/*
 * Copyright (C) 2019 Gunar Schorcht
 *
 * This file is subject to the terms and conditions of the GNU Lesser
 * General Public License v2.1. See the file LICENSE in the top level
 * directory for more details.
 */

/**
 * @ingroup     cpu_esp_common
 * @{
 *
 * @file
 * @brief       Implementation of required system calls
 *
 * @author      Gunar Schorcht <gunar@schorcht.net>
 *
 * @}
 */

#include <assert.h>
#include <string.h>
#include <stdio_ext.h>
#include <sys/unistd.h>
#include <sys/reent.h>

#include "irq_arch.h"
#include "mutex.h"
#include "rmutex.h"
#include "timex.h"

#include "esp_attr.h"
#include "syscalls.h"

#ifdef MODULE_ESP_IDF_HEAP
#include "esp_heap_caps.h"
#else
#include "malloc.h"
#endif

#define ENABLE_DEBUG 0
#include "debug.h"

#ifndef MODULE_PTHREAD

#define PTHREAD_CANCEL_DISABLE 1
/*
 * This is a dummy function to avoid undefined references when linking
 * against newlib and module pthread is not used.
 */
int pthread_setcancelstate(int state, int *oldstate)
{
    (void)state;
    if (oldstate) {
        *oldstate = PTHREAD_CANCEL_DISABLE;
    }
    return 0;
}
#endif /*  MODULE_PTHREAD */

/**
 * @name Locking functions
 *
 * Following functions implement the locking mechanism for newlib.
 */

#ifdef CPU_ESP8266
/**
 * _malloc_rmtx is defined as static variable to avoid recursive calls of
 * malloc when _malloc_r tries to lock __malloc_lock_object the first
 * time. All other mutexes that are used for the lock mechanism are allocated
 * dynamically.
 */
static rmutex_t _malloc_rmtx = RMUTEX_INIT;

/**
 * To properly handle the static rmutex _malloc_rmtx, we have to know
 * the address of newlib's static variable __malloc_lock_object.
 */
static _lock_t *__malloc_static_object = NULL;

#define _lock_critical_enter()
#define _lock_critical_exit()

#else

/* Operations with recursive locking variable operations have to be guarded
 * for the ESP32x SoCs by disabling interrupts to prevent unwanted context
 * switches. */
#define _lock_critical_enter()  uint32_t __lock_state = irq_disable();
#define _lock_critical_exit()   irq_restore(__lock_state);

#endif

void IRAM_ATTR _lock_init(_lock_t *lock)
{
    assert(lock != NULL);   /* lock must not be NULL */

    /* prevent a context switch between the allocation and the initialization */
    uint32_t state = irq_disable();

    mutex_t* mtx = malloc(sizeof(mutex_t));
    if (mtx) {
        memset(mtx, 0, sizeof(mutex_t));
        *lock = (_lock_t)mtx;
    }
    /* cppcheck-suppress memleak; mtx is stored in lock */

    irq_restore(state);
}

void IRAM_ATTR _lock_init_recursive(_lock_t *lock)
{
    assert(lock != NULL);   /* lock must not be NULL */

#ifdef CPU_ESP8266
    /* _malloc_rmtx is static and has not to be allocated */
    if (lock == __malloc_static_object) {
        return;
    }
#endif

    /* prevent a context switch between the allocation and the initialization */
    uint32_t state = irq_disable();

    rmutex_t* rmtx = malloc(sizeof(rmutex_t));
    if (rmtx) {
        memset(rmtx, 0, sizeof(rmutex_t));
        *lock = (_lock_t)rmtx;
    }
    /* cppcheck-suppress memleak; rmtx is stored in lock */

    irq_restore(state);
}

void IRAM_ATTR _lock_close(_lock_t *lock)
{
    /* locking variable has to be valid and initialized */
    assert(lock != NULL && *lock != 0);
#ifdef CPU_ESP8266
    assert(lock != __malloc_static_object);
#endif

    /* prevent a context switch between freeing and resetting */
    uint32_t state = irq_disable();

    free((void*)*lock);
    *lock = 0;

    irq_restore(state);
}

void IRAM_ATTR _lock_close_recursive(_lock_t *lock)
{
    /* locking variable has to be valid and initialized */
    assert(lock != NULL && *lock != 0);
#ifdef CPU_ESP8266
    assert(lock != __malloc_static_object);
#endif

