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/* SPDX-License-Identifier: MIT
* Copyright (c) 2026 Leah Rowe <leah@libreboot.org>
*
* String handling.
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <stddef.h>
#include <unistd.h>
#include "../include/common.h"
/*
* Portable strcmp() but blocks NULL/empty/unterminated
* strings. Even stricter than strncmp().
*/
int
xstrxcmp(const char *a, const char *b, unsigned long maxlen)
{
unsigned long i;
if (a == NULL || b == NULL)
err(EINVAL, "NULL input to xstrxcmp");
if (*a == '\0' || *b == '\0')
err(EINVAL, "Empty string in xstrxcmp");
for (i = 0; i < maxlen; i++) {
unsigned char ac = (unsigned char)a[i];
unsigned char bc = (unsigned char)b[i];
if (ac == '\0' || bc == '\0') {
if (ac == bc)
return 0;
return ac - bc;
}
if (ac != bc)
return ac - bc;
}
/*
* We reached maxlen, so assume unterminated string.
*/
err(EINVAL, "Unterminated string in xstrxcmp");
/*
* Should never reach here. This keeps compilers happy.
*/
errno = EINVAL;
return -1;
}
/*
* strnlen() but aborts on NULL input, and empty strings.
* Our version also prohibits unterminated strings.
* strnlen() was standardized in POSIX.1-2008 and is not
* available on some older systems, so we provide our own.
*/
unsigned long
xstrxlen(const char *scmp, unsigned long maxlen)
{
unsigned long xstr_index;
if (scmp == NULL)
err(EINVAL, "NULL input to xstrxlen");
if (*scmp == '\0')
err(EINVAL, "Empty string in xstrxlen");
for (xstr_index = 0;
xstr_index < maxlen && scmp[xstr_index] != '\0';
xstr_index++);
if (xstr_index == maxlen)
err(EINVAL, "Unterminated string in xstrxlen");
return xstr_index;
}
char *
x_c_strrchr(const char *s, int c)
{
const char *p = NULL;
for ( ; *s; s++)
if (*s == (char)c)
p = s;
if (c == '\0')
return (char *)s;
return (char *)p;
}
void *
x_v_memcpy(void *dst, const void *src, unsigned long n)
{
unsigned char *d = (unsigned char *)dst;
const unsigned char *s = (const unsigned char *)src;
while (n--)
*d++ = *s++;
return dst;
}
int
x_i_memcmp(const void *a, const void *b, unsigned long n)
{
const unsigned char *pa = (const unsigned char *)a;
const unsigned char *pb = (const unsigned char *)b;
for ( ; n--; ++pa, ++pb)
if (*pa != *pb)
return *pa - *pb;
return 0;
}
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