diff --git a/.gitmodules b/.gitmodules
index 25b3b54..e69de29 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,4 +0,0 @@
-[submodule "chck"]
-   path = lib/chck
-   url = git://github.com/Cloudef/chck.git
-   branch = master
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 0845729..3f75814 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -4,7 +4,6 @@ list(APPEND CMAKE_MODULE_PATH "${PROJECT_SOURCE_DIR}/CMake")
 
 # Subprojects
 include(subproject)
-add_subdirectory(lib)
 
 # CPack
 set(CPACK_SYSTEM_NAME "${CMAKE_SYSTEM_NAME}-${CMAKE_SYSTEM_PROCESSOR}")
@@ -74,7 +73,7 @@ set(CMAKE_C_EXTENSIONS OFF)
 set(CMAKE_POSITION_INDEPENDENT_CODE ON)
 add_definitions(-D_DEFAULT_SOURCE)
 
-include_directories(${CMAKE_CURRENT_SOURCE_DIR}/src ${CHCK_INCLUDE_DIRS})
+include_directories(${CMAKE_CURRENT_SOURCE_DIR}/src)
 add_subdirectory(src)
 
 if (PI9_BUILD_BINARIES)
@@ -82,6 +81,8 @@ if (PI9_BUILD_BINARIES)
 endif ()
 
 file(COPY src/pi9.h src/pi9_string.h DESTINATION include/pi9)
+file(COPY src/chck/buffer/buffer.h src/chck/buffer/endianess.h DESTINATION include/chck/buffer)
+file(COPY src/chck/overflow/overflow.h DESTINATION include/chck/overflow)
 
 if ("${CMAKE_PROJECT_NAME}" STREQUAL "${PROJECT_NAME}")
    feature_summary(WHAT ALL)
diff --git a/lib/CMakeLists.txt b/lib/CMakeLists.txt
deleted file mode 100644
index 9c0b336..0000000
--- a/lib/CMakeLists.txt
+++ /dev/null
@@ -1,3 +0,0 @@
-set(CHCK_BUILD_STATIC ON CACHE STRING "Build chck statically if not found systemwide" FORCE)
-set(CHCK_BUILD_TESTS OFF CACHE STRING "Do not build chck tests" FORCE)
-add_subproject(chck Chck)
diff --git a/lib/chck b/lib/chck
deleted file mode 160000
index 7fd2a73..0000000
--- a/lib/chck
+++ /dev/null
@@ -1 +0,0 @@
-Subproject commit 7fd2a7375492c0704286f7073fa22dbfe2218653
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index ebc3116..27bb0f1 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -1,4 +1,4 @@
-add_library(pi9 pi9.c pi9_string.c)
+add_library(pi9 pi9.c pi9_string.c chck/buffer/buffer.c chck/buffer/buffer.h chck/buffer/endianess.h chck/overflow.h)
 target_link_libraries(pi9 PRIVATE ${CHCK_LIBRARIES})
 
 # Parse soversion version
diff --git a/src/chck/buffer/buffer.c b/src/chck/buffer/buffer.c
new file mode 100644
index 0000000..3e31996
--- /dev/null
+++ b/src/chck/buffer/buffer.c
@@ -0,0 +1,568 @@
+#include "buffer.h"
+#include <chck/overflow/overflow.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdarg.h>
+
+#if HAS_ZLIB
+#  include <zlib.h>
+#elif !defined(HAS_ZLIB)
+#  define HAS_ZLIB 0
+#endif
+
+struct chck_variant {
+   union {
+      uint64_t u64;
+      uint32_t u32;
+      uint16_t u16;
+      uint8_t u8;
+      uint8_t b[sizeof(uint64_t)];
+   };
+   enum chck_bits bits;
+};
+
+static inline bool
+valid_bits(enum chck_bits bits)
+{
+   return (bits == CHCK_BUFFER_B8  ||
+           bits == CHCK_BUFFER_B16 ||
+           bits == CHCK_BUFFER_B32 ||
+           bits == CHCK_BUFFER_B64);
+}
+
+static inline enum chck_bits
+smallest_bits_for_value(uintmax_t v)
+{
+   static const struct {
+      uintmax_t off;
+      enum chck_bits bits;
+   } map[3] = {
+      { ~(uint32_t)0, CHCK_BUFFER_B64 },
+      { ~(uint16_t)0, CHCK_BUFFER_B32 },
+      { ~(uint8_t)0, CHCK_BUFFER_B16 },
+   };
+
+   for (size_t i = 0; i < sizeof(map) / sizeof(map[0]); ++i) {
+      if (v <= map[i].off)
+         continue;
+
+      return map[i].bits;
+   }
+
