1 files changed, 567 insertions, 0 deletions
diff --git a/third_party/git/streaming.c b/third_party/git/streaming.c
new file mode 100644
index 000000000000..fcd63032192f
--- /dev/null
+++ b/third_party/git/streaming.c
@@ -0,0 +1,567 @@
+/*
+ * Copyright (c) 2011, Google Inc.
+ */
+#include "cache.h"
+#include "streaming.h"
+#include "repository.h"
+#include "object-store.h"
+#include "replace-object.h"
+#include "packfile.h"
+
+enum input_source {
+	stream_error = -1,
+	incore = 0,
+	loose = 1,
+	pack_non_delta = 2
+};
+
+typedef int (*open_istream_fn)(struct git_istream *,
+			       struct object_info *,
+			       const struct object_id *,
+			       enum object_type *);
+typedef int (*close_istream_fn)(struct git_istream *);
+typedef ssize_t (*read_istream_fn)(struct git_istream *, char *, size_t);
+
+struct stream_vtbl {
+	close_istream_fn close;
+	read_istream_fn read;
+};
+
+#define open_method_decl(name) \
+	int open_istream_ ##name \
+	(struct git_istream *st, struct object_info *oi, \
+	 const struct object_id *oid, \
+	 enum object_type *type)
+
+#define close_method_decl(name) \
+	int close_istream_ ##name \
+	(struct git_istream *st)
+
+#define read_method_decl(name) \
+	ssize_t read_istream_ ##name \
+	(struct git_istream *st, char *buf, size_t sz)
+
+/* forward declaration */
+static open_method_decl(incore);
+static open_method_decl(loose);
+static open_method_decl(pack_non_delta);
+static struct git_istream *attach_stream_filter(struct git_istream *st,
+						struct stream_filter *filter);
+
+
+static open_istream_fn open_istream_tbl[] = {
+	open_istream_incore,
+	open_istream_loose,
+	open_istream_pack_non_delta,
+};
+
+#define FILTER_BUFFER (1024*16)
+
+struct filtered_istream {
+	struct git_istream *upstream;
+	struct stream_filter *filter;
+	char ibuf[FILTER_BUFFER];
+	char obuf[FILTER_BUFFER];
+	int i_end, i_ptr;
+	int o_end, o_ptr;
+	int input_finished;
+};
+
+struct git_istream {
+	const struct stream_vtbl *vtbl;
+	unsigned long size; /* inflated size of full object */
+	git_zstream z;
+	enum { z_unused, z_used, z_done, z_error } z_state;
+
+	union {
+		struct {
+			char *buf; /* from read_object() */
+			unsigned long read_ptr;
+		} incore;
+
+		struct {
+			void *mapped;
+			unsigned long mapsize;
+			char hdr[32];
+			int hdr_avail;
+			int hdr_used;
+		} loose;
+
+		struct {
+			struct packed_git *pack;
+			off_t pos;
+		} in_pack;
+
+		struct filtered_istream filtered;
+	} u;
+};
+
+int close_istream(struct git_istream *st)
+{
+	int r = st->vtbl->close(st);
+	free(st);
+	return r;
+}
+
+ssize_t read_istream(struct git_istream *st, void *buf, size_t sz)
+{
+	return st->vtbl->read(st, buf, sz);
+}
+
+static enum input_source istream_source(const struct object_id *oid,
+					enum object_type *type,
+					struct object_info *oi)
+{
+	unsigned long size;
+	int status;
+
+	oi->typep = type;
+	oi->sizep = &size;
+	status = oid_object_info_extended(the_repository, oid, oi, 0);
+	if (status < 0)
+		return stream_error;
+
+	switch (oi->whence) {
+	case OI_LOOSE:
+		return loose;
+	case OI_PACKED:
+		if (!oi->u.packed.is_delta && big_file_threshold < size)
+			return pack_non_delta;
+		/* fallthru */
+	default:
+		return incore;
+	}
+}
+
+struct git_istream *open_istream(const struct object_id *oid,
+				 enum object_type *type,
+				 unsigned long *size,
+				 struct stream_filter *filter)
+{
+	struct git_istream *st;