    /* prevent a context switch between freeing and resetting */
    uint32_t state = irq_disable();

    free((void*)*lock);
    *lock = 0;

    irq_restore(state);
}

void IRAM_ATTR _lock_acquire(_lock_t *lock)
{
    assert(lock != NULL);   /* lock must not be NULL */
    assert(!irq_is_in());   /* _lock_acquire must not be called in
                               interrupt context */

    /* if scheduler is not running, we have not to lock the mutex */
    if (thread_getpid() == KERNEL_PID_UNDEF) {
        return;
    }

    /* if the locking variable is not initialized, initialize it implicitly */
    if (*lock == 0) {
        _lock_init(lock);
        assert(*lock != 0);
    }

    /* disable warning about increasing cast alignment from 4 to 8 via
     * intermediate cast to uintptr_t */
    mutex_lock((mutex_t *)(uintptr_t)*lock);
}

void IRAM_ATTR _lock_acquire_recursive(_lock_t *lock)
{
    assert(lock != NULL);   /* lock must not be NULL */
    assert(!irq_is_in());   /* _lock_acquire must not be called in
                               interrupt context */
#ifdef CPU_ESP8266
    /**
     * Since we don't have direct access to newlib's static variable
     * __malloc_lock_object, we have to rely on the fact that function
     * _lock_aqcuire_recursive, and thus function _lock_init_recursive
     * is called for the first time with newlib's static variable
     * __malloc_lock_object as parameter. This is ensured by calling
     * malloc in the function syscalls_init.
     */
    if (__malloc_static_object == NULL) {
        *lock = (_lock_t)&_malloc_rmtx;
        __malloc_static_object = lock;
        return;
    }
#endif

    /* if scheduler is not running, we have not to lock the mutex */
    if (thread_getpid() == KERNEL_PID_UNDEF) {
        return;
    }

    /* if the locking variable is not initialized, initialize it implicitly */
    if (*lock == 0) {
        _lock_init_recursive(lock);
        assert(*lock != 0);
    }

    _lock_critical_enter();

    /* disable warning about increasing cast alignment from 4 to 8 via
     * intermediate cast to uintptr_t */
    rmutex_lock((rmutex_t *)(uintptr_t)*lock);

    _lock_critical_exit();
}

int IRAM_ATTR _lock_try_acquire(_lock_t *lock)
{
    assert(lock != NULL);   /* lock must not be NULL */

    /* if scheduler is not running, we have not to lock the mutex */
    if (thread_getpid() == KERNEL_PID_UNDEF) {
        return 0;
    }

    if (irq_is_in()) {
        return 0;
    }

    /* if the locking variable is not initialized, initialize it implicitly */
    if (*lock == 0) {
        _lock_init(lock);
        assert(*lock != 0);
    }

    /* disable warning about increasing cast alignment from 4 to 8 via
     * intermediate cast to uintptr_t */
    return mutex_trylock((mutex_t *)(uintptr_t)*lock);
}

int IRAM_ATTR _lock_try_acquire_recursive(_lock_t *lock)
{
    assert(lock != NULL);   /* lock must not be NULL */

    /* if scheduler is not running, we have not to lock the mutex */
    if (thread_getpid() == KERNEL_PID_UNDEF) {
        return 0;
    }

    if (irq_is_in()) {
        return 0;
    }

    /* if the locking variable is not initialized, initialize it implicitly */
    if (*lock == 0) {
        _lock_init_recursive(lock);
        assert(*lock != 0);
    }

    _lock_critical_enter();

    /* disable warning about increasing cast alignment from 4 to 8 via
     * intermediate cast to uintptr_t */
    int res = rmutex_trylock((rmutex_t *)(uintptr_t)*lock);

    _lock_critical_exit();

    return res;
}

void IRAM_ATTR _lock_release(_lock_t *lock)
{
    /* if scheduler is not running, we have not to unlock the mutex */
    if (thread_getpid() == KERNEL_PID_UNDEF) {
        return;
    }

    /* the locking variable has to be valid and initialized */
    assert(lock != NULL && *lock != 0);

    /* disable warning about increasing cast alignment from 4 to 8 via
     * intermediate cast to uintptr_t */
    mutex_unlock((mutex_t *)(uintptr_t)*lock);
}

void IRAM_ATTR _lock_release_recursive(_lock_t *lock)
{
    /* if scheduler is not running, we have not to unlock the mutex */
    if (thread_getpid() == KERNEL_PID_UNDEF) {
        return;
    }

    /* the locking variable has to be valid and initialized */
    assert(lock != NULL && *lock != 0);

