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| author | Lennart Poettering <lennart@poettering.net> | 2024-10-31 10:05:13 +0100 |
|---|---|---|
| committer | Lennart Poettering <lennart@poettering.net> | 2024-10-31 11:38:08 +0100 |
| commit | b8311af8101577aa4ad431d827191cb7526b3435 (patch) | |
| tree | 03133ea195bfe70760889022f72b373fc1194bcc /src/basic | |
| parent | string-util: it's called OSC sequence, not CSO sequence (diff) | |
| download | systemd-b8311af8101577aa4ad431d827191cb7526b3435.tar.xz systemd-b8311af8101577aa4ad431d827191cb7526b3435.zip | |
tree-wide: prefer generating 0x1B 0x5C as ANSI sequence "ST"
OSC sequences can be closed with one of three terminators:
1. ASCII code 7, aka BEL, aka ^G, aka \x07, aka \a
2. ASCII code 156, aka \x9c
2. Pair of ASCII code 27 followed by ASCII code 92, aka \x1b\x5c
Of these, in some corner case scenarios BEL makes problem (see #34604).
Hence switch away from that wherever we use it, and prefer the \x1b\x5c
instead. That's preferable over \x9c, since the latter is also a valid
UTF-8 codepoint. See discussion here for example:
https://gist.github.com/egmontkob/eb114294efbcd5adb1944c9f3cb5feda#the-escape-sequence
Fixes: #34604
Diffstat (limited to 'src/basic')
| -rw-r--r-- | src/basic/terminal-util.c | 4 | ||||
| -rw-r--r-- | src/basic/terminal-util.h | 7 |
2 files changed, 9 insertions, 2 deletions
diff --git a/src/basic/terminal-util.c b/src/basic/terminal-util.c index 8ded46f493..4172db12a5 100644 --- a/src/basic/terminal-util.c +++ b/src/basic/terminal-util.c @@ -1923,12 +1923,12 @@ int get_default_background_color(double *ret_red, double *ret_green, double *ret if (tcsetattr(STDIN_FILENO, TCSADRAIN, &new_termios) < 0) return -errno; - r = loop_write(STDOUT_FILENO, "\x1B]11;?\x07", SIZE_MAX); + r = loop_write(STDOUT_FILENO, "\x1B]11;?" ANSI_ST, SIZE_MAX); if (r < 0) goto finish; usec_t end = usec_add(now(CLOCK_MONOTONIC), 333 * USEC_PER_MSEC); - char buf[STRLEN("\x1B]11;rgb:0/0/0\x07")]; /* shortest possible reply */ + char buf[STRLEN("\x1B]11;rgb:0/0/0" ANSI_ST)]; /* shortest possible reply */ size_t buf_full = 0; BackgroundColorContext context = {}; diff --git a/src/basic/terminal-util.h b/src/basic/terminal-util.h index b446e547d6..3d02e92d0b 100644 --- a/src/basic/terminal-util.h +++ b/src/basic/terminal-util.h @@ -27,6 +27,13 @@ #define ANSI_WINDOW_TITLE_PUSH "\x1b[22;2t" #define ANSI_WINDOW_TITLE_POP "\x1b[23;2t" +/* ANSI "string terminator" character ("ST"). Terminal emulators typically allow three different ones: 0x07, + * 0x9c, and 0x1B 0x5C. We'll avoid 0x07 (BEL, aka ^G) since it might trigger unexpected TTY signal + * handling. And we'll avoid 0x9c since that's also valid regular codepoint in UTF-8 and elsewhere, and + * creates ambiguities. Because of that some terminal emulators explicitly choose not to support it. Hence we + * use 0x1B 0x5c */ +#define ANSI_ST "\e\\" + bool isatty_safe(int fd); int terminal_reset_defensive(int fd, bool switch_to_text); |