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-rw-r--r--lib/string_helpers.c674
1 files changed, 674 insertions, 0 deletions
diff --git a/lib/string_helpers.c b/lib/string_helpers.c
new file mode 100644
index 000000000..7f2d5fbaf
--- /dev/null
+++ b/lib/string_helpers.c
@@ -0,0 +1,674 @@
+// 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/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;
+ 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 matched to the printable class, if asked, and in
+ * case of match it passes through to the output.
+ * 2. The character is not matched to the one from @only string and thus
+ * must go as-is to the output.
+ * 3. 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:
+ * '\\' - 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)
+ *
+ * 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;
+
+ while (isz--) {
+ unsigned char c = *src++;
+
+ /*
+ * Apply rules in the following sequence:
+ * - the character is printable, when @flags has
+ * %ESCAPE_NP bit set
+ * - the @only string is supplied and does not contain a
+ * character under question
+ * - 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.
+ */
+ if ((flags & ESCAPE_NP && isprint(c)) ||
+ (is_dict && !strchr(only, c))) {
+ /* do nothing */
+ } else {
+ 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);
+
+int string_escape_mem_ascii(const char *src, size_t isz, char *dst,
+ size_t osz)
+{
+ char *p = dst;
+ char *end = p + osz;
+
+ while (isz--) {
+ unsigned char c = *src++;
+
+ if (!isprint(c) || !isascii(c) || c == '"' || c == '\\')
+ escape_hex(c, &p, end);
+ else
+ escape_passthrough(c, &p, end);
+ }
+
+ return p - dst;
+}
+EXPORT_SYMBOL(string_escape_mem_ascii);
+
+/*
+ * 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);
+
+/**
+ * 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);
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