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 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Helpers for formatting and printing strings
  *
  * Copyright 31 August 2008 James Bottomley
  * Copyright (C) 2013, Intel Corporation
  */
 #include <linux/bug.h>
 #include <linux/kernel.h>
 #include <linux/math64.h>
 #include <linux/export.h>
 #include <linux/ctype.h>
 #include <linux/device.h>
 #include <linux/errno.h>
 #include <linux/fs.h>
 #include <linux/limits.h>
 #include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/string.h>
 #include <linux/string_helpers.h>
 
 /**
  * string_get_size - get the size in the specified units
  * @size:   The size to be converted in blocks
  * @blk_size:   Size of the block (use 1 for size in bytes)
  * @units:  units to use (powers of 1000 or 1024)
  * @buf:    buffer to format to
  * @len:    length of buffer
  *
  * This function returns a string formatted to 3 significant figures
  * giving the size in the required units.  @buf should have room for
  * at least 9 bytes and will always be zero terminated.
  *
  */
 void string_get_size(u64 size, u64 blk_size, const enum string_size_units units,
              char *buf, int len)
 {
     static const char *const units_10[] = {
         "B", "kB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB"
     };
     static const char *const units_2[] = {
         "B", "KiB", "MiB", "GiB", "TiB", "PiB", "EiB", "ZiB", "YiB"
     };
     static const char *const *const units_str[] = {
         [STRING_UNITS_10] = units_10,
         [STRING_UNITS_2] = units_2,
     };
     static const unsigned int divisor[] = {
         [STRING_UNITS_10] = 1000,
         [STRING_UNITS_2] = 1024,
     };
     static const unsigned int rounding[] = { 500, 50, 5 };
     int i = 0, j;
     u32 remainder = 0, sf_cap;
     char tmp[8];
     const char *unit;
 
     tmp[0] = '\0';
 
     if (blk_size == 0)
         size = 0;
     if (size == 0)
         goto out;
 
     /* This is Napier's algorithm.  Reduce the original block size to
      *
      * coefficient * divisor[units]^i
      *
      * we do the reduction so both coefficients are just under 32 bits so
      * that multiplying them together won't overflow 64 bits and we keep
      * as much precision as possible in the numbers.
      *
      * Note: it's safe to throw away the remainders here because all the
      * precision is in the coefficients.
      */
     while (blk_size >> 32) {
         do_div(blk_size, divisor[units]);
         i++;
     }
 
     while (size >> 32) {
         do_div(size, divisor[units]);
         i++;
     }
 
     /* now perform the actual multiplication keeping i as the sum of the
      * two logarithms */
     size *= blk_size;
 
     /* and logarithmically reduce it until it's just under the divisor */
     while (size >= divisor[units]) {
         remainder = do_div(size, divisor[units]);
         i++;
     }
 
     /* work out in j how many digits of precision we need from the
      * remainder */
     sf_cap = size;
     for (j = 0; sf_cap*10 < 1000; j++)
         sf_cap *= 10;
 
     if (units == STRING_UNITS_2) {
         /* express the remainder as a decimal.  It's currently the
          * numerator of a fraction whose denominator is
          * divisor[units], which is 1 << 10 for STRING_UNITS_2 */
         remainder *= 1000;
         remainder >>= 10;
     }
 
     /* add a 5 to the digit below what will be printed to ensure
      * an arithmetical round up and carry it through to size */
     remainder += rounding[j];
     if (remainder >= 1000) {
         remainder -= 1000;
         size += 1;
     }
 
     if (j) {
         snprintf(tmp, sizeof(tmp), ".%03u", remainder);
         tmp[j+1] = '\0';
     }
 
  out:
     if (i >= ARRAY_SIZE(units_2))
         unit = "UNK";
     else
         unit = units_str[units][i];
 
     snprintf(buf, len, "%u%s %s", (u32)size,
          tmp, unit);
 }
 EXPORT_SYMBOL(string_get_size);
 
 static bool unescape_space(char **src, char **dst)
 {
     char *p = *dst, *q = *src;
 
