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/* SPDX-License-Identifier: LGPL-2.1-or-later */
#pragma once
#include <stddef.h>
#if SD_BOOT
# include "efi-string.h"
#else
# include <string.h>
#endif
#include "macro-fundamental.h"
#if !SD_BOOT && HAVE_EXPLICIT_BZERO
static inline void *explicit_bzero_safe(void *p, size_t l) {
if (p && l > 0)
explicit_bzero(p, l);
return p;
}
#else
static inline void *explicit_bzero_safe(void *p, size_t l) {
if (p && l > 0) {
memset(p, 0, l);
__asm__ __volatile__("" : : "r"(p) : "memory");
}
return p;
}
#endif
struct VarEraser {
/* NB: This is a pointer to memory to erase in case of CLEANUP_ERASE(). Pointer to pointer to memory
* to erase in case of CLEANUP_ERASE_PTR() */
void *p;
size_t size;
};
static inline void erase_var(struct VarEraser *e) {
explicit_bzero_safe(e->p, e->size);
}
/* Mark var to be erased when leaving scope. */
#define CLEANUP_ERASE(var) \
_cleanup_(erase_var) _unused_ struct VarEraser CONCATENATE(_eraser_, UNIQ) = { \
.p = &(var), \
.size = sizeof(var), \
}
static inline void erase_varp(struct VarEraser *e) {
/* Very similar to erase_var(), but assumes `p` is a pointer to a pointer whose memory shall be destructed. */
if (!e->p)
return;
explicit_bzero_safe(*(void**) e->p, e->size);
}
/* Mark pointer so that memory pointed to is erased when leaving scope. Note: this takes a pointer to the
* specified pointer, instead of just a copy of it. This is to allow callers to invalidate the pointer after
* use, if they like, disabling our automatic erasure (for example because they succeeded with whatever they
* wanted to do and now intend to return the allocated buffer to their caller without it being erased). */
#define CLEANUP_ERASE_PTR(ptr, sz) \
_cleanup_(erase_varp) _unused_ struct VarEraser CONCATENATE(_eraser_, UNIQ) = { \
.p = (ptr), \
.size = (sz), \
}
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