102 lines
3.6 KiB
C
102 lines
3.6 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#include <stdlib.h>
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#include "ansi-color.h"
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#include "log.h"
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#include "process-util.h"
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#include "string-table.h"
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#include "string-util.h"
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#include "strv.h"
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#include "terminal-util.h"
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static volatile int cached_color_mode = _COLOR_MODE_INVALID;
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static volatile int cached_underline_enabled = -1;
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bool underline_enabled(void) {
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if (cached_underline_enabled < 0) {
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/* The Linux console doesn't support underlining, turn it off, but only there. */
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if (colors_enabled())
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cached_underline_enabled = !streq_ptr(getenv("TERM"), "linux");
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else
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cached_underline_enabled = false;
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}
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return cached_underline_enabled;
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}
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void reset_ansi_feature_caches(void) {
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cached_color_mode = _COLOR_MODE_INVALID;
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cached_underline_enabled = -1;
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}
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ColorMode parse_systemd_colors(void) {
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const char *e;
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e = getenv("SYSTEMD_COLORS");
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if (!e)
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return _COLOR_MODE_INVALID;
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ColorMode m = color_mode_from_string(e);
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if (m < 0)
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return log_debug_errno(m, "Failed to parse $SYSTEMD_COLORS value '%s', ignoring: %m", e);
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return m;
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}
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static ColorMode get_color_mode_impl(void) {
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/* Returns the mode used to choose output colors. The possible modes are COLOR_OFF for no colors,
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* COLOR_16 for only the base 16 ANSI colors, COLOR_256 for more colors, and COLOR_24BIT for
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* unrestricted color output. */
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/* First, we check $SYSTEMD_COLORS, which is the explicit way to change the mode. */
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ColorMode m = parse_systemd_colors();
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if (m >= 0)
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return m;
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/* Next, check for the presence of $NO_COLOR; value is ignored. */
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if (getenv("NO_COLOR"))
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return COLOR_OFF;
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/* If the above didn't work, we turn colors off unless we are on a TTY. And if we are on a TTY we
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* turn it off if $TERM is set to "dumb". There's one special tweak though: if we are PID 1 then we
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* do not check whether we are connected to a TTY, because we don't keep /dev/console open
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* continuously due to fear of SAK, and hence things are a bit weird. */
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if (getpid_cached() == 1 ? getenv_terminal_is_dumb() : terminal_is_dumb())
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return COLOR_OFF;
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/* We failed to figure out any reason to *disable* colors. Let's see how many colors we shall use. */
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if (STRPTR_IN_SET(getenv("COLORTERM"),
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"truecolor",
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"24bit"))
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return COLOR_24BIT;
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/* Note that the Linux console can only display 16 colors. We still enable 256 color mode
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* even for PID1 output though (which typically goes to the Linux console), since the Linux
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* console is able to parse the 256 color sequences and automatically map them to the closest
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* color in the 16 color palette (since kernel 3.16). Doing 256 colors is nice for people who
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* invoke systemd in a container or via a serial link or such, and use a true 256 color
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* terminal to do so. */
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return COLOR_256;
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}
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ColorMode get_color_mode(void) {
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if (cached_color_mode < 0)
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cached_color_mode = get_color_mode_impl();
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return cached_color_mode;
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}
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static const char* const color_mode_table[_COLOR_MODE_MAX] = {
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[COLOR_OFF] = "off",
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[COLOR_16] = "16",
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[COLOR_256] = "256",
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[COLOR_24BIT] = "24bit",
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};
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DEFINE_STRING_TABLE_LOOKUP_WITH_BOOLEAN(color_mode, ColorMode, COLOR_24BIT);
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