[PATCH 4/9] sparse-checkout: 'add' subcommand

[Derrick Stolee via GitGitGadget]

From: Derrick Stolee <dsto...@microsoft.com>

The 'git sparse-checkout add' subcommand takes a list of patterns
over stdin and writes them to the sparse-checkout file. Then, it
updates the working directory using 'git read-tree -mu HEAD'.

Note: if a user adds a negative pattern that would lead to the
removal of a non-empty directory, then Git may not delete that
directory (on Windows).

Signed-off-by: Derrick Stolee <dsto...@microsoft.com>
---
 Documentation/git-sparse-checkout.txt |  4 ++++
 builtin/sparse-checkout.c             | 32 ++++++++++++++++++++++++++-
 t/t1091-sparse-checkout-builtin.sh    | 20 +++++++++++++++++
 3 files changed, 55 insertions(+), 1 deletion(-)

diff --git a/Documentation/git-sparse-checkout.txt 
b/Documentation/git-sparse-checkout.txt
index 50c53ee60a..6f540a3443 100644
--- a/Documentation/git-sparse-checkout.txt
+++ b/Documentation/git-sparse-checkout.txt
@@ -34,6 +34,10 @@ COMMANDS
        by Git. Add patterns to the sparse-checkout file to
        repopulate the working directory.
 
+'add'::
+       Add a set of patterns to the sparse-checkout file, as given over
+       stdin. Updates the working directory to match the new patterns.
+
 SPARSE CHECKOUT
 ----------------
 
diff --git a/builtin/sparse-checkout.c b/builtin/sparse-checkout.c
index 86d24e6295..ec6134fecc 100644
--- a/builtin/sparse-checkout.c
+++ b/builtin/sparse-checkout.c
@@ -8,7 +8,7 @@
 #include "strbuf.h"
 
 static char const * const builtin_sparse_checkout_usage[] = {
-       N_("git sparse-checkout [init|list]"),
+       N_("git sparse-checkout [init|add|list]"),
        NULL
 };
 
@@ -166,6 +166,34 @@ static int sparse_checkout_init(int argc, const char 
**argv)
        return sc_read_tree();
 }
 
+static int sparse_checkout_add(int argc, const char **argv)
+{
+       struct exclude_list el;
+       char *sparse_filename;
+       FILE *fp;
+       struct strbuf line = STRBUF_INIT;
+
+       memset(&el, 0, sizeof(el));
+
+       sparse_filename = get_sparse_checkout_filename();
+       add_excludes_from_file_to_list(sparse_filename, "", 0, &el, NULL);
+
+       fp = fopen(sparse_filename, "w");
+       write_excludes_to_file(fp, &el);
+
+       while (!strbuf_getline(&line, stdin)) {
+               strbuf_trim(&line);
+               fprintf(fp, "%s\n", line.buf);
+       }
+
+       fclose(fp);
+       free(sparse_filename);
+
+       clear_exclude_list(&el);
+
+       return sc_read_tree();
+}
+
 int cmd_sparse_checkout(int argc, const char **argv, const char *prefix)
 {
        static struct option builtin_sparse_checkout_options[] = {
@@ -187,6 +215,8 @@ int cmd_sparse_checkout(int argc, const char **argv, const 
char *prefix)
                        return sparse_checkout_list(argc, argv);
                if (!strcmp(argv[0], "init"))
                        return sparse_checkout_init(argc, argv);
+               if (!strcmp(argv[0], "add"))
+                       return sparse_checkout_add(argc, argv);
        }
 
        usage_with_options(builtin_sparse_checkout_usage,
diff --git a/t/t1091-sparse-checkout-builtin.sh 
b/t/t1091-sparse-checkout-builtin.sh
index b7d5f15830..499bd8d6d0 100755
--- a/t/t1091-sparse-checkout-builtin.sh
+++ b/t/t1091-sparse-checkout-builtin.sh
@@ -100,4 +100,24 @@ test_expect_success 'clone --sparse' '
        test_cmp expect dir
 '
 
+test_expect_success 'add to existing sparse-checkout' '
+       echo "/folder2/*" | git -C repo sparse-checkout add &&
+       cat >expect <<-EOF &&
+               /*
+               !/*/*
+               /folder1/*
+               /folder2/*
+       EOF
+       git -C repo sparse-checkout list >actual &&
+       test_cmp expect actual &&
+       test_cmp expect repo/.git/info/sparse-checkout &&
+       ls repo >dir  &&
+       cat >expect <<-EOF &&
+               a
+               folder1
+               folder2
+       EOF
+       test_cmp expect dir
+'
+
 test_done
\ No newline at end of file
-- 
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