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The regex '^a|b' means "does the string start with a, or does it have
a b anywhere", not "does the string start with a or b" (the latter
should be spelled '^[ab]' or '^(a|b)'). It should match exactly the
same strings as 'b|^a'. But the current implementation hard-codes an
assumption that when the regex starts with a ^, the whole regex must
match from the beginning, i.e. it only attempts at offset 0.
It really should be completely symmetrical to 'b|c$' ("does it have a
b anywhere or end with c?"), which is treated correctly.
Another quirk is that currently the regex 'x*$', which should match
all strings (because it just means "does the string end
with 0 or more x'es"), does not, because in the unanchored case we
never attempt to match at ofs==len. In the anchored case, '^x*$', this
works correctly and matches exactly strings (including the empty
string) consisting entirely of x'es.
Fix both of these issues by dropping all use of the slre->anchored
member and always test at all possible offsets. If the regex does have
a ^ somewhere (including after a | branch character), that is
correctly handled by the match engine by only matching when *ofs is 0.
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Rasmus Villemoes <ravi@prevas.dk>
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Downloaded from http://slre.sourceforge.net/
and adapted for U-Boot environment.
Used to implement regex operations on environment variables.
Code size is ~ 3.5 KiB on PPC.
To enable this code, define the CONFIG_REGEX option in your board
config file.
Note: There are more recent versions of the SLRE library available at
http://slre.googlecode.com ; unfortunately, the new code has a heavily
reorked API which makes it less usable for our purposes:
- the return code is strings, which are more difficult to process
- we don't get any information any more which sub-string of the data
was matched by the given regex
- it is much more cumbersome to work with arbitrary expressions, where
for example the number of substrings for capturing are not known at
compile time
Also, there does not seem to be any real changes or improvements of
the functionality.
Because of this, we deliberately stick with the older code.
Note 2: the test code (built when SLRE_TEST is defined) was modified
to allow for more extensive testing; now we can test the regexp
matching on all lines on a text file (instead of the whole data in the
file as a single block).
Signed-off-by: Wolfgang Denk <wd@denx.de>
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