[CRIU] [PATCH 3/5] protobuf: Add protobuf engine

[Cyrill Gorcunov]

Since protobuf is not that simple to deal with we provide
helpers to work with it

 - pbimg_write_obj to write PB objects
 - pbimg_read_obj_eof to read PB objects

Note the plural case of "objects" here. While in previous commit
descibes the ability to use pretty flexible structure of objects
which can be stored on disk, at moment most simple way is used
to not crash overall crtools code but make a transition to new
format via small steps.

So at moment the img files with PB objects do have the following
structure

        | 4 bytes magic number as a header
        +---
        | 24 bytes message obj_hdr
        +---
        | X bytes protobuf-object
        +---
        ...

        and so on

Ie it's not that efficient but enough for this stage.

Because messages obj_hdr and img_hdr and fixed in size
and immutable we provide a fast way to encode/decode them
via pbimg_write_img_hdr/pbimg_write_obj_hdr helpers. The
read speed up achieved via img_hrd_t and obj_hdr_t structures
which are 1:1 binary representation of PB ABI and will never
change.

Signed-off-by: Cyrill Gorcunov <gorcunov at openvz.org>
---
 Makefile           |    1 +
 include/protobuf.h |   83 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 protobuf.c         |   38 ++++++++++++++++++++++++
 3 files changed, 122 insertions(+), 0 deletions(-)
 create mode 100644 include/protobuf.h
 create mode 100644 protobuf.c

diff --git a/Makefile b/Makefile
index db2e6f7..9905c3d 100644
--- a/Makefile
+++ b/Makefile
@@ -59,6 +59,7 @@ OBJS		+= eventpoll.o
 OBJS		+= mount.o
 OBJS		+= inotify.o
 OBJS		+= pstree.o
+OBJS		+= protobuf.o
 
 PROTOBUF-LIB	:= protobuf/protobuf-lib.o
 
diff --git a/include/protobuf.h b/include/protobuf.h
new file mode 100644
index 0000000..74b1bb1
--- /dev/null
+++ b/include/protobuf.h
@@ -0,0 +1,83 @@
+#ifndef PROTOBUF_H__
+#define PROTOBUF_H__
+
+#include "types.h"
+#include "compiler.h"
+
+#include "syscall.h"
+
+typedef struct {
+	u8	___tag_pad1;
+	u64	magic;
+	u8	___tag_pad2;
+	u64	version;
+	u8	___tag_pad3;
+	u64	flags;
+} __packed img_hrd_t;
+
+typedef struct {
+	u8	___tag_pad1;
+	u32	type;
+	u8	___tag_pad2;
+	u64	pksize;
+} __packed obj_hdr_t;
+
+#define pbimg_read_img_hdr(fd, h)	read_img(fd, h)
+#define pbimg_read_obj_hdr(fd, h)	read_img(fd, h)
+
+#define pbimg_read_img_hdr_eof(fd, h)	read_img_eof(fd, h)
+#define pbimg_read_obj_hdr_eof(fd, h)	read_img_eof(fd, h)
+
+extern int pbimg_write_img_hdr(int fd, img_hrd_t *h);
+extern int pbimg_write_obj_hdr(int fd, obj_hdr_t *h);
+
+#define pbimg_write_obj(__fd, __object, __type, __get_packed_size, __pack)			\
+({												\
+	u8  ___buf[KILO(16)];									\
+	u32 ___size = __get_packed_size(__object);						\
+	int ___ret = -1;									\
+												\
+	if (___size <= sizeof(___buf)) {							\
+		obj_hdr_t ___ohdr = { .type = __type, .pksize = ___size };			\
+		___ret = pbimg_write_obj_hdr(__fd, &___ohdr);					\
+		if (!___ret) {									\
+			__pack(__object, ___buf);						\
+			___ret = write_img(__fd, &___size);					\
+			if (!___ret)								\
+				___ret = write_img_buf(__fd, ___buf, ___size);			\
+		}										\
+	} else											\
+		pr_err("Protobuf entry passed is too big (%dK)",				\
+		       (int)KBYTES(___size));							\
+	___ret;											\
+})
+
+/* Don't forget to free unpacked data on return */
+#define pbimg_read_obj_eof(__fd, __object, __type, __unpack)					\
+({												\
+	u8  ___buf[KILO(16)];									\
+	obj_hdr_t ___ohdr;									\
+	u32 ___size;										\
+	int ___ret;										\
+												\
+	*(__object) = NULL;									\
+	___ret = pbimg_read_obj_hdr_eof(__fd, &___ohdr);						\
+	if (___ret > 0) {									\
+		if (__type == ___ohdr.type) {							\
+			___ret = read_img_eof(__fd, &___size);					\
+			if (___ret > 0) {							\
+				if (___size <= sizeof(___buf))					\
+					___ret = read_img_buf(__fd, ___buf, ___size);		\
+					if (___ret == 1)					\
+						*(__object) = __unpack(NULL, ___size, ___buf);	\
+			}									\
+		} else {									\
+			pr_err("Corrupted image, type mismatch (%x %x)\n",			\
+				(int)__type, (int)___ohdr.type);				\
+			___ret = -1;								\
+		}										\
+	}											\
+	___ret;											\
+})
+
+#endif /* PROTOBUF_H__ */
diff --git a/protobuf.c b/protobuf.c
new file mode 100644
index 0000000..17b2052
--- /dev/null
+++ b/protobuf.c
@@ -0,0 +1,38 @@
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <stdlib.h>
+
+#include "compiler.h"
+#include "types.h"
+#include "log.h"
+#include "util.h"
+
+#include "protobuf.h"
+
+enum {
+	CR_PROTOBUF_C_WIRE_TYPE_VARINT,
+	CR_PROTOBUF_C_WIRE_TYPE_64BIT,
+	CR_PROTOBUF_C_WIRE_TYPE_LENGTH_PREFIXED,
+	CR_PROTOBUF_C_WIRE_TYPE_START_GROUP,
+	CR_PROTOBUF_C_WIRE_TYPE_END_GROUP,
+	CR_PROTOBUF_C_WIRE_TYPE_32BIT
+};
+
+int pbimg_write_img_hdr(int fd, img_hrd_t *h)
+{
+	h->___tag_pad1 = (1 << 3) | CR_PROTOBUF_C_WIRE_TYPE_64BIT;
+	h->___tag_pad2 = (2 << 3) | CR_PROTOBUF_C_WIRE_TYPE_64BIT;
+	h->___tag_pad3 = (3 << 3) | CR_PROTOBUF_C_WIRE_TYPE_64BIT;
+
+	return write_img(fd, h);
+}
+
+int pbimg_write_obj_hdr(int fd, obj_hdr_t *h)
+{
+	h->___tag_pad1 = (1 << 3) | CR_PROTOBUF_C_WIRE_TYPE_32BIT;
+	h->___tag_pad2 = (2 << 3) | CR_PROTOBUF_C_WIRE_TYPE_64BIT;
+
+	return write_img(fd, h);
+}
-- 
1.7.7.6