     switch (*q) {
     case 'n':
         *p = '\n';
         break;
     case 'r':
         *p = '\r';
         break;
     case 't':
         *p = '\t';
         break;
     case 'v':
         *p = '\v';
         break;
     case 'f':
         *p = '\f';
         break;
     default:
         return false;
     }
     *dst += 1;
     *src += 1;
     return true;
 }
 
 static bool unescape_octal(char **src, char **dst)
 {
     char *p = *dst, *q = *src;
     u8 num;
 
     if (isodigit(*q) == 0)
         return false;
 
     num = (*q++) & 7;
     while (num < 32 && isodigit(*q) && (q - *src < 3)) {
         num <<= 3;
         num += (*q++) & 7;
     }
     *p = num;
     *dst += 1;
     *src = q;
     return true;
 }
 
 static bool unescape_hex(char **src, char **dst)
 {
     char *p = *dst, *q = *src;
     int digit;
     u8 num;
 
     if (*q++ != 'x')
         return false;
 
     num = digit = hex_to_bin(*q++);
     if (digit < 0)
         return false;
 
     digit = hex_to_bin(*q);
     if (digit >= 0) {
         q++;
         num = (num << 4) | digit;
     }
     *p = num;
     *dst += 1;
     *src = q;
     return true;
 }
 
 static bool unescape_special(char **src, char **dst)
 {
     char *p = *dst, *q = *src;
 
     switch (*q) {
     case '\"':
         *p = '\"';
         break;
     case '\\':
         *p = '\\';
         break;
     case 'a':
         *p = '\a';
         break;
     case 'e':
         *p = '\e';
         break;
     default:
         return false;
     }
     *dst += 1;
     *src += 1;
     return true;
 }
 
 /**
  * string_unescape - unquote characters in the given string
  * @src:    source buffer (escaped)
  * @dst:    destination buffer (unescaped)
  * @size:   size of the destination buffer (0 to unlimit)
  * @flags:  combination of the flags.
  *
  * Description:
  * The function unquotes characters in the given string.
  *
  * Because the size of the output will be the same as or less than the size of
  * the input, the transformation may be performed in place.
  *
  * Caller must provide valid source and destination pointers. Be aware that
  * destination buffer will always be NULL-terminated. Source string must be
  * NULL-terminated as well.  The supported flags are::
  *
  *  UNESCAPE_SPACE:
  *      '\f' - form feed
  *      '\n' - new line
  *      '\r' - carriage return
  *      '\t' - horizontal tab
  *      '\v' - vertical tab
  *  UNESCAPE_OCTAL:
  *      '\NNN' - byte with octal value NNN (1 to 3 digits)
  *  UNESCAPE_HEX:
  *      '\xHH' - byte with hexadecimal value HH (1 to 2 digits)
  *  UNESCAPE_SPECIAL:
  *      '\"' - double quote
  *      '\\' - backslash
  *      '\a' - alert (BEL)
  *      '\e' - escape
  *  UNESCAPE_ANY:
  *      all previous together
  *
  * Return:
  * The amount of the characters processed to the destination buffer excluding
  * trailing '\0' is returned.
  */
 int string_unescape(char *src, char *dst, size_t size, unsigned int flags)
 {
     char *out = dst;
 
     while (*src && --size) {
         if (src[0] == '\\' && src[1] != '\0' && size > 1) {
             src++;
             size--;
 
             if (flags & UNESCAPE_SPACE &&
                     unescape_space(&src, &out))
                 continue;
 
             if (flags & UNESCAPE_OCTAL &&
                     unescape_octal(&src, &out))
                 continue;
 
             if (flags & UNESCAPE_HEX &&
                     unescape_hex(&src, &out))
                 continue;
 
             if (flags & UNESCAPE_SPECIAL &&
                     unescape_special(&src, &out))
                 continue;
 
