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lib/string_helpers.c
13.5 KB
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/* * Helpers for formatting and printing strings * * Copyright 31 August 2008 James Bottomley |
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* Copyright (C) 2013, Intel Corporation |
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*/ |
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#include <linux/bug.h> |
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#include <linux/kernel.h> #include <linux/math64.h> |
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#include <linux/export.h> |
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#include <linux/ctype.h> |
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#include <linux/errno.h> |
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#include <linux/fs.h> #include <linux/limits.h> |
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#include <linux/mm.h> |
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#include <linux/slab.h> |
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#include <linux/string.h> |
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#include <linux/string_helpers.h> /** * string_get_size - get the size in the specified units |
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* @size: The size to be converted in blocks * @blk_size: Size of the block (use 1 for size in bytes) |
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* @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 |
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* giving the size in the required units. @buf should have room for * at least 9 bytes and will always be zero terminated. |
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* */ |
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void string_get_size(u64 size, u64 blk_size, const enum string_size_units units, |
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char *buf, int len) |
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{ |
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static const char *const units_10[] = { |
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"B", "kB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB" |
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}; static const char *const units_2[] = { |
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"B", "KiB", "MiB", "GiB", "TiB", "PiB", "EiB", "ZiB", "YiB" |
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}; static const char *const *const units_str[] = { [STRING_UNITS_10] = units_10, |
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[STRING_UNITS_2] = units_2, }; |
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static const unsigned int divisor[] = { |
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[STRING_UNITS_10] = 1000, [STRING_UNITS_2] = 1024, }; |
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static const unsigned int rounding[] = { 500, 50, 5 }; int i = 0, j; u32 remainder = 0, sf_cap; |
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char tmp[8]; |
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const char *unit; |
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tmp[0] = '\0'; |
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if (blk_size == 0) size = 0; if (size == 0) |
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goto out; |
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|
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/* 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]); |
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i++; } |
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while (size >> 32) { do_div(size, divisor[units]); |
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i++; |
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} |
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/* now perform the actual multiplication keeping i as the sum of the * two logarithms */ |
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size *= blk_size; |
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|
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/* and logarithmically reduce it until it's just under the divisor */ |
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while (size >= divisor[units]) { remainder = do_div(size, divisor[units]); i++; |
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} |
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/* work out in j how many digits of precision we need from the * remainder */ |
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sf_cap = size; for (j = 0; sf_cap*10 < 1000; j++) sf_cap *= 10; |
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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 */ |
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remainder *= 1000; |
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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) { |
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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]; |
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snprintf(buf, len, "%u%s %s", (u32)size, |
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tmp, unit); |
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} EXPORT_SYMBOL(string_get_size); |
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static bool unescape_space(char **src, char **dst) { char *p = *dst, *q = *src; switch (*q) { case 'n': *p = ' '; 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; } |
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/** * 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 (bitwise OR): * %UNESCAPE_SPACE: * '\f' - form feed * ' ' - 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 * * 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. * * Return: * The amount of the characters processed to the destination buffer excluding * trailing '\0' is returned. */ |
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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); |
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static bool escape_passthrough(unsigned char c, char **dst, char *end) |
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{ char *out = *dst; |
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if (out < end) *out = c; *dst = out + 1; return true; |
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} |
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static bool escape_space(unsigned char c, char **dst, char *end) |
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{ char *out = *dst; unsigned char to; |
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switch (c) { case ' ': to = 'n'; break; case '\r': to = 'r'; break; case '\t': to = 't'; break; case '\v': to = 'v'; break; case '\f': to = 'f'; break; default: |
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return false; |
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} |
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if (out < end) *out = '\\'; ++out; if (out < end) *out = to; ++out; |
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|
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*dst = out; return true; |
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} |
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static bool escape_special(unsigned char c, char **dst, char *end) |
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{ char *out = *dst; unsigned char to; |
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switch (c) { case '\\': to = '\\'; break; case '\a': to = 'a'; break; case '\e': to = 'e'; break; default: |
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return false; |
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} |
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if (out < end) *out = '\\'; ++out; if (out < end) *out = to; ++out; |
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*dst = out; return true; |
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} |
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static bool escape_null(unsigned char c, char **dst, char *end) |
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{ char *out = *dst; |
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if (c) |
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return false; |
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if (out < end) *out = '\\'; ++out; if (out < end) *out = '0'; ++out; |
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*dst = out; return true; |
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} |
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static bool escape_octal(unsigned char c, char **dst, char *end) |
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{ char *out = *dst; |
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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; |
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*dst = out; |
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return true; |
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} |
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static bool escape_hex(unsigned char c, char **dst, char *end) |
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{ char *out = *dst; |
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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; |
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*dst = out; |
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return true; |
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} /** * 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 (bitwise OR): |
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* %ESCAPE_SPACE: (special white space, not space itself) |
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* '\f' - form feed * ' ' - 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) |
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* @only: NULL-terminated string containing characters used to limit * the selected escape class. If characters are included in @only |
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* that would not normally be escaped by the classes selected * in @flags, they will be copied to @dst unescaped. |
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* * 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. |
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* 2. The character is not matched to the one from @only string and thus |
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* must go as-is to the output. |
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* 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. * * Return: |
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* 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. |
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*/ |
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int string_escape_mem(const char *src, size_t isz, char *dst, size_t osz, |
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unsigned int flags, const char *only) |
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{ |
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char *p = dst; |
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char *end = p + osz; |
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bool is_dict = only && *only; |
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while (isz--) { unsigned char c = *src++; /* * Apply rules in the following sequence: * - the character is printable, when @flags has * %ESCAPE_NP bit set |
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* - the @only string is supplied and does not contain a |
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* 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)) || |
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(is_dict && !strchr(only, c))) { |
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/* do nothing */ } else { |
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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; |
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/* ESCAPE_OCTAL and ESCAPE_HEX always go last */ |
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if (flags & ESCAPE_OCTAL && escape_octal(c, &p, end)) |
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continue; |
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if (flags & ESCAPE_HEX && escape_hex(c, &p, end)) |
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continue; |
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} |
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escape_passthrough(c, &p, end); |
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} |
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return p - dst; |
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} EXPORT_SYMBOL(string_escape_mem); |
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/* * 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 \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); |
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/* * 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_TEMPORARY); 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); |
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/* * 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_TEMPORARY); 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); |