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846cb23585
i had this idea in my head of later porting this to k&r c for fun. but screw it. compiling on everything since 1989 is enough Signed-off-by: Leah Rowe <leah@libreboot.org>
84 lines
1.7 KiB
C
84 lines
1.7 KiB
C
/* SPDX-License-Identifier: MIT
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* Copyright (c) 2026 Leah Rowe <leah@libreboot.org>
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*
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* String handling.
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*/
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <errno.h>
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#include <stddef.h>
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#include <unistd.h>
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#include "../include/common.h"
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/*
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* Portable strcmp() but blocks NULL/empty/unterminated
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* strings. Even stricter than strncmp().
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*/
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int
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xstrxcmp(const char *a, const char *b, unsigned long maxlen)
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{
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unsigned long i;
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if (a == NULL || b == NULL)
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err(EINVAL, "NULL input to xstrxcmp");
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if (*a == '\0' || *b == '\0')
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err(EINVAL, "Empty string in xstrxcmp");
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for (i = 0; i < maxlen; i++) {
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unsigned char ac = (unsigned char)a[i];
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unsigned char bc = (unsigned char)b[i];
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if (ac == '\0' || bc == '\0') {
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if (ac == bc)
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return 0;
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return ac - bc;
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}
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if (ac != bc)
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return ac - bc;
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}
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/*
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* We reached maxlen, so assume unterminated string.
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*/
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err(EINVAL, "Unterminated string in xstrxcmp");
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/*
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* Should never reach here. This keeps compilers happy.
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*/
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errno = EINVAL;
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return -1;
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}
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/*
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* strnlen() but aborts on NULL input, and empty strings.
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* Our version also prohibits unterminated strings.
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* strnlen() was standardized in POSIX.1-2008 and is not
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* available on some older systems, so we provide our own.
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*/
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unsigned long
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xstrxlen(const char *scmp, unsigned long maxlen)
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{
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unsigned long xstr_index;
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if (scmp == NULL)
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err(EINVAL, "NULL input to xstrxlen");
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if (*scmp == '\0')
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err(EINVAL, "Empty string in xstrxlen");
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for (xstr_index = 0;
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xstr_index < maxlen && scmp[xstr_index] != '\0';
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xstr_index++);
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if (xstr_index == maxlen)
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err(EINVAL, "Unterminated string in xstrxlen");
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return xstr_index;
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}
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