Introduce tarerofs I/O API

Previously, erofs-utils was integrated into overlaybd by
using the `mkfs.erofs` executable file. It's not optimial
since raw data needs to be dumped first and output data
needs to be write into overlaybd then.

This commit introduces the I/O API in tarerofs, that the data
stream of the:
- output image
- input tar file
can be controlled by the I/O manager.

This also adds block read/write cache support for IFile to
improve the efficiency of making file system images.

Signed-off-by: Hongzhen Luo <hongzhen@linux.alibaba.com>

src/overlaybd/tar/CMakeLists.txt

@@ -8,3 +8,6 @@ target_include_directories(tar_lib PUBLIC
 if(BUILD_TESTING)
   add_subdirectory(test)
 endif()
+
+add_subdirectory(erofs)
+target_link_libraries(tar_lib PRIVATE erofs_lib)

src/overlaybd/tar/erofs/CMakeLists.txt

@@ -0,0 +1,43 @@
+include(FetchContent)
+
+FetchContent_Declare(
+    erofs-utils
+    GIT_REPOSITORY https://gitee.com/anolis/erofs-utils.git
+    GIT_TAG      overlaybd-dev-2
+)
+
+FetchContent_MakeAvailable(erofs-utils)
+
+execute_process(
+    COMMAND ./autogen.sh
+    WORKING_DIRECTORY ${erofs-utils_SOURCE_DIR}
+)
+execute_process(
+    COMMAND ./configure --disable-lz4 --without-liblzma
+    WORKING_DIRECTORY ${erofs-utils_SOURCE_DIR}
+)
+execute_process(
+    COMMAND make
+    WORKING_DIRECTORY ${erofs-utils_SOURCE_DIR}
+)
+
+set(EROFS_LIB_INCLUDE_DIR "${erofs-utils_SOURCE_DIR}/include/" CACHE PATH "erofs-utils include path.")
+set(EROFS_CONFIG_FILE "${erofs-utils_SOURCE_DIR}/config.h" CACHE PATH "erofs-utils config file.")
+set(EROFS_LIB_STATIC "${erofs-utils_SOURCE_DIR}/lib/.libs/liberofs.a" CACHE PATH "erofs-utils static lib.")
+
+file(GLOB EROFS_SOURCE "*.cpp")
+
+add_library(erofs_lib STATIC ${EROFS_SOURCE})
+
+target_include_directories(erofs_lib PRIVATE
+    ${PHOTON_INCLUDE_DIR}
+)
+
+target_include_directories(erofs_lib PRIVATE
+    ${EROFS_LIB_INCLUDE_DIR}
+)
+
+target_link_libraries(erofs_lib PRIVATE uuid)
+
+target_compile_options(erofs_lib PRIVATE "-include${EROFS_CONFIG_FILE}")
+target_link_libraries(erofs_lib PRIVATE ${EROFS_LIB_STATIC})