Merge branch 'nd/stream-to-archive'

Stream large blobs directly out to archive files without slurping
everything in memory first.

By René Scharfe (6) and Nguyễn Thái Ngọc Duy (4)
* nd/stream-to-archive:
  t5000: rationalize unzip tests
  archive-zip: streaming for deflated files
  archive-zip: streaming for stored files
  archive-zip: factor out helpers for writing sizes and CRC
  archive-zip: remove uncompressed_size
  archive-tar: stream large blobs to tar file
  archive: delegate blob reading to backend
  archive-tar: unindent write_tar_entry by one level
  archive-tar: turn write_tar_entry into blob-writing only
  streaming: void pointer instead of char pointer

8 files changed, 404 insertions, 135 deletions

diff --git a/archive-tar.c b/archive-tar.c
index 20af0051a3..93387ea336 100644
--- a/archive-tar.c
+++ b/archive-tar.c
@@ -4,6 +4,7 @@
 #include "cache.h"
 #include "tar.h"
 #include "archive.h"
+#include "streaming.h"
 #include "run-command.h"
 
 #define RECORDSIZE	(512)
@@ -30,10 +31,9 @@ static void write_if_needed(void)
  * queues up writes, so that all our write(2) calls write exactly one
  * full block; pads writes to RECORDSIZE
  */
-static void write_blocked(const void *data, unsigned long size)
+static void do_write_blocked(const void *data, unsigned long size)
 {
 	const char *buf = data;
-	unsigned long tail;
 
 	if (offset) {
 		unsigned long chunk = BLOCKSIZE - offset;
@@ -54,6 +54,11 @@ static void write_blocked(const void *data, unsigned long size)
 		memcpy(block + offset, buf, size);
 		offset += size;
 	}
+}
+
+static void finish_record(void)
+{
+	unsigned long tail;
 	tail = offset % RECORDSIZE;
 	if (tail)  {
 		memset(block + offset, 0, RECORDSIZE - tail);
@@ -62,6 +67,12 @@ static void write_blocked(const void *data, unsigned long size)
 	write_if_needed();
 }
 
+static void write_blocked(const void *data, unsigned long size)
+{
+	do_write_blocked(data, size);
+	finish_record();
+}
+
 /*
  * The end of tar archives is marked by 2*512 nul bytes and after that
  * follows the rest of the block (if any).
@@ -78,6 +89,33 @@ static void write_trailer(void)
 }
 
 /*
+ * queues up writes, so that all our write(2) calls write exactly one
+ * full block; pads writes to RECORDSIZE
+ */
+static int stream_blocked(const unsigned char *sha1)
+{
+	struct git_istream *st;
+	enum object_type type;
+	unsigned long sz;
+	char buf[BLOCKSIZE];
+	ssize_t readlen;
+
+	st = open_istream(sha1, &type, &sz, NULL);
+	if (!st)
+		return error("cannot stream blob %s", sha1_to_hex(sha1));
+	for (;;) {
+		readlen = read_istream(st, buf, sizeof(buf));
+		if (readlen <= 0)
+			break;
+		do_write_blocked(buf, readlen);
+	}
+	close_istream(st);
+	if (!readlen)
+		finish_record();
+	return readlen;
+}
+
+/*
  * pax extended header records have the format "%u %s=%s\n".  %u contains
  * the size of the whole string (including the %u), the first %s is the
  * keyword, the second one is the value.  This function constructs such a
@@ -123,56 +161,101 @@ static size_t get_path_prefix(const char *path, size_t pathlen, size_t maxlen)
 	return i;
 }
 