+   return CHCK_BUFFER_B8;
+}
+
+static inline uintmax_t
+variant_get_value(struct chck_variant v)
+{
+   switch (v.bits) {
+      case CHCK_BUFFER_B8:
+         return v.u8;
+      case CHCK_BUFFER_B16:
+         return v.u16;
+      case CHCK_BUFFER_B32:
+         return v.u32;
+      case CHCK_BUFFER_B64:
+         return v.u64;
+   }
+
+   assert(0 && "should not happen");
+   return 0;
+}
+
+void
+chck_buffer_flush(struct chck_buffer *buf)
+{
+   assert(buf);
+
+   if (buf->copied)
+      free(buf->buffer);
+
+   buf->copied = false;
+   buf->curpos = buf->buffer = NULL;
+}
+
+void
+chck_buffer_release(struct chck_buffer *buf)
+{
+   if (!buf)
+      return;
+
+   chck_buffer_flush(buf);
+   *buf = (struct chck_buffer){0};
+}
+
+bool
+chck_buffer_from_pointer(struct chck_buffer *buf, void *ptr, size_t size, enum chck_endianess endianess)
+{
+   assert(buf);
+   *buf = (struct chck_buffer){ .step = 32 };
+   chck_buffer_set_pointer(buf, ptr, size, endianess);
+   return true;
+}
+
+bool
+chck_buffer(struct chck_buffer *buf, size_t size, enum chck_endianess endianess)
+{
+   assert(buf);
+
+   void *data = NULL;
+   if (size > 0 && !(data = malloc(size)))
+      return false;
+
+   if (unlikely(!chck_buffer_from_pointer(buf, data, size, endianess)))
+      goto fail;
+
+   buf->copied = true;
+   return true;
+
+fail:
+   free(data);
+   return false;
+}
+
+void
+chck_buffer_set_pointer(struct chck_buffer *buf, void *ptr, size_t size, enum chck_endianess endianess)
+{
+   assert(buf);
+
+   if (buf->copied) {
+      free(buf->buffer);
+      buf->buffer = NULL;
+   }
+
+   if (endianess == CHCK_ENDIANESS_NATIVE) {
+      buf->endianess = chck_endianess();
+   } else {
+      buf->endianess = endianess;
+   }
+
+   buf->size = size;
+   buf->buffer = buf->curpos = ptr;
+   buf->copied = false;
+}
+
+bool
+chck_buffer_resize(struct chck_buffer *buf, size_t size)
+{
+   assert(buf);
+
+   if (unlikely(size == buf->size))
+      return true;
+
+   if (unlikely(size == 0)) {
+      chck_buffer_flush(buf);
+      return true;
+   }
+
+   uint8_t *tmp;
+   if (!(tmp = realloc((buf->copied ? buf->buffer : NULL), size)))
+      return false;
+
+   /* set new buffer position */
+   if (buf->curpos - buf->buffer > (ptrdiff_t)size) {
+      buf->curpos = tmp + (buf->size - size);
+   } else {
+      buf->curpos = tmp + (buf->curpos - buf->buffer);
+   }
+
+   buf->size = size;
+   buf->buffer = tmp;
+   buf->copied = true;
+   return true;
+}
+
+ptrdiff_t
+chck_buffer_seek(struct chck_buffer *buf, long offset, int whence)
+{
+   assert(buf);
+   assert(whence == SEEK_SET || whence == SEEK_END || whence == SEEK_CUR);
+
+   switch (whence) {
+      case SEEK_SET:
+         if (buf->buffer + offset > buf->buffer + buf->size) {
+            buf->curpos = buf->buffer + buf->size;
+         } else if (offset >= 0) {
+            buf->curpos = buf->buffer + offset;
+         }
+      break;
+      case SEEK_CUR:
+         if (buf->curpos + offset > buf->buffer + buf->size) {
+            buf->curpos = buf->curpos + buf->size;
+         } else if (buf->curpos + offset < buf->buffer) {
+            buf->curpos = buf->buffer;
+         } else {
+            buf->curpos = buf->curpos + offset;
+         }
+      break;
+      case SEEK_END:
+         buf->curpos = buf->buffer + buf->size;
+      break;
+      default:break;
+   }
+
+   return buf->curpos - buf->buffer;
+}
+
