Add flog to CRIU

Change made through this commit:
- Include copy of flog as a seperate tree.
- Modify the makefile to add and compile flog code.

Signed-off-by: prakritigoyal19 <prakritigoyal19@gmail.com>

12 files changed, 744 insertions, 0 deletions

diff --git a/flog/Makefile b/flog/Makefile
new file mode 100644
index 000000000..12255af71
--- /dev/null
+++ b/flog/Makefile
@@ -0,0 +1,29 @@
+OPTS=-ggdb3 -Wall -Werror
+export OPTS
+
+CFLAGS			+= -iquote include
+CFLAGS			+= -iquote flog/include
+CFLAGS			+= -iquote flog/include/uapi
+
+include $(__nmk_dir)msg.mk
+
+$(eval $(call gen-built-in,src))
+
+flog:
+	$(Q) $(MAKE) $(build)=$(obj)/src all
+.PHONY: flog
+
+clean-flog:
+	$(call msg-gen, $@)
+	$(Q) $(MAKE) $(build)=$(obj)/src clean
+	$(Q) $(RM) built-in.o
+.PHONY: clean-flog
+
+clean: clean-flog
+mrproper: clean
+
+test:
+	./tests/test00
+
+all-y += flog
+
diff --git a/flog/built-in.S b/flog/built-in.S
new file mode 100644
index 000000000..26627d054
--- /dev/null
+++ b/flog/built-in.S
@@ -0,0 +1,4 @@
+SECTIONS
+{
+	.rodata : { _rodata_start = . ; *(.rodata*) ; _rodata_end = . ;}
+}
diff --git a/flog/include/compiler.h b/flog/include/compiler.h
new file mode 100644
index 000000000..3e56eb0e6
--- /dev/null
+++ b/flog/include/compiler.h
@@ -0,0 +1,71 @@
+#ifndef __COMPILER_H__
+#define __COMPILER_H__
+
+/*
+ * Various definitions for success build,
+ * picked from various places, mostly from
+ * the linux kernel.
+ */
+
+#define ARRAY_SIZE(x)		(sizeof(x) / sizeof((x)[0]))
+#define BUILD_BUG_ON(condition)	((void)sizeof(char[1 - 2*!!(condition)]))
+
+#define __stringify_1(x...)	#x
+#define __stringify(x...)	__stringify_1(x)
+
+#define NORETURN		__attribute__((__noreturn__))
+#define __packed		__attribute__((__packed__))
+#define __used			__attribute__((__used__))
+#define __maybe_unused		__attribute__((unused))
+#define __always_unused		__attribute__((unused))
+
+#define __section(S)		__attribute__ ((__section__(#S)))
+
+#ifndef __always_inline
+# define __always_inline	inline __attribute__((always_inline))
+#endif
+
+#define likely(x)		__builtin_expect(!!(x), 1)
+#define unlikely(x)		__builtin_expect(!!(x), 0)
+
+#ifndef always_inline
+# define always_inline		__always_inline
+#endif
+
+#ifndef noinline
+# define noinline		__attribute__((noinline))
+#endif
+
+#define __aligned(x)		__attribute__((aligned(x)))
+
+#ifndef offsetof
+# define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
+#endif
+
+#define barrier()		asm volatile("" ::: "memory")
+
+#define container_of(ptr, type, member) ({			\
