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console: a bare ESC[m is a reset, and OSC sequences are consumed

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Two ANSI bugs, both found by running fastfetch rather than by reading the
parser, and both invisible to anything that spells its escapes out in full.

ESC[m with no parameters means ESC[0m. ECMA-48 is explicit that an omitted
parameter takes its default and SGR's default is 0, and sgr() iterated its
parameter list -- which is empty in exactly that case, so the loop body never
ran and the reset was silently dropped.

Programs emit the bare form constantly. fastfetch writes "\x1b[32m1%\x1b[m", so
everything after the first coloured character stayed green forever. With a
background colour it is much worse: its palette swatch sets a white background
and resets, the reset did nothing, and the console went white-on-white and
stayed there -- filling the screen with white rectangles as it scrolled, which
looks like a corrupted framebuffer rather than one missing branch.

OSC sequences were not a state at all, so ESC ] fell through and the payload
printed as text: a hyperlinked path arrived as "Disk (]8;;file:///\]8;;\)".
Nothing here acts on an operating-system command -- there is no window title and
no hyperlink to follow -- but *discarding* one is not optional, because the
alternative is printing somebody's URL into the middle of their output. ESC \
ends it, and an ESC followed by anything else is handed back to the escape state
rather than eaten, so a malformed OSC does not swallow the sequence after it.

Verified by screendumping the framebuffer after two consecutive fastfetch runs:
identical output both times, near-white coverage down from most of the screen to
2% (the palette swatch's own white cell), and the disk line reading "Disk (/)".

Also installs docs/branding/Ascii/ascii_50.txt as /usr/share/schos/logo.txt --
Shift as characters, at the width that leaves room for an info block on an
80-column console. Installed from the branding directory rather than copied into
sysroot by hand, so there is one source.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VQ7Qx8E1q1M1bbCq8QLHS2
This commit is contained in:
Nexoniarz 2026-09-12 19:38:00 +02:00
commit 1754cbf1aa
8 changed files with 292 additions and 4 deletions
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15
Makefile
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@ -901,10 +901,21 @@ SCHINIT_JOBS = $(wildcard etc/schinit/*.job) etc/schinit/README
ETC_FILES = $(wildcard etc/*)
ETC_PLAIN = $(filter-out etc/schinit,$(ETC_FILES))
etc-install: $(SCHINIT_JOBS) $(ETC_PLAIN)
@mkdir -p $(SYSROOT)/etc/schinit
# The mark as characters, for anything that draws a logo into a terminal --
# fastfetch takes it with --file-raw. Installed from docs/branding rather than
# copied into sysroot by hand, so there is one source and `make` keeps them in
# step; see docs/branding/README.md.
#
# The 50-column one, because that is what fits beside an info block on an
# 80-column console. The wider renderings are in the same directory for
# anything with more room.
LOGO_ASCII = docs/branding/Ascii/ascii_50.txt
etc-install: $(SCHINIT_JOBS) $(ETC_PLAIN) $(LOGO_ASCII)
@mkdir -p $(SYSROOT)/etc/schinit $(SYSROOT)/usr/share/schos
@cp $(ETC_PLAIN) $(SYSROOT)/etc/
@cp $(SCHINIT_JOBS) $(SYSROOT)/etc/schinit/
@cp $(LOGO_ASCII) $(SYSROOT)/usr/share/schos/logo.txt
@echo "installed $(words $(ETC_PLAIN)) /etc file(s) and $(words $(SCHINIT_JOBS)) schinit manifest(s)"
sysroot-install: $(addprefix $(SYSROOT)/bin/, $(CMDS)) etc-install