             *out++ = '\\';
         }
         *out++ = *src++;
     }
     *out = '\0';
 
     return out - dst;
 }
 EXPORT_SYMBOL(string_unescape);
 
 static bool escape_passthrough(unsigned char c, char **dst, char *end)
 {
     char *out = *dst;
 
     if (out < end)
         *out = c;
     *dst = out + 1;
     return true;
 }
 
 static bool escape_space(unsigned char c, char **dst, char *end)
 {
     char *out = *dst;
     unsigned char to;
 
     switch (c) {
     case '\n':
         to = 'n';
         break;
     case '\r':
         to = 'r';
         break;
     case '\t':
         to = 't';
         break;
     case '\v':
         to = 'v';
         break;
     case '\f':
         to = 'f';
         break;
     default:
         return false;
     }
 
     if (out < end)
         *out = '\\';
     ++out;
     if (out < end)
         *out = to;
     ++out;
 
     *dst = out;
     return true;
 }
 
 static bool escape_special(unsigned char c, char **dst, char *end)
 {
     char *out = *dst;
     unsigned char to;
 
     switch (c) {
     case '\\':
         to = '\\';
         break;
     case '\a':
         to = 'a';
         break;
     case '\e':
         to = 'e';
         break;
     case '"':
         to = '"';
         break;
     default:
         return false;
     }
 
     if (out < end)
         *out = '\\';
     ++out;
     if (out < end)
         *out = to;
     ++out;
 
     *dst = out;
     return true;
 }
 
 static bool escape_null(unsigned char c, char **dst, char *end)
 {
     char *out = *dst;
 
     if (c)
         return false;
 
     if (out < end)
         *out = '\\';
     ++out;
     if (out < end)
         *out = '0';
     ++out;
 
     *dst = out;
     return true;
 }
 
 static bool escape_octal(unsigned char c, char **dst, char *end)
 {
     char *out = *dst;
 
     if (out < end)
         *out = '\\';
     ++out;
     if (out < end)
         *out = ((c >> 6) & 0x07) + '0';
     ++out;
     if (out < end)
         *out = ((c >> 3) & 0x07) + '0';
     ++out;
     if (out < end)
         *out = ((c >> 0) & 0x07) + '0';
     ++out;
 
     *dst = out;
     return true;
 }
 
 static bool escape_hex(unsigned char c, char **dst, char *end)
 {
     char *out = *dst;
 
     if (out < end)
         *out = '\\';
     ++out;
     if (out < end)
         *out = 'x';
     ++out;
     if (out < end)
         *out = hex_asc_hi(c);
     ++out;
     if (out < end)
         *out = hex_asc_lo(c);
     ++out;
 
