filters: rewrite colorize in c

Since its introduction, we had multiple issues with the colorize awk
script with regard to non-GNU awk compatibility.

Also, this script is standalone and the color theme must be hard coded
into it. Reading from an external configuration file (aerc's styleset)
from a non-GNU awk is close to impossible (and even far from trivial
with GNU awk).

Rewrite the builtin colorize filter in C to allow getting the color
theme from aerc's active styleset. The theme is configured using the
existing styleset syntax and attributes under a separate [viewer]
section (see examples and man page).

Export the active styleset file path to AERC_STYLESET env var when
invoking the filter command so that colorize can access it and use it.

I have tested compilation (with clang-analyzer and gcc -fanalyzer) and
basic operation on FreeBSD, Fedora (glibc) and Alpine (muslibc). More
tests would probably be required on MacOSX and older Linux distros.
I also added test vectors to give some confidence that this works as
expected. The execution with these vectors passed valgrind
--leak-check=full without errors.

NB: the default theme has changed to be more minimal. Sample stylesets
have more colorful examples. The awk -v theme=xxx option is no longer
supported.

  usage: colorize [-h] [-s FILE] [-f FILE]

  options:
    -h       show this help message
    -s FILE  use styleset file (default $AERC_STYLESET)
    -f FILE  read from filename (default stdin)

Signed-off-by: Robin Jarry <robin@jarry.cc>
Tested-by: Bence Ferdinandy <bence@ferdinandy.com>
Acked-by: Moritz Poldrack <moritz@poldrack.dev>

1 files changed, 3 insertions, 0 deletions

diff --git a/config/style.go b/config/style.go
index 5ce2c1cf..65c5a3b1 100644
--- a/config/style.go
+++ b/config/style.go
@@ -254,6 +254,7 @@ func (s Style) composeWith(styles []*Style) Style {
 type StyleSet struct {
 	objects  map[StyleObject]*Style
 	selected map[StyleObject]*Style
+	path     string
 }
 
 func NewStyleSet() StyleSet {
@@ -453,6 +454,8 @@ func (ss *StyleSet) LoadStyleSet(stylesetName string, stylesetDirs []string) err
 		return err
 	}
 
+	ss.path = filepath
+
 	return ss.ParseStyleSet(file)
 }