+	struct object_info oi = OBJECT_INFO_INIT;
+	const struct object_id *real = lookup_replace_object(the_repository, oid);
+	enum input_source src = istream_source(real, type, &oi);
+
+	if (src < 0)
+		return NULL;
+
+	st = xmalloc(sizeof(*st));
+	if (open_istream_tbl[src](st, &oi, real, type)) {
+		if (open_istream_incore(st, &oi, real, type)) {
+			free(st);
+			return NULL;
+		}
+	}
+	if (filter) {
+		/* Add "&& !is_null_stream_filter(filter)" for performance */
+		struct git_istream *nst = attach_stream_filter(st, filter);
+		if (!nst) {
+			close_istream(st);
+			return NULL;
+		}
+		st = nst;
+	}
+
+	*size = st->size;
+	return st;
+}
+
+
+/*****************************************************************
+ *
+ * Common helpers
+ *
+ *****************************************************************/
+
+static void close_deflated_stream(struct git_istream *st)
+{
+	if (st->z_state == z_used)
+		git_inflate_end(&st->z);
+}
+
+
+/*****************************************************************
+ *
+ * Filtered stream
+ *
+ *****************************************************************/
+
+static close_method_decl(filtered)
+{
+	free_stream_filter(st->u.filtered.filter);
+	return close_istream(st->u.filtered.upstream);
+}
+
+static read_method_decl(filtered)
+{
+	struct filtered_istream *fs = &(st->u.filtered);
+	size_t filled = 0;
+
+	while (sz) {
+		/* do we already have filtered output? */
+		if (fs->o_ptr < fs->o_end) {
+			size_t to_move = fs->o_end - fs->o_ptr;
+			if (sz < to_move)
+				to_move = sz;
+			memcpy(buf + filled, fs->obuf + fs->o_ptr, to_move);
+			fs->o_ptr += to_move;
+			sz -= to_move;
+			filled += to_move;
+			continue;
+		}
+		fs->o_end = fs->o_ptr = 0;
+
+		/* do we have anything to feed the filter with? */
+		if (fs->i_ptr < fs->i_end) {
+			size_t to_feed = fs->i_end - fs->i_ptr;
+			size_t to_receive = FILTER_BUFFER;
+			if (stream_filter(fs->filter,
+					  fs->ibuf + fs->i_ptr, &to_feed,
+					  fs->obuf, &to_receive))
+				return -1;
+			fs->i_ptr = fs->i_end - to_feed;
+			fs->o_end = FILTER_BUFFER - to_receive;
+			continue;
+		}
+
+		/* tell the filter to drain upon no more input */
+		if (fs->input_finished) {
+			size_t to_receive = FILTER_BUFFER;
+			if (stream_filter(fs->filter,
+					  NULL, NULL,
+					  fs->obuf, &to_receive))
+				return -1;
+			fs->o_end = FILTER_BUFFER - to_receive;
+			if (!fs->o_end)
+				break;
+			continue;
+		}
+		fs->i_end = fs->i_ptr = 0;
+
+		/* refill the input from the upstream */
+		if (!fs->input_finished) {
+			fs->i_end = read_istream(fs->upstream, fs->ibuf, FILTER_BUFFER);
+			if (fs->i_end < 0)
+				return -1;
+			if (fs->i_end)
+				continue;
+		}
+		fs->input_finished = 1;
+	}
+	return filled;
+}
+
+static struct stream_vtbl filtered_vtbl = {
+	close_istream_filtered,
+	read_istream_filtered,
+};
+
+static struct git_istream *attach_stream_filter(struct git_istream *st,
+						struct stream_filter *filter)
+{
+	struct git_istream *ifs = xmalloc(sizeof(*ifs));
+	struct filtered_istream *fs = &(ifs->u.filtered);
+
+	ifs->vtbl = &filtered_vtbl;
+	fs->upstream = st;
+	fs->filter = filter;
+	fs->i_end = fs->i_ptr = 0;
+	fs->o_end = fs->o_ptr = 0;
+	fs->input_finished = 0;
+	ifs->size = -1; /* unknown */
+	return ifs;
+}
+
+/*****************************************************************
+ *
+ * Loose object stream
+ *