+static void prepare_header(struct archiver_args *args,
+			   struct ustar_header *header,
+			   unsigned int mode, unsigned long size)
+{
+	sprintf(header->mode, "%07o", mode & 07777);
+	sprintf(header->size, "%011lo", S_ISREG(mode) ? size : 0);
+	sprintf(header->mtime, "%011lo", (unsigned long) args->time);
+
+	sprintf(header->uid, "%07o", 0);
+	sprintf(header->gid, "%07o", 0);
+	strlcpy(header->uname, "root", sizeof(header->uname));
+	strlcpy(header->gname, "root", sizeof(header->gname));
+	sprintf(header->devmajor, "%07o", 0);
+	sprintf(header->devminor, "%07o", 0);
+
+	memcpy(header->magic, "ustar", 6);
+	memcpy(header->version, "00", 2);
+
+	sprintf(header->chksum, "%07o", ustar_header_chksum(header));
+}
+
+static int write_extended_header(struct archiver_args *args,
+				 const unsigned char *sha1,
+				 const void *buffer, unsigned long size)
+{
+	struct ustar_header header;
+	unsigned int mode;
+	memset(&header, 0, sizeof(header));
+	*header.typeflag = TYPEFLAG_EXT_HEADER;
+	mode = 0100666;
+	sprintf(header.name, "%s.paxheader", sha1_to_hex(sha1));
+	prepare_header(args, &header, mode, size);
+	write_blocked(&header, sizeof(header));
+	write_blocked(buffer, size);
+	return 0;
+}
+
 static int write_tar_entry(struct archiver_args *args,
-		const unsigned char *sha1, const char *path, size_t pathlen,
-		unsigned int mode, void *buffer, unsigned long size)
+			   const unsigned char *sha1,
+			   const char *path, size_t pathlen,
+			   unsigned int mode)
 {
 	struct ustar_header header;
 	struct strbuf ext_header = STRBUF_INIT;
+	unsigned int old_mode = mode;
+	unsigned long size;
+	void *buffer;
 	int err = 0;
 
 	memset(&header, 0, sizeof(header));
 
-	if (!sha1) {
-		*header.typeflag = TYPEFLAG_GLOBAL_HEADER;
-		mode = 0100666;
-		strcpy(header.name, "pax_global_header");
-	} else if (!path) {
-		*header.typeflag = TYPEFLAG_EXT_HEADER;
-		mode = 0100666;
-		sprintf(header.name, "%s.paxheader", sha1_to_hex(sha1));
+	if (S_ISDIR(mode) || S_ISGITLINK(mode)) {
+		*header.typeflag = TYPEFLAG_DIR;
+		mode = (mode | 0777) & ~tar_umask;
+	} else if (S_ISLNK(mode)) {
+		*header.typeflag = TYPEFLAG_LNK;
+		mode |= 0777;
+	} else if (S_ISREG(mode)) {
+		*header.typeflag = TYPEFLAG_REG;
+		mode = (mode | ((mode & 0100) ? 0777 : 0666)) & ~tar_umask;
 	} else {
-		if (S_ISDIR(mode) || S_ISGITLINK(mode)) {
-			*header.typeflag = TYPEFLAG_DIR;
-			mode = (mode | 0777) & ~tar_umask;
-		} else if (S_ISLNK(mode)) {
-			*header.typeflag = TYPEFLAG_LNK;
-			mode |= 0777;
-		} else if (S_ISREG(mode)) {
-			*header.typeflag = TYPEFLAG_REG;
-			mode = (mode | ((mode & 0100) ? 0777 : 0666)) & ~tar_umask;
+		return error("unsupported file mode: 0%o (SHA1: %s)",
+			     mode, sha1_to_hex(sha1));
+	}
+	if (pathlen > sizeof(header.name)) {
+		size_t plen = get_path_prefix(path, pathlen,
+					      sizeof(header.prefix));
+		size_t rest = pathlen - plen - 1;
+		if (plen > 0 && rest <= sizeof(header.name)) {
+			memcpy(header.prefix, path, plen);
+				memcpy(header.name, path + plen + 1, rest);
 		} else {
-			return error("unsupported file mode: 0%o (SHA1: %s)",
-					mode, sha1_to_hex(sha1));
+			sprintf(header.name, "%s.data",
+				sha1_to_hex(sha1));
+			strbuf_append_ext_header(&ext_header, "path",
+						 path, pathlen);
 		}
-		if (pathlen > sizeof(header.name)) {
-			size_t plen = get_path_prefix(path, pathlen,
-					sizeof(header.prefix));
-			size_t rest = pathlen - plen - 1;
-			if (plen > 0 && rest <= sizeof(header.name)) {
-				memcpy(header.prefix, path, plen);
-				memcpy(header.name, path + plen + 1, rest);
-			} else {
-				sprintf(header.name, "%s.data",
-				        sha1_to_hex(sha1));
-				strbuf_append_ext_header(&ext_header, "path",
-						path, pathlen);
-			}
-		} else
-			memcpy(header.name, path, pathlen);
+	} else
+		memcpy(header.name, path, pathlen);
+
+	if (S_ISREG(mode) && !args->convert &&
+	    sha1_object_info(sha1, &size) == OBJ_BLOB &&
+	    size > big_file_threshold)
+		buffer = NULL;
+	else if (S_ISLNK(mode) || S_ISREG(mode)) {
+		enum object_type type;
+		buffer = sha1_file_to_archive(args, path, sha1, old_mode, &type, &size);
+		if (!buffer)
+			return error("cannot read %s", sha1_to_hex(sha1));
+	} else {
+		buffer = NULL;
+		size = 0;
 	}
 
