One-time tool that makes OWB reuse a pre-built fontconfig cache instead of rescannning all fonts on the first run after installing AROS from an ISO.

On AROS, fontconfig decides that a font directory cache is still valid by comparing the checksum field stored in the cache file header with the modification time (in seconds) of the font directory itself. For the OWB that ships in the AROS ISO (built against fontconfig 2.11.0) this is:

FcCacheTimeValid: cache->checksum == (int) dir_stat->st_mtime

(see FcCacheTimeValid() / FcDirCacheValidateHelper() in fontconfig 2.11.0's src/fccache.c). The AROS fontconfig port has no checksum_nano field (that was only added upstream in 2.13.1) and shortens the cache file name to the first 8 characters of the MD5 of the font directory path:

PROGDIR:Conf/29a5abb3-x86_64-aros.cache-4     (29a5abb3 = first 8 of MD5("Fonts:TrueType"))

If a cache file is generated on the build machine but the ISO installer stamps the font directory with the install time, the stored checksum no longer matches, so fontconfig discards the cache and rescans every font on the first OWB run (the splash screen indexation bar).

fcachefix rewrites the checksum field of an existing cache file to match the current mtime of the font directory, so fontconfig accepts the pre-built cache. It must be run once, right after installation, while the font directory contents are known to match the cache.

The tool also understands the newer fontconfig 2.13.1+/2.16.0 cache format (cache version 9, full 32-character MD5 names, checksum_nano field): for those files it additionally zeroes checksum_nano, since the AROS stat layer reports st_mtim.tv_nsec == 0 always.

• The cache must have been built on AROS with the same fontconfig version that OWB actually loads in the ISO. A cache produced by fontconfig 2.16.0 (cache-9) is rejected by fontconfig 2.11.0 and vice versa.
• The font directory path string must be identical to the one used when the cache was built (OWB AROS default: Fonts:TrueType), because the cache file name is derived from its MD5.
• The cache file must live in the directory listed in <cachedir> of the fonts.conf that OWB loads. On the current ISO stack that is PROGDIR:Conf; fcachefix also falls back to PROGDIR:Conf/font, PROGDIR:fonts/cache and T:fonts/cache.

Using the AROS cross compiler:

make CC=x86_64-aros-gcc       # or i386-aros-gcc

Or through the normal OWB CMake build (target fcachefix).

The tool is pure C and links nothing beyond the standard AROS POSIX layer.

fcachefix [cachedir] [fontdir]

Defaults: cachedir = PROGDIR:Conf, fontdir = Fonts:TrueType.

The cache file layout is detected from the version suffix in the file name: .cache-9 and newer also get checksum_nano zeroed, older versions only get checksum patched. The checksum field offset is derived with offsetof() from the target ABI (48 on x86_64, 28 on i386).

Exit code 0 on success, 20 on bad arguments, 21 on errors (including "no cache file found").

1. On an AROS system (e.g. a VM) with the final font set installed in Fonts:TrueType, run OWB once and let the font indexation finish. Use the OWB + fontconfig that the ISO will actually ship.
2. Copy the generated file from PROGDIR:Conf/ (the 29a5abb3-*.cache-* file) into the ISO so it lands in PROGDIR:Conf/.
3. Ship fcachefix and the FontCacheFix script, e.g. in PROGDIR:Scripts/ (make install copies them to Dist/Scripts/).
4. After installing the ISO, run FontCacheFix once. The next OWB start loads the cache and skips the font scan.

• Compare stat Fonts:TrueType (mtime, in seconds) with the checksum field in the cache file header (offset 48 on x86_64 / 28 on i386) — they must be equal.
• First OWB run after FontCacheFix should show no font indexation progress.
• Negative test: add a font to Fonts:TrueType — the directory mtime changes, the cache becomes invalid and OWB rescans again (the fixup is not repeated).

• Run the fixup only at install time, when the shipped fonts are in place. If OWB is updated/reinstalled with a different font set, run it again.
• The cache format must match the fontconfig that OWB loads. If the ISO stack is changed (e.g. to fontconfig 2.16.0), regenerate the pre-built cache with that fontconfig; fcachefix itself handles both formats.