+static bool
+bounds_check(struct chck_buffer *buf, size_t size, size_t memb)
+{
+   size_t nsz;
+   if (unlikely(chck_mul_ofsz(size, memb, &nsz)))
+      return false;
+
+   const size_t sz = buf->size - (buf->curpos - buf->buffer);
+   if (nsz > sz) {
+      /* buf->size + size * memb + buf->step */
+      if (unlikely(chck_add_ofsz(buf->size, nsz, &nsz)) || unlikely(chck_add_ofsz(buf->step, nsz, &nsz)))
+         return false;
+
+      if (!chck_buffer_resize(buf, nsz))
+         return false;
+   }
+
+   return true;
+}
+
+size_t
+chck_buffer_fill(const void *src, size_t size, size_t memb, struct chck_buffer *buf)
+{
+   assert(src && buf);
+
+   if (!bounds_check(buf, size, memb) || !buf->curpos || !src)
+      return 0;
+
+   memcpy(buf->curpos, src, size * memb);
+   return memb;
+}
+
+size_t
+chck_buffer_fill_from_file(FILE *src, size_t size, size_t memb, struct chck_buffer *buf)
+{
+   assert(src && buf);
+
+   if (!bounds_check(buf, size, memb) || !buf->curpos || !src)
+      return 0;
+
+   return fread(buf->curpos, size, memb, src);
+}
+
+size_t
+chck_buffer_fill_from_fd(int fd, size_t size, size_t memb, struct chck_buffer *buf)
+{
+   assert(fd && buf);
+
+   if (!bounds_check(buf, size, memb) || !buf->curpos)
+      return 0;
+
+   const ssize_t ret = read(fd, buf->curpos, size * memb);
+   if (unlikely(ret == -1 || ret == 0))
+      return 0;
+
+   return (size_t)ret / size;
+}
+
+size_t
+chck_buffer_read(void *dst, size_t size, size_t memb, struct chck_buffer *buf)
+{
+   assert(dst && buf);
+
+   size_t nsz;
+   if (unlikely(chck_mul_ofsz(size, memb, &nsz)))
+      return 0;
+
+   if (unlikely(nsz > buf->size - (buf->curpos - buf->buffer))) {
+      assert(size != 0); // should never happen
+      // read as much as we can
+      memb = (buf->size - (buf->curpos - buf->buffer)) / size;
+   }
+
+   memcpy(dst, buf->curpos, size * memb);
+   buf->curpos += size * memb;
+   return memb;
+}
+
+bool
+chck_buffer_read_int(void *i, enum chck_bits bits, struct chck_buffer *buf)
+{
+   assert(i && buf);
+
+   if (!valid_bits(bits))
+      return false;
+
+   if (unlikely(chck_buffer_read(i, bits, 1, buf) != 1))
+      return false;
+
+   if (!chck_buffer_native_endianess(buf))
+      chck_bswap_single(i, bits);
+
+   return true;
+}
+
+bool
+chck_buffer_read_string_of_type(char **str, size_t *out_len, enum chck_bits bits, struct chck_buffer *buf)
+{
+   assert(buf && str);
+   *str = NULL;
+
+   if (out_len)
+      *out_len = 0;
+
+   struct chck_variant v = { .bits = bits };
+   if (unlikely(!chck_buffer_read_int(v.b, bits, buf)))
+      return false;
+
+   const size_t len = variant_get_value(v);
+
+   if (out_len)
+      *out_len = len;
+
+   if (len <= 0)
+      return true;
+
+   if (!(*str = chck_calloc_add_of(len, 1)))
+      return false;
+
+   if (unlikely(chck_buffer_read(*str, 1, len, buf) != len)) {
+      free(*str);
+      return false;
+   }
+
+   return true;
+}
+
+bool
+chck_buffer_read_string(char **str, size_t *len, struct chck_buffer *buf)
+{
+   assert(str && buf);
+   *str = NULL;
+
+   if (len)
+      *len = 0;
+
+   uint8_t bits;
+   if (unlikely(!chck_buffer_read_int(&bits, sizeof(bits), buf)))
+      return false;
+
+   return likely(chck_buffer_read_string_of_type(str, len, bits, buf));
+}
+
+size_t
+chck_buffer_write(const void *src, size_t size, size_t memb, struct chck_buffer *buf)
+{
+   memb = chck_buffer_fill(src, size, memb, buf);