+	const typeof( ((type *)0)->member ) *__mptr = (ptr);	\
+	(type *)( (char *)__mptr - offsetof(type,member) );})
+
+#define __round_mask(x, y)	((__typeof__(x))((y) - 1))
+#define round_up(x, y)		((((x) - 1) | __round_mask(x, y)) + 1)
+#define round_down(x, y)	((x) & ~__round_mask(x, y))
+#define DIV_ROUND_UP(n,d)	(((n) + (d) - 1) / (d))
+#define ALIGN(x, a)		(((x) + (a) - 1) & ~((a) - 1))
+
+#define min(x, y) ({				\
+	typeof(x) _min1 = (x);			\
+	typeof(y) _min2 = (y);			\
+	(void) (&_min1 == &_min2);		\
+	_min1 < _min2 ? _min1 : _min2; })
+
+#define max(x, y) ({				\
+	typeof(x) _max1 = (x);			\
+	typeof(y) _max2 = (y);			\
+	(void) (&_max1 == &_max2);		\
+	_max1 > _max2 ? _max1 : _max2; })
+
+#define is_log2(v)		(((v) & ((v) - 1)) == 0)
+
+#endif /* __COMPILER_H__ */
diff --git a/flog/include/flog.h b/flog/include/flog.h
new file mode 100644
index 000000000..f00c20541
--- /dev/null
+++ b/flog/include/flog.h
@@ -0,0 +1,9 @@
+#ifndef __FLOG_H__
+#define __FLOG_H__
+
+#include <string.h>
+#include <errno.h>
+
+#include "uapi/flog.h"
+
+#endif /* __FLOG_H__ */
diff --git a/flog/include/log.h b/flog/include/log.h
new file mode 100644
index 000000000..1a165ea9f
--- /dev/null
+++ b/flog/include/log.h
@@ -0,0 +1,17 @@
+#ifndef __LOG_H__
+#define __LOG_H__
+
+#include <stdio.h>
+
+#define pr_out(fmt, ...)	fprintf(stdout, fmt, ##__VA_ARGS__)
+
+#if 1
+# define pr_debug(fmt, ...)	fprintf(stderr, fmt, ##__VA_ARGS__)
+#else
+# define pr_debug(fmt, ...)
+#endif
+
+#define pr_err(fmt, ...)	fprintf(stderr, "Error (%s:%d): "fmt, __FILE__, __LINE__, ##__VA_ARGS__)
+#define pr_perror(fmt, ...)	fprintf(stderr, "Error (%s:%d): "fmt "%m\n", __FILE__, __LINE__, ##__VA_ARGS__)
+
+#endif /* __LOG_H__ */
diff --git a/flog/include/types.h b/flog/include/types.h
new file mode 100644
index 000000000..0e15bfbff
--- /dev/null
+++ b/flog/include/types.h
@@ -0,0 +1,16 @@
+#ifndef __FLOG_TYPES_H__
+#define __FLOG_TYPES_H__
+
+#include <stdint.h>
+#include <stdbool.h>
+
+typedef uint64_t	u64;
+typedef int64_t		s64;
+typedef uint32_t	u32;
+typedef int32_t		s32;
+typedef uint16_t	u16;
+typedef int16_t		s16;
+typedef uint8_t		u8;
+typedef int8_t		s8;
+
+#endif /* __FLOG_TYPES_H__ */
diff --git a/flog/include/uapi/flog.h b/flog/include/uapi/flog.h
new file mode 100644
index 000000000..2d879110f
--- /dev/null
+++ b/flog/include/uapi/flog.h
@@ -0,0 +1,149 @@
+#ifndef __UAPI_FLOG_H__
+#define __UAPI_FLOG_H__
+
+#include <stdbool.h>
+#include <string.h>
+#include <errno.h>
+
+/*
+ * We work with up to 32 arguments in macros here.
+ * If more provided -- behaviour is undefined.