-	if (S_ISLNK(mode) && buffer) {
+	if (S_ISLNK(mode)) {
 		if (size > sizeof(header.linkname)) {
 			sprintf(header.linkname, "see %s.paxheader",
 			        sha1_to_hex(sha1));
@@ -182,32 +265,25 @@ static int write_tar_entry(struct archiver_args *args,
 			memcpy(header.linkname, buffer, size);
 	}
 
-	sprintf(header.mode, "%07o", mode & 07777);
-	sprintf(header.size, "%011lo", S_ISREG(mode) ? size : 0);
-	sprintf(header.mtime, "%011lo", (unsigned long) args->time);
-
-	sprintf(header.uid, "%07o", 0);
-	sprintf(header.gid, "%07o", 0);
-	strlcpy(header.uname, "root", sizeof(header.uname));
-	strlcpy(header.gname, "root", sizeof(header.gname));
-	sprintf(header.devmajor, "%07o", 0);
-	sprintf(header.devminor, "%07o", 0);
-
-	memcpy(header.magic, "ustar", 6);
-	memcpy(header.version, "00", 2);
-
-	sprintf(header.chksum, "%07o", ustar_header_chksum(&header));
+	prepare_header(args, &header, mode, size);
 
 	if (ext_header.len > 0) {
-		err = write_tar_entry(args, sha1, NULL, 0, 0, ext_header.buf,
-				ext_header.len);
-		if (err)
+		err = write_extended_header(args, sha1, ext_header.buf,
+					    ext_header.len);
+		if (err) {
+			free(buffer);
 			return err;
+		}
 	}
 	strbuf_release(&ext_header);
 	write_blocked(&header, sizeof(header));
-	if (S_ISREG(mode) && buffer && size > 0)
-		write_blocked(buffer, size);
+	if (S_ISREG(mode) && size > 0) {
+		if (buffer)
+			write_blocked(buffer, size);
+		else
+			err = stream_blocked(sha1);
+	}
+	free(buffer);
 	return err;
 }
 
@@ -215,11 +291,18 @@ static int write_global_extended_header(struct archiver_args *args)
 {
 	const unsigned char *sha1 = args->commit_sha1;
 	struct strbuf ext_header = STRBUF_INIT;
-	int err;
+	struct ustar_header header;
+	unsigned int mode;
+	int err = 0;
 
 	strbuf_append_ext_header(&ext_header, "comment", sha1_to_hex(sha1), 40);
-	err = write_tar_entry(args, NULL, NULL, 0, 0, ext_header.buf,
-			ext_header.len);
+	memset(&header, 0, sizeof(header));
+	*header.typeflag = TYPEFLAG_GLOBAL_HEADER;
+	mode = 0100666;
+	strcpy(header.name, "pax_global_header");
+	prepare_header(args, &header, mode, ext_header.len);
+	write_blocked(&header, sizeof(header));
+	write_blocked(ext_header.buf, ext_header.len);
 	strbuf_release(&ext_header);
 	return err;
 }
diff --git a/archive-zip.c b/archive-zip.c
index 02d1f3787a..f5af81f904 100644
--- a/archive-zip.c
+++ b/archive-zip.c
@@ -3,6 +3,7 @@
  */
 #include "cache.h"
 #include "archive.h"
+#include "streaming.h"
 
 static int zip_date;
 static int zip_time;
@@ -15,6 +16,7 @@ static unsigned int zip_dir_offset;
 static unsigned int zip_dir_entries;
 
