I just checked out their third_party/curl repository, and here is the full diffstat from the upstream they based it on: $ git diff --stat origin/upstream/mas

I just checked out their third_party/curl repository, and here is the full diffstat from the upstream they based it on: $ git diff --stat origin/upstream/master origin/master BUILD.gn | 438 ++ include/curl/curlbuild.h.fuchsia | 198 + lib/curl_config.h.fuchsia | 1034 +++++ src/.gitignore | 1 - src/tool_hugehelp.c | 9000 ++++++++++++++++++++++++++++++++++++++ 5 files changed, 10670 insertions(+), 1 deletion(-) This adds a build file for the build system they use, and a couple of the config files that would normally be generated by the configure script but presumably the configure script doesn't support Fuchsia, along with an auto-generated source file containing the help output. So it looks like they have had to make zero actual source changes to cURL; the POSIX compatibility layer and setting the appropriate defines in cURL's config files are sufficient.