GMS Linux: start?

userprog/cp/Makefile

@@ -0,0 +1,15 @@
+TARGET = cp
+SRCS = cp.c
+CC = gcc
+CFLAGS = -static -Wall
+
+OUT_BIN ?= $(TARGET)
+
+all: $(OUT_BIN)
+
+$(OUT_BIN): $(SRCS)
+	@echo "   [CC] Compiling to $(OUT_BIN)..."
+	$(CC) $(CFLAGS) -o $@ $^
+
+clean:
+	rm -f $(TARGET)

userprog/cp/cp.c

@@ -0,0 +1,42 @@
+#include <stdio.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+
+#define BUF_SIZE 4096
+
+int main(int argc, char *argv[]) {
+    if (argc != 3) {
+        printf("Usage: cp <source> <dest>\n");
+        return 1;
+    }
+
+    int src_fd = open(argv[1], O_RDONLY);
+    if (src_fd < 0) {
+        perror("cp: source open error");
+        return 1;
+    }
+
+    // dest 파일 생성 (이미 있으면 덮어쓰기)
+    int dest_fd = open(argv[2], O_CREAT | O_TRUNC | O_WRONLY, 0644);
+    if (dest_fd < 0) {
+        perror("cp: dest open error");
+        close(src_fd);
+        return 1;
+    }
+
+    char buf[BUF_SIZE];
+    int n;
+
+    // EOF(0)가 될 때까지 읽어서 씀
+    while ((n = read(src_fd, buf, BUF_SIZE)) > 0) {
+        if (write(dest_fd, buf, n) != n) {
+            perror("cp: write error");
+            break;
+        }
+    }
+
+    close(src_fd);
+    close(dest_fd);
+    return 0;
+}