Merge branch 'nd/large-blobs'

Teach a few codepaths to punt (instead of dying) when large blobs
that would not fit in core are involved in the operation.

* nd/large-blobs:
  diff: shortcut for diff'ing two binary SHA-1 objects
  diff --stat: mark any file larger than core.bigfilethreshold binary
  diff.c: allow to pass more flags to diff_populate_filespec
  sha1_file.c: do not die failing to malloc in unpack_compressed_entry
  wrapper.c: introduce gentle xmallocz that does not die()

Documentation/config.txt

@@ -499,7 +499,8 @@ core.bigFileThreshold::
 	Files larger than this size are stored deflated, without
 	attempting delta compression.  Storing large files without
 	delta compression avoids excessive memory usage, at the
-	slight expense of increased disk usage.
+	slight expense of increased disk usage. Additionally files
+	larger than this size are always treated as binary.
 +
 Default is 512 MiB on all platforms.  This should be reasonable
 for most projects as source code and other text files can still

Documentation/gitattributes.txt

@@ -440,8 +440,8 @@ Unspecified::
 
 	A path to which the `diff` attribute is unspecified
 	first gets its contents inspected, and if it looks like
-	text, it is treated as text.  Otherwise it would
-	generate `Binary files differ`.
+	text and is smaller than core.bigFileThreshold, it is treated
+	as text. Otherwise it would generate `Binary files differ`.
 
 String::
 

diff.c

@@ -376,7 +376,7 @@ static unsigned long diff_filespec_size(struct diff_filespec *one)
 {
 	if (!DIFF_FILE_VALID(one))
 		return 0;
-	diff_populate_filespec(one, 1);
+	diff_populate_filespec(one, CHECK_SIZE_ONLY);
 	return one->size;
 }
 
@@ -1910,11 +1910,11 @@ static void show_dirstat(struct diff_options *options)
 			diff_free_filespec_data(p->one);
 			diff_free_filespec_data(p->two);
 		} else if (DIFF_FILE_VALID(p->one)) {
-			diff_populate_filespec(p->one, 1);
+			diff_populate_filespec(p->one, CHECK_SIZE_ONLY);
 			copied = added = 0;
 			diff_free_filespec_data(p->one);
 		} else if (DIFF_FILE_VALID(p->two)) {
-			diff_populate_filespec(p->two, 1);
+			diff_populate_filespec(p->two, CHECK_SIZE_ONLY);
 			copied = 0;
 			added = p->two->size;
 			diff_free_filespec_data(p->two);
@@ -2188,8 +2188,8 @@ int diff_filespec_is_binary(struct diff_filespec *one)
 			one->is_binary = one->driver->binary;
 		else {
 			if (!one->data && DIFF_FILE_VALID(one))
-				diff_populate_filespec(one, 0);
-			if (one->data)
+				diff_populate_filespec(one, CHECK_BINARY);
+			if (one->is_binary == -1 && one->data)
 				one->is_binary = buffer_is_binary(one->data,
 						one->size);
 			if (one->is_binary == -1)
@@ -2324,6 +2324,19 @@ static void builtin_diff(const char *name_a,
 	} else if (!DIFF_OPT_TST(o, TEXT) &&
 	    ( (!textconv_one && diff_filespec_is_binary(one)) ||
 	      (!textconv_two && diff_filespec_is_binary(two)) )) {
+		if (!one->data && !two->data &&
+		    S_ISREG(one->mode) && S_ISREG(two->mode) &&
+		    !DIFF_OPT_TST(o, BINARY)) {
+			if (!hashcmp(one->sha1, two->sha1)) {
+				if (must_show_header)
+					fprintf(o->file, "%s", header.buf);
+				goto free_ab_and_return;
+			}
+			fprintf(o->file, "%s", header.buf);
+			fprintf(o->file, "%sBinary files %s and %s differ\n",
+				line_prefix, lbl[0], lbl[1]);
+			goto free_ab_and_return;
+		}
 		if (fill_mmfile(&mf1, one) < 0 || fill_mmfile(&mf2, two) < 0)
 			die("unable to read files to diff");
 		/* Quite common confusing case */
@@ -2668,8 +2681,9 @@ static int diff_populate_gitlink(struct diff_filespec *s, int size_only)
  * grab the data for the blob (or file) for our own in-core comparison.
  * diff_filespec has data and size fields for this purpose.
  */
-int diff_populate_filespec(struct diff_filespec *s, int size_only)
+int diff_populate_filespec(struct diff_filespec *s, unsigned int flags)
 {
+	int size_only = flags & CHECK_SIZE_ONLY;
 	int err = 0;
 	/*
 	 * demote FAIL to WARN to allow inspecting the situation
@@ -2724,6 +2738,11 @@ int diff_populate_filespec(struct diff_filespec *s, int size_only)
 		}
 		if (size_only)
 			return 0;
+		if ((flags & CHECK_BINARY) &&
+		    s->size > big_file_threshold && s->is_binary == -1) {
+			s->is_binary = 1;
+			return 0;
+		}
 		fd = open(s->path, O_RDONLY);
 		if (fd < 0)
 			goto err_empty;
@@ -2745,16 +2764,21 @@ int diff_populate_filespec(struct diff_filespec *s, int size_only)
 	}
 	else {
 		enum object_type type;
-		if (size_only) {
+		if (size_only || (flags & CHECK_BINARY)) {
 			type = sha1_object_info(s->sha1, &s->size);
 			if (type < 0)
 				die("unable to read %s", sha1_to_hex(s->sha1));
-		} else {
-			s->data = read_sha1_file(s->sha1, &type, &s->size);
-			if (!s->data)
-				die("unable to read %s", sha1_to_hex(s->sha1));
-			s->should_free = 1;
+			if (size_only)
+				return 0;
+			if (s->size > big_file_threshold && s->is_binary == -1) {
+				s->is_binary = 1;
+				return 0;
+			}
 		}
+		s->data = read_sha1_file(s->sha1, &type, &s->size);
+		if (!s->data)
+			die("unable to read %s", sha1_to_hex(s->sha1));
+		s->should_free = 1;
 	}
 	return 0;
 }
@@ -4688,8 +4712,8 @@ static int diff_filespec_check_stat_unmatch(struct diff_filepair *p)
 	    !DIFF_FILE_VALID(p->two) ||
 	    (p->one->sha1_valid && p->two->sha1_valid) ||
 	    (p->one->mode != p->two->mode) ||
-	    diff_populate_filespec(p->one, 1) ||
-	    diff_populate_filespec(p->two, 1) ||
+	    diff_populate_filespec(p->one, CHECK_SIZE_ONLY) ||
+	    diff_populate_filespec(p->two, CHECK_SIZE_ONLY) ||
 	    (p->one->size != p->two->size) ||
 	    !diff_filespec_is_identical(p->one, p->two)) /* (2) */
 		p->skip_stat_unmatch_result = 1;