+   buf->curpos += size * memb;
+   return memb;
+}
+
+size_t
+chck_buffer_write_from_file(FILE *src, size_t size, size_t memb, struct chck_buffer *buf)
+{
+   memb = chck_buffer_fill_from_file(src, size, memb, buf);
+   buf->curpos += size * memb;
+   return memb;
+}
+
+size_t
+chck_buffer_write_from_fd(int fd, size_t size, size_t memb, struct chck_buffer *buf)
+{
+   memb = chck_buffer_fill_from_fd(fd, size, memb, buf);
+   buf->curpos += size * memb;
+   return memb;
+}
+
+bool
+chck_buffer_write_int(const void *i, enum chck_bits bits, struct chck_buffer *buf)
+{
+   assert(buf);
+
+   if (!valid_bits(bits))
+      return false;
+
+   bool ret;
+   if (!chck_buffer_native_endianess(buf)) {
+      uint8_t b[sizeof(uint64_t)];
+      memcpy(b, i, bits);
+      chck_bswap_single(b, bits);
+      ret = (chck_buffer_write(b, bits, 1, buf) == 1);
+   } else {
+      ret = (chck_buffer_write(i, bits, 1, buf) == 1);
+   }
+
+   return ret;
+}
+
+bool
+chck_buffer_write_string_of_type(const char *str, size_t len, enum chck_bits bits, struct chck_buffer *buf)
+{
+   assert(buf);
+
+   bool ret = false;
+   switch (bits) {
+      case CHCK_BUFFER_B8:
+         ret = chck_buffer_write_int((uint8_t[]){len}, bits, buf);
+         break;
+      case CHCK_BUFFER_B16:
+         ret = chck_buffer_write_int((uint16_t[]){len}, bits, buf);
+         break;
+      case CHCK_BUFFER_B32:
+         ret = chck_buffer_write_int((uint32_t[]){len}, bits, buf);
+         break;
+      case CHCK_BUFFER_B64:
+         ret = chck_buffer_write_int((uint64_t[]){len}, bits, buf);
+         break;
+   }
+
+   if (unlikely(!ret))
+      return false;
+
+   return likely(chck_buffer_write(str, 1, len, buf) == len);
+}
+
+bool
+chck_buffer_write_string(const char *str, size_t len, struct chck_buffer *buf)
+{
+   assert(buf);
+
+   const uint8_t bits = smallest_bits_for_value(len);
+   if (unlikely(!chck_buffer_write_int(&bits, sizeof(bits), buf)))
+      return false;
+
+   return likely(chck_buffer_write_string_of_type(str, len, bits, buf));
+}
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wformat-nonliteral"
+
+size_t
+chck_buffer_write_format(struct chck_buffer *buf, const char *fmt, ...)
+{
+   va_list argp;
+   va_start(argp, fmt);
+   const size_t wrote = chck_buffer_write_varg(buf, fmt, argp);
+   va_end(argp);
+   return wrote;
+}
+
+size_t
+chck_buffer_write_varg(struct chck_buffer *buf, const char *fmt, va_list args)
+{
+   va_list cpy;
+   va_copy(cpy, args);
+
+   char *str = NULL;
+   const size_t len = vsnprintf(NULL, 0, fmt, args);
+   if (len > 0 && !(str = chck_malloc_add_of(len, 1))) {
+      va_end(cpy);
+      return false;
+   }
+
+   vsnprintf(str, len + 1, fmt, cpy);
+   va_end(cpy);
+
+   const size_t wrote = chck_buffer_write(str, 1, len, buf);
+   free(str);
+   return wrote;
+}
+
+#pragma GCC diagnostic pop
+
+bool
+chck_buffer_has_zlib(void)
+{
+   return HAS_ZLIB;
+}
+
+#pragma GCC diagnostic ignored "-Wsuggest-attribute=const"
+
+bool
+chck_buffer_compress_zlib(struct chck_buffer *buf)
+{
+#if HAS_ZLIB
+   uLongf dsize, bsize;
+   dsize = bsize = compressBound(buf->size);
+
+   void *compressed;
+   if (!(compressed = malloc(dsize)))
+      return false;
+
+   int ret;
+   while ((ret = compress(compressed, &dsize, buf->buffer, buf->size)) == Z_BUF_ERROR) {
+      void *tmp;
+      if (!(tmp = chck_realloc_mul_of(compressed, bsize, 2)))
