Add Git LFS support via package extension

Author: mortenpi

Project.toml

@@ -1,19 +1,26 @@
 name = "Git"
 uuid = "d7ba0133-e1db-5d97-8f8c-041e4b3a1eb2"
-version = "1.4.0"
 authors = ["Dilum Aluthge", "contributors"]
+version = "1.4.0"
 
 [deps]
 Git_jll = "f8c6e375-362e-5223-8a59-34ff63f689eb"
 JLLWrappers = "692b3bcd-3c85-4b1f-b108-f13ce0eb3210"
 OpenSSH_jll = "9bd350c2-7e96-507f-8002-3f2e150b4e1b"
 
+[weakdeps]
+Git_LFS_jll = "020c3dae-16b3-5ae5-87b3-4cb189e250b2"
+
 [compat]
+Git_LFS_jll = "3"
 Git_jll = "2.44"
 JLLWrappers = "1.1"
 OpenSSH_jll = "9, 10"
 julia = "1.6"
 
+[extensions]
+GitLFSExt = "Git_LFS_jll"
+
 [extras]
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 

ext/GitLFSExt.jl

@@ -0,0 +1,6 @@
+module GitLFSExt
+using Git_LFS_jll
+
+git_lfs_path() = Git_LFS_jll.PATH[]
+
+end

src/git_function.jl

@@ -20,7 +20,7 @@ julia> run(git(["clone", "https://github.com/JuliaRegistries/General"]))
 
 to bypass the parsing of the command string.
 """
-function git(; adjust_PATH::Bool = true, adjust_LIBPATH::Bool = true)
+function git(; adjust_PATH::Bool = true, adjust_LIBPATH::Bool = true, lfs::Bool = false)
     git_cmd = @static if Sys.iswindows()
         Git_jll.git(; adjust_PATH, adjust_LIBPATH)::Cmd
     else
@@ -67,6 +67,13 @@ function git(; adjust_PATH::Bool = true, adjust_LIBPATH::Bool = true)
         git_cmd = addenv(git_cmd, "PATH" => join(path, pathsep), LIBPATH_env => join(libpath, pathsep))
     end
 
+    # If the Git_LFS_jll is loaded _and_ the user has explicitly requested it, we'll enable
+    # the support got `git lfs` subcommands (by modifying the PATH, so that Git could find
+    # the subcommand from the other JLL).
+    if lfs
+        git_cmd = _push_git_lfs_to_path!(git_cmd)
+    end
+
     return git_cmd
 end
 
@@ -75,3 +82,26 @@ function git(args::AbstractVector{<:AbstractString}; kwargs...)
     append!(cmd.exec, args)
     return cmd
 end
+
+# This function is used to implement the LFS support
+function _push_git_lfs_to_path!(git_cmd::Cmd)
+    GitLFSExt = Base.get_extension(@__MODULE__, :GitLFSExt)
+    if isnothing(GitLFSExt)
+        throw(GitLFSNotLoadedError())
+    end
+
+    idx = findfirst(startswith("PATH="), git_cmd.env)
+    path = if isnothing(idx)
+        ""
+    else
+        # dropping the `PATH=` part
+        git_cmd.env[idx][6:end]
+    end
+    path = split(get(ENV, LIBPATH_env, ""), path)
+    pushfirst!(path, GitLFSExt.git_lfs_path())
+
+    return addenv(git_cmd, "PATH" => join(path, pathsep))
+end
+
+struct GitLFSNotLoadedError <: Exception end
+Base.showerror(io::IO, ::GitLFSNotLoadedError) = print(io, "GitLFSNotLoadedError: Unable to set up LFS support for Git: lfs=true, but Git_LFS_jll is not loaded.")

test/runtests.jl

@@ -107,3 +107,35 @@ end
         @test_skip false
     end # if
 end # testset
+
+# This testset will only pass if the Git_LFS_jll has not been loaded
+@testset "Git LFS (not loaded)" begin
+    @test_throws Git.GitLFSNotLoadedError Git.git(; lfs=true)
+end
+
+# Ensure that we can call `git lfs`
+using Git_LFS_jll
+@testset "Git LFS" begin
+    cmd = Git.git(; lfs=true)
+    cmd = `$cmd lfs version`
+    @test success(cmd)
+
+    version_output = read(cmd, String)
+    # The output here will be something like
+    #
+    # git-lfs/3.7.0 (GitHub; linux amd64; go 1.24.0)\n
+    #
+    # So we'll match the first part. In case Git is unable to find `git lfs`, then
+    # this should throw an error, since `git` will exit with a non-zero exit code.
+    @test occursin(r"^git-lfs/\d+\.\d+\.\d+", version_output)
+
+    # If we set `lfs=false`, then `lfs` should not be available.
+    cmd = Git.git(; lfs=false)
+    cmd = `$cmd lfs version`
+    @test success(cmd)
+
+    # And the same with the default value
+    cmd = Git.git()
+    cmd = `$cmd lfs version`
+    @test !success(cmd)
+end