     *dst = out;
     return true;
 }
 
 /**
  * string_escape_mem - quote characters in the given memory buffer
  * @src:    source buffer (unescaped)
  * @isz:    source buffer size
  * @dst:    destination buffer (escaped)
  * @osz:    destination buffer size
  * @flags:  combination of the flags
  * @only:   NULL-terminated string containing characters used to limit
  *      the selected escape class. If characters are included in @only
  *      that would not normally be escaped by the classes selected
  *      in @flags, they will be copied to @dst unescaped.
  *
  * Description:
  * The process of escaping byte buffer includes several parts. They are applied
  * in the following sequence.
  *
  *  1. The character is not matched to the one from @only string and thus
  *     must go as-is to the output.
  *  2. The character is matched to the printable and ASCII classes, if asked,
  *     and in case of match it passes through to the output.
  *  3. The character is matched to the printable or ASCII class, if asked,
  *     and in case of match it passes through to the output.
  *  4. The character is checked if it falls into the class given by @flags.
  *     %ESCAPE_OCTAL and %ESCAPE_HEX are going last since they cover any
  *     character. Note that they actually can't go together, otherwise
  *     %ESCAPE_HEX will be ignored.
  *
  * Caller must provide valid source and destination pointers. Be aware that
  * destination buffer will not be NULL-terminated, thus caller have to append
  * it if needs. The supported flags are::
  *
  *  %ESCAPE_SPACE: (special white space, not space itself)
  *      '\f' - form feed
  *      '\n' - new line
  *      '\r' - carriage return
  *      '\t' - horizontal tab
  *      '\v' - vertical tab
  *  %ESCAPE_SPECIAL:
  *      '\"' - double quote
  *      '\\' - backslash
  *      '\a' - alert (BEL)
  *      '\e' - escape
  *  %ESCAPE_NULL:
  *      '\0' - null
  *  %ESCAPE_OCTAL:
  *      '\NNN' - byte with octal value NNN (3 digits)
  *  %ESCAPE_ANY:
  *      all previous together
  *  %ESCAPE_NP:
  *      escape only non-printable characters, checked by isprint()
  *  %ESCAPE_ANY_NP:
  *      all previous together
  *  %ESCAPE_HEX:
  *      '\xHH' - byte with hexadecimal value HH (2 digits)
  *  %ESCAPE_NA:
  *      escape only non-ascii characters, checked by isascii()
  *  %ESCAPE_NAP:
  *      escape only non-printable or non-ascii characters
  *  %ESCAPE_APPEND:
  *      append characters from @only to be escaped by the given classes
  *
  * %ESCAPE_APPEND would help to pass additional characters to the escaped, when
  * one of %ESCAPE_NP, %ESCAPE_NA, or %ESCAPE_NAP is provided.
  *
  * One notable caveat, the %ESCAPE_NAP, %ESCAPE_NP and %ESCAPE_NA have the
  * higher priority than the rest of the flags (%ESCAPE_NAP is the highest).
  * It doesn't make much sense to use either of them without %ESCAPE_OCTAL
  * or %ESCAPE_HEX, because they cover most of the other character classes.
  * %ESCAPE_NAP can utilize %ESCAPE_SPACE or %ESCAPE_SPECIAL in addition to
  * the above.
  *
  * Return:
  * The total size of the escaped output that would be generated for
  * the given input and flags. To check whether the output was
  * truncated, compare the return value to osz. There is room left in
  * dst for a '\0' terminator if and only if ret < osz.
  */
 int string_escape_mem(const char *src, size_t isz, char *dst, size_t osz,
               unsigned int flags, const char *only)
 {
     char *p = dst;
     char *end = p + osz;
     bool is_dict = only && *only;
     bool is_append = flags & ESCAPE_APPEND;
 
     while (isz--) {
         unsigned char c = *src++;
         bool in_dict = is_dict && strchr(only, c);
 
         /*
          * Apply rules in the following sequence:
          *  - the @only string is supplied and does not contain a
          *    character under question
          *  - the character is printable and ASCII, when @flags has
          *    %ESCAPE_NAP bit set
          *  - the character is printable, when @flags has
          *    %ESCAPE_NP bit set
          *  - the character is ASCII, when @flags has
          *    %ESCAPE_NA bit set
          *  - the character doesn't fall into a class of symbols
          *    defined by given @flags
          * In these cases we just pass through a character to the
          * output buffer.
          *
          * When %ESCAPE_APPEND is passed, the characters from @only
          * have been excluded from the %ESCAPE_NAP, %ESCAPE_NP, and
          * %ESCAPE_NA cases.
          */
         if (!(is_append || in_dict) && is_dict &&
                       escape_passthrough(c, &p, end))
             continue;
 
         if (!(is_append && in_dict) && isascii(c) && isprint(c) &&
             flags & ESCAPE_NAP && escape_passthrough(c, &p, end))
             continue;
 
         if (!(is_append && in_dict) && isprint(c) &&
             flags & ESCAPE_NP && escape_passthrough(c, &p, end))
             continue;
 
         if (!(is_append && in_dict) && isascii(c) &&
             flags & ESCAPE_NA && escape_passthrough(c, &p, end))
             continue;
 
         if (flags & ESCAPE_SPACE && escape_space(c, &p, end))
             continue;
 
         if (flags & ESCAPE_SPECIAL && escape_special(c, &p, end))
             continue;
 
         if (flags & ESCAPE_NULL && escape_null(c, &p, end))
             continue;
 
         /* ESCAPE_OCTAL and ESCAPE_HEX always go last */
         if (flags & ESCAPE_OCTAL && escape_octal(c, &p, end))
             continue;
 
         if (flags & ESCAPE_HEX && escape_hex(c, &p, end))
             continue;
 
         escape_passthrough(c, &p, end);
     }
 
     return p - dst;
 }
 EXPORT_SYMBOL(string_escape_mem);
 
