Follow ups for #39806

[thirdparty/systemd.git] / src / basic / memory-util.h

/* SPDX-License-Identifier: LGPL-2.1-or-later */
#pragma once

#include <string.h>

#include "basic-forward.h"
#include "memory-util-fundamental.h" /* IWYU pragma: export */

size_t page_size(void) _pure_;
#define PAGE_ALIGN(l)          ALIGN_TO(l, page_size())
#define PAGE_ALIGN_U64(l)      ALIGN_TO_U64(l, page_size())
#define PAGE_ALIGN_DOWN(l)     ALIGN_DOWN(l, page_size())
#define PAGE_ALIGN_DOWN_U64(l) ALIGN_DOWN_U64(l, page_size())
#define PAGE_OFFSET(l)         ALIGN_OFFSET(l, page_size())
#define PAGE_OFFSET_U64(l)     ALIGN_OFFSET_U64(l, page_size())

/* Normal memcpy() requires src to be nonnull. We do nothing if n is 0. */
static inline void* memcpy_safe(void *dst, const void *src, size_t n) {
        if (n == 0)
                return dst;
        assert(src);
        return memcpy(dst, src, n);
}

/* Normal mempcpy() requires src to be nonnull. We do nothing if n is 0. */
static inline void* mempcpy_safe(void *dst, const void *src, size_t n) {
        if (n == 0)
                return dst;
        assert(src);
        return mempcpy(dst, src, n);
}

#define _mempcpy_typesafe(dst, src, n, sz)                              \
        ({                                                              \
                size_t sz;                                              \
                assert_se(MUL_SAFE(&sz, sizeof((dst)[0]), n));          \
                (typeof((dst)[0])*) mempcpy_safe(dst, src, sz);         \
        })

#define mempcpy_typesafe(dst, src, n)                                   \
        _mempcpy_typesafe(dst, src, n, UNIQ_T(sz, UNIQ))

/* Normal memcmp() requires s1 and s2 to be nonnull. We do nothing if n is 0. */
static inline int memcmp_safe(const void *s1, const void *s2, size_t n) {
        if (n == 0)
                return 0;
        assert(s1);
        assert(s2);
        return memcmp(s1, s2, n);
}

/* Compare s1 (length n1) with s2 (length n2) in lexicographic order. */
static inline int memcmp_nn(const void *s1, size_t n1, const void *s2, size_t n2) {
        return memcmp_safe(s1, s2, MIN(n1, n2))
            ?: CMP(n1, n2);
}

#define zero(x) (memzero(&(x), sizeof(x)))

bool memeqbyte(uint8_t byte, const void *data, size_t length) _nonnull_if_nonzero_(2, 3);

#define memeqzero(data, length) memeqbyte(0x00, data, length)

#define eqzero(x) memeqzero(x, sizeof(x))

static inline void* mempset(void *s, int c, size_t n) {
        memset(s, c, n);
        return (uint8_t*) s + n;
}

/* Normal memmem() requires haystack to be nonnull, which is annoying for zero-length buffers */
static inline void* memmem_safe(const void *haystack, size_t haystacklen, const void *needle, size_t needlelen) {

        if (needlelen <= 0)
                return (void*) haystack;

        if (haystacklen < needlelen)
                return NULL;

        assert(haystack);
        assert(needle);

        return memmem(haystack, haystacklen, needle, needlelen);
}

static inline void* mempmem_safe(const void *haystack, size_t haystacklen, const void *needle, size_t needlelen) {
        const uint8_t *p;

        p = memmem_safe(haystack, haystacklen, needle, needlelen);
        if (!p)
                return NULL;

        return (uint8_t*) p + needlelen;
}

void* erase_and_free(void *p);

static inline void erase_and_freep(void *p) {
        erase_and_free(*(void**) p);
}

/* Use with _cleanup_ to erase a single 'char' when leaving scope */
static inline void erase_char(char *p) {
        explicit_bzero_safe(p, sizeof(char));
}

/* Makes a copy of the buffer with reversed order of bytes */
void* memdup_reverse(const void *mem, size_t size);