 #define ZIP_DIRECTORY_MIN_SIZE	(1024 * 1024)
+#define ZIP_STREAM (8)
 
 struct zip_local_header {
 	unsigned char magic[4];
@@ -31,6 +33,14 @@ struct zip_local_header {
 	unsigned char _end[1];
 };
 
+struct zip_data_desc {
+	unsigned char magic[4];
+	unsigned char crc32[4];
+	unsigned char compressed_size[4];
+	unsigned char size[4];
+	unsigned char _end[1];
+};
+
 struct zip_dir_header {
 	unsigned char magic[4];
 	unsigned char creator_version[2];
@@ -70,6 +80,7 @@ struct zip_dir_trailer {
  * we're interested in.
  */
 #define ZIP_LOCAL_HEADER_SIZE	offsetof(struct zip_local_header, _end)
+#define ZIP_DATA_DESC_SIZE	offsetof(struct zip_data_desc, _end)
 #define ZIP_DIR_HEADER_SIZE	offsetof(struct zip_dir_header, _end)
 #define ZIP_DIR_TRAILER_SIZE	offsetof(struct zip_dir_trailer, _end)
 
@@ -120,20 +131,59 @@ static void *zlib_deflate(void *data, unsigned long size,
 	return buffer;
 }
 
+static void write_zip_data_desc(unsigned long size,
+				unsigned long compressed_size,
+				unsigned long crc)
+{
+	struct zip_data_desc trailer;
+
+	copy_le32(trailer.magic, 0x08074b50);
+	copy_le32(trailer.crc32, crc);
+	copy_le32(trailer.compressed_size, compressed_size);
+	copy_le32(trailer.size, 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,
+				     unsigned long crc)
+{
+	copy_le32(header->crc32, crc);
+	copy_le32(header->compressed_size, compressed_size);
+	copy_le32(header->size, size);
+}
+
+#define STREAM_BUFFER_SIZE (1024 * 16)
+
 static int write_zip_entry(struct archiver_args *args,
-		const unsigned char *sha1, const char *path, size_t pathlen,
-		unsigned int mode, void *buffer, unsigned long size)
+			   const unsigned char *sha1,
+			   const char *path, size_t pathlen,
+			   unsigned int mode)
 {
 	struct zip_local_header header;
 	struct zip_dir_header dirent;
 	unsigned long attr2;
 	unsigned long compressed_size;
-	unsigned long uncompressed_size;
 	unsigned long crc;
 	unsigned long direntsize;
 	int method;
 	unsigned char *out;
 	void *deflated = NULL;
+	void *buffer;
+	struct git_istream *stream = NULL;
+	unsigned long flags = 0;
+	unsigned long size;
 
 	crc = crc32(0, NULL, 0);
 
@@ -146,24 +196,43 @@ static int write_zip_entry(struct archiver_args *args,
 		method = 0;
 		attr2 = 16;
 		out = NULL;
-		uncompressed_size = 0;
+		size = 0;
 		compressed_size = 0;
+		buffer = NULL;
+		size = 0;
 	} else if (S_ISREG(mode) || S_ISLNK(mode)) {
+		enum object_type type = sha1_object_info(sha1, &size);
+
 		method = 0;
 		attr2 = S_ISLNK(mode) ? ((mode | 0777) << 16) :
 			(mode & 0111) ? ((mode) << 16) : 0;
-		if (S_ISREG(mode) && args->compression_level != 0)
+		if (S_ISREG(mode) && args->compression_level != 0 && size > 0)
 			method = 8;
-		crc = crc32(crc, buffer, size);
-		out = buffer;
-		uncompressed_size = size;
 		compressed_size = size;
+
+		if (S_ISREG(mode) && type == OBJ_BLOB && !args->convert &&
+		    size > big_file_threshold) {
+			stream = open_istream(sha1, &type, &size, NULL);
+			if (!stream)
+				return error("cannot stream blob %s",
+					     sha1_to_hex(sha1));
+			flags |= ZIP_STREAM;
+			out = buffer = NULL;
+		} else {
+			buffer = sha1_file_to_archive(args, path, sha1, mode,
+						      &type, &size);
+			if (!buffer)
+				return error("cannot read %s",
+					     sha1_to_hex(sha1));
+			crc = crc32(crc, buffer, size);
+			out = buffer;
+		}
 	} else {
 		return error("unsupported file mode: 0%o (SHA1: %s)", mode,
 				sha1_to_hex(sha1));
 	}
 
