Add depth to git_clone()

NEWS.md

@@ -13,6 +13,7 @@
 - Use `NEWS.md` instead of `NEWS` (@olivroy, #209)
 - Add git_revert() function (#206)
 - new function `git_branch_switch()`, an alias to `git_branch_checkout()` (#254)
+- Add argument `depth` in `git_clone()` (#281, @etiennebacher).
 
 # 2.3.1
 

R/fetch.R

@@ -183,6 +183,10 @@ git_push <- function(
 #' @param password a string or a callback function to get passwords for authentication
 #' or password protected ssh keys. Defaults to [askpass][askpass::askpass()] which
 #' checks `getOption('askpass')`.
+#' @param depth number of commits to fetch when creating a shallow clone. The
+#' default `0` clones the entire history. A positive value truncates the history
+#' to the given number of commits from the tip of each branch. Requires
+#' libgit2 >= 1.7.0.
 #' @param verbose display some progress info while downloading
 #' @examples {# Clone a small repository
 #' git_dir <- file.path(tempdir(), 'antiword')
@@ -220,6 +224,7 @@ git_clone <- function(
   ssh_key = NULL,
   bare = FALSE,
   mirror = FALSE,
+  depth = 0,
   verbose = interactive()
 ) {
   stopifnot(is.character(url))
@@ -233,6 +238,12 @@ git_clone <- function(
   }
   stopifnot(is.character(path))
   stopifnot(is.null(branch) || is.character(branch))
+  stopifnot(
+    "`depth` must be an integer >= 0" = is.numeric(depth) &&
+      length(depth) == 1 &&
+      depth >= 0
+  )
+  depth <- as.integer(depth)
   verbose <- as.logical(verbose)
   path <- normalizePath(path.expand(path), mustWork = FALSE)
   host <- url_to_host(url)
@@ -247,6 +258,7 @@ git_clone <- function(
     cred_cb,
     bare,
     mirror,
+    depth,
     verbose
   )
   git_repo_path(repo)

src/clone.c

@@ -320,7 +320,7 @@ static int repository_enable_cache(git_repository **out, const char *path, int b
 }
 
 SEXP R_git_repository_clone(SEXP url, SEXP path, SEXP branch, SEXP getkey, SEXP getcred,
-                            SEXP bare, SEXP mirror, SEXP verbose){
+                            SEXP bare, SEXP mirror, SEXP depth, SEXP verbose){
   git_repository *repo = NULL;
   git_clone_options clone_opts = GIT_CLONE_OPTIONS_INIT;
   clone_opts.checkout_opts.checkout_strategy = GIT_CHECKOUT_SAFE;
@@ -331,6 +331,16 @@ SEXP R_git_repository_clone(SEXP url, SEXP path, SEXP branch, SEXP getkey, SEXP
 
   set_verify_handler(&clone_opts.fetch_opts.callbacks);
 
+  /* shallow clone: fetch only the last 'depth' commits (libgit2 >= 1.7) */
+  int clone_depth = Rf_asInteger(depth);
+  if(clone_depth > 0){
+#if AT_LEAST_LIBGIT2(1, 7)
+    clone_opts.fetch_opts.depth = clone_depth;
+#else
+    Rf_warning("Shallow clone (depth) requires libgit2 >= 1.7.0. Ignoring the depth parameter.");
+#endif
+  }
+
   /* Also enables download progress and user interrupt */
   if(Rf_asLogical(verbose)){
     clone_opts.checkout_opts.progress_cb = checkout_progress;

src/init.c

@@ -56,7 +56,7 @@ extern SEXP R_git_remote_set_url(SEXP, SEXP, SEXP);
 extern SEXP R_git_restore(SEXP, SEXP, SEXP);
 extern SEXP R_git_revert(SEXP, SEXP);
 extern SEXP R_git_repository_add(SEXP, SEXP, SEXP);
-extern SEXP R_git_repository_clone(SEXP, SEXP, SEXP, SEXP, SEXP, SEXP, SEXP, SEXP);
+extern SEXP R_git_repository_clone(SEXP, SEXP, SEXP, SEXP, SEXP, SEXP, SEXP, SEXP, SEXP);
 extern SEXP R_git_repository_find(SEXP);
 extern SEXP R_git_repository_info(SEXP);
 extern SEXP R_git_repository_init(SEXP, SEXP);
@@ -140,7 +140,7 @@ static const R_CallMethodDef CallEntries[] = {
   {"R_git_remote_remove",       (DL_FUNC) &R_git_remote_remove,       2},
   {"R_git_remote_set_url",      (DL_FUNC) &R_git_remote_set_url,      3},
   {"R_git_repository_add",      (DL_FUNC) &R_git_repository_add,      3},
-  {"R_git_repository_clone",    (DL_FUNC) &R_git_repository_clone,    8},
+  {"R_git_repository_clone",    (DL_FUNC) &R_git_repository_clone,    9},
   {"R_git_repository_find",     (DL_FUNC) &R_git_repository_find,     1},
   {"R_git_repository_info",     (DL_FUNC) &R_git_repository_info,     1},
   {"R_git_repository_init",     (DL_FUNC) &R_git_repository_init,     2},

tests/testthat/test-clone.R

@@ -45,3 +45,32 @@ test_that("cloning repositories works, no path", {
   repo <- git_clone('https://github.com/r-lib/gert.git')
   expect_true(file.exists(file.path(path, "gert", 'DESCRIPTION')))
 })
+
+test_that("shallow cloning with depth works", {
+  skip_if_offline('github.com')
+  skip_if_not(libgit2_config()$version >= "1.7.0")
+  path <- file.path(tempdir(), 'gert-shallow')
+  on.exit(unlink(path, recursive = TRUE))
+  repo <- git_clone('https://github.com/r-lib/gert', path = path, depth = 1)
+  expect_true(file.exists(file.path(path, 'DESCRIPTION')))
+  expect_equal(nrow(git_log(repo = repo)), 1L)
+})
+
+test_that("git_clone() validates depth argument", {
+  expect_error(
+    git_clone('https://github.com/r-lib/gert', depth = -1),
+    "`depth` must be an integer >= 0"
+  )
+  expect_error(
+    git_clone('https://github.com/r-lib/gert', depth = NA),
+    "`depth` must be an integer >= 0"
+  )
+  expect_error(
+    git_clone('https://github.com/r-lib/gert', depth = "a"),
+    "`depth` must be an integer >= 0"
+  )
+  expect_error(
+    git_clone('https://github.com/r-lib/gert', depth = c(1, 2)),
+    "`depth` must be an integer >= 0"
+  )
+})