grep -I: do not bother to read known-binary files

Incidentally, this makes grep -I respect the "binary" attribute (actually,
the "-text" attribute, but "binary" implies that).

Since the attributes are not thread-safe, we now need to switch off
threading if -I was passed.

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

builtin/grep.c

@@ -18,6 +18,7 @@
 #include "quote.h"
 #include "dir.h"
 #include "pathspec.h"
+#include "attr.h"
 
 static char const * const grep_usage[] = {
 	N_("git grep [options] [-e] <pattern> [<rev>...] [[--] <path>...]"),
@@ -163,6 +164,22 @@ static void work_done(struct work_item *w)
 	grep_unlock();
 }
 
+static int skip_binary(struct grep_opt *opt, const char *filename)
+{
+	if ((opt->binary & GREP_BINARY_NOMATCH)) {
+		static struct git_attr *attr_text;
+		struct git_attr_check check;
+
+		if (!attr_text)
+			attr_text = git_attr("text");
+		memset(&check, 0, sizeof(check));
+		check.attr = attr_text;
+		return !git_check_attr(filename, 1, &check) &&
+				ATTR_FALSE(check.value);
+	}
+	return 0;
+}
+
 static void *run(void *arg)
 {
 	int hit = 0;
@@ -173,6 +190,9 @@ static void *run(void *arg)
 		if (!w)
 			break;
 
+		if (skip_binary(opt, (const char *)w->source.identifier))
+			continue;
+
 		opt->output_priv = w;
 		hit |= grep_source(opt, &w->source);
 		grep_source_clear_data(&w->source);
@@ -381,6 +401,9 @@ static int grep_cache(struct grep_opt *opt, const struct pathspec *pathspec, int
 			continue;
 		if (!ce_path_match(ce, pathspec, NULL))
 			continue;
+		if (skip_binary(opt, ce->name))
+			continue;
+
 		/*
 		 * If CE_VALID is on, we assume worktree file and its cache entry
 		 * are identical, even if worktree file has been modified, so use
@@ -805,6 +828,8 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 		string_list_append(&path_list, show_in_pager);
 		use_threads = 0;
 	}
+	if ((opt.binary & GREP_BINARY_NOMATCH))
+		use_threads = 0;
 
 	if (!opt.pattern_list)
 		die(_("no pattern given."));