filters: rewrite wrap in c

This utility introduced in commit c9524d265793 ("filters: add wrap
utility written in go") allows to reflow text to view emails that have
very long lines without breaking quotes, lists and indentation.

For such a simple task, go produces a binary that is 2.0M bytes on disk.
After stripping debugging symbols, it can be reduced to 1.2M bytes. All
of this for 267 lines of source code. This is a bit ridiculous, provided
people may load this binary into memory multiple times per minute. This
tool is a small side-project that seems not suitable for golang.

Rewrite it in C. It now only depends on a POSIX libc to run. It is safe
to assume that there is one available on all *NIX systems in the world
of 2023. The resulting binary is now 27K bytes (15K after stripping).

To build it, a C compiler and libc headers are required. These should
most likely be available since they are dependencies of the go compiler
toolchain.

I have tested compilation (with clang-analyzer and gcc -fanalyzer) and
basic operation on FreeBSD, Fedora (glibc) and Alpine (musl libc). 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.

Update CI with aggressive gcc hardening flags and to run these tests
with valgrind --leak-check=full.

Command line options are unchanged:

  usage: wrap [-h] [-w INT] [-r] [-l INT] [-f FILE]

  Wrap text without messing up email quotes.

  options:
    -h       show this help message
    -w INT   preferred wrap margin (default 80)
    -r       reflow all paragraphs even if no trailing space
    -l INT   minimum percentage of letters in a line to be considered
             a paragaph
    -f FILE  read from filename (default stdin)

Signed-off-by: Robin Jarry <robin@jarry.cc>
Tested-by: Bence Ferdinandy <bence@ferdinandy.com>
Tested-by: Maxwell G <gotmax@e.email>

1 files changed, 24 insertions, 0 deletions

diff --git a/filters/test.sh b/filters/test.sh
new file mode 100755
index 00000000..65a1d4d3
--- /dev/null
+++ b/filters/test.sh
@@ -0,0 +1,24 @@
+#!/bin/sh
+
+set -e
+
+here=$(dirname $0)
+fail=0
+
+for vec in $here/vectors/*.in; do
+	tool=$(basename $vec | sed 's/-.*//')
+	expected=${vec%%.in}.expected
+	tmp=$(mktemp)
+	if ! $FILTERS_TEST_PREFIX $here/../$tool -f $vec > $tmp; then
+		fail=1
+	fi
+	if diff -u "$expected" "$tmp"; then
+		echo "ok      $tool < $vec > $tmp"
+	else
+		echo "error   $tool < $vec > $tmp"
+		fail=1
+	fi
+	rm -f -- "$tmp"
+done
+
+exit $fail