Move buffer_is_binary() to xdiff-interface.h

We already have two instances where we want to determine if a buffer
contains binary data as opposed to text.

[jc: cherry-picked 6bfce93e from 'master']

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff.c

@@ -1107,10 +1107,8 @@ static void setup_diff_attr_check(struct git_attr_check *check)
 	check->attr = attr_diff;
 }
 
-#define FIRST_FEW_BYTES 8000
 static int file_is_binary(struct diff_filespec *one)
 {
-	unsigned long sz;
 	struct git_attr_check attr_diff_check;
 
 	setup_diff_attr_check(&attr_diff_check);
@@ -1127,10 +1125,7 @@ static int file_is_binary(struct diff_filespec *one)
 			return 0;
 		diff_populate_filespec(one, 0);
 	}
-	sz = one->size;
-	if (FIRST_FEW_BYTES < sz)
-		sz = FIRST_FEW_BYTES;
-	return !!memchr(one->data, 0, sz);
+	return buffer_is_binary(one->data, one->size);
 }
 
 static void builtin_diff(const char *name_a,

grep.c

@@ -1,5 +1,6 @@
 #include "cache.h"
 #include "grep.h"
+#include "xdiff-interface.h"
 
 void append_grep_pattern(struct grep_opt *opt, const char *pat,
 			 const char *origin, int no, enum grep_pat_token t)
@@ -232,17 +233,6 @@ static void show_line(struct grep_opt *opt, const char *bol, const char *eol,
 	printf("%.*s\n", (int)(eol-bol), bol);
 }
 
-/*
- * NEEDSWORK: share code with diff.c
- */
-#define FIRST_FEW_BYTES 8000
-static int buffer_is_binary(const char *ptr, unsigned long size)
-{
-	if (FIRST_FEW_BYTES < size)
-		size = FIRST_FEW_BYTES;
-	return !!memchr(ptr, 0, size);
-}
-
 static int fixmatch(const char *pattern, char *line, regmatch_t *match)
 {
 	char *hit = strstr(line, pattern);

xdiff-interface.c

@@ -122,4 +122,12 @@ int read_mmfile(mmfile_t *ptr, const char *filename)
 	return 0;
 }
 
+#define FIRST_FEW_BYTES 8000
+int buffer_is_binary(const char *ptr, unsigned long size)
+{
+	if (FIRST_FEW_BYTES < size)
+		size = FIRST_FEW_BYTES;
+	return !!memchr(ptr, 0, size);
+}
+
 

xdiff-interface.h

@@ -18,5 +18,6 @@ int parse_hunk_header(char *line, int len,
 		      int *ob, int *on,
 		      int *nb, int *nn);
 int read_mmfile(mmfile_t *ptr, const char *filename);
+int buffer_is_binary(const char *ptr, unsigned long size);
 
 #endif