[PATCH 5/5] scalar diagnose: show a spinner while staging content

["Johannes Schindelin via GitGitGadget" <gitgitgadget@gmail.com>]

From: Johannes Schindelin <johannes.schindelin@gmx.de>

It can take a while to gather all the information that `scalar diagnose`
wants to accumulate. Typically this happens when the user is in need of
quick solutions and therefore their patience is tested already. By
showing a little spinner that spins around, we hope to help the user
muster just a tiny bit more patience until `scalar diagnose` is done.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 contrib/scalar/scalar.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/contrib/scalar/scalar.c b/contrib/scalar/scalar.c
index c0ad4948215..224329f38f5 100644
--- a/contrib/scalar/scalar.c
+++ b/contrib/scalar/scalar.c
@@ -259,12 +259,26 @@ static int unregister_dir(void)
 	return res;
 }
 
+static void spinner(void)
+{
+	static const char whee[] = "|\010/\010-\010\\\010", *next = whee;
+
+	if (!next)
+		return;
+	if (write(2, next, 2) < 0)
+		next = NULL;
+	else
+		next = next[2] ? next + 2 : whee;
+}
+
 static int stage(const char *git_dir, struct strbuf *buf, const char *path)
 {
 	struct strbuf cacheinfo = STRBUF_INIT;
 	struct child_process cp = CHILD_PROCESS_INIT;
 	int res;
 
+	spinner();
+
 	strbuf_addstr(&cacheinfo, "100644,");
 
 	cp.git_cmd = 1;
-- 
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