crlf: tick the index forward to work around racy-git behaviour

In order to avoid racy-git, we zero out the file size for entries with
the same timestamp as the index (or during the initial checkout). This
is the case in a couple of crlf tests, as the code is fast enough to do
everything in the same second.

As we know that we do not perform the modification just after writing
out the index, which is what this is designed to work around, tick the
mtime of the index file such that it doesn't agree with the files
anymore, and we do not zero out these entries.

src/unix/posix.h

@@ -26,6 +26,7 @@ typedef int GIT_SOCKET;
 #define p_mkdir(p,m) mkdir(p, m)
 #define p_fsync(fd) fsync(fd)
 extern char *p_realpath(const char *, char *);
+#define p_utimensat(fd, path, times, flags) utimensat(fd, path, times, flags)
 
 #define p_recv(s,b,l,f) recv(s,b,l,f)
 #define p_send(s,b,l,f) send(s,b,l,f)

tests/checkout/crlf.c

@@ -4,6 +4,7 @@
 
 #include "git2/checkout.h"
 #include "repository.h"
+#include "index.h"
 #include "posix.h"
 
 static git_repository *g_repo;
@@ -31,6 +32,25 @@ void test_checkout_crlf__detect_crlf_autocrlf_false(void)
 	check_file_contents("./crlf/all-crlf", ALL_CRLF_TEXT_RAW);
 }
 
+static void tick_index(git_index *index)
+{
+	git_time_t ts;
+	struct timespec times[2];
+
+	cl_assert(index->on_disk);
+	cl_assert(git_index_path(index));
+
+	cl_git_pass(git_index_read(index, true));
+	ts = index->stamp.mtime;
+
+	times[0].tv_sec  = UTIME_OMIT; /* dont' change the atime */
+	times[0].tv_nsec = UTIME_OMIT; /* dont' change the atime */
+	times[1].tv_sec  = ts + 1;
+	times[1].tv_nsec = 0;
+	cl_git_pass(p_utimensat(AT_FDCWD, git_index_path(index), times, 0));
+	cl_git_pass(git_index_read(index, true));
+}
+
 void test_checkout_crlf__autocrlf_false_index_size_is_unfiltered_size(void)
 {
 	git_index *index;
@@ -40,9 +60,10 @@ void test_checkout_crlf__autocrlf_false_index_size_is_unfiltered_size(void)
 
 	cl_repo_set_bool(g_repo, "core.autocrlf", false);
 
-	git_checkout_head(g_repo, &opts);
-
 	git_repository_index(&index, g_repo);
+	tick_index(index);
+
+	git_checkout_head(g_repo, &opts);
 
 	cl_assert((entry = git_index_get_bypath(index, "all-lf", 0)) != NULL);
 	cl_assert(entry->file_size == strlen(ALL_LF_TEXT_RAW));
@@ -140,9 +161,10 @@ void test_checkout_crlf__autocrlf_true_index_size_is_filtered_size(void)
 
 	cl_repo_set_bool(g_repo, "core.autocrlf", true);
 
-	git_checkout_head(g_repo, &opts);
-
 	git_repository_index(&index, g_repo);
+	tick_index(index);
+
+	git_checkout_head(g_repo, &opts);
 
 	cl_assert((entry = git_index_get_bypath(index, "all-lf", 0)) != NULL);