+ */
+
+/*
+ * By Laurent Deniau at https://groups.google.com/forum/#!topic/comp.std.c/d-6Mj5Lko_s
+ */
+#define FLOG_PP_NARG_(...)			FLOG_PP_ARG_N(__VA_ARGS__)
+#define FLOG_PP_NARG(...)			FLOG_PP_NARG_(1, ##__VA_ARGS__, FLOG_PP_RSEQ_N())
+
+#define FLOG_PP_ARG_N( _0, _1, _2, _3, _4,	\
+		       _5, _6, _7, _8, _9,	\
+		      _10,_11,_12,_13,_14,	\
+		      _15,_16,_17,_18,_19,	\
+		      _20,_21,_22,_23,_24,	\
+		      _25,_26,_27,_28,_29,	\
+		      _30,_31,  N, ...)		N
+
+#define FLOG_PP_RSEQ_N()			\
+		       31, 30, 29, 28, 27,	\
+		       26, 25, 24, 23, 22,	\
+		       21, 20, 19, 18, 17,	\
+		       16, 15, 14, 13, 12,	\
+		       11, 10,  9,  8,  7,	\
+		        6,  5,  4,  3,  2,	\
+		        1,  0
+
+#define FLOG_GENMASK_0(N, x)		0
+#define FLOG_GENMASK_1(N,  op, x, ...)	 (op(N,  0, x))
+#define FLOG_GENMASK_2(N,  op, x, ...)	((op(N,  1, x)) | FLOG_GENMASK_1(N,  op,  __VA_ARGS__))
+#define FLOG_GENMASK_3(N,  op, x, ...)	((op(N,  2, x)) | FLOG_GENMASK_2(N,  op,  __VA_ARGS__))
+#define FLOG_GENMASK_4(N,  op, x, ...)	((op(N,  3, x)) | FLOG_GENMASK_3(N,  op,  __VA_ARGS__))
+#define FLOG_GENMASK_5(N,  op, x, ...)	((op(N,  4, x)) | FLOG_GENMASK_4(N,  op,  __VA_ARGS__))
+#define FLOG_GENMASK_6(N,  op, x, ...)	((op(N,  5, x)) | FLOG_GENMASK_5(N,  op,  __VA_ARGS__))
+#define FLOG_GENMASK_7(N,  op, x, ...)	((op(N,  6, x)) | FLOG_GENMASK_6(N,  op,  __VA_ARGS__))
+#define FLOG_GENMASK_8(N,  op, x, ...)	((op(N,  7, x)) | FLOG_GENMASK_7(N,  op,  __VA_ARGS__))
+#define FLOG_GENMASK_9(N,  op, x, ...)	((op(N,  8, x)) | FLOG_GENMASK_8(N,  op,  __VA_ARGS__))
+#define FLOG_GENMASK_10(N, op, x, ...)	((op(N,  9, x)) | FLOG_GENMASK_9(N,  op,  __VA_ARGS__))
+#define FLOG_GENMASK_11(N, op, x, ...)	((op(N, 10, x)) | FLOG_GENMASK_10(N, op,  __VA_ARGS__))
+#define FLOG_GENMASK_12(N, op, x, ...)	((op(N, 11, x)) | FLOG_GENMASK_11(N, op,  __VA_ARGS__))
+#define FLOG_GENMASK_13(N, op, x, ...)	((op(N, 12, x)) | FLOG_GENMASK_12(N, op,  __VA_ARGS__))
+#define FLOG_GENMASK_14(N, op, x, ...)	((op(N, 13, x)) | FLOG_GENMASK_13(N, op,  __VA_ARGS__))
+#define FLOG_GENMASK_15(N, op, x, ...)	((op(N, 14, x)) | FLOG_GENMASK_14(N, op,  __VA_ARGS__))
+#define FLOG_GENMASK_16(N, op, x, ...)	((op(N, 15, x)) | FLOG_GENMASK_15(N, op,  __VA_ARGS__))
+#define FLOG_GENMASK_17(N, op, x, ...)	((op(N, 16, x)) | FLOG_GENMASK_16(N, op,  __VA_ARGS__))
+#define FLOG_GENMASK_18(N, op, x, ...)	((op(N, 17, x)) | FLOG_GENMASK_17(N, op,  __VA_ARGS__))
+#define FLOG_GENMASK_19(N, op, x, ...)	((op(N, 18, x)) | FLOG_GENMASK_18(N, op,  __VA_ARGS__))
+#define FLOG_GENMASK_20(N, op, x, ...)	((op(N, 19, x)) | FLOG_GENMASK_19(N, op,  __VA_ARGS__))
+#define FLOG_GENMASK_21(N, op, x, ...)	((op(N, 20, x)) | FLOG_GENMASK_20(N, op,  __VA_ARGS__))