+         goto fail;
+
+      compressed = tmp;
+      dsize = (bsize *= 2);
+   }
+
+   if (unlikely(ret != Z_OK))
+      goto fail;
+
+   chck_buffer_set_pointer(buf, compressed, bsize, buf->endianess);
+   buf->copied = true;
+
+   if (buf->size > dsize)
+      chck_buffer_resize(buf, dsize);
+
+   return true;
+
+fail:
+   free(compressed);
+   return false;
+#else
+   (void)buf;
+   return false;
+#endif
+}
+
+bool
+chck_buffer_decompress_zlib(struct chck_buffer *buf)
+{
+#if HAS_ZLIB
+   uLongf dsize, bsize;
+
+   {
+      size_t sz;
+      if (unlikely(chck_mul_ofsz(buf->size, 2, &sz)) || (uLongf)sz < sz)
+         return false;
+
+      dsize = bsize = sz;
+   }
+
+   if (!dsize)
+      return false;
+
+   void *decompressed;
+   if (!(decompressed = malloc(dsize)))
+      return false;
+
+   int ret;
+   while ((ret = uncompress(decompressed, &dsize, buf->buffer, buf->size)) == Z_BUF_ERROR) {
+      void *tmp;
+      if (!(tmp = chck_realloc_mul_of(decompressed, bsize, 2)))
+         goto fail;
+
+      decompressed = tmp;
+      dsize = (bsize *= 2);
+   }
+
+   if (unlikely(ret != Z_OK))
+      goto fail;
+
+   chck_buffer_set_pointer(buf, decompressed, bsize, buf->endianess);
+   buf->copied = true;
+
+   if (bsize > dsize)
+      chck_buffer_resize(buf, dsize);
+
+   return true;
+
+fail:
+   free(decompressed);
+   return false;
+#else
+   (void)buf;
+   return false;
+#endif
+}
diff --git a/src/chck/buffer/buffer.h b/src/chck/buffer/buffer.h
new file mode 100644
index 0000000..2494efe
--- /dev/null
+++ b/src/chck/buffer/buffer.h
@@ -0,0 +1,75 @@
+#ifndef __chck_buffer__
+#define __chck_buffer__
+
+#include <stddef.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdarg.h>
+
+#include "endianess.h"
+
+enum chck_bits {
+   CHCK_BUFFER_B8 = sizeof(int8_t),
+   CHCK_BUFFER_B16 = sizeof(int16_t),
+   CHCK_BUFFER_B32 = sizeof(int32_t),
+   CHCK_BUFFER_B64 = sizeof(int64_t),
+};
+
+struct chck_buffer {
+   // pointer to current buffer and the current position
+   uint8_t *buffer, *curpos;
+
+   // size of the buffer
+   size_t size;
+
+   // growth step for the buffer incase writing to full buffer
+   size_t step;
+
+   // endianess true == big, false == little
+   bool endianess;
+
+   // copied == true, means that buffer is owned by this struct and will be freed on chck_buffer_release
+   bool copied;
+};
+
+static inline bool
+chck_buffer_native_endianess(const struct chck_buffer *buf)
+{
+   return (chck_endianess() == buf->endianess);
+}
+
+void chck_buffer_release(struct chck_buffer *buf);
+void chck_buffer_flush(struct chck_buffer *buf);
+bool chck_buffer_from_pointer(struct chck_buffer *buf, void *ptr, size_t size, enum chck_endianess endianess);
+bool chck_buffer(struct chck_buffer *buf, size_t size, enum chck_endianess endianess);
+void chck_buffer_set_pointer(struct chck_buffer *buf, void *ptr, size_t size, enum chck_endianess endianess);
+
+size_t chck_buffer_fill(const void *src, size_t size, size_t memb, struct chck_buffer *buf);
+size_t chck_buffer_fill_from_file(FILE *src, size_t size, size_t memb, struct chck_buffer *buf);
+size_t chck_buffer_fill_from_fd(int fd, size_t size, size_t memb, struct chck_buffer *buf);
+
+size_t chck_buffer_write(const void *src, size_t size, size_t nmemb, struct chck_buffer *buf);
+size_t chck_buffer_write_from_file(FILE *src, size_t size, size_t nmemb, struct chck_buffer *buf);
