lib: c: io: implement standard FILE and DIR interfaces

lib/libc/io/stdio/dir.c

@@ -0,0 +1,81 @@
+#include "dir.h"
+
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#define DEFAULT_BUFFER_SIZE 4096
+
+static void dirent_convert(const struct dentry *in, struct dirent *out)
+{
+	out->d_ino = in->d_ino;
+	out->d_type = in->d_type;
+	out->d_reclen = in->d_reclen;
+	strncpy(out->d_name, in->d_name, sizeof out->d_name - 1);
+	out->d_name[sizeof out->d_name - 1] = 0;
+}
+
+int __libc_dir_refill(struct __opaque_dir *d)
+{
+	if (d->d_fd < 0) {
+		return EBADF;
+	}
+
+	if (d->d_flags & DIR_ERR) {
+		return EIO;
+	}
+
+	if (d->d_flags & DIR_EOF) {
+		return SUCCESS;
+	}
+
+	if (!d->d_buf) {
+		d->d_buf_max = DEFAULT_BUFFER_SIZE;
+		d->d_buf = malloc(d->d_buf_max);
+		if (!d->d_buf) {
+			d->d_buf_max = 0;
+			return ENOMEM;
+		}
+	}
+
+	long r = getdents(d->d_fd, (struct dentry *)d->d_buf, d->d_buf_max);
+	if (r < 0) {
+		return -r;
+	}
+
+	d->d_buf_datalen = r;
+
+	if (r > 0) {
+		struct dentry *dent
+			= (struct dentry *)(d->d_buf + d->d_buf_readptr);
+		dirent_convert(dent, &d->d_current);
+	}
+
+	return SUCCESS;
+}
+
+int __libc_dir_move_next(struct __opaque_dir *d)
+{
+	if (d->d_fd < 0) {
+		return -EBADF;
+	}
+
+	if (d->d_flags & DIR_ERR) {
+		return -EIO;
+	}
+
+	if (d->d_flags & DIR_EOF) {
+		return -SUCCESS;
+	}
+
+	d->d_buf_readptr += d->d_current.d_reclen;
+	if (d->d_buf_readptr >= d->d_buf_datalen) {
+		return 0;
+	}
+
+	struct dentry *dent = (struct dentry *)(d->d_buf + d->d_buf_readptr);
+	dirent_convert(dent, &d->d_current);
+
+	return 1;
+}