514 lines
10 KiB
C
514 lines
10 KiB
C
/*
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* Helpers for formatting and printing strings
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*
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* 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>
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#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/string.h>
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#include <linux/string_helpers.h>
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/**
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* string_get_size - get the size in the specified units
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* @size: The size to be converted in blocks
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* @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)
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* @buf: buffer to format to
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* @len: length of buffer
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*
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* 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
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* at least 9 bytes and will always be zero terminated.
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*
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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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};
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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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};
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static const char *const *const units_str[] = {
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[STRING_UNITS_10] = units_10,
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[STRING_UNITS_2] = units_2,
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};
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static const unsigned int divisor[] = {
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[STRING_UNITS_10] = 1000,
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[STRING_UNITS_2] = 1024,
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};
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int i, j;
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u32 remainder = 0, sf_cap, exp;
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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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i = 0;
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if (!size)
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goto out;
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while (blk_size >= divisor[units]) {
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remainder = do_div(blk_size, divisor[units]);
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i++;
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}
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exp = divisor[units] / (u32)blk_size;
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/*
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* size must be strictly greater than exp here to ensure that remainder
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* is greater than divisor[units] coming out of the if below.
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*/
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if (size > exp) {
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remainder = do_div(size, divisor[units]);
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remainder *= blk_size;
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i++;
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} else {
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remainder *= size;
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}
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size *= blk_size;
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size += remainder / divisor[units];
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remainder %= divisor[units];
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while (size >= divisor[units]) {
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remainder = do_div(size, divisor[units]);
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i++;
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}
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sf_cap = size;
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for (j = 0; sf_cap*10 < 1000; j++)
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sf_cap *= 10;
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if (j) {
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remainder *= 1000;
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remainder /= divisor[units];
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snprintf(tmp, sizeof(tmp), ".%03u", remainder);
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tmp[j+1] = '\0';
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}
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out:
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if (i >= ARRAY_SIZE(units_2))
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unit = "UNK";
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else
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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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}
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EXPORT_SYMBOL(string_get_size);
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static bool unescape_space(char **src, char **dst)
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{
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char *p = *dst, *q = *src;
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switch (*q) {
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case 'n':
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*p = '\n';
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break;
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case 'r':
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*p = '\r';
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break;
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case 't':
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*p = '\t';
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break;
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case 'v':
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*p = '\v';
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break;
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case 'f':
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*p = '\f';
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break;
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default:
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return false;
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}
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*dst += 1;
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*src += 1;
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return true;
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}
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static bool unescape_octal(char **src, char **dst)
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{
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char *p = *dst, *q = *src;
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u8 num;
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if (isodigit(*q) == 0)
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return false;
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num = (*q++) & 7;
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while (num < 32 && isodigit(*q) && (q - *src < 3)) {
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num <<= 3;
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num += (*q++) & 7;
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}
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*p = num;
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*dst += 1;
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*src = q;
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return true;
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}
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static bool unescape_hex(char **src, char **dst)
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{
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char *p = *dst, *q = *src;
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int digit;
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u8 num;
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if (*q++ != 'x')
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return false;
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num = digit = hex_to_bin(*q++);
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if (digit < 0)
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return false;
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digit = hex_to_bin(*q);
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if (digit >= 0) {
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q++;
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num = (num << 4) | digit;
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}
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*p = num;
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*dst += 1;
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*src = q;
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return true;
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}
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static bool unescape_special(char **src, char **dst)
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{
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char *p = *dst, *q = *src;
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switch (*q) {
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case '\"':
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*p = '\"';
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break;
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case '\\':
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*p = '\\';
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break;
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case 'a':
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*p = '\a';
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break;
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case 'e':
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*p = '\e';
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break;
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default:
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return false;
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}
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*dst += 1;
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*src += 1;
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return true;
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}
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/**
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* string_unescape - unquote characters in the given string
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* @src: source buffer (escaped)
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* @dst: destination buffer (unescaped)
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* @size: size of the destination buffer (0 to unlimit)
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* @flags: combination of the flags (bitwise OR):
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* %UNESCAPE_SPACE:
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* '\f' - form feed
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* '\n' - new line
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* '\r' - carriage return
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* '\t' - horizontal tab
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* '\v' - vertical tab
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* %UNESCAPE_OCTAL:
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* '\NNN' - byte with octal value NNN (1 to 3 digits)
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* %UNESCAPE_HEX:
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* '\xHH' - byte with hexadecimal value HH (1 to 2 digits)
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* %UNESCAPE_SPECIAL:
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* '\"' - double quote
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* '\\' - backslash
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* '\a' - alert (BEL)
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* '\e' - escape
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* %UNESCAPE_ANY:
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* all previous together
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*
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* Description:
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* The function unquotes characters in the given string.
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*
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* Because the size of the output will be the same as or less than the size of
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* the input, the transformation may be performed in place.
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*
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* Caller must provide valid source and destination pointers. Be aware that
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* destination buffer will always be NULL-terminated. Source string must be
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* NULL-terminated as well.
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*
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* Return:
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* The amount of the characters processed to the destination buffer excluding
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* trailing '\0' is returned.
