1 files changed, 37 insertions, 0 deletions
diff --git a/user/lib/fopen.c b/user/lib/fopen.c
new file mode 100644
index 0000000..cb2529f
--- /dev/null
+++ b/user/lib/fopen.c
@@ -0,0 +1,37 @@
+#include <stdio.h>
+#include <unistd.h>
+
+FILE *fopen(const char *restrict filename, const char *restrict modes)
+{
+	int flags = 0;
+	int fd;
+
+	char c;
+	while (c = *modes, c) {
+		switch (c) {
+		case 'r':
+			flags |= O_RDONLY;
+			break;
+		case 'w':
+			flags |= O_CREATE | O_WRONLY;
+			break;
+		case 'a':
+			flags |= O_APPEND;
+			break;
+		case '+':
+			flags |= O_RDWR;
+			break;
+		default:
+			return NULL;
+		}
+	}
+
+	if (flags == 0)
+		return NULL;
+
+	fd = open(filename, flags);
+	if (fd < 0)
+		return NULL;
+
+	return (FILE *)(uintptr_t)fd;
+}