diff options
Diffstat (limited to 'kernel/lib/string_helpers.c')
| -rw-r--r-- | kernel/lib/string_helpers.c | 507 |
1 files changed, 507 insertions, 0 deletions
diff --git a/kernel/lib/string_helpers.c b/kernel/lib/string_helpers.c new file mode 100644 index 000000000..c98ae818e --- /dev/null +++ b/kernel/lib/string_helpers.c @@ -0,0 +1,507 @@ +/* + * 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/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, + }; + int i, j; + u32 remainder = 0, sf_cap, exp; + char tmp[8]; + const char *unit; + + tmp[0] = '\0'; + i = 0; + if (!size) + goto out; + + while (blk_size >= divisor[units]) { + remainder = do_div(blk_size, divisor[units]); + i++; + } + + exp = divisor[units] / (u32)blk_size; + if (size >= exp) { + remainder = do_div(size, divisor[units]); + remainder *= blk_size; + i++; + } else { + remainder *= size; + } + + size *= blk_size; + size += remainder / divisor[units]; + remainder %= divisor[units]; + + while (size >= divisor[units]) { + remainder = do_div(size, divisor[units]); + i++; + } + + sf_cap = size; + for (j = 0; sf_cap*10 < 1000; j++) + sf_cap *= 10; + + if (j) { + remainder *= 1000; + remainder /= divisor[units]; + 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 (bitwise OR): + * %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 + * + * 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. + */ +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 (bitwise OR): + * %ESCAPE_SPACE: + * '\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) + * @esc: NULL-terminated string of characters any of which, if found in + * the source, has to be escaped + * + * 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 @esc 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. + * + * 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 *esc) +{ + char *p = dst; + char *end = p + osz; + bool is_dict = esc && *esc; + + while (isz--) { + unsigned char c = *src++; + + /* + * Apply rules in the following sequence: + * - the character is printable, when @flags has + * %ESCAPE_NP bit set + * - the @esc 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(esc, 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); |