+#define FLOG_GENMASK_22(N, op, x, ...)	((op(N, 21, x)) | FLOG_GENMASK_21(N, op,  __VA_ARGS__))
+#define FLOG_GENMASK_23(N, op, x, ...)	((op(N, 22, x)) | FLOG_GENMASK_22(N, op,  __VA_ARGS__))
+#define FLOG_GENMASK_24(N, op, x, ...)	((op(N, 23, x)) | FLOG_GENMASK_23(N, op,  __VA_ARGS__))
+#define FLOG_GENMASK_25(N, op, x, ...)	((op(N, 24, x)) | FLOG_GENMASK_24(N, op,  __VA_ARGS__))
+#define FLOG_GENMASK_26(N, op, x, ...)	((op(N, 25, x)) | FLOG_GENMASK_25(N, op,  __VA_ARGS__))
+#define FLOG_GENMASK_27(N, op, x, ...)	((op(N, 26, x)) | FLOG_GENMASK_26(N, op,  __VA_ARGS__))
+#define FLOG_GENMASK_28(N, op, x, ...)	((op(N, 27, x)) | FLOG_GENMASK_27(N, op,  __VA_ARGS__))
+#define FLOG_GENMASK_29(N, op, x, ...)	((op(N, 28, x)) | FLOG_GENMASK_28(N, op,  __VA_ARGS__))
+#define FLOG_GENMASK_30(N, op, x, ...)	((op(N, 29, x)) | FLOG_GENMASK_29(N, op,  __VA_ARGS__))
+#define FLOG_GENMASK_31(N, op, x, ...)	((op(N, 30, x)) | FLOG_GENMASK_30(N, op,  __VA_ARGS__))
+#define FLOG_GENMASK_32(N, op, x, ...)	((op(N, 31, x)) | FLOG_GENMASK_31(N, op,  __VA_ARGS__))
+
+#define FLOG_CONCAT(arg1, arg2)		FLOG_CONCAT1(arg1, arg2)
+#define FLOG_CONCAT1(arg1, arg2)	FLOG_CONCAT2(arg1, arg2)
+#define FLOG_CONCAT2(arg1, arg2)	arg1##arg2
+
+#define FLOG_GENMASK_(N, op, ...)	FLOG_CONCAT(FLOG_GENMASK_, N)(N, op, ##__VA_ARGS__)
+#define FLOG_GENMASK(op, ...)		FLOG_GENMASK_(FLOG_PP_NARG(__VA_ARGS__), op, ##__VA_ARGS__)
+
+#define flog_genbit(ord, n, v, ...)					\
+	_Generic((v),							\
+									\
+		 /* Basic types */					\
+		 char:				0,			\
+		 signed char:			0,			\
+		 unsigned char:			0,			\
+		 signed short int:		0,			\
+		 unsigned short int:		0,			\
+		 signed int:			0,			\
+		 unsigned int:			0,			\
+		 signed long:			0,			\
+		 unsigned long:			0,			\
+		 signed long long:		0,			\
+		 unsigned long long:		0,			\
+									\
+		 /* Not used for a while */				\
+		 /* float:			12, */			\
+		 /* double:			13, */			\
+		 /* long double:		14, */			\
+									\
+		 /* Basic poniters */					\
+		 char *:			(1u << (ord - n - 1)),	\
+		 signed char *:			(1u << (ord - n - 1)),	\
+		 unsigned char *:		(1u << (ord - n - 1)),	\
+		 signed short int *:		0,			\
+		 unsigned short int *:		0,			\
+		 signed int *:			0,			\
+		 unsigned int *:		0,			\
+		 signed long *:			0,			\
+		 unsigned long *:		0,			\
+		 signed long long *:		0,			\
+		 unsigned long long *:		0,			\
+		 void *:			0,			\
+									\
+		 /* Const basic pointers */				\
+		 const char *:			(1u << (ord - n - 1)),	\
+		 const signed char *:		(1u << (ord - n - 1)),	\
+		 const unsigned char *:		(1u << (ord - n - 1)),	\
+		 const signed short int *:	0,			\
+		 const unsigned short int *:	0,			\
+		 const signed int *:		0,			\
+		 const unsigned int *:		0,			\
+		 const signed long *:		0,			\
+		 const unsigned long *:		0,			\