-	if (method == 8) {
+	if (buffer && method == 8) {
 		deflated = zlib_deflate(buffer, size, args->compression_level,
 				&compressed_size);
 		if (deflated && compressed_size - 6 < size) {
@@ -188,13 +257,11 @@ static int write_zip_entry(struct archiver_args *args,
 	copy_le16(dirent.creator_version,
 		S_ISLNK(mode) || (S_ISREG(mode) && (mode & 0111)) ? 0x0317 : 0);
 	copy_le16(dirent.version, 10);
-	copy_le16(dirent.flags, 0);
+	copy_le16(dirent.flags, flags);
 	copy_le16(dirent.compression_method, method);
 	copy_le16(dirent.mtime, zip_time);
 	copy_le16(dirent.mdate, zip_date);
-	copy_le32(dirent.crc32, crc);
-	copy_le32(dirent.compressed_size, compressed_size);
-	copy_le32(dirent.size, uncompressed_size);
+	set_zip_dir_data_desc(&dirent, size, compressed_size, crc);
 	copy_le16(dirent.filename_length, pathlen);
 	copy_le16(dirent.extra_length, 0);
 	copy_le16(dirent.comment_length, 0);
@@ -202,33 +269,120 @@ static int write_zip_entry(struct archiver_args *args,
 	copy_le16(dirent.attr1, 0);
 	copy_le32(dirent.attr2, attr2);
 	copy_le32(dirent.offset, zip_offset);
-	memcpy(zip_dir + zip_dir_offset, &dirent, ZIP_DIR_HEADER_SIZE);
-	zip_dir_offset += ZIP_DIR_HEADER_SIZE;
-	memcpy(zip_dir + zip_dir_offset, path, pathlen);
-	zip_dir_offset += pathlen;
-	zip_dir_entries++;
 
 	copy_le32(header.magic, 0x04034b50);
 	copy_le16(header.version, 10);
-	copy_le16(header.flags, 0);
+	copy_le16(header.flags, flags);
 	copy_le16(header.compression_method, method);
 	copy_le16(header.mtime, zip_time);
 	copy_le16(header.mdate, zip_date);
-	copy_le32(header.crc32, crc);
-	copy_le32(header.compressed_size, compressed_size);
-	copy_le32(header.size, uncompressed_size);
+	if (flags & ZIP_STREAM)
+		set_zip_header_data_desc(&header, 0, 0, 0);
+	else
+		set_zip_header_data_desc(&header, size, compressed_size, crc);
 	copy_le16(header.filename_length, pathlen);
 	copy_le16(header.extra_length, 0);
 	write_or_die(1, &header, ZIP_LOCAL_HEADER_SIZE);
 	zip_offset += ZIP_LOCAL_HEADER_SIZE;
 	write_or_die(1, path, pathlen);
 	zip_offset += pathlen;
-	if (compressed_size > 0) {
+	if (stream && method == 0) {
+		unsigned char buf[STREAM_BUFFER_SIZE];
+		ssize_t readlen;
+
+		for (;;) {
+			readlen = read_istream(stream, buf, sizeof(buf));
+			if (readlen <= 0)
+				break;
+			crc = crc32(crc, buf, readlen);
+			write_or_die(1, buf, readlen);
+		}
+		close_istream(stream);
+		if (readlen)
+			return readlen;
+
+		compressed_size = size;
+		zip_offset += compressed_size;
+
+		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;
+		git_zstream zstream;
+		int result;
+		size_t out_len;
+		unsigned char compressed[STREAM_BUFFER_SIZE * 2];
+
+		memset(&zstream, 0, sizeof(zstream));
+		git_deflate_init(&zstream, args->compression_level);
+
+		compressed_size = 0;
+		zstream.next_out = compressed;
+		zstream.avail_out = sizeof(compressed);
+
+		for (;;) {
+			readlen = read_istream(stream, buf, sizeof(buf));
+			if (readlen <= 0)
+				break;
+			crc = crc32(crc, buf, readlen);
+
+			zstream.next_in = buf;
+			zstream.avail_in = readlen;
+			result = git_deflate(&zstream, 0);
+			if (result != Z_OK)
+				die("deflate error (%d)", result);
+			out = compressed;
+			if (!compressed_size)
+				out += 2;
+			out_len = zstream.next_out - out;
+
+			if (out_len > 0) {
+				write_or_die(1, out, out_len);
+				compressed_size += out_len;
+				zstream.next_out = compressed;
+				zstream.avail_out = sizeof(compressed);
+			}
+
+		}
+		close_istream(stream);
+		if (readlen)
+			return readlen;
+
+		zstream.next_in = buf;
+		zstream.avail_in = 0;
+		result = git_deflate(&zstream, Z_FINISH);
+		if (result != Z_STREAM_END)
+			die("deflate error (%d)", result);
+
+		git_deflate_end(&zstream);
+		out = compressed;
+		if (!compressed_size)
+			out += 2;
+		out_len = zstream.next_out - out - 4;
+		write_or_die(1, out, out_len);
+		compressed_size += out_len;
+		zip_offset += compressed_size;
+
+		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;
 	}
 
