From fc00c656c96528112d05cf0edf8631bd5eaea446 Mon Sep 17 00:00:00 2001
From: Kacper <kacper@mail.openlinux.dev>
Date: Sun, 7 Dec 2025 20:10:31 +0100
Subject: Add build system scaffolding and libc headers

---
 lib/libc/stdio/fopen.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)
 create mode 100644 lib/libc/stdio/fopen.c

(limited to 'lib/libc/stdio/fopen.c')

diff --git a/lib/libc/stdio/fopen.c b/lib/libc/stdio/fopen.c
new file mode 100644
index 00000000..7d01fd38
--- /dev/null
+++ b/lib/libc/stdio/fopen.c
@@ -0,0 +1,56 @@
+#include <io.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <libc.h>
+
+weak void __stdio_cleanup(void)
+{
+}
+
+FILE *fopen(const char *restrict pathname, const char *restrict mode)
+{
+	int fd, flags, _mode;
+	FILE *fp;
+
+	_mode = 0;
+	if (mode[0] == 'r') {
+		flags = O_RDONLY;
+	} else if (mode[0] == 'w') {
+		flags = O_WRONLY | O_CREAT | O_TRUNC;
+	} else if (mode[0] == 'a') {
+		flags = O_WRONLY | O_CREAT | O_APPEND;
+		_mode = 0666;
+	} else {
+		errno = EINVAL;
+		return NULL;
+	}
+
+	if (strchr(mode, '+')) {
+		flags = (flags & ~(O_RDONLY | O_WRONLY)) | O_RDWR;
+	}
+
+	if ((fd = open(pathname, flags, _mode)) < 0)
+		return NULL;
+
+	if ((fp = calloc(1, sizeof(FILE))) == NULL)
+		return NULL;
+
+	fp->fd = fd;
+	fp->buf_size = BUFSIZ;
+	fp->flags = flags;
+	fp->type = _IOLBF;
+	atomic_flag_clear(&fp->lock);
+	if ((fp->buf = malloc(BUFSIZ)) == NULL) {
+		close(fd);
+		free(fp);
+		return NULL;
+	}
+
+	__libc_fadd(fp);
+
+	return fp;
+}
-- 
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