+		 const signed long long *:	0,			\
+		 const unsigned long long *:	0,			\
+		 const void *:			0,			\
+									\
+		 /* Systypes and pointers */				\
+		 default:			-1)
+
+typedef struct {
+	unsigned int	magic;
+	unsigned int	size;
+	unsigned int	nargs;
+	unsigned int	mask;
+	long		fmt;
+	long		args[0];
+} flog_msg_t;
+
+extern int flog_encode_msg(int fdout, unsigned int nargs, unsigned int mask, const char *format, ...);
+void flog_decode_msg(int fdout, const char *format, ...);
+extern int flog_decode_all(int fdin, int fdout);
+
+#define flog_encode(fdout, fmt, ...)							\
+	flog_encode_msg(fdout, FLOG_PP_NARG(__VA_ARGS__),				\
+			FLOG_GENMASK(flog_genbit, ##__VA_ARGS__), fmt, ##__VA_ARGS__)
+
+int flog_map_buf(int fdout);
+int flog_close(int fdout);
+
+#endif /* __UAPI_FLOG_H__ */
diff --git a/flog/include/util.h b/flog/include/util.h
new file mode 100644
index 000000000..17a4d7799
--- /dev/null
+++ b/flog/include/util.h
@@ -0,0 +1,37 @@
+#ifndef __UTIL_H__
+#define __UTIL_H__
+
+#include <string.h>
+#include <errno.h>
+
+#include "log.h"
+#include "types.h"
+
+#define __xalloc(op, size, ...)						\
+	({								\
+		void *___p = op(__VA_ARGS__);				\
+		___p;							\
+	})
+
+#define xstrdup(str)		__xalloc(strdup, strlen(str) + 1, str)
+#define xmalloc(size)		__xalloc(malloc, size, size)
+#define xzalloc(size)		__xalloc(calloc, size, 1, size)
+#define xrealloc(p, size)	__xalloc(realloc, size, p, size)
+
+#define xfree(p)		do { if (p) free(p); } while (0)
+
+#define xrealloc_safe(pptr, size)					\
+	({								\
+		int __ret = -ENOMEM;					\
+		void *new = xrealloc(*pptr, size);			\
+		if (new) {						\
+			*pptr = new;					\
+			__ret = 0;					\
+		}							\
+		__ret;							\
+	 })
+
+#define memzero_p(p)		memset(p, 0, sizeof(*p))
+#define memzero(p, size)	memset(p, 0, size)
+
+#endif /* __UTIL_H__ */
diff --git a/flog/src/Makefile b/flog/src/Makefile
new file mode 100644
index 000000000..ee73ea725
--- /dev/null
+++ b/flog/src/Makefile
@@ -0,0 +1,5 @@
+ccflags-y += -DCONFIG_X86_64 -iquote ./include $(OPTS)
+ldflags-y		+= -r
+
+#obj-y += main.o
+obj-y += flog.o
diff --git a/flog/src/flog.c b/flog/src/flog.c
new file mode 100644
index 000000000..533625de6
--- /dev/null
+++ b/flog/src/flog.c
@@ -0,0 +1,215 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdarg.h>
+#include <unistd.h>
+#include <stdint.h>
+#include <sys/param.h>
+#include <sys/mman.h>
+
+//#include <ffi.h>
+
+#include "uapi/flog.h"
+#include "util.h"
+
+#define MAGIC 0xABCDABCD
+
+#define BUF_SIZE (1<<20)
+static char _mbuf[BUF_SIZE];
+static char *mbuf = _mbuf;
+static char *fbuf;
+static uint64_t fsize;
+static uint64_t mbuf_size = sizeof(_mbuf);
+
+/*int flog_decode_all(int fdin, int fdout)
+{
+	flog_msg_t *m = (void *)mbuf;
