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fb63362c63
There are two problems with both strcmp and strncmp: (1) The C standard is clear that the contents should be compared as "unsigned char": The sign of a nonzero value returned by the comparison functions memcmp, strcmp, and strncmp is determined by the sign of the difference between the values of the first pair of characters (both interpreted as unsigned char) that differ in the objects being compared. (2) The difference between two char (or unsigned char) values can range from -255 to +255; so that's (due to integer promotion) the range of values we could get in the *cs-*ct expressions, but when that is then shoe-horned into an 8-bit quantity the sign may of course change. The impact is somewhat limited by the way these functions are used in practice: - Most of the time, one is only interested in equality (or for strncmp, "starts with"), and the existing functions do correctly return 0 if and only if the strings are equal [for strncmp, up to the given bound]. - Also most of the time, the strings being compared only consist of ASCII characters, i.e. have values in the range [0, 127], and in that case it doesn't matter if they are interpreted as signed or unsigned char, and the possible difference range is bounded to [-127, 127] which does fit the signed char. For size, one could implement strcmp() in terms of strncmp() - just make it "return strncmp(a, b, (size_t)-1);". However, performance of strcmp() does matter somewhat, since it is used all over when parsing and matching DT nodes and properties, so let's find some other place to save those ~30 bytes. Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
785 lines
15 KiB
C
785 lines
15 KiB
C
/*
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* linux/lib/string.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*/
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/*
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* stupid library routines.. The optimized versions should generally be found
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* as inline code in <asm-xx/string.h>
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*
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* These are buggy as well..
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*
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* * Fri Jun 25 1999, Ingo Oeser <ioe@informatik.tu-chemnitz.de>
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* - Added strsep() which will replace strtok() soon (because strsep() is
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* reentrant and should be faster). Use only strsep() in new code, please.
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*/
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#include <config.h>
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#include <linux/compiler.h>
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#include <linux/types.h>
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#include <linux/string.h>
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#include <linux/ctype.h>
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#include <malloc.h>
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/**
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* strncasecmp - Case insensitive, length-limited string comparison
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* @s1: One string
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* @s2: The other string
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* @len: the maximum number of characters to compare
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*/
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int strncasecmp(const char *s1, const char *s2, size_t len)
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{
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/* Yes, Virginia, it had better be unsigned */
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unsigned char c1, c2;
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c1 = 0; c2 = 0;
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if (len) {
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do {
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c1 = *s1; c2 = *s2;
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s1++; s2++;
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if (!c1)
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break;
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if (!c2)
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break;
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if (c1 == c2)
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continue;
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c1 = tolower(c1);
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c2 = tolower(c2);
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if (c1 != c2)
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break;
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} while (--len);
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}
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return (int)c1 - (int)c2;
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}
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/**
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* strcasecmp - Case insensitive string comparison
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* @s1: One string
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* @s2: The other string
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*/
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int strcasecmp(const char *s1, const char *s2)
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{
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return strncasecmp(s1, s2, -1U);
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}
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char * ___strtok;
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#ifndef __HAVE_ARCH_STRCPY
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/**
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* strcpy - Copy a %NUL terminated string
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* @dest: Where to copy the string to
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* @src: Where to copy the string from
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*/
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char * strcpy(char * dest,const char *src)
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{
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char *tmp = dest;
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while ((*dest++ = *src++) != '\0')
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/* nothing */;
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return tmp;
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}
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#endif
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#ifndef __HAVE_ARCH_STRNCPY
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/**
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* strncpy - Copy a length-limited, %NUL-terminated string
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* @dest: Where to copy the string to
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* @src: Where to copy the string from
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* @count: The maximum number of bytes to copy
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*
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* Note that unlike userspace strncpy, this does not %NUL-pad the buffer.
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* However, the result is not %NUL-terminated if the source exceeds
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* @count bytes.
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*/
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char * strncpy(char * dest,const char *src,size_t count)
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{
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char *tmp = dest;
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while (count-- && (*dest++ = *src++) != '\0')
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/* nothing */;
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return tmp;
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}
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#endif
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#ifndef __HAVE_ARCH_STRLCPY
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/**
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* strlcpy - Copy a C-string into a sized buffer
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* @dest: Where to copy the string to
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* @src: Where to copy the string from
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* @size: size of destination buffer
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*
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* Compatible with *BSD: the result is always a valid
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* NUL-terminated string that fits in the buffer (unless,
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* of course, the buffer size is zero). It does not pad
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* out the result like strncpy() does.