    _lock_critical_enter();

    /* disable warning about increasing cast alignment from 4 to 8 via
     * intermediate cast to uintptr_t */
    rmutex_unlock((rmutex_t *)(uintptr_t)*lock);

    _lock_critical_exit();
}

#if defined(_RETARGETABLE_LOCKING)

/* check whether `struct __lock` is large enough to hold a recursive mutex */
static_assert(sizeof(struct __lock) >= sizeof(rmutex_t),
              "struct __lock is too small to hold a recursive mutex of type rmutex_t");

/* map newlib's `__retarget_*` functions to the existing `_lock_*` functions */

void __retarget_lock_init(_LOCK_T *lock)
{
    _lock_init(lock);
}

extern void __retarget_lock_init_recursive(_LOCK_T *lock)
{
    _lock_init_recursive(lock);
}

void __retarget_lock_close(_LOCK_T lock)
{
    _lock_close(&lock);
}

void __retarget_lock_close_recursive(_LOCK_T lock)
{
    _lock_close_recursive(&lock);
}

void __retarget_lock_acquire(_LOCK_T lock)
{
    _lock_acquire(&lock);
}

void __retarget_lock_acquire_recursive(_LOCK_T lock)
{
    _lock_acquire_recursive(&lock);
}

int __retarget_lock_try_acquire(_LOCK_T lock)
{
    return _lock_try_acquire(&lock);
}

int __retarget_lock_try_acquire_recursive(_LOCK_T lock)
{
    return _lock_try_acquire_recursive(&lock);
}

void __retarget_lock_release(_LOCK_T lock)
{
    _lock_release(&lock);
}

void __retarget_lock_release_recursive(_LOCK_T lock)
{
    _lock_release(&lock);
}

#endif /* _RETARGETABLE_LOCKING */

/**
 * @name Memory allocation functions
 */

#ifdef MODULE_ESP_IDF_HEAP

#define heap_caps_malloc_default(s)         heap_caps_malloc(s, MALLOC_CAP_DEFAULT)
#define heap_caps_realloc_default(p, s)     heap_caps_realloc(p, s, MALLOC_CAP_DEFAULT)

void* IRAM_ATTR __wrap__malloc_r(struct _reent *r, size_t size)
{
    return heap_caps_malloc_default( size );
}

void IRAM_ATTR __wrap__free_r(struct _reent *r, void *ptr)
{
    heap_caps_free( ptr );
}

void* IRAM_ATTR __wrap__realloc_r(struct _reent *r, void* ptr, size_t size)
{
    return heap_caps_realloc_default( ptr, size );
}

void* IRAM_ATTR __wrap__calloc_r(struct _reent *r, size_t count, size_t size)
{
    size_t size_total;
    if (__builtin_mul_overflow(count, size, &size_total)) {
        return NULL;
    }
    void *result = heap_caps_malloc_default(size_total);
    if (result) {
        memset(result, 0, size_total);
    }
    return result;
}

#else /* MODULE_ESP_IDF_HEAP */

void* IRAM_ATTR __wrap__calloc_r(struct _reent *r, size_t nmemb, size_t size)
{
    /* The xtensa support has not yet upstreamed to newlib. Hence, the fixed
     * calloc implementation of newlib >= 4.0.0 is not available to the ESP
     * platform. We fix this by implementing calloc on top of malloc ourselves */
    size_t total_size;
    if (__builtin_mul_overflow(nmemb, size, &total_size)) {
        return NULL;
    }

    void *res = _malloc_r(r, total_size);

    if (res) {
        memset(res, 0, total_size);
    }

    return res;
}

/* for compatibility with ESP-IDF heap functions */

#ifndef CPU_ESP8266
void* heap_caps_malloc(size_t size, uint32_t caps, const char *file, size_t line)
                       __attribute__((alias("_heap_caps_malloc")));
void* heap_caps_calloc(size_t n, size_t size, uint32_t caps, const char *file, size_t line)
                       __attribute__((alias("_heap_caps_calloc")));
void* heap_caps_realloc(void *ptr, size_t size, uint32_t caps, const char *file, size_t line)
                        __attribute__((alias("_heap_caps_realloc")));
void *heap_caps_zalloc(size_t size, uint32_t caps, const char *file, size_t line)
                       __attribute__((alias("_heap_caps_zalloc")));
void heap_caps_free(void *ptr, const char *file, size_t line)
                    __attribute__((alias("_heap_caps_free")));
#endif