 /*
  * Return an allocated string that has been escaped of special characters
  * and double quotes, making it safe to log in quotes.
  */
 char *kstrdup_quotable(const char *src, gfp_t gfp)
 {
     size_t slen, dlen;
     char *dst;
     const int flags = ESCAPE_HEX;
     const char esc[] = "\f\n\r\t\v\a\e\\\"";
 
     if (!src)
         return NULL;
     slen = strlen(src);
 
     dlen = string_escape_mem(src, slen, NULL, 0, flags, esc);
     dst = kmalloc(dlen + 1, gfp);
     if (!dst)
         return NULL;
 
     WARN_ON(string_escape_mem(src, slen, dst, dlen, flags, esc) != dlen);
     dst[dlen] = '\0';
 
     return dst;
 }
 EXPORT_SYMBOL_GPL(kstrdup_quotable);
 
 /*
  * Returns allocated NULL-terminated string containing process
  * command line, with inter-argument NULLs replaced with spaces,
  * and other special characters escaped.
  */
 char *kstrdup_quotable_cmdline(struct task_struct *task, gfp_t gfp)
 {
     char *buffer, *quoted;
     int i, res;
 
     buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
     if (!buffer)
         return NULL;
 
     res = get_cmdline(task, buffer, PAGE_SIZE - 1);
     buffer[res] = '\0';
 
     /* Collapse trailing NULLs, leave res pointing to last non-NULL. */
     while (--res >= 0 && buffer[res] == '\0')
         ;
 
     /* Replace inter-argument NULLs. */
     for (i = 0; i <= res; i++)
         if (buffer[i] == '\0')
             buffer[i] = ' ';
 
     /* Make sure result is printable. */
     quoted = kstrdup_quotable(buffer, gfp);
     kfree(buffer);
     return quoted;
 }
 EXPORT_SYMBOL_GPL(kstrdup_quotable_cmdline);
 
 /*
  * Returns allocated NULL-terminated string containing pathname,
  * with special characters escaped, able to be safely logged. If
  * there is an error, the leading character will be "<".
  */
 char *kstrdup_quotable_file(struct file *file, gfp_t gfp)
 {
     char *temp, *pathname;
 
     if (!file)
         return kstrdup("<unknown>", gfp);
 
     /* We add 11 spaces for ' (deleted)' to be appended */
     temp = kmalloc(PATH_MAX + 11, GFP_KERNEL);
     if (!temp)
         return kstrdup("<no_memory>", gfp);
 
     pathname = file_path(file, temp, PATH_MAX + 11);
     if (IS_ERR(pathname))
         pathname = kstrdup("<too_long>", gfp);
     else
         pathname = kstrdup_quotable(pathname, gfp);
 
     kfree(temp);
     return pathname;
 }
 EXPORT_SYMBOL_GPL(kstrdup_quotable_file);
 
 /**
  * kasprintf_strarray - allocate and fill array of sequential strings
  * @gfp: flags for the slab allocator
  * @prefix: prefix to be used
  * @n: amount of lines to be allocated and filled
  *
  * Allocates and fills @n strings using pattern "%s-%zu", where prefix
  * is provided by caller. The caller is responsible to free them with
  * kfree_strarray() after use.
  *
  * Returns array of strings or NULL when memory can't be allocated.
  */
 char **kasprintf_strarray(gfp_t gfp, const char *prefix, size_t n)
 {
     char **names;
     size_t i;
 
     names = kcalloc(n + 1, sizeof(char *), gfp);
     if (!names)
         return NULL;
 
     for (i = 0; i < n; i++) {
         names[i] = kasprintf(gfp, "%s-%zu", prefix, i);
         if (!names[i]) {
             kfree_strarray(names, i);
             return NULL;
         }
     }
 
     return names;
 }
 EXPORT_SYMBOL_GPL(kasprintf_strarray);
 
