Merge tag 'timers_urgent_for_v6.13_rc1' of git://git.kernel.org/pub/scm/linux/kernel...

[drm/drm-misc.git] / lib / string_helpers.c

// 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>
#include <kunit/test.h>
#include <kunit/test-bug.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), whether to include space separator
 * @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.
 *
 * Return value: number of characters of output that would have been written
 * (which may be greater than len, if output was truncated).
 */
int string_get_size(u64 size, u64 blk_size, const enum string_size_units units,
                    char *buf, int len)
{
        enum string_size_units units_base = units & STRING_UNITS_MASK;
        static const char *const units_10[] = {
                "", "k", "M", "G", "T", "P", "E", "Z", "Y",
        };
        static const char *const units_2[] = {
                "", "Ki", "Mi", "Gi", "Ti", "Pi", "Ei", "Zi", "Yi",
        };
        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[12];
        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_base]^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_base]);
                i++;
        }

        while (size >> 32) {
                do_div(size, divisor[units_base]);
                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_base]) {
                remainder = do_div(size, divisor[units_base]);
                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_base == STRING_UNITS_2) {
                /* express the remainder as a decimal.  It's currently the
                 * numerator of a fraction whose denominator is
                 * divisor[units_base], 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_base][i];

        return snprintf(buf, len, "%u%s%s%s%s", (u32)size, tmp,
                        (units & STRING_UNITS_NO_SPACE) ? "" : " ",
                        unit,
                        (units & STRING_UNITS_NO_BYTES) ? "" : "B");
}
EXPORT_SYMBOL(string_get_size);

/**
 * parse_int_array_user - Split string into a sequence of integers
 * @from:       The user space buffer to read from
 * @count:      The maximum number of bytes to read
 * @array:      Returned pointer to sequence of integers
 *
 * On success @array is allocated and initialized with a sequence of
 * integers extracted from the @from plus an additional element that
 * begins the sequence and specifies the integers count.
 *
 * Caller takes responsibility for freeing @array when it is no longer
 * needed.
 */
int parse_int_array_user(const char __user *from, size_t count, int **array)
{
        int *ints, nints;
        char *buf;
        int ret = 0;

        buf = memdup_user_nul(from, count);
        if (IS_ERR(buf))
                return PTR_ERR(buf);

        get_options(buf, 0, &nints);
        if (!nints) {
                ret = -ENOENT;
                goto free_buf;
        }

        ints = kcalloc(nints + 1, sizeof(*ints), GFP_KERNEL);
        if (!ints) {
                ret = -ENOMEM;
                goto free_buf;
        }

        get_options(buf, nints + 1, ints);
        *array = ints;

free_buf:
        kfree(buf);
        return ret;
}
EXPORT_SYMBOL(parse_int_array_user);

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;

        if (!size)
                size = SIZE_MAX;

        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);

/*
 * Returns duplicate string in which the @old characters are replaced by @new.
 */
char *kstrdup_and_replace(const char *src, char old, char new, gfp_t gfp)
{
        char *dst;

        dst = kstrdup(src, gfp);
        if (!dst)
                return NULL;

        return strreplace(dst, old, new);
}
EXPORT_SYMBOL_GPL(kstrdup_and_replace);

/**
 * 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);

/**
 * 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.
 * @str: The string to operate on.
 * @old: The character being replaced.
 * @new: The character @old is replaced with.
 *
 * Replaces the each @old character with a @new one in the given string @str.
 *
 * Return: pointer to the string @str itself.
 */
char *strreplace(char *str, char old, char new)
{
        char *s = str;

        for (; *s; ++s)
                if (*s == old)
                        *s = new;
        return str;
}
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);

static const char * const fortify_func_name[] = {
#define MAKE_FORTIFY_FUNC_NAME(func)    [MAKE_FORTIFY_FUNC(func)] = #func
        EACH_FORTIFY_FUNC(MAKE_FORTIFY_FUNC_NAME)
#undef  MAKE_FORTIFY_FUNC_NAME
};

void __fortify_report(const u8 reason, const size_t avail, const size_t size)
{
        const u8 func = FORTIFY_REASON_FUNC(reason);
        const bool write = FORTIFY_REASON_DIR(reason);
        const char *name;

        name = fortify_func_name[umin(func, FORTIFY_FUNC_UNKNOWN)];
        WARN(1, "%s: detected buffer overflow: %zu byte %s of buffer size %zu\n",
                 name, size, str_read_write(!write), avail);
}
EXPORT_SYMBOL(__fortify_report);

void __fortify_panic(const u8 reason, const size_t avail, const size_t size)
{
        __fortify_report(reason, avail, size);
        BUG();
}
EXPORT_SYMBOL(__fortify_panic);
#endif /* CONFIG_FORTIFY_SOURCE */