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terminal-util: several cleanups for ColorMode

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- introduce or rename usual enum values _MAX and _INVALID,
- introduce and use string table lookup functions,
- split out implementation of get_color_mode() to _impl(),
- add tests for get_color_mode().
This commit is contained in:
Yu Watanabe 2024-06-24 04:18:04 +09:00
parent 5f0b72e53b
commit c8210d98a4
3 changed files with 99 additions and 70 deletions
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114
src/basic/terminal-util.c
View file

@ -40,6 +40,7 @@
#include "socket-util.h"
#include "stat-util.h"
#include "stdio-util.h"
#include "string-table.h"
#include "string-util.h"
#include "strv.h"
#include "terminal-util.h"
@ -51,7 +52,7 @@ static volatile unsigned cached_lines = 0;
static volatile int cached_on_tty = -1;
static volatile int cached_on_dev_null = -1;
static volatile int cached_color_mode = _COLOR_INVALID;
static volatile int cached_color_mode = _COLOR_MODE_INVALID;
static volatile int cached_underline_enabled = -1;
bool isatty_safe(int fd) {
@ -959,7 +960,7 @@ void reset_terminal_feature_caches(void) {
cached_columns = 0;
cached_lines = 0;
cached_color_mode = _COLOR_INVALID;
cached_color_mode = _COLOR_MODE_INVALID;
cached_underline_enabled = -1;
cached_on_tty = -1;
cached_on_dev_null = -1;
@ -1315,69 +1316,68 @@ bool terminal_is_dumb(void) {
return getenv_terminal_is_dumb();
}
static const char* const color_mode_table[_COLOR_MODE_MAX] = {
[COLOR_OFF] = "off",
[COLOR_16] = "16",
[COLOR_256] = "256",
[COLOR_24BIT] = "24bit",
};
DEFINE_STRING_TABLE_LOOKUP_WITH_BOOLEAN(color_mode, ColorMode, COLOR_24BIT);
static ColorMode parse_systemd_colors(void) {
const char *e;
int r;
e = getenv("SYSTEMD_COLORS");
if (!e)
return _COLOR_INVALID;
if (streq(e, "16"))
return COLOR_16;
if (streq(e, "256"))
return COLOR_256;
r = parse_boolean(e);
if (r >= 0)
return r > 0 ? COLOR_24BIT : COLOR_OFF;
return _COLOR_INVALID;
return _COLOR_MODE_INVALID;
ColorMode m = color_mode_from_string(e);
if (m < 0)
return log_debug_errno(m, "Failed to parse $SYSTEMD_COLORS value '%s', ignoring: %m", e);
return m;
}
static ColorMode get_color_mode_impl(void) {
/* Returns the mode used to choose output colors. The possible modes are COLOR_OFF for no colors,
* COLOR_16 for only the base 16 ANSI colors, COLOR_256 for more colors, and COLOR_24BIT for
* unrestricted color output. */
/* First, we check $SYSTEMD_COLORS, which is the explicit way to change the mode. */
ColorMode m = parse_systemd_colors();
if (m >= 0)
return m;
/* Next, check for the presence of $NO_COLOR; value is ignored. */
if (getenv("NO_COLOR"))
return COLOR_OFF;
/* If the above didn't work, we turn colors off unless we are on a TTY. And if we are on a TTY we
* turn it off if $TERM is set to "dumb". There's one special tweak though: if we are PID 1 then we
* do not check whether we are connected to a TTY, because we don't keep /dev/console open
* continuously due to fear of SAK, and hence things are a bit weird. */
if (getpid_cached() == 1 ? getenv_terminal_is_dumb() : terminal_is_dumb())
return COLOR_OFF;
/* We failed to figure out any reason to *disable* colors. Let's see how many colors we shall use. */
if (STRPTR_IN_SET(getenv("COLORTERM"),
"truecolor",
"24bit"))
return COLOR_24BIT;
/* Note that the Linux console can only display 16 colors. We still enable 256 color mode
* even for PID1 output though (which typically goes to the Linux console), since the Linux
* console is able to parse the 256 color sequences and automatically map them to the closest
* color in the 16 color palette (since kernel 3.16). Doing 256 colors is nice for people who
* invoke systemd in a container or via a serial link or such, and use a true 256 color
* terminal to do so. */
return COLOR_256;
}
ColorMode get_color_mode(void) {
/* Returns the mode used to choose output colors. The possible modes are COLOR_OFF for no colors,
* COLOR_16 for only the base 16 ANSI colors, COLOR_256 for more colors, and COLOR_24BIT for
* unrestricted color output. For that we check $SYSTEMD_COLORS first (which is the explicit way to
* change the mode). If that didn't work we turn colors off unless we are on a TTY. And if we are on a TTY
* we turn it off if $TERM is set to "dumb". There's one special tweak though: if we are PID 1 then we do not
* check whether we are connected to a TTY, because we don't keep /dev/console open continuously due to fear
* of SAK, and hence things are a bit weird. */
ColorMode m;
if (cached_color_mode < 0) {
m = parse_systemd_colors();
if (m >= 0)
cached_color_mode = m;
else if (getenv("NO_COLOR"))
/* We only check for the presence of the variable; value is ignored. */
cached_color_mode = COLOR_OFF;
else if (getpid_cached() == 1) {
/* PID1 outputs to the console without holding it open all the time.
*
* Note that the Linux console can only display 16 colors. We still enable 256 color
* mode even for PID1 output though (which typically goes to the Linux console),
* since the Linux console is able to parse the 256 color sequences and automatically
* map them to the closest color in the 16 color palette (since kernel 3.16). Doing
* 256 colors is nice for people who invoke systemd in a container or via a serial
* link or such, and use a true 256 color terminal to do so. */
if (getenv_terminal_is_dumb())
cached_color_mode = COLOR_OFF;
} else {
if (terminal_is_dumb())
cached_color_mode = COLOR_OFF;
}
if (cached_color_mode < 0) {
/* We failed to figure out any reason to *disable* colors.
* Let's see how many colors we shall use. */
if (STRPTR_IN_SET(getenv("COLORTERM"),
"truecolor",
"24bit"))
cached_color_mode = COLOR_24BIT;
else
cached_color_mode = COLOR_256;
}
}
if (cached_color_mode < 0)
cached_color_mode = get_color_mode_impl();
return cached_color_mode;
}

