/* SPDX-License-Identifier: LGPL-3.0-or-later */
/*
 * io_stdin.c
 *
 * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
 */
#define SQFS_BUILDING_DLL
#include "config.h"

#include "sqfs/io.h"
#include "sqfs/error.h"

#include <stdlib.h>
#include <unistd.h>
#include <errno.h>


typedef struct {
	sqfs_file_t base;

	uint64_t offset;
	uint64_t size;
} sqfs_file_stdin_t;


static void stdin_destroy(sqfs_file_t *base)
{
	free(base);
}

static int stdin_read_at(sqfs_file_t *base, uint64_t offset,
			 void *buffer, size_t size)
{
	sqfs_file_stdin_t *file = (sqfs_file_stdin_t *)base;
	size_t temp_size = 0;
	uint8_t *temp = NULL;
	uint64_t diff;
	ssize_t ret;

	if (offset < file->offset)
		return SQFS_ERROR_IO;

	if (offset > file->offset) {
		temp_size = 1024;
		temp = alloca(temp_size);
	}

	if (offset >= file->size || (offset + size) > file->size)
		return SQFS_ERROR_OUT_OF_BOUNDS;

	while (size > 0) {
		if (offset > file->offset) {
			diff = file->offset - offset;
			diff = diff > (uint64_t)temp_size ? temp_size : diff;

			ret = read(STDIN_FILENO, temp, diff);
		} else {
			ret = read(STDIN_FILENO, buffer, size);
		}

		if (ret < 0) {
			if (errno == EINTR)
				continue;
			return SQFS_ERROR_IO;
		}

		if (ret == 0)
			return SQFS_ERROR_OUT_OF_BOUNDS;

		if (offset <= file->offset) {
			buffer = (char *)buffer + ret;
			size -= ret;
			offset += ret;
		}

		file->offset += ret;
	}

	return 0;
}

static int stdin_write_at(sqfs_file_t *base, uint64_t offset,
			  const void *buffer, size_t size)
{
	(void)base; (void)offset; (void)buffer; (void)size;
	return SQFS_ERROR_IO;
}

static uint64_t stdin_get_size(const sqfs_file_t *base)
{
	return ((const sqfs_file_stdin_t *)base)->size;
}

static int stdin_truncate(sqfs_file_t *base, uint64_t size)
{
	(void)base; (void)size;
	return SQFS_ERROR_IO;
}

sqfs_file_t *sqfs_get_stdin_file(uint64_t size)
{
	sqfs_file_stdin_t *file = calloc(1, sizeof(*file));
	sqfs_file_t *base = (sqfs_file_t *)file;

	if (file == NULL)
		return NULL;

	file->size = size;
	base->destroy = stdin_destroy;
	base->read_at = stdin_read_at;
	base->write_at = stdin_write_at;
	base->get_size = stdin_get_size;
	base->truncate = stdin_truncate;
	return base;
}