+	ffi_type *args[34] = {
+		[0]		= &ffi_type_sint,
+		[1]		= &ffi_type_pointer,
+		[2 ... 33]	= &ffi_type_slong
+	};
+	void *values[34];
+	ffi_cif cif;
+	ffi_arg rc;
+	size_t i, ret;
+	char *fmt;
+
+	values[0] = (void *)&fdout;
+
+	while (1) {
+		ret = read(fdin, mbuf, sizeof(m));
+		if (ret == 0)
+			break;
+		if (ret < 0) {
+			fprintf(stderr, "Unable to read a message: %m");
+			return -1;
+		}
+		if (m->magic != MAGIC) {
+			fprintf(stderr, "The log file was not properly closed\n");
+			break;
+		}
+		ret = m->size - sizeof(m);
+		if (m->size > mbuf_size) {
+			fprintf(stderr, "The buffer is too small");
+			return -1;
+		}
+		if (read(fdin, mbuf + sizeof(m), ret) != ret) {
+			fprintf(stderr, "Unable to read a message: %m");
+			return -1;
+		}
+
+		fmt = mbuf + m->fmt;
+		values[1] = &fmt;
+
+		for (i = 0; i < m->nargs; i++) {
+			values[i + 2] = (void *)&m->args[i];
+			if (m->mask & (1u << i)) {
+				m->args[i] = (long)(mbuf + m->args[i]);
+			}
+		}
+
+		if (ffi_prep_cif(&cif, FFI_DEFAULT_ABI, m->nargs + 2,
+				 &ffi_type_sint, args) == FFI_OK)
+			ffi_call(&cif, FFI_FN(dprintf), &rc, values);
+	}
+	return 0;
+}*/
+
+static int flog_enqueue(flog_msg_t *m)
+{
+	if (write(1, m, m->size) != m->size) {
+		fprintf(stderr, "Unable to write a message\n");
+		return -1;
+	}
+	return 0;
+}
+
+/*extern char *rodata_start;
+extern char *rodata_end;
+*/
+/* Pre-allocate a buffer in a file and map it into memory. */
+int flog_map_buf(int fdout)
+{
+	uint64_t off = 0;
+	void *addr;
+
+	/*
+	 * Two buffers are mmaped into memory. A new one is mapped when a first
+	 * one is completly filled.
+	 */
+	if (fbuf && (mbuf - fbuf < BUF_SIZE))
+		return 0;
+
+	if (fbuf) {
+		if (munmap(fbuf, BUF_SIZE * 2)) {
+			fprintf(stderr, "Unable to unmap a buffer: %m");
+			return -1;
+		}
+		off = mbuf - fbuf - BUF_SIZE;
+		fbuf = NULL;
+	}
+
+	if (fsize == 0)
+		fsize += BUF_SIZE;
+	fsize += BUF_SIZE;
+
+	if (ftruncate(fdout, fsize)) {
+		fprintf(stderr, "Unable to truncate a file: %m");
+		return -1;
+	}
+
+	if (!fbuf)
+		addr = mmap(NULL, BUF_SIZE * 2, PROT_WRITE | PROT_READ,
+			    MAP_FILE | MAP_SHARED, fdout, fsize - 2 * BUF_SIZE);
+	else
+		addr = mremap(fbuf + BUF_SIZE, BUF_SIZE,
+				BUF_SIZE * 2, MREMAP_FIXED, fbuf);
+	if (addr == MAP_FAILED) {
+		fprintf(stderr, "Unable to map a buffer: %m");
+		return -1;
+	}
+
+	fbuf = addr;
+	mbuf = fbuf + off;
+	mbuf_size = 2 * BUF_SIZE;
+
+	return 0;
+}
+
+int flog_close(int fdout)
+{
+	if (mbuf == _mbuf)
+		return 0;
+
+	munmap(fbuf, BUF_SIZE * 2);
+
+	if (ftruncate(fdout, fsize - 2 * BUF_SIZE + mbuf - fbuf)) {
+		fprintf(stderr, "Unable to truncate a file: %m");
+		return -1;
+	}
+	return 0;
+}
+
+int flog_encode_msg(int fdout, unsigned int nargs, unsigned int mask, const char *format, ...)