 /**
  * kfree_strarray - free a number of dynamically allocated strings contained
  *                  in an array and the array itself
  *
  * @array: Dynamically allocated array of strings to free.
  * @n: Number of strings (starting from the beginning of the array) to free.
  *
  * Passing a non-NULL @array and @n == 0 as well as NULL @array are valid
  * use-cases. If @array is NULL, the function does nothing.
  */
 void kfree_strarray(char **array, size_t n)
 {
     unsigned int i;
 
     if (!array)
         return;
 
     for (i = 0; i < n; i++)
         kfree(array[i]);
     kfree(array);
 }
 EXPORT_SYMBOL_GPL(kfree_strarray);
 
 struct strarray {
     char **array;
     size_t n;
 };
 
 static void devm_kfree_strarray(struct device *dev, void *res)
 {
     struct strarray *array = res;
 
     kfree_strarray(array->array, array->n);
 }
 
 char **devm_kasprintf_strarray(struct device *dev, const char *prefix, size_t n)
 {
     struct strarray *ptr;
 
     ptr = devres_alloc(devm_kfree_strarray, sizeof(*ptr), GFP_KERNEL);
     if (!ptr)
         return ERR_PTR(-ENOMEM);
 
     ptr->array = kasprintf_strarray(GFP_KERNEL, prefix, n);
     if (!ptr->array) {
         devres_free(ptr);
         return ERR_PTR(-ENOMEM);
     }
 
     ptr->n = n;
     devres_add(dev, ptr);
 
     return ptr->array;
 }
 EXPORT_SYMBOL_GPL(devm_kasprintf_strarray);
 
 /**
  * strscpy_pad() - Copy a C-string into a sized buffer
  * @dest: Where to copy the string to
  * @src: Where to copy the string from
  * @count: Size of destination buffer
  *
  * Copy the string, or as much of it as fits, into the dest buffer.  The
  * behavior is undefined if the string buffers overlap.  The destination
  * buffer is always %NUL terminated, unless it's zero-sized.
  *
  * If the source string is shorter than the destination buffer, zeros
  * the tail of the destination buffer.
  *
  * For full explanation of why you may want to consider using the
  * 'strscpy' functions please see the function docstring for strscpy().
  *
  * Returns:
  * * The number of characters copied (not including the trailing %NUL)
  * * -E2BIG if count is 0 or @src was truncated.
  */
 ssize_t strscpy_pad(char *dest, const char *src, size_t count)
 {
     ssize_t written;
 
     written = strscpy(dest, src, count);
     if (written < 0 || written == count - 1)
         return written;
 
     memset(dest + written + 1, 0, count - written - 1);
 
     return written;
 }
 EXPORT_SYMBOL(strscpy_pad);
 
 /**
  * skip_spaces - Removes leading whitespace from @str.
  * @str: The string to be stripped.
  *
  * Returns a pointer to the first non-whitespace character in @str.
  */
 char *skip_spaces(const char *str)
 {
     while (isspace(*str))
         ++str;
     return (char *)str;
 }
 EXPORT_SYMBOL(skip_spaces);
 
 /**
  * strim - Removes leading and trailing whitespace from @s.
  * @s: The string to be stripped.
  *
  * Note that the first trailing whitespace is replaced with a %NUL-terminator
  * in the given string @s. Returns a pointer to the first non-whitespace
  * character in @s.
  */
 char *strim(char *s)
 {
     size_t size;
     char *end;
 
     size = strlen(s);
     if (!size)
         return s;
 
     end = s + size - 1;
     while (end >= s && isspace(*end))
         end--;
     *(end + 1) = '\0';
 
     return skip_spaces(s);
 }
 EXPORT_SYMBOL(strim);
 
 /**
  * sysfs_streq - return true if strings are equal, modulo trailing newline
  * @s1: one string
  * @s2: another string
  *
  * This routine returns true iff two strings are equal, treating both
  * NUL and newline-then-NUL as equivalent string terminations.  It's
  * geared for use with sysfs input strings, which generally terminate
  * with newlines but are compared against values without newlines.
  */
 bool sysfs_streq(const char *s1, const char *s2)
 {
     while (*s1 && *s1 == *s2) {
         s1++;
         s2++;
     }
 
     if (*s1 == *s2)
         return true;
     if (!*s1 && *s2 == '\n' && !s2[1])
         return true;
     if (*s1 == '\n' && !s1[1] && !*s2)
         return true;
     return false;
 }
 EXPORT_SYMBOL(sysfs_streq);
 
