Userspace: add basic 'touch' command

userspace/CMakeLists.txt

@@ -11,6 +11,7 @@ set(USERSPACE_PROJECTS
 	Shell
 	tee
 	test
+	touch
 	u8sum
 	yes
 )

userspace/touch/CMakeLists.txt

@@ -0,0 +1,16 @@
+cmake_minimum_required(VERSION 3.26)
+
+project(touch CXX)
+
+set(SOURCES
+	main.cpp
+)
+
+add_executable(touch ${SOURCES})
+target_compile_options(touch PUBLIC -O2 -g)
+target_link_libraries(touch PUBLIC libc)
+
+add_custom_target(touch-install
+	COMMAND cp ${CMAKE_CURRENT_BINARY_DIR}/touch ${BANAN_BIN}/
+	DEPENDS touch
+)

userspace/touch/main.cpp

@@ -0,0 +1,21 @@
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+
+int main(int argc, char** argv)
+{
+	for (int i = 1; i < argc; i++)
+	{
+		int fd = open(argv[i], O_WRONLY | O_CREAT, 0644);
+		if (fd == -1)
+		{
+			if (errno != EEXISTS)
+				perror(argv[i]);
+		}
+		else
+		{
+			close(fd);
+		}
+	}
+	return 0;
+}