// SPDX-License-Identifier: Apache-2.0
//
// <string.h> for lwIP, shadowing the host's.
//
// lwIP includes <string.h> in thirty-odd files. The kernel is built
// -ffreestanding and has its own string functions, but the compiler's default
// include path still finds /usr/include/string.h -- which declares strlen
// returning size_t against a kernel that returns int, and drags sigset_t and
// __float128 in behind it. So the lwIP include path puts this directory first.
//
// The prototypes are repeated here rather than taken from defs.h on purpose.
// lwIP includes <string.h> at the very top of a translation unit, before any
// kernel header has been seen, so pulling defs.h in from here would drop the
// whole kernel's declarations into a context where its own types are not
// defined yet -- which shows up as errors in unrelated headers, like file.h
// not knowing what NDIRECT is.
//
// They must match kernel/core/string.c exactly. Only what lwIP calls is here;
// anything else should be added deliberately rather than by growing this into
// a libc.
#ifndef LWIP_SHIM_STRING_H
#define LWIP_SHIM_STRING_H

int    memcmp(const void *, const void *, unsigned long);
void  *memmove(void *, const void *, unsigned long);
void  *memset(void *, int, unsigned long);
int    strlen(const char *);
int    strncmp(const char *, const char *, unsigned long);
char  *strncpy(char *, const char *, int);

// The kernel deliberately provides only memmove, on the grounds that a copy
// which happens to overlap should not be undefined behaviour. lwIP calls
// memcpy in a handful of places, always on buffers it has just allocated, so
// mapping it onto memmove is correct and costs nothing.
#define memcpy(d, s, n) memmove((d), (s), (n))

#endif