 /**
  * match_string - matches given string in an array
  * @array:  array of strings
  * @n:      number of strings in the array or -1 for NULL terminated arrays
  * @string: string to match with
  *
  * This routine will look for a string in an array of strings up to the
  * n-th element in the array or until the first NULL element.
  *
  * Historically the value of -1 for @n, was used to search in arrays that
  * are NULL terminated. However, the function does not make a distinction
  * when finishing the search: either @n elements have been compared OR
  * the first NULL element was found.
  *
  * Return:
  * index of a @string in the @array if matches, or %-EINVAL otherwise.
  */
 int match_string(const char * const *array, size_t n, const char *string)
 {
     int index;
     const char *item;
 
     for (index = 0; index < n; index++) {
         item = array[index];
         if (!item)
             break;
         if (!strcmp(item, string))
             return index;
     }
 
     return -EINVAL;
 }
 EXPORT_SYMBOL(match_string);
 
 /**
  * __sysfs_match_string - matches given string in an array
  * @array: array of strings
  * @n: number of strings in the array or -1 for NULL terminated arrays
  * @str: string to match with
  *
  * Returns index of @str in the @array or -EINVAL, just like match_string().
  * Uses sysfs_streq instead of strcmp for matching.
  *
  * This routine will look for a string in an array of strings up to the
  * n-th element in the array or until the first NULL element.
  *
  * Historically the value of -1 for @n, was used to search in arrays that
  * are NULL terminated. However, the function does not make a distinction
  * when finishing the search: either @n elements have been compared OR
  * the first NULL element was found.
  */
 int __sysfs_match_string(const char * const *array, size_t n, const char *str)
 {
     const char *item;
     int index;
 
     for (index = 0; index < n; index++) {
         item = array[index];
         if (!item)
             break;
         if (sysfs_streq(item, str))
             return index;
     }
 
     return -EINVAL;
 }
 EXPORT_SYMBOL(__sysfs_match_string);
 
 /**
  * strreplace - Replace all occurrences of character in string.
  * @s: The string to operate on.
  * @old: The character being replaced.
  * @new: The character @old is replaced with.
  *
  * Returns pointer to the nul byte at the end of @s.
  */
 char *strreplace(char *s, char old, char new)
 {
     for (; *s; ++s)
         if (*s == old)
             *s = new;
     return s;
 }
 EXPORT_SYMBOL(strreplace);
 
 /**
  * memcpy_and_pad - Copy one buffer to another with padding
  * @dest: Where to copy to
  * @dest_len: The destination buffer size
  * @src: Where to copy from
  * @count: The number of bytes to copy
  * @pad: Character to use for padding if space is left in destination.
  */
 void memcpy_and_pad(void *dest, size_t dest_len, const void *src, size_t count,
             int pad)
 {
     if (dest_len > count) {
         memcpy(dest, src, count);
         memset(dest + count, pad,  dest_len - count);
     } else {
         memcpy(dest, src, dest_len);
     }
 }
 EXPORT_SYMBOL(memcpy_and_pad);
 
 #ifdef CONFIG_FORTIFY_SOURCE
 /* These are placeholders for fortify compile-time warnings. */
 void __read_overflow2_field(size_t avail, size_t wanted) { }
 EXPORT_SYMBOL(__read_overflow2_field);
 void __write_overflow_field(size_t avail, size_t wanted) { }
 EXPORT_SYMBOL(__write_overflow_field);
 
 void fortify_panic(const char *name)
 {
     pr_emerg("detected buffer overflow in %s\n", name);
     BUG();
 }
 EXPORT_SYMBOL(fortify_panic);
 #endif /* CONFIG_FORTIFY_SOURCE */

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