Define basic IO abstractions, implement for FD

CMakeLists.txt

@@ -1,7 +1,10 @@
 cmake_minimum_required(VERSION 3.13)
 project(gemhadar LANGUAGES C)
 
+add_subdirectory(lib)
+
 add_executable(gemhadar
     "main.c"
 )
 set_property(TARGET gemhadar PROPERTY C_STANDARD 11)
+target_link_libraries(gemhadar gemhadar_lib)

lib/CMakeLists.txt

@@ -0,0 +1,5 @@
+add_library(gemhadar_lib
+    "fd_io.c"
+)
+target_include_directories(gemhadar_lib PUBLIC "include")
+set_property(TARGET gemhadar_lib PROPERTY C_STANDARD 11)

lib/fd_io.c

@@ -0,0 +1,25 @@
+#include "io_abs.h"
+
+#include <unistd.h>
+
+static ssize_t fd_reader_read(void *ctx, uint8_t *buf, size_t len)
+{
+    return read((intptr_t)ctx, buf, len);
+}
+
+void fd_reader(int fd, struct io_reader *reader_out)
+{
+    reader_out->ctx = (void *)(intptr_t)fd;
+    reader_out->read = fd_reader_read;
+}
+
+static ssize_t fd_writer_write(void *ctx, const uint8_t *buf, size_t len)
+{
+    return write((intptr_t)ctx, buf, len);
+}
+
+void fd_writer(int fd, struct io_writer *writer_out)
+{
+    writer_out->ctx = (void *)(intptr_t)fd;
+    writer_out->write = fd_writer_write;
+}

lib/include/fd_io.h

@@ -0,0 +1,9 @@
+#ifndef FD_IO_H
+#define FD_IO_H
+
+#include "io_abs.h"
+
+void fd_reader(int fd, struct io_reader *reader_out);
+void fd_writer(int fd, struct io_writer *writer_out);
+
+#endif

lib/include/io_abs.h

@@ -0,0 +1,17 @@
+#ifndef IO_ABS_H
+#define IO_ABS_H
+
+#include <stdlib.h>
+#include <stdint.h>
+
+struct io_reader {
+    void *ctx;
+    ssize_t (*read)(void *ctx, uint8_t *buf, size_t len);
+};
+
+struct io_writer {
+    void *ctx;
+    ssize_t (*write)(void *ctx, const uint8_t *buf, size_t len);
+};
+
+#endif