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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;
}
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