+{
+	flog_msg_t *m;
+	va_list argptr;
+	char *str_start, *p;
+	size_t i;
+
+	if (mbuf != _mbuf && flog_map_buf(fdout))
+		return -1;
+
+	m = (void *) mbuf;
+
+	m->nargs = nargs;
+	m->mask = mask;
+
+	str_start = (void *)m->args + sizeof(m->args[0]) * nargs;
+	p = memccpy(str_start, format, 0, mbuf_size - (str_start - mbuf));
+	if (p == NULL) {
+		fprintf(stderr, "No memory for string argument\n");
+		return -1;
+	}
+	m->fmt = str_start - mbuf;
+	str_start = p;
+
+	va_start(argptr, format);
+	for (i = 0; i < nargs; i++) {
+		m->args[i] = (long)va_arg(argptr, long);
+		/*
+		 * If we got a string, we should either
+		 * reference it when in rodata, or make
+		 * a copy (FIXME implement rodata refs).
+		 */
+		if (mask & (1u << i)) {
+			p = memccpy(str_start, (void *)m->args[i], 0, mbuf_size - (str_start - mbuf));
+			if (p == NULL) {
+				fprintf(stderr, "No memory for string argument\n");
+				return -1;
+			}
+			m->args[i] = str_start - mbuf;
+			str_start = p;
+		}
+	}
+	va_end(argptr);
+	m->size = str_start - mbuf;
+
+	/*
+	 * A magic is required to know where we stop writing into a log file,
+	 * if it was not properly closed.  The file is mapped into memory, so a
+	 * space in the file is allocated in advance and at the end it can have
+	 * some unused tail.
+	 */
+	m->magic = MAGIC;
+
+	m->size = roundup(m->size, 8);
+	if (mbuf == _mbuf) {
+		if (flog_enqueue(m))
+			return -1;
+	} else {
+		mbuf += m->size;
+		mbuf_size -= m->size;
+	}
+	return 0;
+}
diff --git a/flog/src/main.c b/flog/src/main.c
new file mode 100644
index 000000000..c84e77478
--- /dev/null
+++ b/flog/src/main.c
@@ -0,0 +1,170 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <getopt.h>
+#include <unistd.h>
+
+#include <sys/stat.h>
+#include <fcntl.h>
+
+#include "flog.h"
+
+extern char _rodata_start, _rodata_end;
+char *rodata_start = &_rodata_start;
+char *rodata_end = &_rodata_end;
+
+enum {
+	MODE_BINARY,
+	MODE_FPRINTF,
+	MODE_SPRINTF,
+	MODE_DPRINTF,
+};
+
+int main(int argc, char *argv[])
+{
+	static const char str1[] = "String1 String1";
+	static const char str2[] = "string2 string2 string2";
+	int fdout = STDOUT_FILENO;
+	bool use_decoder = false;
+	int mode = MODE_BINARY;
+	size_t niter = 100;
+	int opt, idx;
+	size_t i;
+
+	static const char short_opts[] = "m:o:di:h";
+	static struct option long_opts[] = {
+		{ "mode",		required_argument,	0, 'm'	},
+		{ "output",		required_argument,	0, 'o'	},
+		{ "decode",		no_argument,		0, 'd'	},
+		{ "iter",		required_argument,	0, 'i'	},
+		{ "help",		no_argument,		0, 'h'	},
+		{ },
+	};
+
+	while (1) {
+		idx = -1;
+		opt = getopt_long(argc, argv, short_opts, long_opts, &idx);
+		if (opt == -1)
+			break;
+
+		switch (opt) {
+		case 'm':
+			if (strcmp(optarg, "binary") == 0) {
+				mode = MODE_BINARY;
+			} else if (strcmp(optarg, "fprintf") == 0) {
+				mode = MODE_FPRINTF;
+			} else if (strcmp(optarg, "sprintf") == 0) {
+				mode = MODE_SPRINTF;
+			} else if (strcmp(optarg, "dprintf") == 0) {
+				mode = MODE_DPRINTF;
+			} else
+				goto usage;
+			break;
+		case 'o':
+			if (strcmp(optarg, "stdout") == 0) {
+				fdout = fileno(stdout);
