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Commit 16c7fa05 authored by Andy Shevchenko's avatar Andy Shevchenko Committed by Linus Torvalds
Browse files

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: default avatarAndy 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e1d12f32

drivers/char/random.c

+1 −0
Original line number Original line Diff line number Diff line
@@ -1485,6 +1485,7 @@ unsigned int get_random_int(void) 




	return ret;

	return ret;

}

}

EXPORT_SYMBOL(get_random_int);





/*

/*

 * randomize_range() returns a start address such that

 * randomize_range() returns a start address such that

include/linux/string_helpers.h

+58 −0
Original line number Original line Diff line number Diff line
@@ -13,4 +13,62 @@ enum string_size_units { 
int string_get_size(u64 size, enum string_size_units units,

int string_get_size(u64 size, enum string_size_units units,

		    char *buf, int len);

		    char *buf, int len);





#define UNESCAPE_SPACE		0x01

#define UNESCAPE_OCTAL		0x02

#define UNESCAPE_HEX		0x04

#define UNESCAPE_SPECIAL	0x08

#define UNESCAPE_ANY		\

	(UNESCAPE_SPACE | UNESCAPE_OCTAL | UNESCAPE_HEX | UNESCAPE_SPECIAL)



/**

 * 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

 *

 * Returns amount of characters processed to the destination buffer excluding

 * trailing '\0'.

 *

 * 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.

 */

int string_unescape(char *src, char *dst, size_t size, unsigned int flags);



static inline int string_unescape_inplace(char *buf, unsigned int flags)

{

	return string_unescape(buf, buf, 0, flags);

}



static inline int string_unescape_any(char *src, char *dst, size_t size)

{

	return string_unescape(src, dst, size, UNESCAPE_ANY);

}



static inline int string_unescape_any_inplace(char *buf)

{

	return string_unescape_any(buf, buf, 0);

}



#endif
 
#endif

lib/Kconfig.debug

+3 −0
Original line number Original line Diff line number Diff line
@@ -1463,5 +1463,8 @@ source "lib/Kconfig.kgdb" 




source "lib/Kconfig.kmemcheck"

source "lib/Kconfig.kmemcheck"





config TEST_STRING_HELPERS

	tristate "Test functions located in the string_helpers module at runtime"



config TEST_KSTRTOX

config TEST_KSTRTOX

	tristate "Test kstrto*() family of functions at runtime"
 
	tristate "Test kstrto*() family of functions at runtime"

lib/Makefile

+3 −1
Original line number Original line Diff line number Diff line
@@ -22,8 +22,10 @@ lib-y += kobject.o klist.o 




obj-y += bcd.o div64.o sort.o parser.o halfmd4.o debug_locks.o random32.o \

obj-y += bcd.o div64.o sort.o parser.o halfmd4.o debug_locks.o random32.o \

	 bust_spinlocks.o hexdump.o kasprintf.o bitmap.o scatterlist.o \

	 bust_spinlocks.o hexdump.o kasprintf.o bitmap.o scatterlist.o \

	 string_helpers.o gcd.o lcm.o list_sort.o uuid.o flex_array.o \

	 gcd.o lcm.o list_sort.o uuid.o flex_array.o \

	 bsearch.o find_last_bit.o find_next_bit.o llist.o memweight.o kfifo.o

	 bsearch.o find_last_bit.o find_next_bit.o llist.o memweight.o kfifo.o

obj-y += string_helpers.o

obj-$(CONFIG_TEST_STRING_HELPERS) += test-string_helpers.o

obj-y += kstrtox.o

obj-y += kstrtox.o

obj-$(CONFIG_TEST_KSTRTOX) += test-kstrtox.o

obj-$(CONFIG_TEST_KSTRTOX) += test-kstrtox.o

lib/string_helpers.c

+133 −0
Original line number Original line Diff line number Diff line
@@ -2,10 +2,12 @@ 
 * Helpers for formatting and printing strings

 * Helpers for formatting and printing strings

 *

 *

 * Copyright 31 August 2008 James Bottomley

 * Copyright 31 August 2008 James Bottomley

 * Copyright (C) 2013, Intel Corporation

 */

 */

#include <linux/kernel.h>

#include <linux/kernel.h>

#include <linux/math64.h>

#include <linux/math64.h>

#include <linux/export.h>

#include <linux/export.h>

#include <linux/ctype.h>

#include <linux/string_helpers.h>

#include <linux/string_helpers.h>





/**

/**
@@ -66,3 +68,134 @@ int string_get_size(u64 size, const enum string_size_units units, 
	return 0;

	return 0;

}

}

EXPORT_SYMBOL(string_get_size);

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;

}



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);