NULL)) != -1) {
+		switch (c) {
+		case 'c':
+			mode = UL_COLORMODE_AUTO;
+			if (optarg) {
+				char *p = *optarg == '=' ? optarg + 1 : optarg;
+
+				mode = colormode_from_string(p);
+				if (mode < 0)
+					errx(EXIT_FAILURE, "'%s' unsupported color mode", p);
+			}
+			break;
+		}
+	}
+
+	colors_init(mode);
+	color_enable(UL_COLOR_RED);
+	printf("Hello World!");
+	color_disable();
+	return EXIT_SUCCESS;
+}
+#endif
+