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terminal-util: add helper that determines terminal default bg color

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This commit is contained in:
Lennart Poettering
2023-12-21 19:15:01 +01:00
parent d02d4f83f0
commit 63e9c38370
3 changed files with 221 additions and 0 deletions
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src/basic/terminal-util.c
+208
View File
@@ -27,6 +27,7 @@
#include "fd-util.h"
#include "fileio.h"
#include "fs-util.h"
#include "hexdecoct.h"
#include "inotify-util.h"
#include "io-util.h"
#include "log.h"
@@ -1559,3 +1560,210 @@ void termios_disable_echo(struct termios *termios) {
termios->c_cc[VMIN] = 1;
termios->c_cc[VTIME] = 0;
}
typedef enum BackgroundColorState {
BACKGROUND_TEXT,
BACKGROUND_ESCAPE,
BACKGROUND_BRACKET,
BACKGROUND_FIRST_ONE,
BACKGROUND_SECOND_ONE,
BACKGROUND_SEMICOLON,
BACKGROUND_R,
BACKGROUND_G,
BACKGROUND_B,
BACKGROUND_RED,
BACKGROUND_GREEN,
BACKGROUND_BLUE,
} BackgroundColorState;
typedef struct BackgroundColorContext {
BackgroundColorState state;
uint32_t red, green, blue;
unsigned red_bits, green_bits, blue_bits;
} BackgroundColorContext;
static int scan_background_color_response(
BackgroundColorContext *context,
const char *buf,
size_t size) {
assert(context);
assert(buf || size == 0);
for (size_t i = 0; i < size; i++) {
char c = buf[i];
switch (context->state) {
case BACKGROUND_TEXT:
context->state = c == '\x1B' ? BACKGROUND_ESCAPE : BACKGROUND_TEXT;
break;
case BACKGROUND_ESCAPE:
context->state = c == ']' ? BACKGROUND_BRACKET : BACKGROUND_TEXT;
break;
case BACKGROUND_BRACKET:
context->state = c == '1' ? BACKGROUND_FIRST_ONE : BACKGROUND_TEXT;
break;
case BACKGROUND_FIRST_ONE:
context->state = c == '1' ? BACKGROUND_SECOND_ONE : BACKGROUND_TEXT;
break;
case BACKGROUND_SECOND_ONE:
context->state = c == ';' ? BACKGROUND_SEMICOLON : BACKGROUND_TEXT;
break;
case BACKGROUND_SEMICOLON:
context->state = c == 'r' ? BACKGROUND_R : BACKGROUND_TEXT;
break;
case BACKGROUND_R:
context->state = c == 'g' ? BACKGROUND_G : BACKGROUND_TEXT;
break;
case BACKGROUND_G:
context->state = c == 'b' ? BACKGROUND_B : BACKGROUND_TEXT;
break;
case BACKGROUND_B:
context->state = c == ':' ? BACKGROUND_RED : BACKGROUND_TEXT;
break;
case BACKGROUND_RED:
if (c == '/')
context->state = context->red_bits > 0 ? BACKGROUND_GREEN : BACKGROUND_TEXT;
else {
int d = unhexchar(c);
if (d < 0 || context->red_bits >= sizeof(context->red)*8)
context->state = BACKGROUND_TEXT;
else {
context->red = (context->red << 4) | d;
context->red_bits += 4;
}
}
break;
case BACKGROUND_GREEN:
if (c == '/')
context->state = context->green_bits > 0 ? BACKGROUND_BLUE : BACKGROUND_TEXT;
else {
int d = unhexchar(c);
if (d < 0 || context->green_bits >= sizeof(context->green)*8)
context->state = BACKGROUND_TEXT;
else {
context->green = (context->green << 4) | d;
context->green_bits += 4;
}
}
break;
case BACKGROUND_BLUE:
if (c == '\x07') {
if (context->blue_bits > 0)
return 1; /* success! */
context->state = BACKGROUND_TEXT;
} else {
int d = unhexchar(c);
if (d < 0 || context->blue_bits >= sizeof(context->blue)*8)
context->state = BACKGROUND_TEXT;
else {
context->blue = (context->blue << 4) | d;
context->blue_bits += 4;
}
}
break;
}
/* Reset any colors we might have picked up */
if (context->state == BACKGROUND_TEXT) {
/* reset color */
context->red = context->green = context->blue = 0;
context->red_bits = context->green_bits = context->blue_bits = 0;
}
}
return 0; /* all good, but not enough data yet */
}
int get_default_background_color(double *ret_red, double *ret_green, double *ret_blue) {
int r;
assert(ret_red);
assert(ret_green);
assert(ret_blue);
if (!colors_enabled())
return -EOPNOTSUPP;
if (isatty(STDOUT_FILENO) < 1 || isatty(STDIN_FILENO) < 1)
return -EOPNOTSUPP;
if (streq_ptr(getenv("TERM"), "linux")) {
/* Linux console is black */
*ret_red = *ret_green = *ret_blue = 0.0;
return 0;
}
struct termios old_termios;
if (tcgetattr(STDIN_FILENO, &old_termios) < 0)
return -errno;
struct termios new_termios = old_termios;
termios_disable_echo(&new_termios);
if (tcsetattr(STDOUT_FILENO, TCSADRAIN, &new_termios) < 0)
return -errno;
r = loop_write(STDOUT_FILENO, "\x1B]11;?\x07", SIZE_MAX);
if (r < 0)
goto finish;
usec_t end = usec_add(now(CLOCK_MONOTONIC), 100 * USEC_PER_MSEC);
char buf[256];
size_t buf_full = 0;
BackgroundColorContext context = {};
for (;;) {
usec_t n = now(CLOCK_MONOTONIC);
if (n >= end) {
r = -EOPNOTSUPP;
goto finish;
}
r = fd_wait_for_event(STDIN_FILENO, POLLIN, usec_sub_unsigned(end, n));
if (r < 0)
goto finish;
ssize_t l;
l = read(STDIN_FILENO, buf, sizeof(buf) - buf_full);
if (l < 0) {
r = -errno;
goto finish;
}
buf_full += l;
assert(buf_full <= sizeof(buf));
r = scan_background_color_response(&context, buf, buf_full);
if (r < 0)
goto finish;
if (r > 0) {
assert(context.red_bits > 0);
*ret_red = (double) context.red / ((UINT64_C(1) << context.red_bits) - 1);
assert(context.green_bits > 0);
*ret_green = (double) context.green / ((UINT64_C(1) << context.green_bits) - 1);
assert(context.blue_bits > 0);
*ret_blue = (double) context.blue / ((UINT64_C(1) << context.blue_bits) - 1);
r = 0;
goto finish;
}
}
finish:
(void) tcsetattr(STDOUT_FILENO, TCSADRAIN, &old_termios);
return r;
}
src/basic/terminal-util.h
+2
View File
@@ -288,3 +288,5 @@ static inline const char* ansi_highlight_green_red(bool b) {
#define TTY_MODE 0620
void termios_disable_echo(struct termios *termios);
int get_default_background_color(double *ret_red, double *ret_green, double *ret_blue);