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/* SPDX-License-Identifier: BSD-2-Clause */
/*
* Copyright (c) 2014, STMicroelectronics International N.V.
*/
/*
* This file provides extensions for functions not defined in <string.h>
*/
#ifndef __STRING_EXT_H
#define __STRING_EXT_H
#include <stddef.h>
#include <sys/cdefs.h>
/*
* Copy src to string dst of siz size. At most siz-1 characters
* will be copied. Always NUL terminates (unless siz == 0).
* Returns strlen(src); if retval >= siz, truncation occurred.
*/
size_t strlcpy(char *dst, const char *src, size_t size);
size_t strlcat(char *dst, const char *src, size_t size);
/* A constant-time version of memcmp() */
int consttime_memcmp(const void *p1, const void *p2, size_t nb);
/* Deprecated. For backward compatibility. */
static inline int buf_compare_ct(const void *s1, const void *s2, size_t n)
{
return consttime_memcmp(s1, s2, n);
}
/* Variant of strdup() that uses nex_malloc() instead of malloc() */
char *nex_strdup(const char *s);
/*
* Like memset(s, 0, count) but prevents the compiler from optimizing the call
* away. Such "dead store elimination" optimizations typically occur when
* clearing a *local* variable that is not used after it is cleared; but
* link-time optimization (LTO) can also trigger code elimination in other
* circumstances. See "Dead Store Elimination (Still) Considered Harmful" [1]
* for details and examples (and note that the Cland compiler enables LTO by
* default!).
*
* [1] https://www.usenix.org/system/files/conference/usenixsecurity17/sec17-yang.pdf
*
* Practically speaking:
*
* - Use memzero_explicit() to *clear* (as opposed to initialize) *sensitive*
* data (such as keys, passwords, cryptographic state);
* - Otherwise, use memset().
*/
void memzero_explicit(void *s, size_t count);
/*
* ins_array_elem() - insert an element in an array
* @base: start of the array
* @elem_count: the number of elements in the array
* @elem_size: the size of each element in the array
* @pos: element position counted in units of @elem_size
* @elem: pointer the the element to inser or NULL
*
* Makes room in the array at @pos by moving the element after this
* position one position further back.
*
* If @elem is non-NULL it's copied into the array at the indicated
* position.
*
* Returns a pointer to the inserted element.
*/
void *ins_array_elem(void *base, size_t elem_count, size_t elem_size,
size_t pos, const void *elem);
/*
* ins_array_elem_zero_init() - insert a zero-initialized element in an array
* @base: start of the array
* @elem_count: the number of elements in the array
* @elem_size: the size of each element in the array
* @pos: element position counted in units of @elem_size
*
* Makes room in the array at @pos by moving the element after this
* position one position further back. The free position is
* zero-initialized.
*
* Returns a pointer to the free position.
*/
void *ins_array_elem_zero_init(void *base, size_t elem_count, size_t elem_size,
size_t pos);
/*
* rem_array_elem() - remove an element from an array
* @base: start of the array
* @elem_count: the number of elements in the array
* @elem_size: the size of each element in the array
* @pos: element position counted in units of @elem_size
*
* Removes the element at @pos by advancing the element after this position
* to fill the space.
*/
void rem_array_elem(void *base, size_t elem_count, size_t elem_size,
size_t pos);
/*
* rem_array_elem_zero_pad() - remove an element from an array
* @base: start of the array
* @elem_count: the number of elements in the array
* @elem_size: the size of each element in the array
* @pos: element position counted in units of @elem_size
*
* Removes the element at @pos by advancing the element after this position
* to fill the space. The now unused element at the end of the array is
* zero-initialized.
*/
void rem_array_elem_zero_pad(void *base, size_t elem_count, size_t elem_size,
size_t pos);
#endif /* __STRING_EXT_H */
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