refactor duplicated encode_header in pack-objects and fast-import

The following function is duplicated:

  encode_header

Move this function to sha1_file.c and rename it 'encode_in_pack_object_header',
as suggested by Junio C Hamano

Signed-off-by: Michael Lukashov <michael.lukashov@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-pack-objects.c

@@ -154,33 +154,6 @@ static unsigned long do_compress(void **pptr, unsigned long size)
 	return stream.total_out;
 }
 
-/*
- * The per-object header is a pretty dense thing, which is
- *  - first byte: low four bits are "size", then three bits of "type",
- *    and the high bit is "size continues".
- *  - each byte afterwards: low seven bits are size continuation,
- *    with the high bit being "size continues"
- */
-static int encode_header(enum object_type type, unsigned long size, unsigned char *hdr)
-{
-	int n = 1;
-	unsigned char c;
-
-	if (type < OBJ_COMMIT || type > OBJ_REF_DELTA)
-		die("bad type %d", type);
-
-	c = (type << 4) | (size & 15);
-	size >>= 4;
-	while (size) {
-		*hdr++ = c | 0x80;
-		c = size & 0x7f;
-		size >>= 7;
-		n++;
-	}
-	*hdr = c;
-	return n;
-}
-
 /*
  * we are going to reuse the existing object data as is.  make
  * sure it is not corrupt.
@@ -321,7 +294,7 @@ static unsigned long write_object(struct sha1file *f,
 		 * The object header is a byte of 'type' followed by zero or
 		 * more bytes of length.
 		 */
-		hdrlen = encode_header(type, size, header);
+		hdrlen = encode_in_pack_object_header(type, size, header);
 
 		if (type == OBJ_OFS_DELTA) {
 			/*
@@ -372,7 +345,7 @@ static unsigned long write_object(struct sha1file *f,
 		if (entry->delta)
 			type = (allow_ofs_delta && entry->delta->idx.offset) ?
 				OBJ_OFS_DELTA : OBJ_REF_DELTA;
-		hdrlen = encode_header(type, entry->size, header);
+		hdrlen = encode_in_pack_object_header(type, entry->size, header);
 
 		offset = entry->in_pack_offset;
 		revidx = find_pack_revindex(p, offset);

cache.h

@@ -911,6 +911,14 @@ extern void *unpack_entry(struct packed_git *, off_t, enum object_type *, unsign
 extern unsigned long unpack_object_header_buffer(const unsigned char *buf, unsigned long len, enum object_type *type, unsigned long *sizep);
 extern unsigned long get_size_from_delta(struct packed_git *, struct pack_window **, off_t);
 extern const char *packed_object_info_detail(struct packed_git *, off_t, unsigned long *, unsigned long *, unsigned int *, unsigned char *);
+/*
+ * The per-object header is a pretty dense thing, which is
+ *  - first byte: low four bits are "size", then three bits of "type",
+ *    and the high bit is "size continues".
+ *  - each byte afterwards: low seven bits are size continuation,
+ *    with the high bit being "size continues"
+ */
+int encode_in_pack_object_header(enum object_type type, uintmax_t size, unsigned char *hdr);
 
 /* Dumb servers support */
 extern int update_server_info(int);

fast-import.c

@@ -980,29 +980,6 @@ static void cycle_packfile(void)
 	start_packfile();
 }
 
-static size_t encode_header(
-	enum object_type type,
-	uintmax_t size,
-	unsigned char *hdr)
-{
-	int n = 1;
-	unsigned char c;
-
-	if (type < OBJ_COMMIT || type > OBJ_REF_DELTA)
-		die("bad type %d", type);
-
-	c = (type << 4) | (size & 15);
-	size >>= 4;
-	while (size) {
-		*hdr++ = c | 0x80;
-		c = size & 0x7f;
-		size >>= 7;
-		n++;
-	}
-	*hdr = c;
-	return n;
-}
-
 static int store_object(
 	enum object_type type,
 	struct strbuf *dat,
@@ -1103,7 +1080,7 @@ static int store_object(
 		delta_count_by_type[type]++;
 		e->depth = last->depth + 1;
 
-		hdrlen = encode_header(OBJ_OFS_DELTA, deltalen, hdr);
+		hdrlen = encode_in_pack_object_header(OBJ_OFS_DELTA, deltalen, hdr);
 		sha1write(pack_file, hdr, hdrlen);
 		pack_size += hdrlen;
 
@@ -1114,7 +1091,7 @@ static int store_object(
 		pack_size += sizeof(hdr) - pos;
 	} else {
 		e->depth = 0;
-		hdrlen = encode_header(type, dat->len, hdr);
+		hdrlen = encode_in_pack_object_header(type, dat->len, hdr);
 		sha1write(pack_file, hdr, hdrlen);
 		pack_size += hdrlen;
 	}
@@ -1188,7 +1165,7 @@ static void stream_blob(uintmax_t len, unsigned char *sha1out, uintmax_t mark)
 	memset(&s, 0, sizeof(s));
 	deflateInit(&s, pack_compression_level);
 
-	hdrlen = encode_header(OBJ_BLOB, len, out_buf);
+	hdrlen = encode_in_pack_object_header(OBJ_BLOB, len, out_buf);
 	if (out_sz <= hdrlen)
 		die("impossibly large object header");
 

sha1_file.c

@@ -1475,6 +1475,26 @@ const char *packed_object_info_detail(struct packed_git *p,
 	}
 }
 
+int encode_in_pack_object_header(enum object_type type, uintmax_t size, unsigned char *hdr)
+{
+	int n = 1;
+	unsigned char c;
+
+	if (type < OBJ_COMMIT || type > OBJ_REF_DELTA)
+		die("bad type %d", type);
+
+	c = (type << 4) | (size & 15);
+	size >>= 4;
+	while (size) {
+		*hdr++ = c | 0x80;
+		c = size & 0x7f;
+		size >>= 7;
+		n++;
+	}
+	*hdr = c;
+	return n;
+}
+
 static int packed_object_info(struct packed_git *p, off_t obj_offset,
 			      unsigned long *sizep)
 {