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*
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* Return: the number of bytes copied
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*/
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size_t strlcpy(char *dest, const char *src, size_t size)
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{
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if (size) {
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size_t srclen = strlen(src);
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size_t len = (srclen >= size) ? size - 1 : srclen;
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memcpy(dest, src, len);
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dest[len] = '\0';
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return len + 1;
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}
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return 0;
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}
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#endif
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#ifndef __HAVE_ARCH_STRCAT
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/**
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* strcat - Append one %NUL-terminated string to another
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* @dest: The string to be appended to
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* @src: The string to append to it
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*/
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char * strcat(char * dest, const char * src)
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{
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char *tmp = dest;
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while (*dest)
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dest++;
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while ((*dest++ = *src++) != '\0')
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;
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return tmp;
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}
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#endif
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#ifndef __HAVE_ARCH_STRNCAT
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/**
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* strncat - Append a length-limited, %NUL-terminated string to another
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* @dest: The string to be appended to
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* @src: The string to append to it
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* @count: The maximum numbers of bytes to copy
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*
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* Note that in contrast to strncpy, strncat ensures the result is
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* terminated.
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*/
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char * strncat(char *dest, const char *src, size_t count)
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{
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char *tmp = dest;
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if (count) {
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while (*dest)
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dest++;
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while ((*dest++ = *src++)) {
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if (--count == 0) {
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*dest = '\0';
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break;
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}
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}
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}
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return tmp;
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}
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#endif
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#ifndef __HAVE_ARCH_STRLCAT
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/**
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* strlcat - Append a length-limited, %NUL-terminated string to another
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* @dest: The string to be appended to
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* @src: The string to append to it
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* @size: The size of @dest
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*
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* Compatible with *BSD: the result is always a valid NUL-terminated string that
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* fits in the buffer (unless, of course, the buffer size is zero). It does not
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* write past @size like strncat() does.
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*/
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size_t strlcat(char *dest, const char *src, size_t size)
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{
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size_t len = strnlen(dest, size);
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return len + strlcpy(dest + len, src, size - len);
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}
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#endif
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#ifndef __HAVE_ARCH_STRCMP
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/**
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* strcmp - Compare two strings
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* @cs: One string
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* @ct: Another string
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*/
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int strcmp(const char *cs, const char *ct)
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{
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int ret;
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while (1) {
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unsigned char a = *cs++;
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unsigned char b = *ct++;
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ret = a - b;
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if (ret || !b)
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break;
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}
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return ret;
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}
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#endif
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#ifndef __HAVE_ARCH_STRNCMP
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/**
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* strncmp - Compare two length-limited strings
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* @cs: One string
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* @ct: Another string
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* @count: The maximum number of bytes to compare
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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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int ret = 0;
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while (count--) {
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unsigned char a = *cs++;
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unsigned char b = *ct++;
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ret = a - b;
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if (ret || !b)
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break;
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}
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return ret;
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}
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#endif
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#ifndef __HAVE_ARCH_STRCHR
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/**
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* strchr - Find the first occurrence of a character in a string
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* @s: The string to be searched
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* @c: The character to search for
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*/
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char * strchr(const char * s, int c)
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{
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for(; *s != (char) c; ++s)
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if (*s == '\0')
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return NULL;
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return (char *) s;
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}
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#endif
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const char *strchrnul(const char *s, int c)
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{
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for (; *s != (char)c; ++s)
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if (*s == '\0')
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break;
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return s;
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}
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#ifndef __HAVE_ARCH_STRRCHR
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/**
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* strrchr - Find the last occurrence of a character in a string
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* @s: The string to be searched
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* @c: The character to search for
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*/
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char * strrchr(const char * s, int c)
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{
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const char *p = s + strlen(s);
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do {
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if (*p == (char)c)
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return (char *)p;
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} while (--p >= s);
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return NULL;
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}
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#endif
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#ifndef __HAVE_ARCH_STRLEN
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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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#endif
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#ifndef __HAVE_ARCH_STRNLEN
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/**
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* strnlen - Find the length of a length-limited string
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* @s: The string to be sized
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* @count: The maximum number of bytes to search
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*/
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size_t strnlen(const char * s, size_t count)
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{
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const char *sc;
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for (sc = s; count-- && *sc != '\0'; ++sc)
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/* nothing */;
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return sc - s;
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}
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#endif
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#ifndef __HAVE_ARCH_STRCSPN
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/**