+size_t chck_buffer_write_from_fd(int fd, size_t size, size_t nmemb, struct chck_buffer *buf);
+
+size_t chck_buffer_read(void *dst, size_t size, size_t memb, struct chck_buffer *buf);
+bool chck_buffer_read_int(void *i, enum chck_bits bits, struct chck_buffer *buf);
+bool chck_buffer_read_string(char **str, size_t *len, struct chck_buffer *buf);
+bool chck_buffer_read_string_of_type(char **str, size_t *len, enum chck_bits bits, struct chck_buffer *buf);
+
+bool chck_buffer_write_int(const void *i, enum chck_bits bits, struct chck_buffer *buf);
+bool chck_buffer_write_string(const char *str, size_t len, struct chck_buffer *buf);
+bool chck_buffer_write_string_of_type(const char *str, size_t len, enum chck_bits bits, struct chck_buffer *buf);
+
+CHCK_FORMAT(printf, 2, 3) size_t chck_buffer_write_format(struct chck_buffer *buf, const char *fmt, ...);
+size_t chck_buffer_write_varg(struct chck_buffer *buf, const char *fmt, va_list args);
+
+ptrdiff_t chck_buffer_seek(struct chck_buffer *buf, long offset, int whence);
+bool chck_buffer_resize(struct chck_buffer *buf, size_t size);
+
+/* -DHAS_ZLIB=1 -lz */
+bool chck_buffer_has_zlib(void);
+bool chck_buffer_compress_zlib(struct chck_buffer *buf);
+bool chck_buffer_decompress_zlib(struct chck_buffer *buf);
+
+#endif /* __chck_buffer__ */
diff --git a/src/chck/buffer/endianess.h b/src/chck/buffer/endianess.h
new file mode 100644
index 0000000..54109e7
--- /dev/null
+++ b/src/chck/buffer/endianess.h
@@ -0,0 +1,133 @@
+#ifndef __chck_endianess__
+#define __chck_endianess__
+
+#include <chck/macros.h>
+#include <stdint.h>
+#include <assert.h>
+#include <string.h>
+
+enum chck_endianess {
+   CHCK_ENDIANESS_LITTLE = 0,
+   CHCK_ENDIANESS_BIG    = 1,
+   CHCK_ENDIANESS_NATIVE = 2,
+};
+
+#if defined(__clang__) || (__GNUC__ >= 4 && __GNUC_MINOR__ >= 3 && !defined(__MINGW32__) && !defined(__MINGW64__))
+#  define bswap16 __builtin_bswap16
+#  define bswap32 __builtin_bswap32
+#  define bswap64 __builtin_bswap64
+#  define HAS_BYTESWAP 1
+#elif defined(__GLIBC__)
+#  include <byteswap.h>
+#  define bswap16 __bswap_16
+#  define bswap32 __bswap_32
+#  define bswap64 __bswap_64
+#  define HAS_BYTESWAP 1
+#elif defined(__NetBSD__)
+#  include <sys/types.h>
+#  include <machine/bswap.h> /* already named bswap16/32/64 */
+#  define HAS_BYTESWAP 1
+#elif defined(_MSC_VER)
+#  define bswap16 _byteswap_ushort
+#  define bswap32 _byteswap_ulong
+#  define bswap64 _byteswap_uint64
+#  define HAS_BYTESWAP 1
+#else
+#  define HAS_BYTESWAP 0
+#endif
+
+#if (defined(__BYTE_ORDER__) && __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__) || \
+    (defined(__BYTE_ORDER) && __BYTE_ORDER == __BIG_ENDIAN) || \
+    defined(__BIG_ENDIAN__) || \
+    defined(__ARMEB__) || \
+    defined(__THUMBEB__) || \
+    defined(__AARCH64EB__) || \
+    defined(_MIBSEB) || defined(__MIBSEB) || defined(__MIBSEB__)
+// compiletime big endian
+#  define chck_endianess() CHCK_ENDIANESS_BIG
+#elif (defined(__BYTE_ORDER__) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__) || \
+    (defined(__BYTE_ORDER) && __BYTE_ORDER == __LITTLE_ENDIAN) || \
+    defined(__LITTLE_ENDIAN__) || \
+    defined(__ARMEL__) || \
+    defined(__THUMBEL__) || \
+    defined(__AARCH64EL__) || \
+    defined(_MIPSEL) || defined(__MIPSEL) || defined(__MIPSEL__)
+// compiletime little endian
+#  define chck_endianess() CHCK_ENDIANESS_LITTLE
+#else
+// runtime endianess check
