lib/string_helpers: introduce generic string_unescape
There are several places in kernel where modules unescapes input to convert C-Style Escape Sequences into byte codes. The patch provides generic implementation of such approach. Test cases are also included into the patch. [akpm@linux-foundation.org: clarify comment] [akpm@linux-foundation.org: export get_random_int() to modules] Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Samuel Thibault <samuel.thibault@ens-lyon.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Jason Baron <jbaron@redhat.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: William Hubbs <w.d.hubbs@gmail.com> Cc: Chris Brannon <chris@the-brannons.com> Cc: Kirk Reiser <kirk@braille.uwo.ca> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andy Shevchenko
Linus Torvalds
Родитель
e1d12f3270
Коммит
16c7fa0582
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@ -1485,6 +1485,7 @@ unsigned int get_random_int(void)
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return ret;
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}
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EXPORT_SYMBOL(get_random_int);
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/*
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* randomize_range() returns a start address such that
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@ -13,4 +13,62 @@ enum string_size_units {
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int string_get_size(u64 size, enum string_size_units units,
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char *buf, int len);
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#define UNESCAPE_SPACE 0x01
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#define UNESCAPE_OCTAL 0x02
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#define UNESCAPE_HEX 0x04
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#define UNESCAPE_SPECIAL 0x08
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#define UNESCAPE_ANY \
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(UNESCAPE_SPACE | UNESCAPE_OCTAL | UNESCAPE_HEX | UNESCAPE_SPECIAL)
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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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* Returns amount of characters processed to the destination buffer excluding
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* trailing '\0'.
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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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int string_unescape(char *src, char *dst, size_t size, unsigned int flags);
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static inline int string_unescape_inplace(char *buf, unsigned int flags)
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{
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return string_unescape(buf, buf, 0, flags);
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}
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static inline int string_unescape_any(char *src, char *dst, size_t size)
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{
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return string_unescape(src, dst, size, UNESCAPE_ANY);
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}
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static inline int string_unescape_any_inplace(char *buf)
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{
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return string_unescape_any(buf, buf, 0);
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}
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#endif
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@ -1463,5 +1463,8 @@ source "lib/Kconfig.kgdb"
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source "lib/Kconfig.kmemcheck"
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config TEST_STRING_HELPERS
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tristate "Test functions located in the string_helpers module at runtime"
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config TEST_KSTRTOX
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tristate "Test kstrto*() family of functions at runtime"
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@ -22,8 +22,10 @@ lib-y += kobject.o klist.o
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obj-y += bcd.o div64.o sort.o parser.o halfmd4.o debug_locks.o random32.o \
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bust_spinlocks.o hexdump.o kasprintf.o bitmap.o scatterlist.o \
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string_helpers.o gcd.o lcm.o list_sort.o uuid.o flex_array.o \
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gcd.o lcm.o list_sort.o uuid.o flex_array.o \
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bsearch.o find_last_bit.o find_next_bit.o llist.o memweight.o kfifo.o
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obj-y += string_helpers.o
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obj-$(CONFIG_TEST_STRING_HELPERS) += test-string_helpers.o
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obj-y += kstrtox.o
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obj-$(CONFIG_TEST_KSTRTOX) += test-kstrtox.o
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@ -2,10 +2,12 @@
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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/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/string_helpers.h>
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/**
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@ -66,3 +68,134 @@ int string_get_size(u64 size, const enum string_size_units units,
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return 0;
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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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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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@ -0,0 +1,103 @@
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/*
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* Test cases for lib/string_helpers.c module.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/random.h>
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#include <linux/string.h>
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#include <linux/string_helpers.h>
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struct test_string {
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const char *in;
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const char *out;
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unsigned int flags;
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};
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static const struct test_string strings[] __initconst = {
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{
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.in = "\\f\\ \\n\\r\\t\\v",
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.out = "\f\\ \n\r\t\v",
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.flags = UNESCAPE_SPACE,
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},
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{
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.in = "\\40\\1\\387\\0064\\05\\040\\8a\\110\\777",
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.out = " \001\00387\0064\005 \\8aH?7",
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.flags = UNESCAPE_OCTAL,
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},
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{
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.in = "\\xv\\xa\\x2c\\xD\\x6f2",
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.out = "\\xv\n,\ro2",
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.flags = UNESCAPE_HEX,
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},
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{
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.in = "\\h\\\\\\\"\\a\\e\\",
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.out = "\\h\\\"\a\e\\",
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.flags = UNESCAPE_SPECIAL,
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},
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};
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static void __init test_string_unescape(unsigned int flags, bool inplace)
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{
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char in[256];
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char out_test[256];
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char out_real[256];
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int i, p = 0, q_test = 0, q_real = sizeof(out_real);
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for (i = 0; i < ARRAY_SIZE(strings); i++) {
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const char *s = strings[i].in;
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int len = strlen(strings[i].in);
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/* Copy string to in buffer */
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memcpy(&in[p], s, len);
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p += len;
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/* Copy expected result for given flags */
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if (flags & strings[i].flags) {
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s = strings[i].out;
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len = strlen(strings[i].out);
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}
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memcpy(&out_test[q_test], s, len);
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q_test += len;
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}
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in[p++] = '\0';
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/* Call string_unescape and compare result */
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if (inplace) {
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memcpy(out_real, in, p);
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if (flags == UNESCAPE_ANY)
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q_real = string_unescape_any_inplace(out_real);
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else
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q_real = string_unescape_inplace(out_real, flags);
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} else if (flags == UNESCAPE_ANY) {
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q_real = string_unescape_any(in, out_real, q_real);
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} else {
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q_real = string_unescape(in, out_real, q_real, flags);
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}
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if (q_real != q_test || memcmp(out_test, out_real, q_test)) {
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pr_warn("Test failed: flags = %u\n", flags);
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print_hex_dump(KERN_WARNING, "Input: ",
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DUMP_PREFIX_NONE, 16, 1, in, p - 1, true);
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print_hex_dump(KERN_WARNING, "Expected: ",
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DUMP_PREFIX_NONE, 16, 1, out_test, q_test, true);
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print_hex_dump(KERN_WARNING, "Got: ",
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DUMP_PREFIX_NONE, 16, 1, out_real, q_real, true);
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}
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}
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static int __init test_string_helpers_init(void)
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{
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unsigned int i;
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pr_info("Running tests...\n");
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for (i = 0; i < UNESCAPE_ANY + 1; i++)
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test_string_unescape(i, false);
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test_string_unescape(get_random_int() % (UNESCAPE_ANY + 1), true);
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return -EINVAL;
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}
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module_init(test_string_helpers_init);
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MODULE_LICENSE("Dual BSD/GPL");
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