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* strcspn - Calculate the length of the initial substring of @s which does
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* not contain letters in @reject
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* @s: The string to be searched
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* @reject: The string to avoid
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*/
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size_t strcspn(const char *s, const char *reject)
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{
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const char *p;
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const char *r;
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size_t count = 0;
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for (p = s; *p != '\0'; ++p) {
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for (r = reject; *r != '\0'; ++r) {
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if (*p == *r)
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return count;
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}
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++count;
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}
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return count;
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}
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#endif
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#ifndef __HAVE_ARCH_STRDUP
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char * strdup(const char *s)
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{
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char *new;
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if ((s == NULL) ||
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((new = malloc (strlen(s) + 1)) == NULL) ) {
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return NULL;
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}
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strcpy (new, s);
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return new;
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}
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char * strndup(const char *s, size_t n)
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{
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size_t len;
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char *new;
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if (s == NULL)
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return NULL;
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len = strlen(s);
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if (n < len)
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len = n;
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new = malloc(len + 1);
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if (new == NULL)
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return NULL;
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strncpy(new, s, len);
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new[len] = '\0';
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return new;
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}
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#endif
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#ifndef __HAVE_ARCH_STRSPN
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/**
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* strspn - Calculate the length of the initial substring of @s which only
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* contain letters in @accept
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* @s: The string to be searched
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* @accept: The string to search for
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*/
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size_t strspn(const char *s, const char *accept)
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{
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const char *p;
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const char *a;
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size_t count = 0;
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for (p = s; *p != '\0'; ++p) {
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for (a = accept; *a != '\0'; ++a) {
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if (*p == *a)
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break;
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}
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if (*a == '\0')
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return count;
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++count;
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}
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return count;
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}
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#endif
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#ifndef __HAVE_ARCH_STRPBRK
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/**
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* strpbrk - Find the first occurrence of a set of characters
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* @cs: The string to be searched
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* @ct: The characters to search for
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*/
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char * strpbrk(const char * cs,const char * ct)
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{
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const char *sc1,*sc2;
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for( sc1 = cs; *sc1 != '\0'; ++sc1) {
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for( sc2 = ct; *sc2 != '\0'; ++sc2) {
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if (*sc1 == *sc2)
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return (char *) sc1;
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}
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}
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return NULL;
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}
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#endif
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#ifndef __HAVE_ARCH_STRTOK
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/**
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* strtok - Split a string into tokens
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* @s: The string to be searched
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* @ct: The characters to search for
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*
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* WARNING: strtok is deprecated, use strsep instead.
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*/
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char * strtok(char * s,const char * ct)
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{
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char *sbegin, *send;
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sbegin = s ? s : ___strtok;
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if (!sbegin) {
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return NULL;
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}
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sbegin += strspn(sbegin,ct);
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if (*sbegin == '\0') {
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___strtok = NULL;
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return( NULL );
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}
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send = strpbrk( sbegin, ct);
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if (send && *send != '\0')
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*send++ = '\0';
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___strtok = send;
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return (sbegin);
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}
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#endif
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#ifndef __HAVE_ARCH_STRSEP
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/**
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* strsep - Split a string into tokens
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* @s: The string to be searched
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* @ct: The characters to search for
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*
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* strsep() updates @s to point after the token, ready for the next call.
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*
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* It returns empty tokens, too, behaving exactly like the libc function
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* of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
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* Same semantics, slimmer shape. ;)
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*/
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char * strsep(char **s, const char *ct)
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{
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char *sbegin = *s, *end;
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if (sbegin == NULL)
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return NULL;
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end = strpbrk(sbegin, ct);
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if (end)
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*end++ = '\0';
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*s = end;
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return sbegin;
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}
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#endif
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#ifndef __HAVE_ARCH_STRSWAB
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/**
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* strswab - swap adjacent even and odd bytes in %NUL-terminated string
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* s: address of the string
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*
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* returns the address of the swapped string or NULL on error. If
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* string length is odd, last byte is untouched.
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*/
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char *strswab(const char *s)
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{
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char *p, *q;
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if ((NULL == s) || ('\0' == *s)) {
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return (NULL);
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}
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for (p=(char *)s, q=p+1; (*p != '\0') && (*q != '\0'); p+=2, q+=2) {
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char tmp;
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tmp = *p;
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*p = *q;
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*q = tmp;
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}
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return (char *) s;
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}
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#endif
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#ifndef __HAVE_ARCH_MEMSET
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/**
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* memset - Fill a region of memory with the given value
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* @s: Pointer to the start of the area.
