archive-zip: write ZIP dir entry directly to strbuf

Write all fields of the ZIP directory record for an archive entry
in the right order directly into the strbuf instead of taking a detour
through a struct.  Do that at end, when we have all necessary data like
checksum and compressed size.  The fields are documented just as well,
the code becomes shorter and we save an extra copy.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 27 insertions, 54 deletions

diff --git a/archive-zip.c b/archive-zip.c
index a6fac59..2d52bb3 100644
--- a/archive-zip.c
+++ b/archive-zip.c
@@ -45,27 +45,6 @@ struct zip_data_desc {
 	unsigned char _end[1];
 };
 
-struct zip_dir_header {
-	unsigned char magic[4];
-	unsigned char creator_version[2];
-	unsigned char version[2];
-	unsigned char flags[2];
-	unsigned char compression_method[2];
-	unsigned char mtime[2];
-	unsigned char mdate[2];
-	unsigned char crc32[4];
-	unsigned char compressed_size[4];
-	unsigned char size[4];
-	unsigned char filename_length[2];
-	unsigned char extra_length[2];
-	unsigned char comment_length[2];
-	unsigned char disk[2];
-	unsigned char attr1[2];
-	unsigned char attr2[4];
-	unsigned char offset[4];
-	unsigned char _end[1];
-};
-
 struct zip_dir_trailer {
 	unsigned char magic[4];
 	unsigned char disk[2];
@@ -166,6 +145,15 @@ static void copy_le16_clamp(unsigned char *dest, uint64_t n, int *clamped)
 	copy_le16(dest, clamp_max(n, 0xffff, clamped));
 }
 
+static int strbuf_add_le(struct strbuf *sb, size_t size, uintmax_t n)
+{
+	while (size-- > 0) {
+		strbuf_addch(sb, n & 0xff);
+		n >>= 8;
+	}
+	return -!!n;
+}
+
 static void *zlib_deflate_raw(void *data, unsigned long size,
 			      int compression_level,
 			      unsigned long *compressed_size)
@@ -212,16 +200,6 @@ static void write_zip_data_desc(unsigned long size,
 	write_or_die(1, &trailer, ZIP_DATA_DESC_SIZE);
 }
 
-static void set_zip_dir_data_desc(struct zip_dir_header *header,
-				  unsigned long size,
-				  unsigned long compressed_size,
-				  unsigned long crc)
-{
-	copy_le32(header->crc32, crc);
-	copy_le32(header->compressed_size, compressed_size);
-	copy_le32(header->size, size);
-}
-
 static void set_zip_header_data_desc(struct zip_local_header *header,
 				     unsigned long size,
 				     unsigned long compressed_size,
@@ -261,7 +239,7 @@ static int write_zip_entry(struct archiver_args *args,
 			   unsigned int mode)
 {
 	struct zip_local_header header;
-	struct zip_dir_header dirent;
+	uintmax_t offset = zip_offset;
 	struct zip_extra_mtime extra;
 	unsigned long attr2;
 	unsigned long compressed_size;
@@ -353,21 +331,6 @@ static int write_zip_entry(struct archiver_args *args,
 	extra.flags[0] = 1;	/* just mtime */
 	copy_le32(extra.mtime, args->time);
 
-	copy_le32(dirent.magic, 0x02014b50);
-	copy_le16(dirent.creator_version, creator_version);
-	copy_le16(dirent.version, 10);
-	copy_le16(dirent.flags, flags);
-	copy_le16(dirent.compression_method, method);
-	copy_le16(dirent.mtime, zip_time);
-	copy_le16(dirent.mdate, zip_date);
-	set_zip_dir_data_desc(&dirent, size, compressed_size, crc);
-	copy_le16(dirent.filename_length, pathlen);
-	copy_le16(dirent.extra_length, ZIP_EXTRA_MTIME_SIZE);
-	copy_le16(dirent.comment_length, 0);
-	copy_le16(dirent.disk, 0);
-	copy_le32(dirent.attr2, attr2);
-	copy_le32(dirent.offset, zip_offset);
-
 	copy_le32(header.magic, 0x04034b50);
 	copy_le16(header.version, 10);
 	copy_le16(header.flags, flags);
@@ -406,8 +369,6 @@ static int write_zip_entry(struct archiver_args *args,
 
 		write_zip_data_desc(size, compressed_size, crc);
 		zip_offset += ZIP_DATA_DESC_SIZE;
-
-		set_zip_dir_data_desc(&dirent, size, compressed_size, crc);
 	} else if (stream && method == 8) {
 		unsigned char buf[STREAM_BUFFER_SIZE];
 		ssize_t readlen;
@@ -464,8 +425,6 @@ static int write_zip_entry(struct archiver_args *args,
 
 		write_zip_data_desc(size, compressed_size, crc);
 		zip_offset += ZIP_DATA_DESC_SIZE;
-
-		set_zip_dir_data_desc(&dirent, size, compressed_size, crc);
 	} else if (compressed_size > 0) {
 		write_or_die(1, out, compressed_size);
 		zip_offset += compressed_size;
@@ -474,9 +433,23 @@ static int write_zip_entry(struct archiver_args *args,
 	free(deflated);
 	free(buffer);
 
-	copy_le16(dirent.attr1, !is_binary);
-
-	strbuf_add(&zip_dir, &dirent, ZIP_DIR_HEADER_SIZE);
+	strbuf_add_le(&zip_dir, 4, 0x02014b50);	/* magic */
+	strbuf_add_le(&zip_dir, 2, creator_version);
+	strbuf_add_le(&zip_dir, 2, 10);		/* version */
+	strbuf_add_le(&zip_dir, 2, flags);
+	strbuf_add_le(&zip_dir, 2, method);
+	strbuf_add_le(&zip_dir, 2, zip_time);
+	strbuf_add_le(&zip_dir, 2, zip_date);
+	strbuf_add_le(&zip_dir, 4, crc);
+	strbuf_add_le(&zip_dir, 4, compressed_size);
+	strbuf_add_le(&zip_dir, 4, size);
+	strbuf_add_le(&zip_dir, 2, pathlen);
+	strbuf_add_le(&zip_dir, 2, ZIP_EXTRA_MTIME_SIZE);
+	strbuf_add_le(&zip_dir, 2, 0);		/* comment length */
+	strbuf_add_le(&zip_dir, 2, 0);		/* disk */
+	strbuf_add_le(&zip_dir, 2, !is_binary);
+	strbuf_add_le(&zip_dir, 4, attr2);
+	strbuf_add_le(&zip_dir, 4, offset);
 	strbuf_add(&zip_dir, path, pathlen);
 	strbuf_add(&zip_dir, &extra, ZIP_EXTRA_MTIME_SIZE);
 	zip_dir_entries++;