From: Philippe Proulx <eeppeliteloop@gmail.com>
Date: Fri, 17 Feb 2017 09:14:40 +0000 (-0500)
Subject: Filtering: add support for star-only globbing patterns
X-Git-Tag: v2.10.0-rc1~16
X-Git-Url: http://git.lttng.org./?a=commitdiff_plain;h=3151a51df2b93554f3e4559a2e7ec08541e8674d;hp=3151a51df2b93554f3e4559a2e7ec08541e8674d;p=lttng-ust.git

Filtering: add support for star-only globbing patterns

This patch adds the support for "full" star-only globbing patterns to be
used in filter literal strings. A star-only globbing pattern is a
globbing pattern with the star (`*`) being the only special character.
This means `?` and character sets (`[abc-k]`) are not supported here. We
cannot support them without a strategy to differentiate the globbing
pattern because `?` and `[` are not special characters in filter literal
strings right now. The eventual strategy to support them would probably
look like this:

    filename =* "?sys*.[ch]"

The filter bytecode generator in LTTng-tools's session daemon creates
the new FILTER_OP_LOAD_STAR_GLOB_STRING operation when the interpreter
should load a star globbing pattern literal string. Even if both
"plain", or legacy strings and star globbing pattern strings are literal
strings, they do not represent the same thing, that is, the == and !=
operators act differently.

The validation process checks that:

1. There's no binary operator between two
   FILTER_OP_LOAD_STAR_GLOB_STRING operations. It is illegal to compare
   two star globbing patterns, as this is not trivial to implement, and
   completely useless as far as I know.

2. Only the == and != binary operators are allowed between a
   star globbing pattern and a string.

For the special case of star globbing patterns with a star at the end
only, the current behaviour is not changed to preserve a maximum of
backward compatibility. This is also why the UST ABI version is changed
from 7.1 to 7.2, not to 8.0.

== or != operations between REG_STRING and REG_STAR_GLOB_STRING
registers is specialized to FILTER_OP_EQ_STAR_GLOB_STRING and
FILTER_OP_NE_STAR_GLOB_STRING. Which side is the actual globbing pattern
(the one with the REG_STAR_GLOB_STRING type) is checked at execution
time. The strutils_star_glob_match() function is used to perform the
match operation. See the implementation for more details.

Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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