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* @c: The byte to fill the area with
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* @count: The size of the area.
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*
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* Do not use memset() to access IO space, use memset_io() instead.
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*/
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__used void * memset(void * s,int c,size_t count)
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{
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unsigned long *sl = (unsigned long *) s;
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char *s8;
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#if !CONFIG_IS_ENABLED(TINY_MEMSET)
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unsigned long cl = 0;
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int i;
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/* do it one word at a time (32 bits or 64 bits) while possible */
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if ( ((ulong)s & (sizeof(*sl) - 1)) == 0) {
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for (i = 0; i < sizeof(*sl); i++) {
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cl <<= 8;
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cl |= c & 0xff;
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}
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while (count >= sizeof(*sl)) {
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*sl++ = cl;
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count -= sizeof(*sl);
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}
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}
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#endif /* fill 8 bits at a time */
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s8 = (char *)sl;
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while (count--)
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*s8++ = c;
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return s;
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}
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#endif
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#ifndef __HAVE_ARCH_MEMCPY
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/**
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* memcpy - Copy one area of memory to another
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* @dest: Where to copy to
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* @src: Where to copy from
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* @count: The size of the area.
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*
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* You should not use this function to access IO space, use memcpy_toio()
|
|
* or memcpy_fromio() instead.
|
|
*/
|
|
__used void * memcpy(void *dest, const void *src, size_t count)
|
|
{
|
|
unsigned long *dl = (unsigned long *)dest, *sl = (unsigned long *)src;
|
|
char *d8, *s8;
|
|
|
|
if (src == dest)
|
|
return dest;
|
|
|
|
/* while all data is aligned (common case), copy a word at a time */
|
|
if ( (((ulong)dest | (ulong)src) & (sizeof(*dl) - 1)) == 0) {
|
|
while (count >= sizeof(*dl)) {
|
|
*dl++ = *sl++;
|
|
count -= sizeof(*dl);
|
|
}
|
|
}
|
|
/* copy the reset one byte at a time */
|
|
d8 = (char *)dl;
|
|
s8 = (char *)sl;
|
|
while (count--)
|
|
*d8++ = *s8++;
|
|
|
|
return dest;
|
|
}
|
|
#endif
|
|
|
|
#ifndef __HAVE_ARCH_MEMMOVE
|
|
/**
|
|
* memmove - Copy one area of memory to another
|
|
* @dest: Where to copy to
|
|
* @src: Where to copy from
|
|
* @count: The size of the area.
|
|
*
|
|
* Unlike memcpy(), memmove() copes with overlapping areas.
|
|
*/
|
|
__used void * memmove(void * dest,const void *src,size_t count)
|
|
{
|
|
char *tmp, *s;
|
|
|
|
if (dest <= src || (src + count) <= dest) {
|
|
/*
|
|
* Use the fast memcpy implementation (ARCH optimized or lib/string.c) when it is possible:
|
|
* - when dest is before src (assuming that memcpy is doing forward-copying)
|
|
* - when destination don't overlap the source buffer (src + count <= dest)
|
|
*
|
|
* WARNING: the first optimisation cause an issue, when __HAVE_ARCH_MEMCPY is defined,
|
|
* __HAVE_ARCH_MEMMOVE is not defined and if the memcpy ARCH-specific
|
|
* implementation is not doing a forward-copying.
|
|
*
|
|
* No issue today because memcpy is doing a forward-copying in lib/string.c and for ARM32
|
|
* architecture; no other arches use __HAVE_ARCH_MEMCPY without __HAVE_ARCH_MEMMOVE.
|
|
*/
|
|
memcpy(dest, src, count);
|
|
} else {
|
|
tmp = (char *) dest + count;
|
|
s = (char *) src + count;
|
|
while (count--)
|
|
*--tmp = *--s;
|
|
}
|
|
|
|
return dest;
|
|
}
|
|
#endif
|
|
|
|
#ifndef __HAVE_ARCH_MEMCMP
|
|
/**
|
|
* memcmp - Compare two areas of memory
|
|
* @cs: One area of memory
|
|
* @ct: Another area of memory
|
|
* @count: The size of the area.