+ *****************************************************************/
+
+static read_method_decl(loose)
+{
+	size_t total_read = 0;
+
+	switch (st->z_state) {
+	case z_done:
+		return 0;
+	case z_error:
+		return -1;
+	default:
+		break;
+	}
+
+	if (st->u.loose.hdr_used < st->u.loose.hdr_avail) {
+		size_t to_copy = st->u.loose.hdr_avail - st->u.loose.hdr_used;
+		if (sz < to_copy)
+			to_copy = sz;
+		memcpy(buf, st->u.loose.hdr + st->u.loose.hdr_used, to_copy);
+		st->u.loose.hdr_used += to_copy;
+		total_read += to_copy;
+	}
+
+	while (total_read < sz) {
+		int status;
+
+		st->z.next_out = (unsigned char *)buf + total_read;
+		st->z.avail_out = sz - total_read;
+		status = git_inflate(&st->z, Z_FINISH);
+
+		total_read = st->z.next_out - (unsigned char *)buf;
+
+		if (status == Z_STREAM_END) {
+			git_inflate_end(&st->z);
+			st->z_state = z_done;
+			break;
+		}
+		if (status != Z_OK && (status != Z_BUF_ERROR || total_read < sz)) {
+			git_inflate_end(&st->z);
+			st->z_state = z_error;
+			return -1;
+		}
+	}
+	return total_read;
+}
+
+static close_method_decl(loose)
+{
+	close_deflated_stream(st);
+	munmap(st->u.loose.mapped, st->u.loose.mapsize);
+	return 0;
+}
+
+static struct stream_vtbl loose_vtbl = {
+	close_istream_loose,
+	read_istream_loose,
+};
+
+static open_method_decl(loose)
+{
+	st->u.loose.mapped = map_loose_object(the_repository,
+					      oid, &st->u.loose.mapsize);
+	if (!st->u.loose.mapped)
+		return -1;
+	if ((unpack_loose_header(&st->z,
+				 st->u.loose.mapped,
+				 st->u.loose.mapsize,
+				 st->u.loose.hdr,
+				 sizeof(st->u.loose.hdr)) < 0) ||
+	    (parse_loose_header(st->u.loose.hdr, &st->size) < 0)) {
+		git_inflate_end(&st->z);
+		munmap(st->u.loose.mapped, st->u.loose.mapsize);
+		return -1;
+	}
+
+	st->u.loose.hdr_used = strlen(st->u.loose.hdr) + 1;
+	st->u.loose.hdr_avail = st->z.total_out;
+	st->z_state = z_used;
+
+	st->vtbl = &loose_vtbl;
+	return 0;
+}
+
+
+/*****************************************************************
+ *
+ * Non-delta packed object stream
+ *
+ *****************************************************************/
+
+static read_method_decl(pack_non_delta)
+{
+	size_t total_read = 0;
+
+	switch (st->z_state) {
+	case z_unused:
+		memset(&st->z, 0, sizeof(st->z));
+		git_inflate_init(&st->z);
+		st->z_state = z_used;
+		break;
+	case z_done:
+		return 0;
+	case z_error:
+		return -1;
+	case z_used:
+		break;
+	}
+
+	while (total_read < sz) {
+		int status;
+		struct pack_window *window = NULL;
+		unsigned char *mapped;
+
+		mapped = use_pack(st->u.in_pack.pack, &window,
+				  st->u.in_pack.pos, &st->z.avail_in);
+
+		st->z.next_out = (unsigned char *)buf + total_read;
+		st->z.avail_out = sz - total_read;
+		st->z.next_in = mapped;
+		status = git_inflate(&st->z, Z_FINISH);
+
+		st->u.in_pack.pos += st->z.next_in - mapped;
+		total_read = st->z.next_out - (unsigned char *)buf;
+		unuse_pack(&window);
+
+		if (status == Z_STREAM_END) {
+			git_inflate_end(&st->z);
+			st->z_state = z_done;
+			break;
+		}
+
+		/*
+		 * Unlike the loose object case, we do not have to worry here
+		 * about running out of input bytes and spinning infinitely. If
+		 * we get Z_BUF_ERROR due to too few input bytes, then we'll
+		 * replenish them in the next use_pack() call when we loop. If
+		 * we truly hit the end of the pack (i.e., because it's corrupt
+		 * or truncated), then use_pack() catches that and will die().