void* _heap_caps_malloc(size_t size, uint32_t caps, const char *file, size_t line)
{
    (void)caps;
    (void)file;
    (void)line;
    return malloc(size);
}

void* _heap_caps_calloc(size_t n, size_t size, uint32_t caps, const char *file, size_t line)
{
    (void)caps;
    (void)file;
    (void)line;
    return calloc(n, size);
}

void* _heap_caps_realloc(void *ptr, size_t size, uint32_t caps, const char *file, size_t line)
{
    (void)caps;
    (void)file;
    (void)line;
    return realloc(ptr, size);
}

void *_heap_caps_zalloc(size_t size, uint32_t caps, const char *file, size_t line)
{
    (void)caps;
    (void)file;
    (void)line;
    void *ptr = malloc(size);
    if (ptr)  {
        memset(ptr, 0, size);
    }
    return ptr;
}

void _heap_caps_free(void *ptr, const char *file, size_t line)
{
    (void)file;
    (void)line;
    free(ptr);
}

void heap_caps_init(void)
{
}

extern uint8_t  _eheap;     /* end of heap (defined in ld script) */
extern uint8_t  _sheap;     /* start of heap (defined in ld script) */

extern uint8_t _sheap1;
extern uint8_t _eheap1;

extern uint8_t _sheap2;
extern uint8_t _eheap2;

extern uint8_t _sheap3;
extern uint8_t _eheap3;

unsigned int IRAM_ATTR get_free_heap_size(void)
{
    struct mallinfo minfo = mallinfo();
    /* cppcheck-suppress comparePointers */
    uintptr_t heap_size = (uintptr_t)&_eheap - (uintptr_t)&_sheap;
#if NUM_HEAPS > 1
    heap_size += &_eheap1 - &_sheap1;
#endif
#if NUM_HEAPS > 2
    heap_size += &_eheap2 - &_sheap2;
#endif
#if NUM_HEAPS > 3
    heap_size += &_eheap3 - &_sheap3;
#endif
    return heap_size - minfo.uordblks;
}

/* alias for compatibility with espressif/wifi_libs */
uint32_t esp_get_free_heap_size( void ) __attribute__((alias("get_free_heap_size")));
uint32_t esp_get_free_internal_heap_size( void ) __attribute__((alias("get_free_heap_size")));

#endif /* MODULE_ESP_IDF_HEAP */

/**
 * @name Other system functions
 */

int _rename_r(struct _reent *r, const char *from, const char *to)
{
    (void)r;
    (void)from;
    (void)to;
    return 0;
}

struct _reent* __getreent(void) {
    return _GLOBAL_REENT;
}

/* in older versions of newlib, the OS has to allocate a reentry structure */
#ifndef __ATTRIBUTE_IMPURE_DATA__
static struct _reent s_reent;
#endif

void syscalls_init(void)
{
    extern void syscalls_init_arch(void);
    syscalls_init_arch();

    /* _GLOBAL_REENT is a pointer to the reentry structure. In older versions
     * of newlib, the OS has to allocate a reentry structure and update
     * _GLOBAL_REENT to point to that. In more recent versions, the allocation
     * is done by newlib. We use a macro introduced by the commit to detect
     * which flavor is used:
     *
     * See https://github.com/espressif/newlib-esp32/commit/ad51d0006a0aaf17aa61ec34221add09bfe01f0c
     * for the commit that introduced the change.
     */
#ifndef __ATTRIBUTE_IMPURE_DATA__
    _GLOBAL_REENT = &s_reent;
#endif

    environ = malloc(sizeof(char*));
    environ[0] = NULL;

    /* initialization of newlib, includes the ctors initialization */
    extern void __libc_init_array(void);
    __libc_init_array();

    /* initialization of global reent data structure */
    _REENT_SMALL_CHECK_INIT(_GLOBAL_REENT);

    /*
     * disable the locking for stdout/stderr to avoid rmutex based locking
     * when puts/printf are called from an ISR
     */
    __fsetlocking(_GLOBAL_REENT->_stdout, FSETLOCKING_BYCALLER);
    __fsetlocking(_GLOBAL_REENT->_stderr, FSETLOCKING_BYCALLER);
}

__attribute__((weak)) void
_system_prevent_memset_lto(void *const  s, int c, const size_t n)
{
    (void)s;
    (void)c;
    (void)n;
}

void *system_secure_memset(void *s, int c, size_t n)
{
    memset(s, c, n);
    _system_prevent_memset_lto(s, c, n);
    return s;
}