|
|
*/
|
|
__used int memcmp(const void * cs,const void * ct,size_t count)
|
|
{
|
|
const unsigned char *su1, *su2;
|
|
int res = 0;
|
|
|
|
for( su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
|
|
if ((res = *su1 - *su2) != 0)
|
|
break;
|
|
return res;
|
|
}
|
|
#endif
|
|
|
|
#ifndef __HAVE_ARCH_MEMSCAN
|
|
/**
|
|
* memscan - Find a character in an area of memory.
|
|
* @addr: The memory area
|
|
* @c: The byte to search for
|
|
* @size: The size of the area.
|
|
*
|
|
* returns the address of the first occurrence of @c, or 1 byte past
|
|
* the area if @c is not found
|
|
*/
|
|
void * memscan(void * addr, int c, size_t size)
|
|
{
|
|
unsigned char * p = (unsigned char *) addr;
|
|
|
|
while (size) {
|
|
if (*p == c)
|
|
return (void *) p;
|
|
p++;
|
|
size--;
|
|
}
|
|
return (void *) p;
|
|
}
|
|
#endif
|
|
|
|
char *memdup(const void *src, size_t len)
|
|
{
|
|
char *p;
|
|
|
|
p = malloc(len);
|
|
if (!p)
|
|
return NULL;
|
|
|
|
memcpy(p, src, len);
|
|
|
|
return p;
|
|
}
|
|
|
|
#ifndef __HAVE_ARCH_STRSTR
|
|
/**
|
|
* strstr - Find the first substring in a %NUL terminated string
|
|
* @s1: The string to be searched
|
|
* @s2: The string to search for
|
|
*/
|
|
char * strstr(const char * s1,const char * s2)
|
|
{
|
|
int l1, l2;
|
|
|
|
l2 = strlen(s2);
|
|
if (!l2)
|
|
return (char *) s1;
|
|
l1 = strlen(s1);
|
|
while (l1 >= l2) {
|
|
l1--;
|
|
if (!memcmp(s1,s2,l2))
|
|
return (char *) s1;
|
|
s1++;
|
|
}
|
|
return NULL;
|
|
}
|
|
#endif
|
|
|
|
#ifndef __HAVE_ARCH_MEMCHR
|
|
/**
|
|
* memchr - Find a character in an area of memory.
|
|
* @s: The memory area
|
|
* @c: The byte to search for
|
|
* @n: The size of the area.
|
|
*
|
|
* returns the address of the first occurrence of @c, or %NULL
|
|
* if @c is not found
|
|
*/
|
|
void *memchr(const void *s, int c, size_t n)
|
|
{
|
|
const unsigned char *p = s;
|
|
while (n-- != 0) {
|
|
if ((unsigned char)c == *p++) {
|
|
return (void *)(p-1);
|
|
}
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
#endif
|
|
#ifndef __HAVE_ARCH_MEMCHR_INV
|
|
static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
|
|
{
|
|
while (bytes) {
|
|
if (*start != value)
|
|
return (void *)start;
|
|
start++;
|
|
bytes--;
|
|
}
|
|
return NULL;
|
|
}
|
|
/**
|
|
* memchr_inv - Find an unmatching character in an area of memory.
|
|
* @start: The memory area
|
|
* @c: Find a character other than c
|
|
* @bytes: The size of the area.
|
|
*
|
|
* returns the address of the first character other than @c, or %NULL
|
|
* if the whole buffer contains just @c.
|
|
*/
|
|
void *memchr_inv(const void *start, int c, size_t bytes)
|
|
{
|
|
u8 value = c;
|
|
u64 value64;
|
|
unsigned int words, prefix;
|
|
|
|
if (bytes <= 16)
|
|
return check_bytes8(start, value, bytes);
|
|
|
|
value64 = value;
|
|
value64 |= value64 << 8;
|
|
value64 |= value64 << 16;
|
|
value64 |= value64 << 32;
|
|
|
|
prefix = (unsigned long)start % 8;
|
|
if (prefix) {
|
|
u8 *r;
|
|
|
|
prefix = 8 - prefix;
|
|
r = check_bytes8(start, value, prefix);
|
|
if (r)
|
|
return r;
|
|
start += prefix;
|
|
bytes -= prefix;
|
|
}
|
|
|
|
words = bytes / 8;
|
|
|
|
while (words) {
|
|
if (*(u64 *)start != value64)
|
|
return check_bytes8(start, value, 8);
|
|
start += 8;
|
|
words--;
|
|
}
|
|
|
|
return check_bytes8(start, value, bytes % 8);
|
|
}
|
|
#endif
|