+		 */
+		if (status != Z_OK && status != Z_BUF_ERROR) {
+			git_inflate_end(&st->z);
+			st->z_state = z_error;
+			return -1;
+		}
+	}
+	return total_read;
+}
+
+static close_method_decl(pack_non_delta)
+{
+	close_deflated_stream(st);
+	return 0;
+}
+
+static struct stream_vtbl pack_non_delta_vtbl = {
+	close_istream_pack_non_delta,
+	read_istream_pack_non_delta,
+};
+
+static open_method_decl(pack_non_delta)
+{
+	struct pack_window *window;
+	enum object_type in_pack_type;
+
+	st->u.in_pack.pack = oi->u.packed.pack;
+	st->u.in_pack.pos = oi->u.packed.offset;
+	window = NULL;
+
+	in_pack_type = unpack_object_header(st->u.in_pack.pack,
+					    &window,
+					    &st->u.in_pack.pos,
+					    &st->size);
+	unuse_pack(&window);
+	switch (in_pack_type) {
+	default:
+		return -1; /* we do not do deltas for now */
+	case OBJ_COMMIT:
+	case OBJ_TREE:
+	case OBJ_BLOB:
+	case OBJ_TAG:
+		break;
+	}
+	st->z_state = z_unused;
+	st->vtbl = &pack_non_delta_vtbl;
+	return 0;
+}
+
+
+/*****************************************************************
+ *
+ * In-core stream
+ *
+ *****************************************************************/
+
+static close_method_decl(incore)
+{
+	free(st->u.incore.buf);
+	return 0;
+}
+
+static read_method_decl(incore)
+{
+	size_t read_size = sz;
+	size_t remainder = st->size - st->u.incore.read_ptr;
+
+	if (remainder <= read_size)
+		read_size = remainder;
+	if (read_size) {
+		memcpy(buf, st->u.incore.buf + st->u.incore.read_ptr, read_size);
+		st->u.incore.read_ptr += read_size;
+	}
+	return read_size;
+}
+
+static struct stream_vtbl incore_vtbl = {
+	close_istream_incore,
+	read_istream_incore,
+};
+
+static open_method_decl(incore)
+{
+	st->u.incore.buf = read_object_file_extended(the_repository, oid, type, &st->size, 0);
+	st->u.incore.read_ptr = 0;
+	st->vtbl = &incore_vtbl;
+
+	return st->u.incore.buf ? 0 : -1;
+}
+
+
+/****************************************************************
+ * Users of streaming interface
+ ****************************************************************/
+
+int stream_blob_to_fd(int fd, const struct object_id *oid, struct stream_filter *filter,
+		      int can_seek)
+{
+	struct git_istream *st;
+	enum object_type type;
+	unsigned long sz;
+	ssize_t kept = 0;
+	int result = -1;
+
+	st = open_istream(oid, &type, &sz, filter);
+	if (!st) {
+		if (filter)
+			free_stream_filter(filter);
+		return result;
+	}
+	if (type != OBJ_BLOB)
+		goto close_and_exit;
+	for (;;) {
+		char buf[1024 * 16];
+		ssize_t wrote, holeto;
+		ssize_t readlen = read_istream(st, buf, sizeof(buf));
+
+		if (readlen < 0)
+			goto close_and_exit;
+		if (!readlen)
+			break;
+		if (can_seek && sizeof(buf) == readlen) {
+			for (holeto = 0; holeto < readlen; holeto++)
+				if (buf[holeto])
+					break;
+			if (readlen == holeto) {
+				kept += holeto;
+				continue;
+			}
+		}
+
+		if (kept && lseek(fd, kept, SEEK_CUR) == (off_t) -1)
+			goto close_and_exit;
+		else
+			kept = 0;
+		wrote = write_in_full(fd, buf, readlen);
+
+		if (wrote < 0)
+			goto close_and_exit;
+	}
+	if (kept && (lseek(fd, kept - 1, SEEK_CUR) == (off_t) -1 ||
+		     xwrite(fd, "", 1) != 1))
+		goto close_and_exit;
+	result = 0;
+
+ close_and_exit:
+	close_istream(st);
+	return result;
+}