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-rw-r--r--streaming.c489
1 files changed, 489 insertions, 0 deletions
diff --git a/streaming.c b/streaming.c
new file mode 100644
index 0000000..25c9a20
--- /dev/null
+++ b/streaming.c
@@ -0,0 +1,489 @@
+/*
+ * Copyright (c) 2011, Google Inc.
+ */
+#include "cache.h"
+#include "streaming.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 unsigned char *,
+ 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 unsigned char *sha1, \
+ 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)
+{
+ return st->vtbl->close(st);
+}
+
+ssize_t read_istream(struct git_istream *st, char *buf, size_t sz)
+{
+ return st->vtbl->read(st, buf, sz);
+}
+
+static enum input_source istream_source(const unsigned char *sha1,
+ enum object_type *type,
+ struct object_info *oi)
+{
+ unsigned long size;
+ int status;
+
+ oi->sizep = &size;
+ status = sha1_object_info_extended(sha1, oi);
+ if (status < 0)
+ return stream_error;
+ *type = status;
+
+ 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 unsigned char *sha1,
+ enum object_type *type,
+ unsigned long *size,
+ struct stream_filter *filter)
+{
+ struct git_istream *st;
+ struct object_info oi;
+ const unsigned char *real = lookup_replace_object(sha1);
+ 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 (st && filter) {
+ /* Add "&& !is_null_stream_filter(filter)" for performance */
+ struct git_istream *nst = attach_stream_filter(st, filter);
+ if (!nst)
+ close_istream(st);
+ 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)
+ break;
+ 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) {
+ 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_sha1_file(sha1, &st->u.loose.mapsize);
+ if (!st->u.loose.mapped)
+ return -1;
+ if (unpack_sha1_header(&st->z,
+ st->u.loose.mapped,
+ st->u.loose.mapsize,
+ st->u.loose.hdr,
+ sizeof(st->u.loose.hdr)) < 0) {
+ git_inflate_end(&st->z);
+ munmap(st->u.loose.mapped, st->u.loose.mapsize);
+ return -1;
+ }
+
+ parse_sha1_header(st->u.loose.hdr, &st->size);
+ 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;
+ }
+ 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_sha1_file_extended(sha1, type, &st->size, 0);
+ st->u.incore.read_ptr = 0;
+ st->vtbl = &incore_vtbl;
+
+ return st->u.incore.buf ? 0 : -1;
+}