diffcore-rename.c

@@ -147,9 +147,11 @@ static int estimate_similarity(struct diff_filespec *src,
 	 * is a possible size - we really should have a flag to
 	 * say whether the size is valid or not!)
 	 */
-	if (!src->cnt_data && diff_populate_filespec(src, 1))
+	if (!src->cnt_data &&
+	    diff_populate_filespec(src, CHECK_SIZE_ONLY))
 		return 0;
-	if (!dst->cnt_data && diff_populate_filespec(dst, 1))
+	if (!dst->cnt_data &&
+	    diff_populate_filespec(dst, CHECK_SIZE_ONLY))
 		return 0;
 
 	max_size = ((src->size > dst->size) ? src->size : dst->size);

diffcore.h

@@ -55,7 +55,9 @@ extern void free_filespec(struct diff_filespec *);
 extern void fill_filespec(struct diff_filespec *, const unsigned char *,
 			  int, unsigned short);
 
-extern int diff_populate_filespec(struct diff_filespec *, int);
+#define CHECK_SIZE_ONLY 1
+#define CHECK_BINARY    2
+extern int diff_populate_filespec(struct diff_filespec *, unsigned int);
 extern void diff_free_filespec_data(struct diff_filespec *);
 extern void diff_free_filespec_blob(struct diff_filespec *);
 extern int diff_filespec_is_binary(struct diff_filespec *);

git-compat-util.h

@@ -609,6 +609,7 @@ extern try_to_free_t set_try_to_free_routine(try_to_free_t);
 extern char *xstrdup(const char *str);
 extern void *xmalloc(size_t size);
 extern void *xmallocz(size_t size);
+extern void *xmallocz_gently(size_t size);
 extern void *xmemdupz(const void *data, size_t len);
 extern char *xstrndup(const char *str, size_t len);
 extern void *xrealloc(void *ptr, size_t size);

sha1_file.c

@@ -1923,7 +1923,9 @@ static void *unpack_compressed_entry(struct packed_git *p,
 	git_zstream stream;
 	unsigned char *buffer, *in;
 
-	buffer = xmallocz(size);
+	buffer = xmallocz_gently(size);
+	if (!buffer)
+		return NULL;
 	memset(&stream, 0, sizeof(stream));
 	stream.next_out = buffer;
 	stream.avail_out = size + 1;

t/t1050-large.sh

@@ -112,6 +112,20 @@ test_expect_success 'diff --raw' '
 	git diff --raw HEAD^
 '
 