+			} else if (strcmp(optarg, "stderr") == 0) {
+				fdout = fileno(stderr);
+			} else {
+				fdout = open(optarg, O_RDWR | O_CREAT | O_TRUNC, 0644);
+				if (fdout < 0) {
+					fprintf(stderr, "Can't open %s: %s\n",
+						optarg, strerror(errno));
+					exit(1);
+				}
+			}
+			break;
+		case 'i':
+			niter = atoi(optarg);
+			break;
+		case 'd':
+			use_decoder = true;
+			break;
+		case 'h':
+		default:
+			goto usage;
+		}
+	}
+
+	switch (mode) {
+	case MODE_BINARY:
+		if (use_decoder)
+			return flog_decode_all(STDIN_FILENO, fdout);
+
+		if (fdout != STDOUT_FILENO && flog_map_buf(fdout))
+			return 1;
+		for (i = 0; i < niter; i++)
+			if (flog_encode(fdout, "Some message %s %s %c %li %d %lu\n",
+				    str1, str2, 'c', (long)-4, (short)2,
+				    (unsigned long)2))
+				return 1;
+		if (flog_close(fdout))
+			return 1;
+	break;
+	case MODE_DPRINTF:
+	{
+		for (i = 0; i < niter; i++) {
+			dprintf(fdout, "Some message %s %s %c %li %d %lu\n",
+				str1, str2, 'c', (long)-4, (short)2,
+				(unsigned long)2);
+		}
+		break;
+	}
+	case MODE_FPRINTF:
+	{
+		FILE *f = fdopen(fdout, "w");
+
+		for (i = 0; i < niter; i++) {
+			fprintf(f, "Some message %s %s %c %li %d %lu\n",
+				str1, str2, 'c', (long)-4, (short)2,
+				(unsigned long)2);
+			fflush(f);
+		}
+		fclose(f);
+		break;
+	}
+	case MODE_SPRINTF:
+	{
+		static char buf[4096];
+
+		for (i = 0; i < niter; i++) {
+			sprintf(buf, "Some message %s %s %c %li %d %lu\n",
+				str1, str2, 'c', (long)-4, (short)2,
+				(unsigned long)2);
+		}
+		break;
+	}
+	default:
+		return 1;
+	}
+
+	return 0;
+usage:
+	fprintf(stderr,
+		"flog [--mode binary|dprintf] [--output stdout|stderr|filename] [--decode] [--iter number]\n"
+		"\n"
+
+		"Examples:\n"
+		"\n"
+
+		" - run 100000 iterations of instant message processing (immediate dprintf calls)\n"
+		"\n"
+		"       flog -m dprintf -i 100000\n"
+		"\n"
+
+		" - run 100000 iterations in binary mode without processing (queue messages only)\n"
+		"\n"
+		"       flog -i 100000\n"
+		"\n"
+
+		" - run 100000 iterations in binary mode with decoding after\n"
+		"\n"
+		"       flog -i 100000 -d\n"
+		"\n"
+
+		" - run 100000 iterations in binary mode with decoding after, writting results into 'out' file\n"
+		"\n"
+		"       flog -i 100000 -d -o out\n"
+		"\n");
+	return 1;
+}
diff --git a/flog/tests/test00 b/flog/tests/test00
new file mode 100755
index 000000000..a7937e4a1
--- /dev/null
+++ b/flog/tests/test00
@@ -0,0 +1,22 @@
+#!/bin/sh
+
+set -e -x
+
+echo Map a log file into memory
+time ./flog run -i 1000000 -o /tmp/flog.raw.map
+echo Write into a log file
+time ./flog run -i 1000000 > /tmp/flog.raw
+echo Use fprintf
+time ./flog run -m fprintf -i 1000000 -o /tmp/flog.fprintf.txt
+echo Use dprintf
+time ./flog run -m dprintf -i 1000000 -o /tmp/flog.dprintf.txt
+echo Use sprintf
+time ./flog run -m sprintf -i 1000000
+
+time ./flog run -d < /tmp/flog.raw > /tmp/flog.raw.txt
+cmp /tmp/flog.raw.txt /tmp/flog.fprintf.txt
+
+time ./flog run -d < /tmp/flog.raw.map > /tmp/flog.raw.map.txt
+cmp /tmp/flog.raw.map.txt /tmp/flog.fprintf.txt
+
+cmp /tmp/flog.dprintf.txt /tmp/flog.fprintf.txt