 	free(deflated);
+	free(buffer);
+
+	memcpy(zip_dir + zip_dir_offset, &dirent, ZIP_DIR_HEADER_SIZE);
+	zip_dir_offset += ZIP_DIR_HEADER_SIZE;
+	memcpy(zip_dir + zip_dir_offset, path, pathlen);
+	zip_dir_offset += pathlen;
+	zip_dir_entries++;
 
 	return 0;
 }
diff --git a/archive.c b/archive.c
index 1ee837d717..cd083eaf9a 100644
--- a/archive.c
+++ b/archive.c
@@ -59,12 +59,15 @@ static void format_subst(const struct commit *commit,
 	free(to_free);
 }
 
-static void *sha1_file_to_archive(const char *path, const unsigned char *sha1,
-		unsigned int mode, enum object_type *type,
-		unsigned long *sizep, const struct commit *commit)
+void *sha1_file_to_archive(const struct archiver_args *args,
+			   const char *path, const unsigned char *sha1,
+			   unsigned int mode, enum object_type *type,
+			   unsigned long *sizep)
 {
 	void *buffer;
+	const struct commit *commit = args->convert ? args->commit : NULL;
 
+	path += args->baselen;
 	buffer = read_sha1_file(sha1, type, sizep);
 	if (buffer && S_ISREG(mode)) {
 		struct strbuf buf = STRBUF_INIT;
@@ -109,12 +112,9 @@ static int write_archive_entry(const unsigned char *sha1, const char *base,
 	write_archive_entry_fn_t write_entry = c->write_entry;
 	struct git_attr_check check[2];
 	const char *path_without_prefix;
-	int convert = 0;
 	int err;
-	enum object_type type;
-	unsigned long size;
-	void *buffer;
 
+	args->convert = 0;
 	strbuf_reset(&path);
 	strbuf_grow(&path, PATH_MAX);
 	strbuf_add(&path, args->base, args->baselen);
@@ -126,28 +126,22 @@ static int write_archive_entry(const unsigned char *sha1, const char *base,
 	if (!git_check_attr(path_without_prefix, ARRAY_SIZE(check), check)) {
 		if (ATTR_TRUE(check[0].value))
 			return 0;
-		convert = ATTR_TRUE(check[1].value);
+		args->convert = ATTR_TRUE(check[1].value);
 	}
 
 	if (S_ISDIR(mode) || S_ISGITLINK(mode)) {
 		strbuf_addch(&path, '/');
 		if (args->verbose)
 			fprintf(stderr, "%.*s\n", (int)path.len, path.buf);
-		err = write_entry(args, sha1, path.buf, path.len, mode, NULL, 0);
+		err = write_entry(args, sha1, path.buf, path.len, mode);
 		if (err)
 			return err;
 		return (S_ISDIR(mode) ? READ_TREE_RECURSIVE : 0);
 	}
 