+static inline enum
+chck_endianess chck_endianess(void)
+{
+   union {
+      uint32_t i;
+      char c[4];
+   } bint = { 0x01020304 };
+   return (bint.c[0] == 1 ? CHCK_ENDIANESS_BIG : CHCK_ENDIANESS_LITTLE);
+};
+#endif
+
+static inline void
+chck_bswap_generic(void *p, size_t size)
+{
+   if (size <= sizeof(uint8_t))
+      return;
+
+   assert(size <= sizeof(intmax_t));
+   uint8_t b[sizeof(intmax_t)];
+   memcpy(b, p, size);
+
+   for (size_t s = 0; s < size; ++s)
+      memset((uint8_t*)p + s, b[size - s - 1], 1);
+}
+
+static inline void
+chck_bswap_single(void *p, size_t size)
+{
+#if HAS_BYTESWAP
+   assert(p);
+   switch (size) {
+      case sizeof(uint32_t):
+         *((uint32_t*)p) = bswap32(*((uint32_t*)p));
+         break;
+      case sizeof(uint16_t):
+         *((uint16_t*)p) = bswap16(*((uint16_t*)p));
+         break;
+      case sizeof(uint64_t):
+         *((uint64_t*)p) = bswap64(*((uint64_t*)p));
+         break;
+      default:
+         chck_bswap_generic(p, size);
+         break;
+   }
+#else
+   chck_bswap_generic(p, size);
+#endif
+}
+
+static inline void
+chck_bswap(void *v, size_t size, size_t memb)
+{
+   assert(v);
+
+   for (uint8_t *p = v; size > sizeof(uint8_t) && p < (uint8_t*)v + (memb * size); p += size)
+      chck_bswap_single(p, size);
+}
+
+/** define chck_bswap{16,32,64} for use **/
+
+#if HAS_BYTESWAP
+#  define generic_swap(T, n) \
+   static inline T chck_bswap##n(T v) { return bswap##n(v); }
+#else
+#  define generic_swap(T, n) \
+   static inline T chck_bswap##n(T v) { chck_bswap_generic(&v, sizeof(v)); return v; }
+#endif
+
+generic_swap(uint16_t, 16)
+generic_swap(uint32_t, 32)
+generic_swap(uint64_t, 64)
+
+#undef generic_swap
+
+#endif /* __chck_endianess__ */
diff --git a/src/chck/overflow/overflow.h b/src/chck/overflow/overflow.h
new file mode 100644
index 0000000..ffa489e
--- /dev/null
+++ b/src/chck/overflow/overflow.h
@@ -0,0 +1,159 @@
+#ifndef __chck_overflow_h__
+#define __chck_overflow_h__
+
+#include <chck/macros.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <assert.h>
+
+/** clang feature detection. */
+#ifndef __has_builtin
+#  define __has_builtin(x) 0
+#endif
+
+#if __GNUC__ >= 5 || __has_builtin(__builtin_add_overflow)
+/** assume clang and gcc (>=5) to only have builtins for now. */
+#  define add_of(a, b, r) __builtin_add_overflow(a, b, r)
+#  define sub_of(a, b, r) __builtin_sub_overflow(a, b, r)
+#  define mul_of(a, b, r) __builtin_mul_overflow(a, b, r)
+#  define of_attr
+#else
+/** else use these generics, note behaviour of these is not strictly defined. */
+#  define add_of(a, b, r) ((*(r) = ((a) + (b))) < (a))
+#  define sub_of(a, b, r) ((*(r) = ((a) - (b))) > (a))
+#  define mul_of(a, b, r) (((*(r) = ((a) * (b))) || *(r) == 0) && ((a) != 0 && (b) > *(r) / (a)))
+#  if __clang__
+#     define of_attr __attribute__((optnone)) // Do not optimize above checks, in most systems this will work, but not defined.
+#     warning "Using non compiler builtins for overflow checks, this will be undefined for signed integers"
+#  elif __GNUC__
+#     define of_attr __attribute__((optimize("wrapv"))) // in older GCC we can make this behavior defined
+#  else
+#     warning "Using non compiler builtins for overflow checks, this will be undefined for signed integers"
+#  endif
+#endif
+
+/** declare overflow functions */
+
+// T = type name, n = function suffix, s = is type signed?
