/* Copyright 2022 The ChromiumOS Authors
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

/**
 *@brief Provides implementations of syscalls needed by libc. The newlib
 * documentation provides a list of the required syscalls:
 * https://sourceware.org/newlib/libc.html#Syscalls and minimal implementations
 * can be found in newlib's "nosys" library:
 * https://sourceware.org/git/?p=newlib-cygwin.git;a=tree;f=libgloss/libnosys.
 */

#include "gettimeofday.h"
#include "link_defs.h"
#include "panic.h"
#include "shared_mem.h"
#include "software_panic.h"
#include "system.h"
#include "task.h"
#include "uart.h"

#include <errno.h>

#include <sys/stat.h>

/**
 * Reboot the system.
 *
 * This function is called from libc functions such as abort() or exit().
 *
 * @param rc exit code
 */
void _exit(int rc)
{
	panic_printf("%s called with rc: %d\n", __func__, rc);
	software_panic(PANIC_SW_EXIT, task_get_current());
}

/**
 * Write to the UART.
 *
 * This function is called from libc functions such as printf().
 *
 * @param fd  ignored
 * @param buf buffer to write
 * @param len number of bytes in @buf to write
 * @return number of bytes successfully written
 */
int _write(int fd, char *buf, int len)
{
	return uart_put(buf, len);
}

/**
 * Create a directory.
 *
 * @warning Not implemented.
 *
 * @note Unlike the other functions in this file, this is not overriding a
 * stub version in libnosys. There's no "_mkdir" stub in libnosys, so this
 * provides the actual "mkdir" function.
 *
 * @param pathname directory to create
 * @param mode mode for the new directory
 * @return -1 (error) always
 */
int mkdir(const char *pathname, mode_t mode)
{
	errno = ENOSYS;
	return -1;
}

/**
 * Get the time.
 *
 * This function is called from the libc gettimeofday() function.
 *
 * @warning This does not match gettimeofday() exactly; it does not return the
 * time since the Unix Epoch.
 *
 * @param[out] tv time
 * @param[in] tz ignored
 * @return 0 on success
 * @return -1 on error (errno is set to indicate error)
 */
int _gettimeofday(struct timeval *restrict tv, void *restrict tz)
{
	enum ec_error_list ret = ec_gettimeofday(tv, tz);

	if (ret == EC_ERROR_INVAL) {
		errno = EFAULT;
		return -1;
	}

	return 0;
}

/**
 * Change program's data space by increment bytes.
 *
 * This function is called from the libc sbrk() function (which is in turn
 * called from malloc() when memory needs to be allocated or released).
 *
 * @param incr[in] amount to increment or decrement. 0 means return current
 * program break.
 * @return the previous program break (address) on success
 * @return (void*)-1 on error and errno is set to ENOMEM.
 */
void *_sbrk(intptr_t incr)
{
	static char *heap_end = __shared_mem_buf;
	char *prev_heap_end;

	if ((heap_end + incr < __shared_mem_buf) ||
	    (heap_end + incr > (__shared_mem_buf + shared_mem_size()))) {
		errno = ENOMEM;
		return (void *)-1;
	}

	prev_heap_end = heap_end;
	heap_end += incr;

	return (void *)prev_heap_end;
}