-	buffer = sha1_file_to_archive(path_without_prefix, sha1, mode,
-			&type, &size, convert ? args->commit : NULL);
-	if (!buffer)
-		return error("cannot read %s", sha1_to_hex(sha1));
 	if (args->verbose)
 		fprintf(stderr, "%.*s\n", (int)path.len, path.buf);
-	err = write_entry(args, sha1, path.buf, path.len, mode, buffer, size);
-	free(buffer);
-	return err;
+	return write_entry(args, sha1, path.buf, path.len, mode);
 }
 
 int write_archive_entries(struct archiver_args *args,
@@ -167,7 +161,7 @@ int write_archive_entries(struct archiver_args *args,
 		if (args->verbose)
 			fprintf(stderr, "%.*s\n", (int)len, args->base);
 		err = write_entry(args, args->tree->object.sha1, args->base,
-				len, 040777, NULL, 0);
+				  len, 040777);
 		if (err)
 			return err;
 	}
diff --git a/archive.h b/archive.h
index 2b0884f1ef..895afcdc7a 100644
--- a/archive.h
+++ b/archive.h
@@ -11,6 +11,7 @@ struct archiver_args {
 	const char **pathspec;
 	unsigned int verbose : 1;
 	unsigned int worktree_attributes : 1;
+	unsigned int convert : 1;
 	int compression_level;
 };
 
@@ -27,11 +28,18 @@ extern void register_archiver(struct archiver *);
 extern void init_tar_archiver(void);
 extern void init_zip_archiver(void);
 
-typedef int (*write_archive_entry_fn_t)(struct archiver_args *args, const unsigned char *sha1, const char *path, size_t pathlen, unsigned int mode, void *buffer, unsigned long size);
+typedef int (*write_archive_entry_fn_t)(struct archiver_args *args,
+					const unsigned char *sha1,
+					const char *path, size_t pathlen,
+					unsigned int mode);
 
 extern int write_archive_entries(struct archiver_args *args, write_archive_entry_fn_t write_entry);
 extern int write_archive(int argc, const char **argv, const char *prefix, int setup_prefix, const char *name_hint, int remote);
 
 const char *archive_format_from_filename(const char *filename);
+extern void *sha1_file_to_archive(const struct archiver_args *args,
+				  const char *path, const unsigned char *sha1,
+				  unsigned int mode, enum object_type *type,
+				  unsigned long *sizep);
 
 #endif	/* ARCHIVE_H */
diff --git a/streaming.c b/streaming.c
index 7e7ee2be6f..3a3cd1206a 100644
--- a/streaming.c
+++ b/streaming.c
@@ -99,7 +99,7 @@ int close_istream(struct git_istream *st)
 	return r;
 }
 
-ssize_t read_istream(struct git_istream *st, char *buf, size_t sz)
+ssize_t read_istream(struct git_istream *st, void *buf, size_t sz)
 {
 	return st->vtbl->read(st, buf, sz);
 }
diff --git a/streaming.h b/streaming.h
index 3e827709c8..1d05c2a465 100644
--- a/streaming.h
+++ b/streaming.h
@@ -10,7 +10,7 @@ struct git_istream;
 
 extern struct git_istream *open_istream(const unsigned char *, enum object_type *, unsigned long *, struct stream_filter *);
 extern int close_istream(struct git_istream *);
-extern ssize_t read_istream(struct git_istream *, char *, size_t);
+extern ssize_t read_istream(struct git_istream *, void *, size_t);
 
 extern int stream_blob_to_fd(int fd, const unsigned char *, struct stream_filter *, int can_seek);
 
diff --git a/t/t1050-large.sh b/t/t1050-large.sh
index 4d127f19b7..55ed955cef 100755
--- a/t/t1050-large.sh
+++ b/t/t1050-large.sh
@@ -134,4 +134,16 @@ test_expect_success 'repack' '
 	git repack -ad
 '
 
