Add more large blob test cases

New test cases list commands that should work when memory is
limited. All memory allocation functions (*) learn to reject any
allocation larger than $GIT_ALLOC_LIMIT if set.

(*) Not exactly all. Some places do not use x* functions, but
malloc/calloc directly, notably diff-delta. These code path should
never be run on large blobs.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t1050-large.sh

@@ -6,11 +6,15 @@ test_description='adding and checking out large blobs'
 . ./test-lib.sh
 
 test_expect_success setup '
-	git config core.bigfilethreshold 200k &&
+	# clone does not allow us to pass core.bigfilethreshold to
+	# new repos, so set core.bigfilethreshold globally
+	git config --global core.bigfilethreshold 200k &&
 	echo X | dd of=large1 bs=1k seek=2000 &&
 	echo X | dd of=large2 bs=1k seek=2000 &&
 	echo X | dd of=large3 bs=1k seek=2000 &&
-	echo Y | dd of=huge bs=1k seek=2500
+	echo Y | dd of=huge bs=1k seek=2500 &&
+	GIT_ALLOC_LIMIT=1500 &&
+	export GIT_ALLOC_LIMIT
 '
 
 test_expect_success 'add a large file or two' '
@@ -100,4 +104,34 @@ test_expect_success 'packsize limit' '
 	)
 '
 
+test_expect_success 'diff --raw' '
+	git commit -q -m initial &&
+	echo modified >>large1 &&
+	git add large1 &&
+	git commit -q -m modified &&
+	git diff --raw HEAD^
+'
+
+test_expect_success 'hash-object' '
+	git hash-object large1
+'
+
+test_expect_failure 'cat-file a large file' '
+	git cat-file blob :large1 >/dev/null
+'
+
+test_expect_failure 'cat-file a large file from a tag' '
+	git tag -m largefile largefiletag :large1 &&
+	git cat-file blob largefiletag >/dev/null
+'
+
+test_expect_failure 'git-show a large file' '
+	git show :large1 >/dev/null
+
+'
+
+test_expect_failure 'repack' '
+	git repack -ad
+'
+
 test_done

wrapper.c

@@ -9,6 +9,18 @@ static void do_nothing(size_t size)
 
 static void (*try_to_free_routine)(size_t size) = do_nothing;
 
+static void memory_limit_check(size_t size)
+{
+	static int limit = -1;
+	if (limit == -1) {
+		const char *env = getenv("GIT_ALLOC_LIMIT");
+		limit = env ? atoi(env) * 1024 : 0;
+	}
+	if (limit && size > limit)
+		die("attempting to allocate %"PRIuMAX" over limit %d",
+		    (intmax_t)size, limit);
+}
+
 try_to_free_t set_try_to_free_routine(try_to_free_t routine)
 {
 	try_to_free_t old = try_to_free_routine;
@@ -32,7 +44,10 @@ char *xstrdup(const char *str)
 
 void *xmalloc(size_t size)
 {
-	void *ret = malloc(size);
+	void *ret;
+
+	memory_limit_check(size);
+	ret = malloc(size);
 	if (!ret && !size)
 		ret = malloc(1);
 	if (!ret) {
@@ -79,7 +94,10 @@ char *xstrndup(const char *str, size_t len)
 
 void *xrealloc(void *ptr, size_t size)
 {
-	void *ret = realloc(ptr, size);
+	void *ret;
+
+	memory_limit_check(size);
+	ret = realloc(ptr, size);
 	if (!ret && !size)
 		ret = realloc(ptr, 1);
 	if (!ret) {
@@ -95,7 +113,10 @@ void *xrealloc(void *ptr, size_t size)
 
 void *xcalloc(size_t nmemb, size_t size)
 {
-	void *ret = calloc(nmemb, size);
+	void *ret;
+
+	memory_limit_check(size * nmemb);
+	ret = calloc(nmemb, size);
 	if (!ret && (!nmemb || !size))
 		ret = calloc(1, 1);
 	if (!ret) {