+test_expect_success 'diff --stat' '
+	git diff --stat HEAD^ HEAD
+'
+
+test_expect_success 'diff' '
+	git diff HEAD^ HEAD >actual &&
+	grep "Binary files.*differ" actual
+'
+
+test_expect_success 'diff --cached' '
+	git diff --cached HEAD^ >actual &&
+	grep "Binary files.*differ" actual
+'
+
 test_expect_success 'hash-object' '
 	git hash-object large1
 '
@@ -163,4 +177,10 @@ test_expect_success 'zip achiving, deflate' '
 	git archive --format=zip HEAD >/dev/null
 '
 
+test_expect_success 'fsck' '
+	test_must_fail git fsck 2>err &&
+	n=$(grep "error: attempting to allocate .* over limit" err | wc -l) &&
+	test "$n" -gt 1
+'
+
 test_done

wrapper.c

@@ -9,16 +9,23 @@ 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 memory_limit_check(size_t size, int gentle)
 {
 	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);
+	if (limit && size > limit) {
+		if (gentle) {
+			error("attempting to allocate %"PRIuMAX" over limit %d",
+			      (intmax_t)size, limit);
+			return -1;
+		} else
+			die("attempting to allocate %"PRIuMAX" over limit %d",
+			    (intmax_t)size, limit);
+	}
+	return 0;
 }
 
 try_to_free_t set_try_to_free_routine(try_to_free_t routine)
@@ -42,11 +49,12 @@ char *xstrdup(const char *str)
 	return ret;
 }
 
-void *xmalloc(size_t size)
+static void *do_xmalloc(size_t size, int gentle)
 {
 	void *ret;
 
-	memory_limit_check(size);
+	if (memory_limit_check(size, gentle))
+		return NULL;
 	ret = malloc(size);
 	if (!ret && !size)
 		ret = malloc(1);
@@ -55,9 +63,16 @@ void *xmalloc(size_t size)
 		ret = malloc(size);
 		if (!ret && !size)
 			ret = malloc(1);
-		if (!ret)
-			die("Out of memory, malloc failed (tried to allocate %lu bytes)",
-			    (unsigned long)size);
+		if (!ret) {
+			if (!gentle)
+				die("Out of memory, malloc failed (tried to allocate %lu bytes)",
+				    (unsigned long)size);
+			else {
+				error("Out of memory, malloc failed (tried to allocate %lu bytes)",
+				      (unsigned long)size);
+				return NULL;
+			}
+		}
 	}
 #ifdef XMALLOC_POISON
 	memset(ret, 0xA5, size);
@@ -65,16 +80,37 @@ void *xmalloc(size_t size)
 	return ret;
 }
 
-void *xmallocz(size_t size)
+void *xmalloc(size_t size)
+{
+	return do_xmalloc(size, 0);
+}
+
+static void *do_xmallocz(size_t size, int gentle)
 {
 	void *ret;
-	if (unsigned_add_overflows(size, 1))
-		die("Data too large to fit into virtual memory space.");
-	ret = xmalloc(size + 1);
-	((char*)ret)[size] = 0;
+	if (unsigned_add_overflows(size, 1)) {
+		if (gentle) {
+			error("Data too large to fit into virtual memory space.");
+			return NULL;
+		} else
+			die("Data too large to fit into virtual memory space.");
+	}
+	ret = do_xmalloc(size + 1, gentle);
+	if (ret)
+		((char*)ret)[size] = 0;
 	return ret;
 }
 
+void *xmallocz(size_t size)
+{
+	return do_xmallocz(size, 0);
+}
+
+void *xmallocz_gently(size_t size)
+{
+	return do_xmallocz(size, 1);
+}
+
 /*
  * xmemdupz() allocates (len + 1) bytes of memory, duplicates "len" bytes of
  * "data" to the allocated memory, zero terminates the allocated memory,
@@ -96,7 +132,7 @@ void *xrealloc(void *ptr, size_t size)
 {
 	void *ret;
 
-	memory_limit_check(size);
+	memory_limit_check(size, 0);
 	ret = realloc(ptr, size);
 	if (!ret && !size)
 		ret = realloc(ptr, 1);
@@ -115,7 +151,7 @@ void *xcalloc(size_t nmemb, size_t size)
 {
 	void *ret;
 
-	memory_limit_check(size * nmemb);
+	memory_limit_check(size * nmemb, 0);
 	ret = calloc(nmemb, size);
 	if (!ret && (!nmemb || !size))
 		ret = calloc(1, 1);