blob: 4f877e9551d5b7116b5e1f028c1eab4d19516c5f [file] [log] [blame]
// 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);
}
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 */