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*/
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int string_unescape(char *src, char *dst, size_t size, unsigned int flags)
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{
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char *out = dst;
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while (*src && --size) {
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if (src[0] == '\\' && src[1] != '\0' && size > 1) {
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src++;
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size--;
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if (flags & UNESCAPE_SPACE &&
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unescape_space(&src, &out))
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continue;
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if (flags & UNESCAPE_OCTAL &&
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unescape_octal(&src, &out))
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continue;
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if (flags & UNESCAPE_HEX &&
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unescape_hex(&src, &out))
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continue;
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if (flags & UNESCAPE_SPECIAL &&
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unescape_special(&src, &out))
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continue;
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*out++ = '\\';
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}
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*out++ = *src++;
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}
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*out = '\0';
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return out - dst;
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}
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EXPORT_SYMBOL(string_unescape);
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static bool escape_passthrough(unsigned char c, char **dst, char *end)
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{
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char *out = *dst;
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if (out < end)
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*out = c;
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*dst = out + 1;
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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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{
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char *out = *dst;
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unsigned char to;
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switch (c) {
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case '\n':
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to = 'n';
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break;
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case '\r':
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to = 'r';
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break;
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case '\t':
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to = 't';
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break;
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case '\v':
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to = 'v';
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break;
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case '\f':
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to = 'f';
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break;
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default:
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return false;
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}
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if (out < end)
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*out = '\\';
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++out;
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if (out < end)
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*out = to;
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++out;
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*dst = out;
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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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{
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char *out = *dst;
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unsigned char to;
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switch (c) {
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case '\\':
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to = '\\';
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break;
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case '\a':
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to = 'a';
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break;
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case '\e':
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to = 'e';
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break;
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default:
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return false;
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}
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if (out < end)
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*out = '\\';
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++out;
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if (out < end)
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*out = to;
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++out;
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*dst = out;
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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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{
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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)
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*out = '\\';
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++out;
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if (out < end)
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*out = '0';
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++out;
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*dst = out;
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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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{
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char *out = *dst;
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if (out < end)
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*out = '\\';
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++out;
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if (out < end)
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*out = ((c >> 6) & 0x07) + '0';
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++out;
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if (out < end)
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*out = ((c >> 3) & 0x07) + '0';
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++out;
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if (out < end)
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*out = ((c >> 0) & 0x07) + '0';
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++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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{
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char *out = *dst;
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if (out < end)
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*out = '\\';
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++out;
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if (out < end)
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*out = 'x';
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++out;
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if (out < end)
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*out = hex_asc_hi(c);
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++out;
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if (out < end)
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*out = hex_asc_lo(c);
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++out;
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*dst = out;
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return true;
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}
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/**
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* string_escape_mem - quote characters in the given memory buffer
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* @src: source buffer (unescaped)
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* @isz: source buffer size
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* @dst: destination buffer (escaped)
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* @osz: destination buffer size
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* @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
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* '\n' - new line
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* '\r' - carriage return
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* '\t' - horizontal tab
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* '\v' - vertical tab
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* %ESCAPE_SPECIAL:
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* '\\' - backslash
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* '\a' - alert (BEL)
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* '\e' - escape
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* %ESCAPE_NULL:
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* '\0' - null
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* %ESCAPE_OCTAL:
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* '\NNN' - byte with octal value NNN (3 digits)
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* %ESCAPE_ANY:
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* all previous together
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* %ESCAPE_NP:
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* escape only non-printable characters (checked by isprint)
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* %ESCAPE_ANY_NP:
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* all previous together
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* %ESCAPE_HEX:
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* '\xHH' - byte with hexadecimal value HH (2 digits)
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* @only: NULL-terminated string containing characters used to limit
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* the selected escape class. If characters are included in @only
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* that would not normally be escaped by the classes selected
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* in @flags, they will be copied to @dst unescaped.
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*
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* Description:
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* The process of escaping byte buffer includes several parts. They are applied
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* in the following sequence.
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* 1. The character is matched to the printable class, if asked, and in
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* 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.
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* %ESCAPE_OCTAL and %ESCAPE_HEX are going last since they cover any
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* character. Note that they actually can't go together, otherwise
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* %ESCAPE_HEX will be ignored.
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*
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* Caller must provide valid source and destination pointers. Be aware that
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* destination buffer will not be NULL-terminated, thus caller have to append
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* it if needs.
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*
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* Return:
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* The total size of the escaped output that would be generated for
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* the given input and flags. To check whether the output was
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* truncated, compare the return value to osz. There is room left in
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* 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--) {
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unsigned char c = *src++;
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/*
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* Apply rules in the following sequence:
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* - the character is printable, when @flags has
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* %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
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* - the character doesn't fall into a class of symbols
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* defined by given @flags
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* In these cases we just pass through a character to the
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* output buffer.
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*/
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if ((flags & ESCAPE_NP && isprint(c)) ||
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(is_dict && !strchr(only, c))) {
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/* do nothing */
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} else {
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if (flags & ESCAPE_SPACE && escape_space(c, &p, end))
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continue;
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if (flags & ESCAPE_SPECIAL && escape_special(c, &p, end))
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continue;
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if (flags & ESCAPE_NULL && escape_null(c, &p, end))
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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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}
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EXPORT_SYMBOL(string_escape_mem);
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