22
src/basic/terminal-util.h
View file

@ -119,21 +119,17 @@ typedef enum AcquireTerminalFlags {
/* Limits the use of ANSI colors to a subset. */
typedef enum ColorMode {
/* No colors, monochrome output. */
COLOR_OFF,
/* Only the base 16 colors. */
COLOR_16,
/* Only 256 colors. */
COLOR_256,
/* For truecolor or 24bit color support, no restrictions. */
COLOR_24BIT,
_COLOR_INVALID = -EINVAL,
COLOR_OFF, /* No colors, monochrome output. */
COLOR_16, /* Only the base 16 colors. */
COLOR_256, /* Only 256 colors. */
COLOR_24BIT, /* For truecolor or 24bit color support, no restriction. */
_COLOR_MODE_MAX,
_COLOR_MODE_INVALID = -EINVAL,
} ColorMode;
const char* color_mode_to_string(ColorMode m) _const_;
ColorMode color_mode_from_string(const char *s) _pure_;
int acquire_terminal(const char *name, AcquireTerminalFlags flags, usec_t timeout);
int release_terminal(void);

33
src/test/test-terminal-util.c
View file

@ -176,4 +176,37 @@ TEST(get_default_background_color) {
log_notice("R=%g G=%g B=%g", red, green, blue);
}
static void test_get_color_mode_with_env(const char *key, const char *val, ColorMode expected) {
ASSERT_OK(setenv(key, val, true));
reset_terminal_feature_caches();
log_info("get_color_mode($%s=%s): %s", key, val, color_mode_to_string(get_color_mode()));
ASSERT_EQ(get_color_mode(), expected);
}
TEST(get_color_mode) {
log_info("get_color_mode(default): %s", color_mode_to_string(get_color_mode()));
ASSERT_OK(get_color_mode());
test_get_color_mode_with_env("SYSTEMD_COLORS", "0", COLOR_OFF);
test_get_color_mode_with_env("SYSTEMD_COLORS", "no", COLOR_OFF);
test_get_color_mode_with_env("SYSTEMD_COLORS", "16", COLOR_16);
test_get_color_mode_with_env("SYSTEMD_COLORS", "256", COLOR_256);
test_get_color_mode_with_env("SYSTEMD_COLORS", "1", COLOR_24BIT);
test_get_color_mode_with_env("SYSTEMD_COLORS", "yes", COLOR_24BIT);
test_get_color_mode_with_env("SYSTEMD_COLORS", "24bit", COLOR_24BIT);
ASSERT_OK(setenv("NO_COLOR", "1", true));
test_get_color_mode_with_env("SYSTEMD_COLORS", "42", COLOR_OFF);
test_get_color_mode_with_env("SYSTEMD_COLORS", "invalid", COLOR_OFF);
ASSERT_OK(unsetenv("NO_COLOR"));
ASSERT_OK(unsetenv("SYSTEMD_COLORS"));
test_get_color_mode_with_env("COLORTERM", "truecolor", terminal_is_dumb() ? COLOR_OFF : COLOR_24BIT);
test_get_color_mode_with_env("COLORTERM", "24bit", terminal_is_dumb() ? COLOR_OFF : COLOR_24BIT);
test_get_color_mode_with_env("COLORTERM", "invalid", terminal_is_dumb() ? COLOR_OFF : COLOR_256);
test_get_color_mode_with_env("COLORTERM", "42", terminal_is_dumb() ? COLOR_OFF : COLOR_256);
unsetenv("COLORTERM");
reset_terminal_feature_caches();
}
DEFINE_TEST_MAIN(LOG_INFO);