+test_expect_success 'tar achiving' '
+	git archive --format=tar HEAD >/dev/null
+'
+
+test_expect_success 'zip achiving, store only' '
+	git archive --format=zip -0 HEAD >/dev/null
+'
+
+test_expect_success 'zip achiving, deflate' '
+	git archive --format=zip HEAD >/dev/null
+'
+
 test_done
diff --git a/t/t5000-tar-tree.sh b/t/t5000-tar-tree.sh
index 527c9e7548..ecf00edab2 100755
--- a/t/t5000-tar-tree.sh
+++ b/t/t5000-tar-tree.sh
@@ -31,6 +31,26 @@ GUNZIP=${GUNZIP:-gzip -d}
 
 SUBSTFORMAT=%H%n
 
+check_zip() {
+	zipfile=$1.zip
+	listfile=$1.lst
+	dir=$1
+	dir_with_prefix=$dir/$2
+
+	test_expect_success UNZIP " extract ZIP archive" "
+		(mkdir $dir && cd $dir && $UNZIP ../$zipfile)
+	"
+
+	test_expect_success UNZIP " validate filenames" "
+		(cd ${dir_with_prefix}a && find .) | sort >$listfile &&
+		test_cmp a.lst $listfile
+	"
+
+	test_expect_success UNZIP " validate file contents" "
+		diff -r a ${dir_with_prefix}a
+	"
+}
+
 test_expect_success \
     'populate workdir' \
     'mkdir a b c &&
@@ -84,6 +104,12 @@ test_expect_success \
     'git archive vs. git tar-tree' \
     'test_cmp b.tar b2.tar'
 
+test_expect_success 'git archive on large files' '
+    test_config core.bigfilethreshold 1 &&
+    git archive HEAD >b3.tar &&
+    test_cmp b.tar b3.tar
+'
+
 test_expect_success \
     'git archive in a bare repo' \
     '(cd bare.git && git archive HEAD) >b3.tar'
@@ -175,10 +201,19 @@ test_expect_success \
       test_cmp a/substfile2 g/prefix/a/substfile2
 '
 
+$UNZIP -v >/dev/null 2>&1
+if [ $? -eq 127 ]; then
+	say "Skipping ZIP tests, because unzip was not found"
+else
+	test_set_prereq UNZIP
+fi
+
 test_expect_success \
     'git archive --format=zip' \
     'git archive --format=zip HEAD >d.zip'
 
+check_zip d
+
 test_expect_success \
     'git archive --format=zip in a bare repo' \
     '(cd bare.git && git archive --format=zip HEAD) >d1.zip'
@@ -201,42 +236,25 @@ test_expect_success 'git archive with --output, override inferred format' '
 	test_cmp b.tar d4.zip
 '
 
-$UNZIP -v >/dev/null 2>&1
-if [ $? -eq 127 ]; then
-	say "Skipping ZIP tests, because unzip was not found"
-else
-	test_set_prereq UNZIP
-fi
-
-test_expect_success UNZIP \
-    'extract ZIP archive' \
-    '(mkdir d && cd d && $UNZIP ../d.zip)'
-
-test_expect_success UNZIP \
-    'validate filenames' \
-    '(cd d/a && find .) | sort >d.lst &&
-     test_cmp a.lst d.lst'
-
-test_expect_success UNZIP \
-    'validate file contents' \
-    'diff -r a d/a'
-
 test_expect_success \
     'git archive --format=zip with prefix' \
     'git archive --format=zip --prefix=prefix/ HEAD >e.zip'
 
-test_expect_success UNZIP \
-    'extract ZIP archive with prefix' \
-    '(mkdir e && cd e && $UNZIP ../e.zip)'
+check_zip e prefix/
 
-test_expect_success UNZIP \
-    'validate filenames with prefix' \
-    '(cd e/prefix/a && find .) | sort >e.lst &&
-     test_cmp a.lst e.lst'
+test_expect_success 'git archive -0 --format=zip on large files' '
+	test_config core.bigfilethreshold 1 &&
+	git archive -0 --format=zip HEAD >large.zip
+'
 
-test_expect_success UNZIP \
-    'validate file contents with prefix' \
-    'diff -r a e/prefix/a'
+check_zip large
+
+test_expect_success 'git archive --format=zip on large files' '
+	test_config core.bigfilethreshold 1 &&
+	git archive --format=zip HEAD >large-compressed.zip
+'
+
+check_zip large-compressed
 
 test_expect_success \
     'git archive --list outside of a git repo' \