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698dca580

Denys Vlasenko

2010-02-01

FAILED Duration: 32s

Subject

add unicode.txt

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Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

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docs/unicode.txt +56 -0

docs/unicode.txt+56 -0

@@ -0,0 +1,56 @@
+	Unicode support in busybox
+
+	There are several scenarios where we need to handle unicode
+	correctly.
+
+	Shell input
+
+	We want to correctly handle input of unicode characters.
+	There are several problems with it. Just handling input
+	as sequence of bytes would break any editing. This was fixed
+	and now lineedit operates on the array of wchar_t's.
+	But we also need to handle the following problematic moments:
+
+	* It is unreasonable to expect that output device supports
+	_any_ unicode chars. Perhaps we need to avoid printing
+	those chars which are not supported by output device.
+	Examples: chars which are not present in the font,
+	chars which are not assigned in unicode,
+	combining chars (especially trying to combine bad pairs:
+	a_chinese_symbol + "combining grave accent" = ??!)
+
+	* We need to account for the fact that unicode chars have
+	different widths: 0 for combining chars, 1 for usual,
+	2 for ideograms (are there 3+ wide chars?).
+
+	* Bidirectional handling. If user wants to echo a phrase
+	in Hebrew, he types: echo "srettel werbeH"
+
+	Editors
+
+	This case is a bit similar to "shell input", but unlike shell,
+	editors may encounder many more unexpected unicode sequences
+	(try to load a random binry file...), and they need to preserve
+	them, unlike shell which can afford to drop bogus input.
+
+
+	more, less
+
+	.
+
+	ls (multi-column display)
+
+	.
+
+	top, ps
+
+	.
+
+	Filename display (in error messages and elsewhere)
+
+	.
+
+
+
+	TODO: write an email to Asmus Freytag ([email protected]),
+	author of http://unicode.org/reports/tr11/