codeql/misc/bazel/lfs.bzl

def lfs_smudge(repository_ctx, srcs, extract = False, stripPrefix = None):
    for src in srcs:
        repository_ctx.watch(src)
    script = Label("//misc/bazel/internal:git_lfs_probe.py")
    python = repository_ctx.which("python3") or repository_ctx.which("python")
    if not python:
        fail("Neither python3 nor python executables found")
    repository_ctx.report_progress("querying LFS url(s) for: %s" % ", ".join([src.basename for src in srcs]))
    res = repository_ctx.execute([python, script] + srcs, quiet = True)
    if res.return_code != 0:
        fail("git LFS probing failed while instantiating @%s:\n%s" % (repository_ctx.name, res.stderr))
    promises = []
    for src, loc in zip(srcs, res.stdout.splitlines()):
        if loc == "local":
            if extract:
                repository_ctx.report_progress("extracting local %s" % src.basename)
                repository_ctx.extract(src, stripPrefix = stripPrefix)
            else:
                repository_ctx.report_progress("symlinking local %s" % src.basename)
                repository_ctx.symlink(src, src.basename)
        else:
            sha256, _, url = loc.partition(" ")
            if extract:
                # we can't use skylib's `paths.split_extension`, as that only gets the last extension, so `.tar.gz`
                # or similar wouldn't work
                # it doesn't matter if file is something like some.name.zip and possible_extension == "name.zip",
                # download_and_extract will just append ".name.zip" its internal temporary name, so extraction works
                possible_extension = ".".join(src.basename.rsplit(".", 2)[-2:])
                repository_ctx.report_progress("downloading and extracting remote %s" % src.basename)
                repository_ctx.download_and_extract(url, sha256 = sha256, stripPrefix = stripPrefix, type = possible_extension)
            else:
                repository_ctx.report_progress("downloading remote %s" % src.basename)
                repository_ctx.download(url, src.basename, sha256 = sha256)

def _download_and_extract_lfs(repository_ctx):
    attr = repository_ctx.attr
    src = repository_ctx.path(attr.src)
    if attr.build_file_content and attr.build_file:
        fail("You should specify only one among build_file_content and build_file for rule @%s" % repository_ctx.name)
    lfs_smudge(repository_ctx, [src], extract = True, stripPrefix = attr.strip_prefix)
    if attr.build_file_content:
        repository_ctx.file("BUILD.bazel", attr.build_file_content)
    elif attr.build_file:
        repository_ctx.symlink(attr.build_file, "BUILD.bazel")

def _download_lfs(repository_ctx):
    attr = repository_ctx.attr
    if int(bool(attr.srcs)) + int(bool(attr.dir)) != 1:
        fail("Exactly one between `srcs` and `dir` must be defined for @%s" % repository_ctx.name)
    if attr.srcs:
        srcs = [repository_ctx.path(src) for src in attr.srcs]
    else:
        dir = repository_ctx.path(attr.dir)
        if not dir.is_dir:
            fail("`dir` not a directory in @%s" % repository_ctx.name)
        srcs = [f for f in dir.readdir() if not f.is_dir]
    lfs_smudge(repository_ctx, srcs)

    # with bzlmod the name is qualified with `~` separators, and we want the base name here
    name = repository_ctx.name.split("~")[-1]
    repository_ctx.file("BUILD.bazel", """
exports_files({files})

filegroup(
    name = "{name}",
    srcs = {files},
    visibility = ["//visibility:public"],
)
""".format(name = name, files = repr([src.basename for src in srcs])))

lfs_archive = repository_rule(
    doc = "Export the contents from an on-demand LFS archive. The corresponding path should be added to be ignored " +
          "in `.lfsconfig`.",
    implementation = _download_and_extract_lfs,
    attrs = {
        "src": attr.label(mandatory = True, doc = "Local path to the LFS archive to extract."),
        "build_file_content": attr.string(doc = "The content for the BUILD file for this repository. " +
                                                "Either build_file or build_file_content can be specified, but not both."),
        "build_file": attr.label(doc = "The file to use as the BUILD file for this repository. " +
                                       "Either build_file or build_file_content can be specified, but not both."),
        "strip_prefix": attr.string(default = "", doc = "A directory prefix to strip from the extracted files. "),
    },
)

lfs_files = repository_rule(
    doc = "Export LFS files for on-demand download. Exactly one between `srcs` and `dir` must be defined. The " +
          "corresponding paths should be added to be ignored in `.lfsconfig`.",
    implementation = _download_lfs,
    attrs = {
        "srcs": attr.label_list(doc = "Local paths to the LFS files to export."),
        "dir": attr.label(doc = "Local path to a directory containing LFS files to export. Only the direct contents " +
                                "of the directory are exported"),
    },
)