+#define decl_generics_for_type(T, n, s) \
+   of_attr static inline bool chck_add_of##n(T a, T b, T *r) { assert((!s || b >= 0) && r); return add_of(a, b, r); } \
+   of_attr static inline bool chck_sub_of##n(T a, T b, T *r) { assert((!s || b >= 0) && r); return sub_of(a, b, r); } \
+   of_attr static inline bool chck_mul_of##n(T a, T b, T *r) { assert(r); return mul_of(a, b, r); }
+
+// UT = unsigned type, un = unsigned function suffix
+// T = signed type, n = signed function suffix
+#define decl_generics(UT, un, T, n) \
+   decl_generics_for_type(UT, un, false) \
+   decl_generics_for_type(T, n, true)
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wtype-limits"
+
+decl_generics_for_type(size_t, sz, false)
+decl_generics(uint64_t, u64, int64_t, 64)
+decl_generics(uint32_t, u32, int32_t, 32)
+decl_generics(uint16_t, u16, int16_t, 16)
+decl_generics(uint8_t, u8, int8_t, 8)
+
+#pragma GCC diagnostic pop
+
+#undef decl_generics
+#undef decl_generics_for_type
+#undef add_of
+#undef sub_of
+#undef mul_of
+#undef of_attr
+
+CHCK_MALLOC static inline void*
+chck_malloc_add_of(size_t size, size_t add)
+{
+   size_t r;
+   if (unlikely(chck_add_ofsz(size, add, &r)) || !r)
+      return NULL;
+
+   return malloc(r);
+}
+
+CHCK_MALLOC static inline void*
+chck_malloc_sub_of(size_t size, size_t sub)
+{
+   size_t r;
+   if (unlikely(chck_sub_ofsz(size, sub, &r)) || !r)
+      return NULL;
+
+   return malloc(r);
+}
+
+CHCK_MALLOC static inline void*
+chck_malloc_mul_of(size_t size, size_t mul)
+{
+   size_t r;
+   if (unlikely(chck_mul_ofsz(size, mul, &r)) || !r)
+      return NULL;
+
+   return malloc(r);
+}
+
+CHCK_MALLOC static inline void*
+chck_calloc_of(size_t nmemb, size_t size)
+{
+   size_t r;
+   if (unlikely(chck_mul_ofsz(nmemb, size, &r)) || !r)
+      return NULL;
+
+   return calloc(nmemb, size);
+}
+
+CHCK_MALLOC static inline void*
+chck_calloc_add_of(size_t size, size_t add)
+{
+   size_t r;
+   if (unlikely(chck_add_ofsz(size, add, &r)) || !r)
+      return NULL;
+
+   return calloc(1, r);
+}
+
+CHCK_MALLOC static inline void*
+chck_calloc_sub_of(size_t size, size_t sub)
+{
+   size_t r;
+   if (unlikely(chck_sub_ofsz(size, sub, &r)) || !r)
+      return NULL;
+
+   return calloc(1, r);
+}
+
+static inline void*
+chck_realloc_add_of(void *ptr, size_t size, size_t add)
+{
+   size_t r;
+   if (unlikely(chck_add_ofsz(size, add, &r)) || !r)
+      return NULL;
+
+   return realloc(ptr, r);
+}
+
+static inline void*
+chck_realloc_sub_of(void *ptr, size_t size, size_t sub)
+{
+   size_t r;
+   if (unlikely(chck_sub_ofsz(size, sub, &r)) || !r)
+      return NULL;
+
+   return realloc(ptr, r);
+}
+
+static inline void*
+chck_realloc_mul_of(void *ptr, size_t size, size_t mul)
+{
+   size_t r;
+   if (unlikely(chck_mul_ofsz(size, mul, &r)) || !r)
+      return NULL;
+
+   return realloc(ptr, r);
+}
+
+#endif /* __chck_overflow_h__ */
diff --git a/src/pi9.pc.in b/src/pi9.pc.in
index 9928702..3bb6292 100644
--- a/src/pi9.pc.in
+++ b/src/pi9.pc.in
@@ -6,6 +6,5 @@ includedir=${prefix}/@CMAKE_INSTALL_INCLUDEDIR@
 Name: @PROJECT_NAME@
 Description: 9p server abstraction library
 Version: @PROJECT_VERSION@
-Requires.private: chck
 Libs: -L${libdir} -lpi9
 Cflags: -I${includedir}