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1c1d046be6
strcmp() is always expected to return 0 when arguments are equal,
negative when its first argument @str1 is less than its second argument
@str2 and a positive value otherwise. Previously strcmp("a", "b")
returned 1. Now it gives -1, as it is supposed to.
Until now this bug never triggered, because all uses for strcmp() in the
boot code tested for nonzero:
triton:~/tip> git grep strcmp arch/x86/boot/
arch/x86/boot/boot.h:int strcmp(const char *str1, const char *str2);
arch/x86/boot/edd.c: if (!strcmp(eddarg, "skipmbr") || !strcmp(eddarg, "skip")) {
arch/x86/boot/edd.c: else if (!strcmp(eddarg, "off"))
arch/x86/boot/edd.c: else if (!strcmp(eddarg, "on"))
should in the future strcmp() be used in a comparative way in the boot
code, it might have led to (not so subtle) bugs.
Signed-off-by: Arjun Sreedharan <arjun024@gmail.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1426520267-1803-1-git-send-email-arjun024@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
158 lines
2.9 KiB
C
158 lines
2.9 KiB
C
/* -*- linux-c -*- ------------------------------------------------------- *
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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* Copyright 2007 rPath, Inc. - All Rights Reserved
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*
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* This file is part of the Linux kernel, and is made available under
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* the terms of the GNU General Public License version 2.
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*
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* ----------------------------------------------------------------------- */
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/*
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* Very basic string functions
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*/
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#include <linux/types.h>
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#include "ctype.h"
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int memcmp(const void *s1, const void *s2, size_t len)
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{
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u8 diff;
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asm("repe; cmpsb; setnz %0"
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: "=qm" (diff), "+D" (s1), "+S" (s2), "+c" (len));
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return diff;
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}
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int strcmp(const char *str1, const char *str2)
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{
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const unsigned char *s1 = (const unsigned char *)str1;
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const unsigned char *s2 = (const unsigned char *)str2;
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int delta = 0;
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while (*s1 || *s2) {
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delta = *s1 - *s2;
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if (delta)
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return delta;
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s1++;
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s2++;
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}
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return 0;
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}
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int strncmp(const char *cs, const char *ct, size_t count)
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{
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unsigned char c1, c2;
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while (count) {
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c1 = *cs++;
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c2 = *ct++;
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if (c1 != c2)
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return c1 < c2 ? -1 : 1;
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if (!c1)
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break;
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count--;
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}
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return 0;
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}
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size_t strnlen(const char *s, size_t maxlen)
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{
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const char *es = s;
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while (*es && maxlen) {
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es++;
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maxlen--;
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}
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return (es - s);
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}
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unsigned int atou(const char *s)
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{
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unsigned int i = 0;
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while (isdigit(*s))
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i = i * 10 + (*s++ - '0');
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return i;
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}
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/* Works only for digits and letters, but small and fast */
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#define TOLOWER(x) ((x) | 0x20)
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static unsigned int simple_guess_base(const char *cp)
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{
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if (cp[0] == '0') {
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if (TOLOWER(cp[1]) == 'x' && isxdigit(cp[2]))
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return 16;
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else
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return 8;
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} else {
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return 10;
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}
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}
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/**
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* simple_strtoull - convert a string to an unsigned long long
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* @cp: The start of the string
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* @endp: A pointer to the end of the parsed string will be placed here
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* @base: The number base to use
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*/
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unsigned long long simple_strtoull(const char *cp, char **endp, unsigned int base)
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{
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unsigned long long result = 0;
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if (!base)
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base = simple_guess_base(cp);
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if (base == 16 && cp[0] == '0' && TOLOWER(cp[1]) == 'x')
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cp += 2;
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while (isxdigit(*cp)) {
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unsigned int value;
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value = isdigit(*cp) ? *cp - '0' : TOLOWER(*cp) - 'a' + 10;
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if (value >= base)
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break;
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result = result * base + value;
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cp++;
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}
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if (endp)
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*endp = (char *)cp;
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return result;
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}
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/**
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* strlen - Find the length of a string
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* @s: The string to be sized
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*/
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size_t strlen(const char *s)
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{
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const char *sc;
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for (sc = s; *sc != '\0'; ++sc)
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/* nothing */;
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return sc - s;
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}
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/**
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* strstr - Find the first substring in a %NUL terminated string
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* @s1: The string to be searched
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* @s2: The string to search for
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*/
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char *strstr(const char *s1, const char *s2)
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{
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size_t l1, l2;
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l2 = strlen(s2);
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if (!l2)
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return (char *)s1;
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l1 = strlen(s1);
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while (l1 >= l2) {
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l1--;
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if (!memcmp(s1, s2, l2))
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return (char *)s1;
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s1++;
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}
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return NULL;
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}
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